Integrated Circuits Teaching Platform

Introduction

Circuit design courses form a fundamental component of almost all engineering programs around the world. Traditionally, students learn the theoretical concepts of circuits from textbooks and use some form of simulation software such as Electronics Workbench Multisim to simulate circuits. However, in a majority of the classes, the hands-on aspect ended at simulation because students were forced learn and use a completely different set of tools, implement the circuit from scratch on actual hardware. Though prototyping in hardware allows students to compare theoretical and simulation results to real-world measurements and is considered extremely valuable in teaching circuit design concepts, the disjointed toolchain from software to hardware as shown in figure 1 has presented difficulties in facilitating a viable implementation for classrooms. Until now.

Bridging the Gap Between Theory and Real-World

Professors have sought tools that help bridge the gap shown in figure 1 between simulation and prototyping because they present an opportunity to vastly enhance student’s knowledge, better preparing them for industry, where engineers prototype and deploy circuits. Through improved use of hands on learning, students electronic assembly will gain a more complete understanding of the intricacies, and fundamentals of circuits. Circuits classes predominantly focus on the design, simulation and prototyping of circuits and throughout this paper, we will explore improvements in these three areas.

In order to bridge this gap between simulation and prototyping as shown in figure 2, there is a need for a single toolchain that enables students to design and simulate circuits and provide real-world I/O integration that will help students to prototype their circuits and test them with real-world signals. Hence, the toolchain should offer professors and students the capability to simulate any circuit they design and a platform that enables them to take advantage of these design and prototype them in order to measure the actual characteristics and finally, being able to compare the performance of the actual circuits to the simulated ones.

Integrated Circuits Teaching Platform

Fortunately, with the introduction of graphical design tools such as Electronics Workbench Multisim 9 and National Instruments LabVIEW and with prototyping platforms such as NI Educational Laboratory Virtual Instrumentation Suite (ELVIS) that are equipped with an integrated suite of instruments commonly used in a laboratory, there exists such a single toolchain that provides professors and students with an integrated circuits teaching platform. With the tight integration that exists between Multisim, NI ELVIS and NI LabVIEW, it is now possible to realize a seamless platform as shown in figure 3 that enables professors and students to design and simulate their circuits in Multisim, prototype the same circuit on NI ELVIS and finally compare the simulated and prototyped circuits in NI LabVIEW.

Case Study: Resistor Network Analysis

In order to illustrate this seamless toolchain, let us use a fundamental construct in circuit design, a resistor network. We will simulate, prototype and analyze its characteristics using a single platform. At each stage of the process we will identify the key features of the tools used and explain how they seamlessly blend together.

Theory – Analysis of the Resistor Network by Hand

Figure 4a shows the resistor network of interest. The problem at hand involves determining the voltages at nodes A and B. First, let us analyze this circuit by hand as shown in figure 4b.

Schematic Capture and Simulation using Multisim

Electronics Workbench’s Multisim provides an intuitive environment for placing electrical components and wiring them together into a schematic. The circuit schematic capture tool in Multisim is built around a sophisticated industry standard SPICE simulator. Multisim provides built-in instruments which can be connected to schematic circuits in the same way they would connect to a real-world circuit. SPICE was developed at the University of California, Berkeley, and stands for “Simulation Program with Integrated Circuit Emphasis”.

Circuits are created in the Circuit Window by placing components from the Component Toolbar. Clicking on the component toolbar will open the component browser. Users can choose the family of components, and select an individual component to place on the circuit window by double-clicking on it. Once a component has been selected, it will attach itself and “ghost” the mouse cursor. Clicking again on the desired location in the schematic will place the component. New users to Multisim should use the BASIC_VIRTUAL family of components, which can be assigned any arbitrary value.

Once the components are placed, the next step is to wire components together. Wiring is simple and can be achieved by a left-click on the source terminal, and then a left-click on the destination terminal. Multisim will automatically choose the best path for the virtual wire between the two terminals. Note that figure 5 shows the resistor network from figure 4 laid out in Multisim and wired together. Notice that the power source for this circuit is from an NI ELVIS schematic. This is one of the ways in which Multisim integrates with NI ELVIS.

With the NI ELVIS Schematic, students have access to exactly the same pins that exist on a standard NI ELVIS prototyping board. Hence, students can now use the function generator or the DMM from NI ELVIS in Multisim to virtually source and measure signals. Students may also choose the traditional schematic in which case they will not have access to these features.

Virtual Prototyping using 3D Virtual NI ELVIS

Once the schematic has been simulated in Multisim, and the results are satisfactory, a prototype can be built. Since Multisim is tightly integrated with NI ELVIS and LabVIEW, students now have the opportunity to use 3D Virtual NI ELVIS to virtually prototype their circuit as shown in figure 6.

The 3D Virtual ELVIS feature in Multisim provides several advantages for students learning circuit design concepts. Since it is virtual, students do not need to have hardware and can experiment with different layouts at their home or dorm. In addition, it helps students try different circuit layouts to find the most efficient one for their circuit. Multisim provides visual feedback on whether all the components have been placed and connected correctly by turning the symbols green on the schematic. Note that if a traditional schematic is chosen, a standard 3D breadboard will be available.

Prototyping and Testing using NI ELVIS Platform

Once the layout of your circuit has been verified using the 3D virtual environment it can be built on the NI ELVIS.

NI ELVIS consists of LabVIEW virtual instruments, a multifunction data acquisition (DAQ) device, and a bench-top workstation. The combination of LabVIEW virtual instruments, a DAQ board, and prototyping workstation provides all the functionality most commonly used in laboratories worldwide in a low-cost, laboratory-friendly form-factor. Professors and students can build customized instruments to suit their application using LabVIEW. Figure 6 shows the components that make the NI ELVIS. The workstation can be customized by using different experiment boards, such as a QuanserR controls board or a FreescaleR MPU board, or in this case a solder-less breadboard.

shows the actual resistor network as wired on the NI ELVIS. Observe that the source of the variable power supply is connected to the input of the resistor network. Similarly, the circuit is referenced to the ground line of the power supply. Notice that similar to the variable power supply, connections to the other instruments such as the oscilloscope, DMM, fixed DC power supply, AM, and FM modulator lines are also available on the breadboard.

Once this circuit has been wired, \the variable power supply provided by NI ELVIS can be used to provide 12 volts (V1) as needed by the experimental circuit and measure the nodal voltages using interactive graphical software.

Verification with Real-world Signals and LabVIEW

shows a screenshot of SignalExpress, an interactive measurement tool based on LabVIEW. SignalExpress provides a step-by-step interface allowing you to perform measurements. For this circuit, the first step is to provide the 12 volts supply which can be achieved by “inserting” a step in SignalExpress

Now a probe is connected to the DMM on NI ELVIS to measure the voltage at Node A. To see the measurement, a DMM step is inserted into SignalExpress. This voltage can now be displayed on the computer, exported to an Excel file or saved for later reference.

The most important step in the laboratory procedure is to compare measurements of the actual circuit to simulations. This will help you determine where potential errors exist in your design. For example, comparisons can help reveal inadequacies in simulation models, or incorrect components values.

After comparison with the theoretical values, you can revisit your design to improve it and prepare it for deployment. When your design is complete, you can use PCB layout software such as Ultiboard to create a PCB Assembly .

Borrowed pcb prototyping system solves major test problems

A circuit board plotter originally purchased for making engineering prototypes is yielding big dividends in the test department at IS0 9001-certified semiconductor manufacturer Supertex Inc., Sunnyvale CA. Test engineers there have been borrowing from their applications engineering department a ProtoMat circuit board plotter system manufactured by LPKF Laser & Electronics to solve some of their most difficult testing problems.

Focused on DMOS, HVCMOS and BiCMOS IC products for use in computer, telecom, medical, instrumentation, defence and consumer-product industries, Supertex designs and manufactures proprietary and industry-standard ICs, and has demonstrated technological leadership in high voltage and mixed signal high voltage semiconductor products.

Supertex applications engineering brought in the plotter to produce prototype boards that are used to demonstrate the company's new high-voltage integrated circuits (ICs). The plotter is now being used to fabricate hundreds of test fixtures as well, yielding big dividends in turnaround time, lower test costs and improved accuracy of test results. The problem that test had is that unreliable test fixtures cause downtime and errors. PCB Assembly Inadequate or unreliable test fixtures had been causing major disruptions to new product introductions at Supertex due to mechanical failures and improper test results.

"We were building typical generic wire-wrap fixtures to adapt our new devices to the dozens of test stations we maintain," Frank Galica, hardware engineer-supervisor, says. "Connectors on the generic fixtures were hard to keep in alignment and always seemed to break down at the worst time, right in the middle of a crunch run."

"As our devices became more sophisticated, other parameters that are difficult to control in a wire-wrap fixture began to affect the measurements themselves," he adds. "Inconsistencies such as improper lead lengths, parasitic inductance and loosening connections forced us to repeat the tests or, at worst, gave us false results that were not caught until much later in the process. Those old fixtures were costing us time and money."

A new semiconductor device is characterized by inserting it into a test fixture that provides support circuitry for power, loads, I/O and other functions and adapts it to instrumentation for measurement of its key parameters. To ensure accurate measurements, the fixture must provide a stable, realistic environment for the device and it needs to withstand repeated insertions and removals without degrading in performance.

"Our fixtures were not keeping up with the demands of the new device technologies," Galica explains, "but we could not let the designs out of our control for pc-board fabrication, since they are proprietary and extremely sensitive."

"Moreover, we do not have the time to wait for an outside vendor to respond. So, we just kept rebuilding and redesigning the fixtures to try to minimize the problems," he adds.

The solution turned out to making custom circuit card fixtures on the spot. Scott Lynch, a Supertex applications engineer showed Galica a prototype circuit board that had just been used to win a design contract. The board had been produced on a newly-installed circuit board plotter and had performed very well in evaluation.

"When I saw the quality of the demo board, I asked Lynch to make us a test fixture board on the same plotter system," Galica says. "The results were excellent: solid performance and mechanical integrity. It was just what we needed, and it only took a couple of hours."

The plotter system downloads files directly from a CAE program and translates them into board layouts. It then automatically produces each board by drilling the through holes and milling the traces from a variety of standard copper-clad FR3, FR4 and G10 laminated materials. Boards are cut to precise sizes and tolerances and most can be produced in a few minutes.

Using the plotter to redesign several other fixtures that had been particularly troublesome resulted in similar results. The plotter provided close control over trace widths and spacing, proper routing of signal paths and optimum placement of parts. Connectors and sockets were precisely aligned and firmly attached for long, reliable lifetimes.

Best of all, the entire process resides in-house, with complete security and instantaneous turnaround. The plotter system is kept in the design lab; no chemicals are used in this process and a built-in vacuuming system keeps the area dust free.

The bottom line is improved performance on the test floor, and it is now time for a second system. Galica had several technicians trained in both CAE design and the board layout programs and they started borrowing Lynch's plotter system on a regular basis. "We have made thousands of boards in the past few years," Galica says. "Our test times are significantly shorter and downtime for broken fixtures is non-existent. We are even making custom test equipment and custom panels for our test stations. Our only problem is that we need to get another system, since demand from the test department has taken over the machine."

LPKF Laser & Electronics is a wholly owned subsidiary of publicly-traded LPKF Laser & Electronics AG of Garbsen, Germany. Founded in 1976, LPKF products target advanced circuit board prototyping and SMD stencil and high-density circuit board designs, eliminating the need for hazardous chemicals. Its MicroLine laser circuit structuring processes are transforming the design of smaller, lower cost, higher-performance products for telecommunications, computing, medical, video and measurement applications, the company says.

LPKF high precision circuit board plotters, multilayer devices and plating systems have become a standard in the industry, with more than 8,000 installations worldwide. The drilling and milling process is simple, safe and economical. High precision tools and superior mechanical design turn circuit designs into holes and traces on a card by removing material.

The ProtoMat C30 plotter provides repetition accuracy of 0.2mil and can produce traces as fine as 4mil with spacing down to 8 mil. A typical card can be produced within one to two hours for US$7 to US$10 in materials and tools.

Plotters handle most demanding RF, microwave circuits Technology breakthroughs have extended the speed, safety and convenience of mechanical pc-board prototyping to the most demanding applications, according to LPKF Laser & Electronics , Wilsonville OR. Unique pneumatic systems control the cutting process far more precisely and gently than with previous methods, making it possible for the first time to create circuits in highly sensitive PTFE (Teflon) substrates such as RT/duroid.

Track width structures as fine as 100-microns with very precise cutting channels and an accuracy of better than 0.2mil ensure the faithful reproduction of fine pitch and higher density circuits. Tool service life and geometric precision electronic assembly are also enhanced through the use of adjustable speed three-phase spindle motors that operate up to 100,000rpm.

What are the marking requirements for vehicles transporting PCBs?

Vehicles transporting either (1) > 45 kg (99.4 lbs) of liquid PCBs with a concentration >=50 ppm of PCBs or (2) one or more PCB Transformers must be marked on each end and each side of the vehicle.

What is the significance of EPA adding 40 CFR Part 761.40(k)(2) about marking PCB Transformers and PCB Large (Low or High Voltage) Capacitors?

40 CFR Part 761.40(k)(2) requires marking of all equipment containing a PCB Transformer or PCB Large (Low or High Voltage) Capacitor that electronic assembly was not marked at the time of manufacture, distribution in commerce, or removal from use. This means that if the mark falls off or otherwise disappears from a PCB Transformer or PCB Large (Low or High Voltage) Capacitor while in use, the owner/operator is responsible for making sure the equipment is remarked. Prior to this amendment, the responsibility for marking had been put solely on the manufacturer or retailer, and no responsibility for maintaining the mark had been placed on the owner/operator of the equipment.

CAUTION CONTAINS PCBs

A toxic environmental contaminant requiring special handling and disposal in accordance with U.S. Environmental Protection Agency Regulation electronic assembly 40 CFR 761 – For Disposal Information contact the nearest U.S. E.P.A. Office.

In case of accident or spill, call toll free the U.S. Coast Guard National Response Center: 800-424-8802

Are there any other labeling requirements?

Yes. In addition to applying the PCB mark to the required PCB and PCB Items, PCB wastes being stored prior to disposal must also be labeled with a notation indicating the date that the item was removed from service for disposal. If the wastes in storage include drums of PCB-contaminated soil from a remediation activity, the “date removed from service for disposal” would be the date on which the soil was excavated and placed into drums. If the wastes are liquid wastes (e.g., solvents used for flushing or decontaminating PCB Items), the “date removed from service for disposal” is defined as the date that the first batch went into the drum. If PCBs in containers or PCB Items are contaminated with hazardous wastes regulated under the authority of the Resource Conservation and Recovery Act (RCRA), they must be marked in accordance with the applicable RCRA hazardous waste marking requirements, as defined in 40 CFR Part 262, as well as with the applicable TSCA marking requirements.

Prototyping tools TRANSFORM design dreams into reality

WHO HAS THE PARTS?

When you have that pc board in hand, you’re well on your way to having a prototype

to debug and demonstrate. But there’s one serious obstacle you still have to overcome: You need to put the electronic components on the board.You can do this step in one of several ways. You can send it to an assembly house, but then you have to provide the necessary documentation, plus all your components on reels or in carefully bagged and

labeled packages. This preparation is time-consuming and again puts you at the mercy of an outside vendor (see sidebar “Can I go out now?”). Furthermore, checking your documentation and resolving placement issues become more difficult.

Alternatively, you can use a pick-andplace machine that targets low volumes, such as the Expert 5000 from Manncorp (www.manncorp-smt.com). This $8000 semiautomatic unit guides the operator via mapping software and a magnified screen image; the device shows where each part should go with placement accuracy of 0.6 mm (25 mils) as standard and 0.4 mm (16 mils) with an optional fine-pitch package. A motorized partssupply tray holds your components, and you can also use tape or stick feeders for components that you are using in quantity.

Don’t rule out the old-fashioned hand-load method, either.Using vacuum tweezers, a foot-operated solder-paste dispenser, and a wide-view 3 or 43magnifier with sufficient lighting, a careful operator can load a pc board one electronic assembly component at a time and can then solder the

board in a regular production setup.Yes, it’s laborious, and you don’t want to do it for more than a few boards, but it takes virtually no setup time, and your costs are just a few hours of labor and some basic equipment that you probably need anyway.

HAVE IT YOUR WAY

These board-producing machines offer options in addition to higher speed spindles for smaller dimensional work and automatic tool changing. These options include a vacuum unit that sucks up the debris that the cutter tool generates, a sound-reduction box that cuts the

typical 80-dB sound level at 3 ft by about 10 dB, and a high-power magnifier— typically 503—for visually checking your fine-pitch design.Consider this last item more of a necessity than a luxury, because you probably need to inspect the board and its design in a few critical areas.

Don’t think that cladding removal is the only way to go, either. In some applications, such as those in which you need special claddings other than copper or those that need a circuit built on a substrate that is unavailable with copper cladding, you may want to consider a

precision writing system (see sidebar “Don’t forget to write”).

MAKE A CASE FOR YOUR PRODUCT

When I first saw a stereolithographyapparatus (SLA) system in action at a trade show, my initial thought was how it functionally paralleled the handy “replicator” of the Star Trek series (in which the crew used the device to create— on the spot—replacement parts, food, or whatever it needed). The SLA I watched magically produced a detailed, 3-D part that matched solid-modeling engineering figures on a nearby screen. To add to the science-fiction aura, this solid rendition of the image I saw on the screen rose from a pool of liquid polymer and emerged ready to use (see sidebar “How’d they do that?”). As the finished

part rose from the pool, I had a distinct Terminator 2 flashback: The sight reminded me of the ultra-advanced,metallic, morphing cyborg who comes after Arnold Schwarzenegger in the movie.

But SLA is not science fiction. SLA and the broader area of rapid prototyping and solid freeform fabrication (SFF) are significantly changing the way that manufacturers are making mechanical parts for both prototyping and short production runs. A design team can plan its enclosure on a PC or workstation using solid-modeling software tools supplemented by special SFF application software; can see whether and electronic assembly how the board, connectors, power source, antenna, and other pieces fit; and can then have an exact prototype of the enclosure or housing in hand—complete with mounting ears, tabs, and openings for a display and keyboard.

Follow Heuristic Guidelines To Make Surface-Mount PC-Board Footprints

Guideline 5: Use a 1:1 ratio for solderstencil openings for all pins/terminal pads, except any exposed heatsink pads or other large apertures. For large apertures (3 by 3 mm and greater), shrink the periphery of the aperture by 0.25 mm to allow sufficient clearance between the large pad and surrounding pin/terminal pads, and break the large pad's aperture into multiple "window panes."

For the terminal pads, the task is automatically accomplished if the PCB-layout software is reset from the "cream" option to "on" for the terminal pads that were created. This creates a 1:1 aperture for each terminal pad's stencil layer—a value that works very well for both fine-pitch and standard-pitch leads when using a 6-mil thick stencil.

For the exposed pad polygon, however, you will need to create the pattern manually. Start by turning on both the top-copper layer (so you can see the polygon) and the stencil layer, where you will draw the corresponding aperture. Next, choose the rectangle function in your PCB-layout software, and create a set of window-pane apertures within the area of the polygon. (Make sure that you're placing these rectangles on electronic assembly the stencil layer.) Figure 5 shows the finished stencil openings for the package overlaid on the top-copper pattern.

Note how the exposed pad stencil openings are pulled away (inward) from the perimeter of the polygon, and especially from the corners. This reduces the likelihood of excess solder and resulting solder shorts.

Top Silkscreen: The top silkscreen carries the human-interface information you wish to appear on top of the PCB. This silkscreen doesn't serve any circuit function, but it is important to prototyping. It will help orient and place components during board assembly and assist in testing and debugging the prototype.

Conventionally, the silkscreen consists of the component-name layer, place layer, and value layer. The component-name layer supplies the IDs for the part on the board—for example, U1, R1, C5, and Q2. The value layer would include any associated values for the component— for example, 1k or 0.01 F. And, the place layer contains an outline and orientation for the component. We'll consider the top-place layer as the minimum requirement for the device.

Guideline 6: Use minimum 7-mil (0.007-in.) line widths for silkscreen features. Change the font type to "vector" and adjust the ratio and size as required to create readable letters and numbers.

Don't be tempted to place numbers by every pin, but do label pin 1 on SOICs. On QFN packages, it's helpful to have the silkscreen note the corner "pin" numbers. Make the top-stop layer visible while drawing on the topplace layer. Be careful not to place the silkscreen numbers/letters/lines too close to the solder-mask-stop apertures. Otherwise, the ink will bleed over into the associated depressions in the solder mask on the finished PCB.

Adjust the font's ratio and size to achieve the most readable text while maintaining the minimum line width. It's also helpful to place an outline around the part perimeter. Figure 6 shows the minimum silkscreen content for the example device, with the soldermask-stop layer shown for reference.

By closely following these steps, you can create any PCB layout package footprint you need. The result is a PCB footprint that, while not optimized for production, is robust for prototype PCB applications. In particular, the achievable goal is to substitute schematic-capture software for "napkin sketches" and quick-turn PCBs with electronic assembly solder stencils in place of hand-wired breadboards, while maintaining a rapid concept-to-labwork cycle that supports the engineer's creative process.

Sensor Mounting Techniques

Introduction

While upgrading one of my Mini-Sumo robots, I found that sensor placement and orientation can have a big impact on your final results. This article will discuss the problems I ran into, trouble-shooting, and solutions.

Time to Upgrade

Mini-Spat has competed in 6 PAReX events, as well as several demos at swap meets, high schools, and colleges. In other words, there's a lot of mileage on the little guy. During the Nov. 2003 event it died twice in competition, and in the Nov. 2004 event, there were a few times when it lost it's mind and wandered the ring aimlessly. The original circuit board was a low-profile wire-wrap board. With the extremely short wraps I was concerned about it's reliability and decided to upgrade to a PCB.

Upgrade Woes

The PCB was finished and mounted to the robot. There were no software changes made, except swapping the left and right servos, due to electronic assembly routing issues. Fired up the robot and watched it act just like it did with the old board, in other words, a robot possessed. Since the PCB seemed to be correct, and nothing else had changed, I started looking at what I had done in software, trying to figure out what went wrong.

Basic Trouble-Shooting

The basic problem was the robot was seeing things that weren't there. When Mini-Spat drops, it's suppose to move forward, then start spinning in a circle looking for the opponent. If there's nothing in range, it should just keep spinning. Most of the time it wouldn't even make one full turn before wandering off in search of a ghost. Other times it would work fine for several runs.

By inserting some breakpoints in the code, I would stop the robot when it thought it saw something, and flash the LED to tell me which sensor was acting up. Turns out the right range sensor, a Sharp GPD012, was at fault. Further investigation showed that two of the three connector pins had broken solder joints! Ahh problem solved!! A quick fix with a soldering iron and it was back on the ring, failing exactly the same way. Insert your favorite expletive here!

Digging Deeper

Well at least I found the intermittent problem. Most Mini-Sumo's don't have a display on them so it can be hard trying to figure out what's going on sometimes. I have a diag routine which can blink an LED to show me an 8-bit sensor value, but you can't use it while the robot is running. I guess the ideal interface would be a wireless link to a PC, then you could receive all kinds of data to see what's going on. Well those links aren't cheap so I fell back on the RS-232 link that I had brought over from the original board. A long 2-wire cable connects the robot to the laptop, but it's still not practical, even on the 30" ring. Since the failure was a range sensor, I did all kinds of tests without the motors running, and the sensor performed perfectly.

Ok, since this is an analog sensor, maybe the motors are generating some electrical noise and hosing things up. Putting the robot on blocks and running the motors during the tests, made no difference, the sensors worked as expected. The only thing left was to monitor the sensors while the robot was running normally. To do this without the cable attached, I would save the sensor readings to RAM, and then connect the cable and dump the data to the laptop.

I had about 250 ram locations to use and as fast as the sensors are updated, it would fill in about 38ms. So I once again set the robot to stop when it saw something and send me the last 250 readings. What I saw was quite interesting, the left sensor read a 0 or 1 the entire log. The right sensor varied from 0x20 to 0x28, before hitting my 0x2C threshold and stopping. The 0x2C is about the length of the ring, so I would "see" things in the ring, but didn't care about what laid beyond. If I did the same test with the motors  electronic assembly off I got readings just like the left sensor, nothing greater then 2. If I ran the motors on blocks, again the readings were good. I changed out the sensor and again had no changes. So the actual motion of the robot had something to do with it.

Requirement of cleaning

 

Cleaning of printed boards is required to remove flux residues and other contaminants which are left behind after soldering . Cleaning or washing of the boards prevent potential electrical failures due to electromigration. Cleaning operations does the removal of the following contaminants:

I.) Ionic contaminants

ii) Non-ionic contaminants

iii) Particulate contaminants

Fluxes that are water soluble generally produce ionic(also called polar) contaminants that require aqueous cleaning. Non-ionic(also called non-polar) electronic assembly contaminants produced by rosin fluxes require non-ionic solvents such as trichloroethane.

2. Cleaning options

Note: Rosin and Rosin Mildly Activated (RMA) fluxes need not be cleaned. However, for high reliability applications and for aesthetic reasons, it may be necessary to clean these boards.

Water soluble fluxes need to be cleaned thoroughly due to corrosive elements that are present in the flux residues, aqueous cleaning is ideal. Because rosin is not soluble in water, when aqueous cleaning is used for rosin fluxes, alkaline chemicals called saponifiers are added to the water. The efficiency of cleaning treatment is significantly increased if the cleaning is assisted by ultrasonic vibration. However, the ultrasonic vibrations are not confined to the cleaning fluid and the surfaces to be cleaned, but are also transferred into the electronic components, which may be damaged . Bonding wires, inside active components between the die and the bonding pads may break if the bonding wires are free and have not been tightly encapsulated in plastic or any other packaging material. High-power, high frequency vibration induce fracture in external leads also. The following set of parameters is generally accepted:

§ maximum frequency of 40 kHz

§ maximum time of ultrasonic load 1 to 5 minutes

§ maximum power of 10 W/ litre

§ boards in racks, so that they cannot touch each other.

In all cases, the time interval between  electronic assembly soldering and cleaning be reduced to a minimum (less than an hour) to obtain good cleaning results.

Prototyping techniques help verify analog-circuit performance

The result is a board similar to the final manufactured double-sided pc board, except that the final board lacks plated-through-hole capability, and you must wire and solder on both sides any vias between the two layers of the board. Minimum trace widths of 25 mils (1 mil=0.001 in.) and 12-mil spacing between traces are standard, although you can achieve smaller trace widths. The size of the milling bit, which is typically 10 to 12 mils, dictates the minimum spacing between lines.

An example of such a prototype board is a daughterboard that interfaces an AD9562

dual PWM board in a 44-pin PLCC package to a test-set motherboard (Figure 4). The

leads are on 50-mil centers, and the traces are approximately 25 mils wide. This board

illustrates the resolution of the milling machine, but you can use the technique to

produce more complex boards.

IC sockets can degrade the performance of high-speed or high-precision analog ICs.

Although low-profile sockets ease prototyping, even these sockets often introduce

enough parasitic capacitance and inductance to degrade circuit performance. If you must use sockets in high-speed circuits, an IC socket comprising individual pin sockets, sometimes called "cage jacks," mounted in the ground plane board may be acceptable (Figure 5). Clear the copper on both sides of the board by about 0.5 mm around each ungrounded pin socket and then solder the grounded pin sockets to ground on both sides of the board. Both capped and uncapped versions of these pin sockets are available from electronic assembly Amp (Harrisburg, PA) (part no. 5-330808-3 and 5-330808-6, respectively). The pin sockets protrude through the board far enough to allow point-to-point wiring interconnections between them.

The spring-loaded, gold-plated contacts within the pin socket make good electrical and mechanical connection to the IC pins. Multiple insertions, however, may degrade the performance of the pin socket. The uncapped versions allow the IC pins to extend from the bottom of the socket. After the prototype is functional and requires no further changes, you can solder the IC pins directly to the bottom of the socket, thereby making a permanent and rugged connection.

Special prototyping considerations

These prototyping techniques apply only to single- or double-sided pc boards. Multilayer pc boards do not easily lend themselves to standard prototyping techniques. If a design requires multilayer-board prototyping, you can use one side of a double-sided board for ground and the other side for power and signals. You can use point-to-point wiring for additional runs, which would normally exist on the additional layers a multilayer board provides. Unfortunately, it's difficult to control the impedance of the

point-to-point wiring runs. The high-frequency performance of a circuit prototyped in this manner may differ significantly from that of the final multilayer board. Other difficulties in prototyping may occur with op amps and other linear devices that have bandwidths greater than a few hundred megahertz. Variations of greater than 1 pF in parasitic capacitance between the prototype and the final board can cause subtle differences in bandwidth and settling time.

If you use DIP packages for the prototype but SOICs for the production packages, you can see differences between the performance of the prototype and the final pc board. For instance, the AD8001 current-feedback op amp (approximately 800-MHz bandwidth for G=1) is available as both an eight-pin DIP and an eight-pin SOIC.Table 1, which contains data collected with the use of an evaluation board, reflects the difference in performance between the two packages after you optimize the feedback (RG) and feed-forward (RF) resistors (Figure 6a). The resistor values in Table 1 produce the highest 0.1-dB flatness bandwidths. The SOIC package's bandwidth is higher because of lower package parasitics. All resistors and capacitors on the board are surface-mount types for low parasitics.

Evaluation boards can be extremely useful in evaluating new analog ICs; these boards let you verify the IC's performance with minimum effort and without constructing your own prototype. Evaluation boards can range from relatively simple ones, with just op amps, for example, to rather complex ones for mixed-signal ICs, such as ADCs. ADC evaluation boards often have onboard memory and DSP μPs for 6 von 8 9/25/00 4:09 PM EDN -- 02.15.96 Prototyping techniques help verify analog-circuit performance http://www.ednmag.com/reg/1996/021596/04df3.htm analyzing the ADC's performance. IC manufacturers often provide software so that these more complex boards can interface with a PC to perform complex signal analysis, such as histogram and FFT testing.

Most manufacturers of analog ICs provide evaluation boards, usually at a nominal cost. Regardless of the product, the manufacturer takes proper precautions regarding grounding, layout, and decoupling to ensure optimum device performance. The layout of the components on the evaluation board can guide both the prototype electronic assembly and the final pc-board layout. The artwork or CAD file is usually free, should you wish to copy the layout directly or change it to suit the application.

Devoted Dog Refuses To Leave Owners Gravesite

An amazingly devoted, and likely very heartbroken, dog refused to leave the gravesite of his beloved master, Lao Pan, who died earlier this month in the Chinese village of Panjiatun. The sweet little yellow mutt has been so dedicated to electronic assembly his vigil that he went an entire week with out food or water at the desolate site before concerned locals persuaded him to eat some food.

Local villagers have been so moved by his dedication that they have been bringing food and water to the dog at the gravesite, and are even electronic assembly planning to build a kennel there for the dog to sleep in.

Dog Shoots Hapless Duck Hunter in Buttocks

Animal attacks are a reality of life, but a sharp-shooting hound has taken his role as a gun dog to a whole new level.

A Brigham City, Utah man is now the butt of jokes everywhere thanks to his dog. The unnamed man and a friend were duck hunting last Sunday when the man got out of the boat and laid his 12-gauge shotgun across the bow of the electronic assembly boat in the process. Upon exiting the boat, his hound inside the vessel jumped up on the bow and (accidentally?) stepped on the gun which then fired, discharging 27 pellets into the 46-year old man's buttocks. Um, ouch.

Doctors at a nearby hospital dislodged the pellets from the 46-year-old man's posterior, according to the Associated Press. Box Elder County Sheriff’s Deputy Kevin Potter has indicated that the man stood about 10 feet from his hound when he got hit and said he wasn't seriously injured perhaps because he wore waders or ......because his posterior provided more than enough additional padding to cushion the blow?

The breed of the dog who shot the man is unknown as of this writing. It is also unclear as to whether the dog was working in collaboration with, or on electronic assembly behalf of Utah-area ducks.

All-In-One Environment Serves PCB/System Designers

Version 6.3 of the Altium Designer environment is targeted directly at those looking to migrate from competing PCB design systems, including OrCAD and PADS. Altium Design 6.3 includes a number of enhancements to entice a switch, as well as features that accelerate design for current users.

Users of legacy point-tools will benefit in general from Altium Designer's system orientation, which includes full FPGA development capabilities as well as PCB design capabilities. The unified development environment is intended to allow users to make the transition from “board designer” or “embedded designer” to “systems designer.”

But what makes Altium Designer work so well for OrCAD or PADS PCB users? For one, there's a new PADS library importer, electronic assembly which enables users to seamlessly import PADS footprint libraries to Altium Designer. It'll import ASCII library files from PADS versions up to PADS PowerPCB 2005. For the OrCAD side, Altium's existing OrCAD importer has been enhanced in v6.3 to support OrCAD design components that include simulation data. This includes both simulation-ready schematics and schematic libraries.

There's also a unified PADS/OrCAD importer that creates integrated libraries from a combination of OrCAD schematic symbols and PADS footprints (patterns). This importer also includes a wizard that supports the importing of OrCAD schematics and PADS PCB documents into a single Altium Designer project in one operation.

Existing Altium Designer users who install v6.3 will see a significant boost in graphics performance for the PCB editor. This comes by way of a new hardware-accelerated graphics engine that makes use of Microsoft's latest DirectX technologies. Users can expect speed increases of around 20X when zooming and panning, making the redraw PCB Assembly speed on design documents virtually instantaneous. It also brings native support for 3D rendering directly in the PCB editor, which enables “real-time” design visualization.

When/Where/Will PCB Technology Hit a Plateau?

Within one of the presentations last week at the IPC Technology Interchange in Washington D.C., the question was raised of whether printed circuit board technology will reach a plateau or whether it will continue to keep pace with the technological demands and innovations to come.  Restated, the question could be:  as trace widths get smaller, nanotechnology improves, PCB Assembly and demand for greater performance continues to increase – when/where/will PCB technology hit a plateau?

This is a complex question with a large number of factors.  One focus of the discussion could be on the pure technical limitations which will be reached according to the laws of physics, or you may consider the unlikelihood that we will ever meet a need that PCB’s can’t handle due to the high costs which would surround that new technology.

I hope to hear your input and comments.  Where do you see the technology going and needing to innovate?  How do you see system-in-a-package and 3D Integration being a factor?  I don’t even have all of the appropriate questions surrounding this topic, but I hope that the comments below will be full of electronic assembly insight and discussion.

PCB Atlanta Social Media Presentation

Last week I had the valuable opportunity to speak at the PCB Assembly Atlanta show put on by UP Media in Alpharetta, GA.  The show is designed to serve professionals within the PCB industry by offering technical seminars for further education and by allowing pertinent companies to exhibit in a table-top format.  The show went very well, and I will be writing more about my experience there in the coming few days.

Below is the media portion of my presentation.  It gives a very general electronic assembly outline of the topics I covered and the order.  If you are interested in learning more about the specifics of the presentation, or are interested in discussing how social media and web 2.0 technology might benefit you or your company, please do not hesitate to get in touch with me.  My contact information is found in the Author Bio’s and Tweets section.

Speaking Engagement at PCB Atlanta

I have been blessed with the opportunity to speak during the afternoon sessions at PCB Assembly Atlanta on October 22.  UP Media has always been very kind to us and have now provided me with this opportunity.

The seminar I will be teaching will be on the topic of marketing yourself using the social media and online tools that are currently available online.  Below is the abstract I submitted when I approached them with the idea.

Are you trying to find a way to stand out among the crowd?  The field of marketing and advertising continues to rapidly change as more and more attention shifts toward Social Media and Online marketing techniques.  A new generation of decision makers and customers who have grown up with these tools is close at hand.  In order to remain current and successful, it is crucial that you have, at the least, a basic understanding of the tools being used.

The Online and Social Media Marketing workshop will give an overview of various online tools and services currently available to help you market yourself and drive business.  You will learn how and where to network with potential customers and ways to develop a strong presence on the web.  Whether you are a novice user, or consider yourself proficient, this workshop is designed to help you develop a comprehensive personal online marketing plan.  Topics covered will include: how to take full advantage of the top social networking sites, making sure you can be found easily online, and creating a pull-marketing campaign.

Do you plan on attending the show?  If you haven’t thought about it, you should.  I do believe that it will be very electronic assembly beneficial to you.  I won’t be as forward as to recommend that you attend the session I will be leading, however, it should be a good time.

If you’re going and you plan on attending this, please feel free to get in touch with me or to comment below with questions you have.  I want to make sure that I address the questions and needs of the people who attend.  Getting your feedback and a feel for your questions beforehand will help me to prepare and provide a more comprehensive and applicable presentation.

Avanti Circuits is Offering Existing Customers a $500 Credit on Future Orders of Printed Circuit Board Products for Referring Any

Printed circuit board manufacturer, Avanti Circuits, based in Phoenix, has recently introduced a new promotion where existing customers electronic assembly will get $500 off all their future orders for introducing any new customer to Avanti. A move like this comes as no surprise really, as Avanti Circuits have been building up a strong customer base for many years now with a variety of unique promotions and they have developed a reputation for the delivery of high quality printed circuit board products that is second to none in the industry today.

Avanti CEO, Jim Keaton, said, “Avanti has recently expanded its promotions department and there are a number of ideas that we are developing at the moment. After talking to a number of our customers we found that our service levels were so good that we had many customers actively promoting us in the printed circuit board industry PCB Assembly as a printed circuit board manufacturer of choice. What we have decided to do with our $500 dollar credit is to say thank you to our customers and to sweeten the deal so to speak. After further talks with our customers we are getting wonderful feedback from our new policy and I am glad to say that we believe our increase in sales is a positive reflection of this new direction."

If market reaction is anything to go by, this new policy is certainly having a big impact with other companies that are also involved in the printed circuit board manufacturing industry. There have been many reports in related industry publications of other companies in a similar line of business to Avanti introducing similar deals for their customers. It looks like Avanti are not only leaders in printed circuit board technology, but have also taken the lead when it comes to new and original ways to develop and market their business.

Many customers of Avanti feel that given the high regard in which this company is held in the printed circuit board industry, their business would be thriving even if they had decided against this promotion.

Having Trouble Refinancing Your Home Mortgage Loan?

As a mortgage broker in San Francisco California, can be an invaluable resource to you if you are seeking commercial loans or super jumbo mortgage loans. Foremost, the best benefit that you will receive when working with us is that you are able to have your funding request reviewed by several different lenders. We work with an electronic assembly expansive database of wholesale lenders. We also have access to private investors if you do not qualify for traditional financing. We have over 11 years home loan and commercial loan experience. We do home mortgage residential loans in California, Colorado, Nevada, Oregon and Washington and commercial loans in all 50 states. Unlike all lenders and banks, we don’t charge any origination points. No points! Zero points!

There are many unscrupulous commercial loan brokers that are primarily seeking to have you pay large upfront fees without ever delivering on their promise to assist you in securing a commercial loan. We don’t charge any upfront fees. By working with a very experienced commercial loan broker like www.mortgagequeen.us you are in an excellent position to receive the commercial loan that you need.

Have you ever wondered how people purchase those million dollar homes? Although many put down substantial down payments, PCB Assembly most finance a mortgage just like the rest of us. These highly priced mortgages are known as Jumbo and Super Jumbo Loans. We can do Super Jumbo Loans up to 10 Million.

Hole for One Foot in the Grave dvd

This mechanism is shown right side up; the disc would sit on top of it. The laser and optical system scans the underside of the disc.

With reference to the photo, just to the right of image center is the disc spin motor, a gray cylinder, with its gray centering hub and black resilient drive ring on top. A clamp not in the photo, retained in the drive’s cover, pulled down by a magnet, clamps the Rome dvd disc when this mechanism rises, after the disc tray stops moving inward. This motor has an external rotor – every visible part of it spins.The gray metal chassis is shock-mounted at its four corners to reduce sensitivity to external shocks, and to reduce drive noise when running fast. The soft shock mount grommets are just below the brass-colored washers at the four corners the left one is obscured. Running through those grommets are screws to fasten them to the black plastic frame that’s underneath.

criminal minds dvd

Two parallel precision guide rods that run between upper left and lower right in the photo carry the sled, the moving optical read-write head. As shown, this “sled” is close to, or at the position where it reads or writes at the edge of the disc.A dark gray disc with two holes on opposite sides has a blue lens surrounded by silver-colored metal. This PCB Assembly is the lens that’s closest to the disc; it serves to both read and write by focusing the laser light to a very small spot. It is likely that this disc rotates half a turn to position a different set of optics the other hole for One Foot in the Grave dvd.

Under the disc is an ingenious actuator comprising permanent magnets and coils that move the lens up and down to maintain focus on the data layer. As well, the actuator moves the lens slightly toward and away from the spin-motor spindle to keep the spot on track. Both focus and tracking are relatively quite fast and very precise. The same actuator rotates the lens mount half a turn as described.

However, unlike previous format changes, audio tape to Compact Disc or VHS videotape to So You Think You Can Dance dvd, there is no immediate indication that production of the standard DVD will gradually wind down, as they still dominate, with around 75% of video sales and approximately one billion DVD player sales worldwide as of 3 April 2011. In fact, experts claim that the DVD will remain the dominant medium for at least another five years as Blu-ray technology is still in its introductory phase, write and read speeds being poor as well as the fact of necessary hardware being expensive and not readily available.

To select tracks or files as well as advancing the sled during continuous read or write operations, a stepping motor rotates a coarse-pitch leadscrew to move the sled throughout its total travel range. The motor, itself, is the gray cylinder just to the left of the most-distant shock mount; its shaft is parallel to the support rods. The leadscrew, itself, is the rod with evenly-spaced darker details; these are the helical groove that engages a pin on the sled.Durability of DVDs is measured by how long the data may be read from the disc, assuming compatible devices exist that can read it: that is the oc dvd, how long the disc can be electronic assembly stored until data is lost. Five factors affect durability: sealing method, reflective layer, organic dye makeup, where it was manufactured, and storage practices.

The irregular orange material is flexible etched copper foil supported by thin sheet plastic; these are “flexible printed circuits” that connect everything to the electronics which is not shown.

Fine Electronic Assembly, Inc

Above table reports Labor Condition Application(LCA) and Labor Certification(LC) filed by Fine electronic assembly, Inc for H1B Visa and Green Card. The data only indicates the number of applications filed by Fine Electronic Assembly, Inc. It does not mean that Fine Electronic Assembly, Inc actually got the visa and hired the workers.

Labor Condition Application(LCA) is different from Labor Certification(LC). LC is for employment based green card while LCA is for H1B visa. Our LCA data not only includes those filed for new h1b visa applications, but also those for H1B Visa tranfers and renews.

Fine Electronic Assembly, Inc has applied for 17 LC and LCA since 2001. But this does not mean they really hired 17 foreign workers during this period. The visa application might have been denied. When an employee renews or transfers his H1B Visa or change work location under some circumstances, he will also file a new LCA application. Department of Labor(DOL) typically certifies more than 3 times the number of foreign work requests than the number of H-1B visas issued by USCIS. So there is no one to one relationship between the number of workers certified by the DOL and the number of H1B work visas issued by the United States Citizenship and Immigration Services (USCIS).

Electronic Assembly Work at Home - How to Get Started

After this, they are willing to send something for applicants to collect, with the promise that applicants will be hired and entitled to high salary if the electronic assembly work finished meets their standards. Now, no one ever matches their standards. The difference between genuine and malicious assembly companies lies on one, thin thread: legitimate corporations really respond and spend. This is perhaps one of the many universal problems of work at home jobs, the security of which employers will really provide you with compensation. In order in order to assess whether an Electronic assembly job is legal or simply not, it is beneficial to consult online employment forums that delivers tips, clues, and discussions on most beneficial online career opportunities available on-line. .Everything today is engineered in a manner that most of us desire a laptop or a desktop to survive and gaze after relevant. Not having one means reviewing the world pass an individual by; and you're positioned wondering what happened. Its the information age and thankfully Singapore has kept abreast of such technological milestones and seems to have its fingers firmly relating to the pulse. Whether for online business or entertainment, education or perhaps plain informational value, there's a lot of electronic stores out that can be found for you to stop by at fulfill your needs. Stores want Harvey Normal, Courts have dedicated home pc and electronic sections which happen to have a whole host with brands and models. From computers to desktop gadgets, there is always something for everyone and therefore the price ranges will fit virtually any budget. The best thing related to these electronic stores is the actual fact that they have an installment policy with reasonable interest rates - or f you've got a credit card, you will enjoy either a 1 -2 year installment plan that's risk and interest free of cost. You might get flooded by using a sea of information here however are neatly displayed using perks and features emboldened by both text and a smiling, and ever waiting sales staff - able to speak to you and additionally fill you in at the details left out. If you wish the more colloquial no frills shopping experience, Least expensive taking a quick trip as a result of Sim Lim Square and turn into amazed at the 6 grounds of Singapore electronic stores which sell handheld computer devices, desktop computers and the entire host of electronic paraphernalia from cameras, digital video recording devices, mp3 competitors, latest computer tech perhaps even cables and pins in a thousand different models. It is typically quite daunting as you could possibly notice that once shop seems suspiciously identical for the other but indeed, this will charm of such a place. Sellers are bold and usually get to the level, with bargaining not being unthinkable if you know towards you around the market area. This place is constantly extremely crowded, even in the early mornings of weekly day so time by yourself right. You should go in knowing what you dream about to buy and what your capacity to pay is, or you will end up being easily distracted by vivid things you don't will need that seem to fall into your credit card costs.