Prototyping has become far more difficult than it was in the old days. For one thing, electronic components have gotten smaller; an IC can now be the size of a peppercorn or a grain of sand. As a result, you must take measures to illuminate, observe, and handle these tiny parts (see sidebar “Prototyping: Think small and work smart”). Making things even more difficult is the fact that many modern circuits operate at high frequencies, so you can no longer just solder wires between components; you must connect those circuits with controlled impedances using traces. Thermal management brings more challenges.

To prototype a PCB (printed-circuit board), you need lamps, tweezers, magnifiers, microscopes, and solder stations. Once you have collected this equipment, you are ready to build your prototype. Remember to take special precautions in the design and layout of analog boards, however (Reference 1).

One of the fastest ways to prototype a circuit—and one that National Semiconductor Staff Scientist and resident analog guru Bob Pease champions—is the “dead-bug” technique, so called because the finished prototype resembles an insect lying on its back with its legs in the air. The technique can use a solid, copper-clad board as a ground plane. You solder the ground pins of the ICs directly to the plane and wire together the other components above the plane. Because the circuit nodes are suspended in the air—hence, the technique’s other nickname, “air-ball” prototyping—the stray capacitance is lower than it would be if the nodes were on a board. The disadvantage of this approach is that it makes it difficult to wire together fast circuits with controlled impedances, although you can use twisted-pair and coaxial cable to connect the parts. For tiny IC packages, you can use a converter board from Digi-Key, Mouser, Newark, Allied, Jameco, or another distributor (Figure 1). Although Pease’s counterpart at Linear Technology, Jim Williams, sometimes uses the dead-bug technique, he prefers to use copper-clad PCB material, cutting off the copper with an X-Acto knife to make the connections.

Another prototyping method is to use perforated Vectorbord, which Vector Electronics introduced decades ago. Start with a perforated board with solder pads (Figure 2) or with both solder pads and plated-through holes. Although this material costs hundreds of dollars per sheet, it allows you to make solid solder joints that can withstand a lot of mechanical stress.

A more traditional prototyping technique, wire wrapping, works well for digital designs; you can employ it for analog designs only if there are no fast signals on the board. With the technique, a process that Cooper Hand Tools developed (Figure 3), you need to be aware of undershoot problems on the clock. In one case, an engineer spent two weeks trying to figure out why his Z80 processor wouldn’t work. He found that the wire-wrapped board had caused 10% undershoot in his design’s 4-MHz clock. To fix the problem, he placed a 33Ω resistor in series with the clock circuit to damp out the undershoot. For moderately sized boards, it is worth buying an electric or a manual squeeze-wrap tool rather than spinning the wraps on with a cheap hexagonal barrel tool. You place the unwrapped side of the barrel tool into a drill and use it to unwrap a large number of pins.

Note that, as with all things analog, no one method always works; you may have to combine techniques to get a working design. For example, you might combine sections of copper-clad wiring with areas of dead-bug wiring along with premade demo boards and wire-wrapped areas. You need not use any of these techniques if you can obtain a demo PCB from an IC manufacturer or a reference design from a distributor, such as Avnet.

If the board has more than a dozen traces, you cannot carve it into copper-clad material. However, copper-clad boards with preapplied photoresist are available from many companies. With photoresist, a light-sensitive material for forming a patterned coating on a surface, you can make films for building two-sided PCBs. The only other tools you need are a darkroom and a laser printer. Be sure to flip the image in your computer so that when you place the art over the photoresist, the laser-toner side presses directly against the photoresist; this approach produces crisper lines. Many companies, including Injectorall, offer both precoated boards and photoresist that you apply to boards yourself.

Another method of prototyping requires no photoresist. You use a laser printer to apply the artwork toner to a special plastic film and press the toner side of this film to a copper-clad board. This toner-transfer method requires heat from an iron or a hot plate; the heat from this equipment transfers the toner on the plastic-film artwork to the board. You can rub a ferric-chloride-soaked sponge over the copper to etch off the exposed copper adhering to the board—a faster copper-removal method than agitated tanks can achieve.

The inventor of this rubbing process, Frank Miller, founder of PCB-fabrication-supply company Pulsar, also added a step to the photoresist process in which a second transfer seals the material. “The key is a hot-roller laminator and the second application of TRF [toner-reactive foil], which adds strength to the toner and allows for direct rub in the etch process,” says Wayne Yamaguchi, owner of Yamaguchi Consulting and a proponent of Miller’s method. “The etch time with direct rubbing is now a minute or two.”

Proving out the protoype

Making boards with CAD (computer-aided-design) files proves the validity of your files early in the design process, so fewer problems emerge when your circuit enters production. The toner-transfer method requires etching and hand drilling. You can also use milling techniques to make your board. LPKF, for example, produces mills such as the one in Figure 4 that can prove out your Gerber and drill files. Prices for the device start at $11,900, including software that converts conventional Gerber files into milling-machine-tool paths that isolate the traces from each other. Running the mill tool through those parts of your board with 100-mil (0.001-in.) spacing between traces reduces those spaces to 10 mils. For RF designs in which the shape and proximity of the copper are important, you can set the mill software to precisely replicate the trace isolations. In this mode, the mill operates in raster fashion—systematically sampling a grid pattern of pixel spaces to represent an overall image—over any large areas of copper that the mill removes. This process takes longer than it does to simply isolate the nets from each other in one pass.

The mill can in a matter of hours put a complex prototype into your hands. Using a mill, you make further cuts until a trace achieves the proper impedance. Note, however, that drilling between the layers cannot make a via connection; you must solder a small wire in the via’s holes to achieve connectivity. LPKF offers a package that fills the vias with conductive epoxy and supplies small plating tanks for creating multilayer boards. Find out whether your employer requires vent hoods or hazardous-materials handling of these materials. If your company requires a million-dollar facilities investment for a small plating tank, you will need to deal with the conductive epoxy or soldering wires in the vias.

Into the boarding house

After you use some or many of these prototype techniques, a board will eventually emerge. Using dead-bug components and X-Acto knives on copper-clad materials provides proof-of-concept checks. If you need to make a product, however, you are almost always better off starting a board design in your CAD package rather than soldering components together without documentation. John Massa, consultant at Datadog Systems, points out that, in his 47 years of experience, every project has always come down to the PCB layout and prototyping. “There is rarely a downside to paying for quick-turnaround boards,” he says. “You always end up with a better product.” Your job is not just to get the circuit working but also to provide a documentation package to manufacturing—whether that manufacturer is your own company or a contract manufacturer in China. Toner-transfer prototypes check out your Gerber files but not your drill files. Milling machines prove out your drill files but do not replicate the silk-screen process. Mills have trouble with micro-SMD (surface-mount-device) packages and other CSPs (chip-scale packages). To make a usable board, you must have a perfectly set up mill that is in good condition.

All these constraints make a good case for sending your board design to a PCB-fabrication house (Figure 5). PCB fabrication has in 10 years gone from taking weeks and thousands of dollars to taking 24 hours and hundreds of dollars. Dozens of reputable PCB shops can in a few days turn your CAD files into a board. However, a few companies stand out in their efforts to serve engineers. One that does, Sierra Proto Express, makes two or three boards from your files, delivers them in a few days, and charges less than $200. According to Sierra’s owner, Ken Bahl, a need for fast-turnaround prototypes emerged in the early 1990s. By 1996, the managers at PCB-fabrication house Advanced Circuits also realized the benefits of quick-turnaround prototypes. Another pioneer, Sunstone Circuits, had previously been the exclusive board producer for Tektronix. These companies can all provide two-layer boards in a day, as well as multilayer boards in a few days, but each emphasizes a different aspect of the prototype service.

Advanced Circuits touts on-time delivery. “We maintain redundant machinery for the entire process,” says Larry McQuinn, vice president of sales and marketing. “If one machine breaks, we can still get you your order on time.” Advanced also provides online, real-time DRC (design-rule checking). You can upload your files to a server, and, within hours, you will receive a report detailing shortages or manufacturing problems. This approach prevents your losing a day or more when the fab house finds a problem and has to halt work while you make a change. Advanced also offers the free PCB Artist layout tool, which creates all the files you need for single-layer and multilayer boards.

Sierra Proto Express has taken another tack: extending the technology in its prototype boards (Figure 6). The company can routinely produce boards with lines as narrow as 3 mils. The company also takes on jobs with 2-mil lines and spaces, buried and blind vias, and laser drilling that allows the buried and blind vias to reside on arbitrary and overlapping layers. Although the company provides copper layers as thick as 6 oz, sensible engineers know that they can’t expect 2-mil spacing and 6-oz-thick copper on the same board. Sierra can also provide 62-mil-thick, 14-layer boards and thicker boards with as many as 30 layers. Features can include 1-mil-diameter test pads and state-of-the-art finishes and laminates.

Sunstone is also far from being a bare-bones single-layer-fab shop. The company offers quick-turnaround prototypes and the free PCB123 CAD tool. The company has also developed DFM (design-for-manufacturing) plug-ins for popular layout packages, such as Altium’s Designer and Cadsoft’s Eagle, that you can set for the appropriate Sunstone design rules. These packages flag any mistakes you make as you are designing the board. Sunstone also works with Screaming Circuits to assemble your board. The company’s CAD package can do price checks from Digi-Key, and Sunstone can save shipping and logistics by overseeing the assembly of your boards.

Although these three US companies meet all local, state, and federal standards for pollution control, you can also find responsible PCB fabrication offshore, such as from PCB-Pool, an Irish company that has been making prototype boards since 1994. The company charges by the panel and does not charge for routing, so if you have many small boards requiring routing, PCB-Pool is a good option. The company does charge for the silk-screening and solder-masking options, but the prices are competitive.

On to assembly

Now that you have a prototype board, you must assemble it or contract with an assembly house to do so (see sidebar “PCB assembly: home-brew or send out?”). During your career, you should endeavor to send out at least one prototype board to a fab and have a contract manufacturer build it. The experience you gain will help you understand the vicissitudes and exigencies of manufacturing. The fab houses are ready to help, even if you drew your design on a cocktail napkin, and you will be able to lower design costs because you have an understanding of the manufacturing process. “Having a good board shop is part of your being an innovative company,” says Amit Bahl, director of marketing for Sierra Proto Express. Even if you have four months to make a prototype, it is well worth it to have a fab house provide a three-day turnaround on your boards. In that way, your marketing and sales organization will have time to review the product and perhaps get one of your prototypes into the hands of a customer. You will then have the opportunity to make improvements and produce a better version of that board in less than a week. By the time the product comes out, you will have a solid design that does even more than your customer expected. As your competitors are trying to catch up, you can be moving to lower cost or improved performance, staying ahead of the pack all the while.

Reference



Analog Breadboarding,” Analog Devices.





Prototyping: think small and work smart

No matter whether you are soldering, testing, or just tryingto get a part out of a reel, you need to be able to see the tiny part.First, make sure that you have an abundance of light in your work area.Electronic-ballast lighting provides good general illumination at areasonable electricity cost. You might also want a halogen spot lamp orcompact fluorescent bulbs in a reflector fixture for illuminating yourwork area. Articulated lamps that mount on your bench are equally useful(Figure A), and several flashlights of different sizes also come in handy (Figure B).You often must look into an enclosure as you troubleshoot, and a smallflashlight lets you clearly see the interior. Flashlights that mount toeyeglass frames are also available, as are the more traditional doctor'slight that you wear on your head. These hands-free lamps can beespecially useful if you need to crawl under some equipment totroubleshoot your prototype.

Once you have enough light on yoursubject, you need to magnify it. Although magnifiers are great forchecking details and reading part numbers (Figure C), you need a microscope to solder parts onto a board (Figure D).Olympus, Nikon, and Leica offer good working models. Microscopes fromWild are of the highest quality but are available only used and from oldstock. For those on a budget, Motic offers microscopes that have thelook and feel of a Wild microscope at a fraction of the price. For eventighter budgets, you can find any of these stereomicroscopes, includingolder models from Bausch & Lomb and American Optical, on eBay. Youshould ensure that the microscope has optics that provide a long visualreach, so the objective lens can be 5 in. or more from the work. Thisfeature allows you to work with soldering irons, scope probes, andX-Acto knives while looking at the board.

Eyepieces should offer amaximum of 10× magnification, and a zoom of 4× is more than adequate. Azoom of 20× offers too much magnification and will require you toconstantly move the board to see what you are soldering. You can fit theMotic microscopes with an optional 0.5× objective to reduce the zoomlevel by 50%. Lower-powered inspection, or assembly, microscopes allow agood working distance between the objective and the work piece. You canilluminate the area under the microscope with a gooseneck fiberilluminator or a ring lamp around the objective lens (Figure E).If you find it difficult to work with your face touching an eyepiece,you might consider Vision Engineering's patented Dynascope or Mantismicroscope (Figure F).By rotating a lenticular mirror inside the viewing head, the Dynascopeprovides a stereo image through a screen 10 in. away from your face.This technology does not come cheap, however; even on eBay, newer modelssell for approximately $2500. Vision Engineering sells the smallerMantis Compact model for $1625 on its Web site.

Once you haveenough light and a microscope to see your prototypes, you still needtools to handle the small boards and parts. A thorough examination ofthe prototyping section of Digi-Key, Newark, Mouser, Jameco, or Alliedcatalogs should give you an idea of the selection of tweezers, tinyscrewdrivers, and other tools you will need (Figure G).Spend as much as you can reasonably afford: a $25 pair of Swisstweezers is preferable to a $5 pair that will bend, warp, and not closeproperly. You can use air-suction tools to handle prototypes, but a viseto hold the board or assembly is more important. Panavise, a leader inthis area, offers a variety of vises, including models that can hold aPCB (printed-circuit board) by the edges (Figure H).One problem with conventional Panavise vises is that applying asoldering iron to the board can melt the vise's polypropylene jaws. Toaddress this problem, Panavise offers Teflon jaws for its vises. Someengineers are blasé about antistatic procedures, but this attitude maybe a result of where they live and work. Those in humid climates maywork for years without an ESD (electrostatic-discharge)-induced failure,whereas someone in Michigan on a dry winter day could destroy everycircuit he touches.

You also have to store your prototype parts in an organized and orderly fashion (Figure I).Think of your bench as a small manufacturing operation for the board.Use the BOM (bill-of-materials) list that comes with your CAD(computer-aided-design) package to print a series of labels. You canthen apply these labels to the bins of a parts cabinet. This organizedinventory eases board assembly, and you can give the cabinet to acontract manufacturer for a handmade production run of boards. It isalso useful for scenarios in which you accidentally damage a part: Youknow exactly where to get the spare. If you are away from your office,you can explain to a technician or another co-worker exactly were theparts are for your board.

Soldering your prototype is your nextproblem. You might want to consider soldering irons from Metcal. Thecompany's irons include a base unit that supplies RF energy to the tip,which absorbs the RF and turns it into heat. When the compound coveringthe tip reaches its curie point—the temperature above which it loses itscharacteristic ferromagnetic ability—it stops absorbing RF energy,controlling the soldering iron tip's temperature. The infinite number oftemperature-control loops provide better thermal-energy transfer downto the joint. This thermal energy travels to the pad and lead throughthe tip's shank and length.

“Look for soldering systems withshanks and tips that are short and fat,” says Joe Curcio,field-application engineer at National Semiconductor, who used to workin technical marketing at Metcal. “This [type] provides the best thermalpathway to deliver heat to the joint.” This principle is always valid,whether in tools for which RF supplies the heat, as in a Metcalsoldering tool, or in conventional resistance-heated tips. In 2005,Curcio found that the Weller Silver series gave the best performance.Wayne Yamaguchi, owner of Yamaguchi Consulting, prefers a tool from JBC.Techni-Tool and Howard Electronic Instruments also distribute JBCirons. This type of tool is expensive, though: A complete kit, includinga control unit, a 50W handpiece, microminiature tweezers fordesoldering, and stands and cartridges, costs $1200 on HowardElectronic's Web site, for example.

Another valuable weapon in your arsenal of soldering technology is a hot-air iron, such as those from Hakko (Figure J).This type of iron is similar to a heat gun, but it allows you tocarefully control the temperature and flow; scores of replaceable metalnozzles ensure that the heat goes where you want it. For solder-bumpparts, such as SMD (surface-mount-device) packages and other CSPs(chip-scale packages), a hot-air iron may be the only way, short of afull reflow oven, to solder the part.

Small circuits requiringtight clearances in modern prototypes also require small heat-shrinktubing. For this requirement, the 250W Weller 6966C heat gun is moreuseful than the large guns, which are better suited to stripping thepaint off battleships (Figure K).

Yamaguchipoints out you don't need a $20,000 tool to do an oven-reflow process.He uses a $20 commercial toaster oven to reflow his prototypes. Thetrick is in characterizing the process for times, temperatures, andpreheats, just as a board house does.

Another challenge insoldering parts arises when you encounter die-attached paddles—the largepads in the center where heat exits the part. You typically solder thispad to a part that thermally connects to a heat sink, so it isdifficult to solder. You could use the brute-force method: Put someliquid flux on the part, use a big soldering iron, and just pour heatinto the plastic area of the part until the die-attached paddle reflows.The lower thermal conductivity of the plastic means that you willsometimes need a second iron on the bottom of the board to heat the viasthat carry the heat away from the paddle. A preferred method is to use ahot-air iron or even a heat gun on the back as well as hot air on thepart itself. Ultimately, you may have to use a hot-air-rework station,in which a small vacuum pump applies suction though a hole in the centerof the soldering-iron tip.

Unsoldering prototypes is even morechallenging than soldering. Yamaguchi reports that he has used histoaster oven to heat an entire board to the point at which all the partsfell off. For a more selective approach, engineers have long usedhand-operated “solder suckers” to draw solder from through holes. Whenyou perform this job correctly, you'll draw virtually all the solderfrom the hole. You then use the soldering iron to pry the lead from theside of the hole; it will pop off with a distinctive click. Once you'veloosened all the leads in this way, you can pull the part off the board.Use a Teflon nozzle on your solder sucker so that the soldering irondoes not melt the nozzle into a shapeless blob. You might want to investin a rework station, in which a small vacuum pump applies suctionthrough a hole in the center of the soldering-iron tip, for situationsrequiring a lot of unsoldering. As with a manual sucker, once the reworkstation has drawn out the solder, you use the side of the tip to popthe lead off the side of the hole.

Another valuable technique issolder wick, a copper mesh embedded with flux. You place the wick on thesolder joint and heat it with any soldering iron. The wick then drawsup the solder with capillary action. As with a solder sucker, you mustpop the lead off the inside barrel of the hole with a momentaryre-application of heat. The use of flux is also critical in reworksituations. The flux not only cleans the joint but also provides theprimary method of transferring heat to the solder. If you fail to removeall the solder, you may need to resolder the joint or fill it withliquid flux. This approach allows the joint to fully melt and likelyremove all the solder on your second try. You can obtain both liquidflux and flux encased in felt-tipped pens from distributors' catalogs.Although the Internet offers a wealth of information, diligent engineersmay want to flip though the paper catalog just to see what parts andtools others are using.

You can unsolder surface-mounts part byeither applying heat sufficient to elevate the entire part and its leadsto the melting point or using two irons—one on each pad of resistors,capacitors, and diodes. Metcal's Talon soldering tweezers provide a moreconvenient approach, however (Figure L).The device features two heated tips, so you can use it tosimultaneously heat both solder pads. Some engineers use the tweezersnot only to grip but also to place components on the board. Using theTalon for placement requires a deft touch, however; you must be carefulnot to draw the part off the pads or “tombstone” the component—that is,make it stand upright on one pad.

Reworking a BGA(ball-grid-array)-type package is more challenging. Getting the BGA offthe board is straightforward enough; you can use a hot-air iron or even aheat gun to remove the BGA from the board. Resoldering a new part ontothe board is difficult, however. Spreading a uniform layer of solderpaste requires using a stainless-steel stencil with holes that match thelocations of the BGA pads. You use a squeegee to drag the paste overthe stencil, applying a precise and repeatable amount of solder paste.The next problem is alignment. When you lay out the board, make “witnessmarks” in the copper to show you where the edges of the BGA packageare. This approach might enable you to align the part as you drop itonto the board. There is also the problem of resoldering. You need auniform method to reheat the board with a hot-air gun, a toaster oven,or some other tool.

All these problems have given rise to hot-air-rework stations (Figure M).These stations apply hot air from both the top and the bottom so thatground planes and heat-sink copper do not draw off the heat and prevent agood solder joint. The topside heat discharge is configurable withspecially made nozzles that fit the BGA. This approach prevents thesolder joints of components other than the BGA from melting.

Theshield needs some clearance around the BGA, and assembly houses expectyou to accommodate for that clearance when you design your board. They,too, need to be able to get that nozzle around the BGA when they reworkyour board. Although the heat control and profiling of thesehot-air-rework stations are important, the most critical feature is adual-image-camera system. This camera slides out between the BGA partand the board before you place the BGA on the board. The camera suppliesone image of the bottom of the BGA and another of the top of yourboard. You can then manipulate the board in the X and Y directions androtate the part on the air-suction nozzle to perfectly align the BGA tothe board. You then push the camera out of the way and start acomputer-controlled motion that brings the BGA to a point just above theboard. At that point, you turn off the vacuum, and the BGA drops a fewmils (thousandths of an inch) onto the solder paste on your board.Because you control the heat and position of the entire process, you canachieve solder-joint success on par with a pick-and-place machine andreflow oven.

PCB assembly: home-brew or send out?

No matter whether you carved a board out of copper clad,milled it with an LPKF machine, or sent it to a fab house formanufacture, you still have to assemble it. Whether you wrote your partslist on a cocktail napkin or you have a computer-generated BOM (bill ofmaterials) from your schematic tool, you can now get parts in a dayfrom all the major distributors. Be aware that if you shop for parts at asalvage yard, you may get gray-market parts that someone stole from adumpster and that have failed final testing. You may also need to makemany more prototypes or enter production, and you don't want to riskbeing unable to find a sufficient number of salvage parts. It is betterto stick with sources that sell new parts and report real-time stock.

Youshould always attempt to assemble the boards you have designed if onlyto better understand the problem areas and difficulties the design mayhave created for the contract manufacturers. Contract manufacturersreport that designers' choices during the design phase determine as muchas 80% of the cost of a product, and no amount of second-sourcing ornegotiating with vendors can appreciably lower the cost of your product.Even if your job is small, don't hesitate to call Flextronics,Aeroflex, or one of the other giant contract manufacturers (Reference A).They can steer you to a local contract-assembly house for yourprototypes. Sierra Proto Express will take over the entire design ofyour project. The company can enter the schematic and lay out,fabricate, and assemble the board—all in a couple of weeks.

Youcan use the Internet to find a small contract manufacturer in your area.A local source is always convenient for emergencies when you needsomeone to rework or assemble a board overnight. Assembly houses withgood track records include Rapid SMT Assembly and Naprotek. Some smallcontract manufacturers use their rework staff to hand-assemble yourboards. Others insist on at least a yard of every tape-and-reel part sothat they can run your board through their pick-and-place machine—not abad idea; it verifies the validity of your insert file that has the X-Ylocation of all the components in it. Just as you can do remote PCBfabrication and get the boards in a day, so, too, can you get boardassembly done quickly. One company is Advanced Assembly (Reference B).Another company that will handle all phases of your build is VSE.Assembly companies are realizing what circuit-board companies figuredout a decade ago. They can make good money helping engineers deliver aform, fit, and function prototype in a few days. It also gets theminvolved on the ground floor so they have a shot at high-volumemanufacturing, as well. This approach is good for everyone.

Manyengineers do not have the budget for a contract manufacturer. Study thefirst sidebar to this article and become familiar with handling andsoldering tiny components. Often there will be a technician orproduction assembler who you can put to work on assembling yourprototype. But realize he might not be so willing to work through thenight to get your prototype assembled. Just as it is good to understandwhat a board house does with your files, you should watch or assemble atleast one of your boards yourself. Doing so will give you an idea ofproblems in the manufacturability of your design, which often involvesdifficulty in rework or access to components. Understanding these issueswill allow you to lay out the next board with better results.

Ifyou do have to hand-assemble a prototype board, you may need a solderstencil. This stainless-steel sheet has holes the same shape as thesolder pads on your board. You smear solder paste on one side of thestencil, lay it on top of your board, and use a squeegee to distribute auniform paste of solder on every pad. You can then stick yourcomponents into the solder and either reflow-solder the board in an ovenor hand-solder the parts, or use a hot-air iron for BGAs and otherparts that have no exposed leads. Advanced Circuits will provide astencil for your board at a moderate additional cost.

If yourboard has BGA or LLP or other package types with no exposed lead,assembly rework and inspection will be far more difficult. Some medicaldevices require visual inspection. They cannot even use these types ofpackages. If you do have a BGA on your board, sometimes the only way toinspect it is with an X-ray machine. Ally yourself with a local assemblyhouse as soon as you can, and make sure it has an X-ray machine and allthe rework tools needed to replace every component on your board.

Ascircuit cards become more complex so, too, do the tools and techniquesneeded to prototype them. You can get a lot done in a garageenvironment, but to produce state-of-the-art boards, you will needpartnerships with fab houses, prototype assemblers, and contractmanufacturers. The sooner you try them out, the sooner you can get a legup on your competition.



References

A “2007 top 100 contract manufacturers,” EDN , Sept 27, 2007.

B Rako, Paul, “SMT assembly for engineers,” EDN , April 19, 2007.