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If you are away from your office, you can explain to a technician or another co-worker exactly were the parts are for your board.Soldering your prototype is your next problem.

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.

But realize he might not be so willing to work through the night to get your prototype assembled.

Although the Internet offers a wealth of information, diligent engineers may want to flip though the paper catalog just to see what parts and tools others are using.).

Although Peases 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.) or with both solder pads and plated-through holes.

Be aware that if you shop for parts at a salvage yard, you may get gray-market parts that someone stole from a dumpster and that have failed final testing.

Using the Talon for placement requires a deft touch, however; you must be careful not to draw the part off the pads or tombstone the componentthat is, make it stand upright on one pad.Reworking a BGA (ball-grid-array)-type package is more challenging.

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.

Assembly companies are realizing what circuit-board companies figured out a decade ago.

You then use the soldering iron to pry the lead from the side of the hole; it will pop off with a distinctive click.

When the compound covering the tip reaches its curie pointthe temperature above which it loses its characteristic ferromagnetic abilityit stops absorbing RF energy, controlling the soldering iron tip’s temperature.

You might want to consider soldering irons from Metcal.

Spreading a uniform layer of solder paste requires using a stainless-steel stencil with holes that match the locations of the BGA pads.

The company has also developed DFM (design-for-manufacturing) plug-ins for popular layout packages, such as Altiums Designer and Cadsofts Eagle, that you can set for the appropriate Sunstone design rules.

The company offers quick-turnaround prototypes and the free PCB123 CAD tool.

The company’s irons include a base unit that supplies RF energy to the tip, which absorbs the RF and turns it into heat.

This type of iron is similar to a heat gun, but it allows you to carefully control the temperature and flow; scores of replaceable metal nozzles ensure that the heat goes where you want it.

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.

You will then have the opportunity to make improvements and produce a better version of that board in less than a week.

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 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.

You need a uniform method to reheat the board with a hot-air gun, a toaster oven, or some other tool.).

Dozens of reputable PCB shops can in a few days turn your CAD files into a board.

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.

There is rarely a downside to paying for quick-turnaround boards, he says.

As with a solder sucker, you must pop the lead off the inside barrel of the hole with a momentary re-application of heat.

A preferred method is to use a hot-air iron or even a heat gun on the back as well as hot air on the part itself.

Often there will be a technician or production assembler who you can put to work on assembling your prototype.

Ultimately, you may have to use a hot-air-rework station, in which a small vacuum pump applies suction though a hole in the center of the soldering-iron tip.Unsoldering prototypes is even more challenging than soldering.

This thermal energy travels to the pad and lead through the tip’s shank and length.Look for soldering systems with shanks and tips that are short and fat, says Joe Curcio, field-application engineer at National Semiconductor, who used to work in technical marketing at Metcal.

Whether you wrote your parts list on a cocktail napkin or you have a computer-generated BOM (bill of materials) from your schematic tool, you can now get parts in a day from all the major distributors.

This feature allows you to work with soldering irons, scope probes, and X-Acto knives while looking at the board.).

To make a usable board, you must have a perfectly set up mill that is in good condition.).

Another pioneer, Sunstone Circuits, had previously been the exclusive board producer for Tektronix.

Some engineers use the tweezers not only to grip but also to place components on the board.

These stations apply hot air from both the top and the bottom so that ground planes and heat-sink copper do not draw off the heat and prevent a good solder joint.

LPKF offers a package that fills the vias with conductive epoxy and supplies small plating tanks for creating multilayer boards.

He found that the wire-wrapped board had caused 10% undershoot in his designs 4-MHz clock.

Think of your bench as a small manufacturing operation for the board.

The flux not only cleans the joint but also provides the primary method of transferring heat to the solder.

You then push the camera out of the way and start a computer-controlled motion that brings the BGA to a point just above the board.

They, too, need to be able to get that nozzle around the BGA when they rework your board.

The camera supplies one image of the bottom of the BGA and another of the top of your board.

If you do have a BGA on your board, sometimes the only way to inspect it is with an X-ray machine.

However, copper-clad boards with preapplied photoresist are available from many companies.

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 can routinely produce boards with lines as narrow as 3 mils.

The device features two heated tips, so you can use it to simultaneously heat both solder pads.

Ally yourself with a local assembly house as soon as you can, and make sure it has an X-ray machine and all the rework tools needed to replace every component on your board.As circuit cards become more complex so, too, do the tools and techniques needed to prototype them.

These packages flag any mistakes you make as you are designing the board.

This approach might enable you to align the part as you drop it onto the board.

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.

Once you’ve loosened all the leads in this way, you can pull the part off the board.

Resoldering a new part onto the board is difficult, however.

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.

As with a manual sucker, once the rework station has drawn out the solder, you use the side of the tip to pop the lead off the side of the hole.Another valuable technique is solder wick, a copper mesh embedded with flux.

This principle is always valid, whether in tools for which RF supplies the heat, as in a Metcal soldering tool, or in conventional resistance-heated tips.

For a more selective approach, engineers have long used hand-operated solder suckers to draw solder from through holes.

Your job is not just to get the circuit working but also to provide a documentation package to manufacturingwhether that manufacturer is your own company or a contract manufacturer in China.

During your career, you should endeavor to send out at least one prototype board to a fab and have a contract manufacturer build it.

Use a Teflon nozzle on your solder sucker so that the soldering iron does not melt the nozzle into a shapeless blob.

Sunstone also works with Screaming Circuits to assemble your board.

When you lay out the board, make witness marks in the copper to show you where the edges of the BGA package are.

This stainless-steel sheet has holes the same shape as the solder pads on your board.

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.

Having a good board shop is part of your being an innovative company, says Amit Bahl, director of marketing for Sierra Proto Express.

For solder-bump parts, such as SMD (surface-mount-device) packages and other CSPs (chip-scale packages), a hot-air iron may be the only way, short of a full reflow oven, to solder the part.Yamaguchi points out you don’t need a $20,000 tool to do an oven-reflow process.

Yamaguchi reports that he has used his toaster oven to heat an entire board to the point at which all the parts fell off.

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.

One problem with conventional Panavise vises is that applying a soldering iron to the board can melt the vise’s polypropylene jaws.

At that point, you turn off the vacuum, and the BGA drops a few mils (thousandths of an inch) onto the solder paste on your board.

You place the wick on the solder joint and heat it with any soldering iron.

You can get a lot done in a garage environment, but to produce state-of-the-art boards, you will need partnerships with fab houses, prototype assemblers, and contract manufacturers.

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.

The lower thermal conductivity of the plastic means that you will sometimes need a second iron on the bottom of the board to heat the vias that carry the heat away from the paddle.

Although the company provides copper layers as thick as 6 oz, sensible engineers know that they cant expect 2-mil spacing and 6-oz-thick copper on the same board.

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.

You typically solder this pad to a part that thermally connects to a heat sink, so it is difficult to solder.

You could use the brute-force method: Put some liquid flux on the part, use a big soldering iron, and just pour heat into the plastic area of the part until the die-attached paddle reflows.

Sierra can also provide 62-mil-thick, 14-layer boards and thicker boards with as many as 30 layers.

Because you control the heat and position of the entire process, you can achieve solder-joint success on par with a pick-and-place machine and reflow oven.No matter whether you carved a board out of copper clad, milled it with an LPKF machine, or sent it to a fab house for manufacture, you still have to assemble it.

You smear solder paste on one side of the stencil, lay it on top of your board, and use a squeegee to distribute a uniform paste of solder on every pad.

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.After you use some or many of these prototype techniques, a board will eventually emerge.

Just as it is good to understand what a board house does with your files, you should watch or assemble at least one of your boards yourself.

This organized inventory eases board assembly, and you can give the cabinet to a contract manufacturer for a handmade production run of boards.

You can then manipulate the board in the X and Y directions and rotate the part on the air-suction nozzle to perfectly align the BGA to the board.

Many companies, including Injectorall, offer both precoated boards and photoresist that you apply to boards yourself.Another method of prototyping requires no photoresist.

This approach prevents the solder joints of components other than the BGA from melting.The shield needs some clearance around the BGA, and assembly houses expect you to accommodate for that clearance when you design your board.

The companys 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.

This camera slides out between the BGA part and the board before you place the BGA on the board.

The trick is in characterizing the process for times, temperatures, and preheats, just as a board house does.Another challenge in soldering parts arises when you encounter die-attached paddlesthe large pads in the center where heat exits the part.

You can then stick your components into the solder and either reflow-solder the board in an oven or hand-solder the parts, or use a hot-air iron for BGAs and other parts that have no exposed leads.

Understanding these issues will allow you to lay out the next board with better results.If you do have to hand-assemble a prototype board, you may need a solder stencil.

Advanced Circuits will provide a stencil for your board at a moderate additional cost.If your board has BGA or LLP or other package types with no exposed lead, assembly rework and inspection will be far more difficult.

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.

Getting the BGA off the board is straightforward enough; you can use a hot-air iron or even a heat gun to remove the BGA from the board.