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 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 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.