Nuts & Volts - April 2005

In The Trenches

Starting with calendar year 2004, we are archiving a years’ worth of issues on a CD that can be searched, printed, and easily stored.

testing is important information for the client.

New production/test machines or special training might also be needed for production. This is where you define exactly what is needed and where to get it.

For example, if the customer needs an oscilloscope for testing, you should specify the important specifications of the oscilloscope (bandwidth, etc.) and provide any manufacturers and models that may be suitable.

It should be noted that, with faster and faster time-to-market development cycles, Steps 4 and 5 are sometimes skipped. Instead of building a prototype and letting the customer examine it, the cycle jumps directly to building a production prototype. This is faster, but carries some risks. A production prototype requires more resources and may include financial commitments that are not needed for an ordinary prototype.

You’ll be able to purchase said disk from us for your own personal use and dispose of your old paper copies that are collecting dust in the garage. (Your spouse will love you for it!)

Build Production Prototypes

We will also be archiving earlier years as well, so stay tuned for their availability.

The expected shipping date is May 15th.

F o r

E l e c t r o n i c s

NUTS & VOLTS E v e r y t h i n g

With the information from the client in the Product Design Review and performance data from the prototype, a small number of production prototypes are build. The number depends upon the size and complexity of the product. Typically, it’s three to six units.

This step has two main purposes. The first is to show that the product can be built in quantity with consistent performance. With a handful of units, you can compare performance and see the variations between them. If the design or approach is poor, it simply may not be possible to produce units with repeatable performance. Talk to any production manager. He’ll have plenty of stories to tell.

The second purpose is to create some “production” units without actually having to set up a full-blown production run. These prototypes are virtually identical to the final product

in every way.

By necessity, there are very slight differences from the actual production units. This is because of the small quantity of the prototypes produced.

For example, parts may be soldered by hand instead of using a wave-solder machine, or the front panel cut-outs may be drilled at the machine shop rather than with a punch-press machine. The performance, form factor, look, and feel will be identical to the full production units, though.

There is one very important additional difference. These units generally don’t pass any quality control tests. They are handcrafted and tested for functionality, but their solder connections are not inspected, nor are the crimp connections, etc. Quite often, engineers themselves will replace parts and, while most engineers can solder adequately, few would pass quality standards.

This means that the prototypes are not suitable for selling. It is important to stress this to the client. Never sell a prototype! It’s bad business. Besides, some time in the future, someone will need a unit for something (an upgrade, revision tracing, or testing). Use the prototypes for that.

The drawing package ( documentation) is also assembled at this stage. Note that I say “ assembled” rather than “generated.” This is because documentation should always be an ongoing effort. Creating everything at the end takes longer, is less accurate, and is rarely complete.

The documentation (for a typical electronic product) should include the items on the following list. Note that the list is not exhaustive and is really more of a minimum guideline. Think of what documentation you would like in order to manufacture the product and then include it.