Good way to affordably manufacture low-quantity PCB?

Question

I am thinking about making an open-source development board for a specific field in power conversion.

If there is interest from local universities, I will manufacture a few hundreds of these boards. Is it better to engage a manufacturer or buy a small pick-n-place machine?

EDIT: It is assumed that the PCBs will be sourced out. The number of components should fall in the <20, 50> range. The DSC/MCU could have ~200 pins, TQFP package.

EDIT2: The answers so far indicate that it is very costly and time demanding to make PCBs at home. But what is the approximate cost to get the minimum viable production line for a few hundred boards? To get done ~20 per hour (e.g. 2" by 4").

Answer 1

This is a no-brainer. There is absolutely no way that the cost of a pick and place machine spread over a few 100 boards will be cheaper than getting the boards assembled by a contract manufacturer. And, a pick and place machine is only one part of the assembly process. Are you going to get a reflow oven, inspection station, etc, etc, too?

Added

As Scott Seidman mentioned in a comment, you have to think about testing whenever you have someone else build your boards. If you don't give the assembler a way of testing the finished board, then they could ship you 100 units that all don't work and you'd have no recourse. The assembler won't like that either since they have no way to find problems with their process and fix them, hopefully without anyone outside ever finding out.

What I usually do is build three test jigs. One goes to the contract manufacturer, one is for our own use, and the third is a spare. Fancy high end ones intended for high volumes usually contact the board with pogo pins and pads designed onto the bottom of the board for that purpose. Then there is a mechanism that closes down on the board. That holds the board in place and provides the force to compress the pogo pins a little, and usually has a switch on it that the test program can read to start the test.

You don't need to have something that automated for a small run like 100 units. You can require the operator to connect a programmer, then run a program on the host to dump the code into the microcontroller, connect cables, push buttons, look at lights, and the like. Consider whether it makes sense to add test functions to the production code, or have special code loaded into the micro just for testing, then the production code loaded after the test passes.

I generally figure the test jig is about of the same complexity as the product being tested, or a bit more. Designing the test jig is something that you need to plan on right from the beginning. In a larger organization, it can be useful to have separate engineers designing the product and the test jig, each working from the same specification of the product.

Answer 2

As someone that has looked into this in the past even if you break even buying your own equipment, it would still be much better to have the boards professionally fabricated for a few reasons.

1. Technique is not necessarily straight forward. For optimal quality it is not always as easy as raising the package to 260C and cooling it down, for instance large QFPN packages are now famous with lead free solder for cracking and premature failure due to the technique used when soldering. Manufactures are familiar with some of these details and what extra steps may be needed to ensure quality such as under-fill or footprint modifications.

2. All machinery has quirks and learning curves, you will spend a lot of time and material figuring out optimal settings for re-flow ovens, pick and places etc.

3. As long as you're not doing any fine pitch BGA components, everything can be cheaply inspected by just about any fabricator or yourself with a microscope, this is usually a cheep but somewhat reliable testing method before you move to a fixture with electronic testing or X-Ray inspection. That being said again even basic Chinese manufactures will often have these sorts of tools available.

4. Finally, if you do end up with quality problems, having someone to talk to can be very helpful (again using experience that is hard to find). To you the problem could be a needle in a haystack, to a fabrication house, they can take one look at your board and identify the common components that have problems.

If you think about some of what I mentioned, it becomes clear doing it yourself has a lot of hidden costs, time commitments and risks.

Unless you plan to start doing a lot of fabrications of different boards yourself in low quantities, I can't come up with a single reason to ever do it yourself.

Answer 3

I agree 100% with Olin that you should contract with an assembly company. Make sure you get pricing from a couple of sources that are happy with making your quantities before you quote your customers (sounds obvious, but if you make assumptions and they turn out to be wrong it could be expensive). Different PCBA companies may or may not be happy with very small orders. Naturally the ones that are happy with small orders will tend to charge significantly more per unit.

There will be setup costs and per-unit costs. Usually any kind of change incurs additional setup charges, so be sure to allow for iterations as may be required.

It's possible to buy the equipment to make such small quantities but it's not economical, and there are many processes to learn (any one of which can seriously compromise the quality).

If your board is open-source and your competitors have access to significantly lower cost manufacturers that are local to them, your run as a profitable manufacturer may be truncated.