2
\$\begingroup\$

I have a project that I've begun to work on, it's sort of an embedded PC type project, with a iMx6 arm processor. However, since this is a (potentially) commercial venture, we can't use prebuilt boards like the Pi etc. I have a thorough understanding of creating PCBs, however I've never made one with SMT ICs, and now I need to make one with BGAs. I've been reading/researching , and it doesn't seem practical to do in a small company- we only have a soldering iron, hot air, and spools of solder. Is there a commercial alternative to making a prototype with these parts? We need to order a pcb, are there companies that can produce ONE OR TWO boards, as opposed to by the thousand? Or is there even a way to do it in house? I don't want to waste time and parts trying it to find that it's best to order, but I don't want to waste money either.

  1. What types of prototyping services are available, and where could I find them (websites)?
  2. What would the cost range be for a 10x10cm square with parts as expensive as a processor/ram?
\$\endgroup\$
2
  • \$\begingroup\$ Google on "prototype pc board assembly" \$\endgroup\$ – WhatRoughBeast Jul 31 '14 at 0:39
  • 5
    \$\begingroup\$ If you have never created a board that uses SMD parts, I would strongly recommend not doing this as your first project that uses them. BGAs are very difficult to lay out properly, including the i.MX series. \$\endgroup\$ – Funkyguy Jul 31 '14 at 0:43
6
\$\begingroup\$

You've already accepted an answer, but I'll add this:

Keep in mind that all but the smallest (number of balls) and crudest (ball pitch) BGA layouts are going to require expensive multilayer boards- 6 or 8 layers, often not even the relatively inexpensive 4-layer type. Costly per board in small quantities and high up-front NRE costs that get charged every time you make a change. Slower, too, unless you pay astronomical rush charges.

They will also likely require microvias, which also increase the cost and limit which suppliers you can use. Companies that act as front ends for offshore factories will typically use a different factory for such multilayer boards.

The iMx6 processors use 21 x 21mm, 0.8 mm BGA, which is not the highest density, but will still likely require microvias, 6 or 8 layers and fine pitch.

Mounting a BGA chip is actually not that difficult if you don't require X-ray inspection- print with a stencil (rework stencils are available) and a pass through a reflow oven will do it. If the process is right they'll almost always be okay.

If you have sufficient budget for that kind of board technology, it is not a particular problem, but keep in mind that multiple spins of even a small board can eat up many weeks and thousands of dollars. Be sure to read the recommendations carefully on BGA layout before doing it (or deal with a layout person who has done this before) as mistakes are unusually costly if you're used to dealing with 1-2-4 layer boards.

\$\endgroup\$
4
  • 2
    \$\begingroup\$ Yeah, you are right. I changed the accepted answer. Although @funkyguy I still greatly appreciate the links. \$\endgroup\$ – Technomad Jul 31 '14 at 17:02
  • \$\begingroup\$ No problem man. Good luck \$\endgroup\$ – Funkyguy Jul 31 '14 at 17:03
  • \$\begingroup\$ Totally agree. For small-volume work, I let PCB specs drive the design. I'll go ahead and start doodling with a few different processors in Altium to find one I can reasonably fan out on a 2 or 4-layer "cheap" (6/6 trace, 12/24 vias) PCB. For example, the QFP version of the iMX233 is easy to work with, while the BGA version isn't. But if you go over to the AT91SAM9 stuff, you'll see that those BGAs are actually quite easy to do 4-layer layouts with. As much as I love Freescale, for low-volume projects, an QFP-packaged AllWinner A13 is going to be way cheaper to design around than the iMX6. \$\endgroup\$ – Jay Carlson Aug 2 '14 at 8:30
  • \$\begingroup\$ Thanks. And I'll look into the A13, thanks for the QFP tip. \$\endgroup\$ – Technomad Aug 4 '14 at 20:59
1
\$\begingroup\$

There are short-run electronics assembly services in most western countries, although they may be hard to find. I'd expect to pay $100-$200 per assembled board for this kind of thing, and possibly a few hundred $ in setup fees.

Note that buying the iMX6 components for short production runs may not be entirely simple.

\$\endgroup\$
2
  • \$\begingroup\$ Getting iMX6 parts looks as simple as placing a Digikey order to me, if you can stomach the single piece price. \$\endgroup\$ – Matt Young Jul 31 '14 at 12:17
  • \$\begingroup\$ Yeah, digikey was where we intended to buy it- unless theseanufacturers had pre established deals with chip manufacturers, not sure how they source their parts to assemble \$\endgroup\$ – Technomad Jul 31 '14 at 13:56
0
\$\begingroup\$

What types of prototyping services are available, and where could I find them (websites)?

Check out OSHpark and OSHstencils

What would the cost range be for a 10x10cm square with parts as expensive as a processor/ram?

That entirely (the biggest emphasis that ever existed on entirely) depends on your application. If you want more RAM, that will cost more. If you want a better processor, that will cost more. You want them to be smaller than cheaper options? That will cost more.

From the vendors, the PCB will cost around $20/3 boards for that since 2.54cm = 1 in and they charge $5/in2.

\$\endgroup\$
8
  • 1
    \$\begingroup\$ Thanks! These seam very reasonably priced. It should make the job a lot easier! \$\endgroup\$ – Technomad Jul 31 '14 at 1:03
  • \$\begingroup\$ Pretty sure he's looking for assembled boards \$\endgroup\$ – Scott Seidman Jul 31 '14 at 1:04
  • 1
    \$\begingroup\$ Please look at pjc50's answer. It is a normal practice within small companies to completely outsource component procurement, PCB manufacture and assembly. You just send them the files and get the boards back. Prototyping with BGAs is not practical unless you have correct tools. Even leaded components can be an issue if you have to solder a few hundred parts. \$\endgroup\$ – Armandas Jul 31 '14 at 8:29
  • 1
    \$\begingroup\$ @Technomad while I did provide you with some services and such, the accepted answer should honestly be Spehro Pefhanys answer. He wrote a very nice answer. \$\endgroup\$ – Funkyguy Jul 31 '14 at 15:11
  • 1
    \$\begingroup\$ Please read the question before answering. Trying to route out a 624-pin BGA on 2 or 4 layers with OSH Park's design rules is going to be a nightmare, if not outright impossible. They are great for through hole and moderate density surface mount, but not for serious BGAs as the question concerns. \$\endgroup\$ – Chris Stratton Jul 31 '14 at 17:33

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.