BGA on 4-layers?

Ha!  Amazingly, I was doing a little poking around on that EXACT topic
last night.  Funny timing...I didn't find a whole lot of info yet, so I
will also be anxiously awaiting a few anecdotal responses (my guess is
the per-project complexity will still have a ton to do with the
answer...for my project, I want to drop a high ball-count FPGA onto a
four-layer board, but I only need ~100 of the i/o lines actually being
used for anything).

Awaiting...

John O.
H wrote:

Very difficult with 32 bits data paths.  Nearly impossible with 64 bits
data paths.  Easier with off-board memory modules.



So, you feel better by having the Taiwanese to go to China for you?
They rarely make the boards in Taiwan themself.  Same for Singapore,
Malaysia, etc.  This is especially true for fine-pitch PCB, the
equipments are too expensive without economy of scale.

All I can say is start the layout and see if you can do it.

If you can fit it in 4 layers, try the no touch service at
http://protoexpress.com It worked nicely for a board I did with a 256 ball
1mm pitch part. About 220 balls were connected. I put some pictures of that
board up at http://dlharmon.com/dspcard That one was particularly difficult
due to the Spartan 3's 3 supply voltages.

Darrell Harmon

to
overseas,
that
difficult

I'm just curious - did you succeed to solder BGA the first time or there
were several attempts?

- Dejan

It worked the first time. I plan to try another batch of them soon.

Darrell Harmon

Your at91rm9200 sbc seems interesting.  However, the 16M memory is too
small.  Can you help us upgrading it to a 256M module?  We can provide
you with the prototyype boards and parts and cash.  We want to hook it
up to the module at http://pcb.linnix.com/mem.jpgThanks

Hi Linnix,



Does your company produce PCBs for prototyping?  Would you offer you
services to the general public?

You mentioned that most/all Taiwanese companies go through China.

What are the environmental laws in China with respect to things like PCB
production?  I know that in the US the chemicals may not (legally) be
disposed of in a harmful manner.

Regards.
H.

Yes, we do prototypes, productions and assemblies.  Right now, we have
clients who need low end SBCs (Arm, PPC or X86) with lots of memory
(256M+).  We are trying to link them up with designers and
manufacturers.  we are still working out the system, but we can provide
Java based PCB (gerber) previews to the manufacturers.  It's good
enough to ask for quotes without sending them the actual files.  We
only send the customer's gerber files to the selected manufacturer.

Right now, we have to send out the Java Applet (but not the data, which
reside on our server), since it does not seem to work consistently with
all browers.  If you send me the gerber files, I will send you the
applet to preview it.  You can see if you feel comfortable with your
design being send out that way, or with more protections.

http://pcb.info-for.us



It's no worse than the Food and Textile industries, or many other
industries there.  Unless we stop buying foods and clothes anywhere
(not just in China), we cannot stop the polutions.  Of course, we can
help by driving older and smaller cars (mine is a 1994 Toyota), since
building a new car also cause lots of pollutions.

Tough laws, on a par with many developed countries, but weak or spotty
enforcement.  

Dealing with ISO 14001 suppliers is probably your best way of handling
this issue.



Best regards,
Spehro Pefhany

I am not sure what you are referring to with the 16M memory. It has a
16Mbit (2Mx8) dataflash for boot, a 64-256MByte NAND flash and 32 to
64Mbytes of SDRAM. I have no interest in further persuing that board.

I am currently persuing production of DSPcard on my own.

Darrell Harmon
http://dlharmon.com/dspcard

Yes, I realize that after studying the design further.



So, I hope you don't mind us taking over your design.  We will keep
your name as the original developer.  We want to add 3 more SDRAM chips
and IDE connector.  We might change to the BGA version of both chips as
well, since we would likely go to 6 layers.

I also send you a email separately.

Since the original developer is no longer interested in this project,
we are looking for volunteers to continue.  We fixed the D2/D5 CF pin
on the layout, but there are additional work to be done.  The updated
source packages (and additional information) are available at
http://pcb.info-for.us/sbc1.html

Anyone interested?  Free prototype boards are available for developers!