I am sure the tariff/tax is to stop people from doing so, but you can always risk it.
Olimex can't do 0.4mm/0.2mm holes/lines. I used them before and I know their limits.
As for myself, I am ready to jump in a plane to get it.
The ARM I am using come in BGA only, not QFP. Even if there is QFP, you need to expand the routing area much bigger than BGA. The final PCB for QFP would be much bigger than with BGA.
The QFP should be cheaper.
-- A. P. Richelieu
Olimex can do 0.2mm (8 mils) track width/space , but it takes 15 working days.
Their minimum drill size is 0.6 mm (24 mils)
Tom
They are probably farming it out as well.
They also want 0.1mm rings around pads, so the minimim pad is 0.8mm. Add another 0.2mm spacing and you can't do BGA under 1.0mm.
Make that 1.27mm; flip-chips typically want 0.55 to 0.60mm pads. A 0.6mm BGA pad + 0.8mm via pad would leave you with only 7 micron clearance on a 1mm grid. :-(
That's with the via pad on the side. I am going to try with it in the middle, kind of doing a PGA (pin grid array) PCB for a BGA. That why I need 0.4mm or small laser holes. I am hopeing the solder ball wouldn't leak too much through the hole. If necessary, I can plug the holes before placing the BGA.
BGA
1mmHave you done this before? Doesn't sound like safe practice to me. 0.8mm pitch BGA solder balls are typically 0.55mm diameter, which means that it may completely disappear in a hole of 0.3mm diameter (1/16" board thickness). Filling the holes may work, but looks like very labour-intensive. What do you want to use for it? Obvously you can't use resin.
No, but willing to try it out.
I can go for smaller holes, as much as 0.1mm.
Or I can fill it with BGA socket pins. It can be machine picked and placed.
Or ask any decent PCB manufacturer to make plugged holes.
Meindert
Hi Tolga,
You can order ARM boards from Olimex . They can send the boards as sample.(or "free of charge" written on it ) With no invoice of course. Airmail costs 5 $ from Bulgaria to Ankara.
I have ordered some MSP430 boards and JTAG several years ago with same method from Olimex. Just send a message them. (Tsevetan can help you)
Making it yourself can be difficult.
Actually, we are going to use the BGA adapter/socket pair. The adapter solders on the BGA device and the socket solders on the board. The adapter can go directly on the PCB with 0.3mm holes or the socket can go on the PCB on 0.6mm pads. This is perfect for 0.6mm/0.3mm pads/holes.
Unfortunately, they won't be cheap. Could be half the price of the BGA ARM. Just hope that we don't have to buy batch of thousands. At least we can re-use the PGA ARM on later versions of PCB. We never stop changing PCB designs anyway.
Anyone tried that approach?
This was incorrect. The cost of adapter/socket is more than the ARM or PCB. I guess we have to roll our own. We can handle the thermo-plastic housing and the socket foil stamping, but the pin fabrication would be touch. Anybody familiar with pin fabrications? Namely, shaping a 0.8mm wire into 0.8-0.6-0.3-0.2 pin. Any commerical machines for doing so?
That last post sounds like a smige of sarcasm...
Seriously though, can anyone direct me (us?) to a something that describes the guidelines for designing a PCB for something like an ARM processor? I have done some PCB design before, but they were very simple circuits, and frankly, design of something like an ARM dev board is drasticly different then a simple PIC.
Btw, my name is Andy, I'm an ECE student at Georgia Tech. Nice to meet ya'll
-Andy
Yes, adapters/connectors are usually more difficult to get than PCB.
Company A has the right BGA layout on their web, but waiting for someone (the first customer) to pay for the housing molding.
Company B wants USD $3000 per 100, and delivers in a few weeks.
For a little more, we can probably get 1000 sets of pins/sockets fabricated, and 2 custom designed injection molded housings. Even without the housings, the sockets might fit in the PCB and pins could be solder to the chip directly.
We are more and more inclined to make the chip removable, in terms of PCB modifications. With a custom housing, we can do more to disspate the 1W generated heat from the chip.
16 bits minimum, 32 bits maximum. The wider bus forces you into high density fine pitch PCBs, and consequently multi-layers (6 to 8).Yes, we tried to avoid BGA, but don't have a choice for this project.
... snip ...
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Google is a terrible interface to the system. Not only does it default to an unsatisfactory method, it also alters the actual messages. However, if you are careful, and follow the instructions in my sig (below) you can use it satisfactorily. In addition here are some general references:
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