On 04/05/12 01:23, Peter Stuge wrote:
Oliver Schinagl wrote:
Unfortunately I have had little feedback so far. But here's a small update.
Thanks for the update.
I did look at your previous board but needed more time to really look closely.
That would be grand!
I have finally received my SO8 memory modules and those babies are small.
Oh it's not so bad. :) Try the 0603 resistors.
Because of this, I have replaced the SO8M footprint with an SO8W footprint,
This is actually correct. All SPI flash chips used in PCs are in the 200 mil wide package, not the standard SO8 which is only 150 mil.
There are 3 SO8 package footprints in PCB, SO8, SO8M and SO8W. None fit 'perfectly'. S08 is way to small to be usefull, SO8M fits 'perfectly' but makes it extremly hard to solder I recon, since the pad, ends at the legs. SO8W seems to be a little to wide, the legs end up perfectly on the inner sides, which might make it not to cover the back 'cavities' perfectly? But I guess it will have to do.
The PCB's that I used as inspiration actually do fit perfectly :)
http://www.ebay.com/itm/10-pc-SOIC-8-DIP-8-Narrow-PCB-SMD-Adapter-DIP-/40022...
I've also saw a screenshot of an Asus motherboard that had the bios chip right next to a Sata port, in the wrong/different orientation, so I've added a 3rd design so all 3 possible insertations are possible. (Left, center and right facing connector).
Ah, so the plan is that your PCB is plugged into the factory BIOS socket? That's a nice idea, but as you discovered there are four ways that the chip can be oriented, so you really have to make four boards to have a solution that works on every board. :\
Yes, the plan was to have the PCB go into the motherboard, and the original bios piggy bags ontop! The
Well, 4 orientations, but I think 1 can be used for 2 orientations. It all depends on what is blocking your board however.
I hope it's quite unlikly that a bios is constrained on 3 sides, but as always possible. If I get bored later this week, I may end up making the missing 4th design then, where the socket sits 'sideways'. Should be considerably easier to route then the ones I have now ...
I've attached the gEDA .pcb file with the 3 orientation,
Thanks. I'll try to give some more detailed feedback, but one big no-no that I've seen already is that your silk is covering pads. Noone will do any cropping for you, so you will indeed get silkscreen on your pads, which 1) potentially makes the board house unhappy because it may make a mess in their machines, and 2) makes it difficult for solder to flow over the pad.
Hmm, I assumed silk screening is applied last, as I have seen soldermasks and silkscreening covering via's. The only thing I cover IS via's ... because of that assumption.
When sending out the final rev. I'll copy/paste the silk screens from the left design so they all look identical.
No, please do not make design changes post final review. Another way to express this is please only send files for review that you believe that you are finished with. Of course there can be iterations and that's fine! But don't make further changes after the final iteration.
I should have clarified this yes, I would of course have posted the final version that would have been sent off to the board house. But that version will fail DRC checking :(
//Peter