In my previous job a design team was forced to resort to board level circuitry after upper management declared "no new ASICs!" for the project. That was a bit of a concern as the circuitry needed to process 16bit words at multiple GHz. The result was a very dense mass of small RF transistors and ECL logic along with 1000's of 0201's. The 0201's were new for the in-house board assembly, and they had major concerns about yield. In the end, they saw almost no tombstoning and surprisingly good yields. Granted this was professional assembly, and they paid a lot of attention to the process parameters.
I was curious as to whether there might be something about 0201's to make them less prone to tombstone than larger sizes. A quick google search found this nice study of the effects of pad geometries and other factors on 0402 and 0201 tombstoning:
0201's had more defects, with grossly oversized pads being the dominating factor.
0402 defect rates were surprisingly insensitive to pad geometry
Thanks for sharing your results Erik,
On Aug 2, 2012, at 11:37 AM, Erik Walthinsen wrote:
> On 08/02/2012 11:32 AM, Rich Hoge wrote:
>> You will probably get more tombstoned devices trying to use the 0201 on
>> the 0402 pads, especially of your placement is shifted too far either
> Only 1 of 4 I've done so far has actually tombstoned. Honestly I was expecting them all to....
>> Depending on how many 0201 devices you have to populate, you
>> might be better off just printing the pads, then manually soldering.
> I'm planning on being better off by not using 0201 ;-)
> dorkbotpdx-blabber mailing list
dorkbotpdx-blabber mailing list