Electronics Forum | Thu May 24 16:45:57 EDT 2001 | kmorris
Hi All: We�ve got a problem here with opens on bottom side wave soldered SOT23s. Based on past experience and review of the SMTnet archives, I feel that our main problem is pad size. We have the same size pads for bottom side SOT23s as we have for
Electronics Forum | Fri Aug 08 12:52:57 EDT 2003 | davef
So, if you give your customers design guidelines and one their products causes a cataclysmic explosion, resulting in the deaths and disfigurement of many handicaped third-world children, could a lawyer consider you responsible? Spec Fir Tree General
Electronics Forum | Tue Apr 01 11:18:47 EST 2003 | cyber_wolf
Is anyone out there successfully screen-printing SMD adhesive on an 0402 layout? We have successfully done 0603 and larger, but the deposition consistency on the 0402's is just not there. We don't always get enough epoxy on the board. We have tried a
Electronics Forum | Tue Jun 24 12:56:26 EDT 2014 | jmathis
Hello, As our company has begun doing an increase production of contract manufacturing I have seen more and more designs with the 0402 pad layouts that are smaller (.015 in width) than the component. Also there is only a .008 longer than the 0402 p
Electronics Forum | Mon Jun 11 14:25:36 EDT 2001 | CPI
I had the very same problem but, did not question my oven as I knew the profile was good and I should have had even heating. So I then looked at pad size and layout. When Layout and size were found to be ok. I attached a prob to each pad and ran a pr
Electronics Forum | Wed Jan 10 20:06:43 EST 2007 | SSS
I've been assembling thousands of boards for dozens of customers over the past 5 years with 0402 chip components. 85% can happen very easily even with newer equipment. Defect challanges with 0402 packages is almost always tombstoning. Capacitors abou
Electronics Forum | Thu Jun 13 11:27:25 EDT 2002 | davef
>*Changing paste >EricD: Yes we are considering that as a point. Because I believe the paste we are using are in syringe packaged and designed for dispensing. We are using an Indium SMQ75 paste and current application naturally is stencil printing.
Electronics Forum | Wed May 10 00:27:46 EDT 2006 | Chris
Russ, By a longer profile you mean a more even slope across the entire profile. Unfortunately I only have a 5 zone oven that is fairly short. How many heated zones are you using? Did you shrink the 0402 pad design and leave less pad exposed out a
Electronics Forum | Thu Jun 01 08:39:36 EDT 2006 | russ
IPC a 610 has this info. An 0402 however mat require more solder than what IPC states (basically evidence of wetted fillet for class2). more paste = more flux = better wetting. Why don't you tell us what pad sizes and layout you have and stencil t
Electronics Forum | Wed Apr 12 21:33:27 EDT 2000 | Micah Newcomb
Billy and Chris have a good point, pad size and geometry will affect proper aperture size and geometry and could result in tombstoning. Also I have seen chips which require special pastes but I have never found this to be the cause of tombstoning, in
