Electronics Forum | Thu Jan 06 06:15:49 EST 2005 | mattkehoe
We need some opinions about a situation that is causing problems in our process. The pcb's in question are .125 thick with a HASL finish. The boards are coming in with a large amount of solder trapped inside the via holes. Sometimes this solder is ac
Electronics Forum | Thu Jan 06 16:11:07 EST 2005 | Chunks
It appears your board house is having a problem with the solder resist (mask). From the couple pix it appear that the holes are being plugged by the mask, so your HASL is not able to be blown out during the hot knife process. Time to call your boar
Electronics Forum | Thu Jan 06 09:03:57 EST 2005 | russ
It appears that this particular PCB supplier has a non-optimum HASL process along with other issues. It is much harder to completely remove the solder out of vias on thicker boards. Looks like more air pressure was needed to remove all of the exces
Electronics Forum | Thu Jan 06 08:03:47 EST 2005 | davef
On solder in vias: It looks like the via are not solder masked well and pick-up solder either: * Solder coating ... OR * During leveling It's possible that the design specifies openings in the solder mask for these via. On solder in the unsupporte
Electronics Forum | Wed Mar 21 17:08:34 EDT 2007 | iit
The biggest problem with double printing is that if the squeegee pressure and speed are correct, the stencil apertures are already filled with paste. Printing again can force paste between the bottom of the stencil and the top of the board creating
Electronics Forum | Wed Nov 02 08:16:31 EST 2005 | pavel_murtishev
Hi! It goes away only for one or two print strokes. After them the problem arises again. After first print stroke I inspect a lot of �dog ears� and a lot of paste not released from the stencil (it�s not a stencil design problem, other machine prints
Electronics Forum | Fri Oct 28 06:55:53 EDT 2005 | pavel_murtishev
Hello! I suspect that our MPM AP25 has separation problems (poor stencil � PCB separation). I observe a lot of �dog ears� after print stroke. And this is 100% machine problem, I�m sure. What machine parts should I check first time to avoid separatio
Electronics Forum | Tue Jul 19 21:48:21 EDT 2005 | grantp
Hi, Yes, and then how do you design a stencil that paste releases reliably. Do people put lots of 01005 components on the board, or just the minimum required to do a tough job? Regards, Grant
Electronics Forum | Mon Jul 18 21:00:22 EDT 2005 | grantp
Hi, Yes, I would love to know this as well. Our machines can handle the component sizes, but how do the printers handle it? We have a DEK, and that's a good printer, but how do you design the stencil to reliably paste release on components this smal
Electronics Forum | Wed Jul 20 16:51:03 EDT 2005 | pjc
There is a spec I read that states +/- 0.001" (0.025mm) print deposition accuracy and repeatability is more than adequate for 0201-chip printing. I don't think any print studies where done for 01005 chips yet. There are several other factors besides
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