Electronics Forum | Tue Mar 21 02:15:26 EST 2006 | pavel_murtishev
Good morning Dave, Here are some of my assumptions. Please correct me if I am wrong. 1. Mask opening. Due to mask to PCB misregistration mask is not always centered relative to pad center how is should be. Sometimes edge of the mask matches with ed
Electronics Forum | Mon Mar 20 22:39:03 EST 2006 | davef
Pavel Point: You suspect that solder paste can easily get to solder mask causing beading, because the aperture is larger than the component pad. Comment: Probably, this is incorrect. We overprint on solder mask all day long when doing paste-in-hol
Electronics Forum | Mon Nov 15 12:13:41 EST 1999 | Dave F
Steve: There are guidelines for determining if your aperture has the correct proportions to the foil thickness. Maybe that�s what you�re looking for: 1 Aspect ratio = aperture width/foil thickness Chemically etched SB GT 1.5 Laser cut SB GT 1.2
Electronics Forum | Tue Jul 31 00:48:55 EDT 2001 | Frank
Sorry I forgot to provide enough information. Stencil thickness is 6 mil Aperture width is 10 mil Aspect ratio (aperture area / wall area) = 0.72 Solder paste mesh size, type 3 (-325 +500) With this aspect ratio we can printing without any probl
Electronics Forum | Mon Jul 30 21:12:32 EDT 2001 | davef
"Poor release" (paste hanging-up in the stencil holes) could have three main (or combination of) causes: 1 Equipment: Stencil is too thick. Specifically, a 6 thou stencil should be OK, providing you don�t violate the area and aspect ratios in the fi
Electronics Forum | Mon Nov 15 12:09:55 EST 1999 | Dave F
Steve: Continuing with Dan�s thinking, generally, "poor release" (paste hanging-up in the stencil holes) could have three main (or combination of) causes: 1 Equipment: Stencil is too thick. Specifically, your 0.006 should be OK, providing you don�
Electronics Forum | Sun Oct 08 00:18:05 EDT 2000 | Arturo
We are working with a 16mil TSOP Land width=0.2mm(8mil) and use: 1.Type 4 particle size solder paste. 2.Laser cut electropolished stencil: Aperture width=0.19mm (we tried lower than this but had solder insufficiency). Thickness=0.005"(130 microns)
Electronics Forum | Tue Sep 21 13:12:56 EDT 1999 | Dave F
| My stencil thickness is 6 mil and we got qfp's with fine pitch. | how many percent should i reduce my stencil aperture using a 6 mil stencil for 0.5 mm pitch and 0.4 mm pitch ? | | thanks | Greg: I was going to link you to the IPC land pattern c
Electronics Forum | Wed Oct 11 12:52:10 EDT 2000 | Antonio A. Medina
Hello all, I'm new at this so forgive me if my question seems common knowledge to everyone else. I've searched the archives but found no clear answer to what exactly is aspect ratio and what the best ratio is. All I really know is that it has to d
Electronics Forum | Wed Sep 18 12:31:16 EDT 2002 | dragonslayr
My suggestion is to conduct a Design For Manufacturing (DFM)study on the assembly in question. Pay particular attention to the pad sizes, component lead dimensions and satisfy yourself that those two factors are correct. Given that pads match compone
