Electronics Forum | Mon Oct 15 11:03:24 EDT 2001 | mikecampbell
Dave, Thanks for the info! Yes, I have read the IBM document and realized that I was missinformed about the paste volume. I need 5000 to 5600 cubic mils of paste. Running the numbers I get a 32 mil aperture with a 7 mil step (the rest of the board
Electronics Forum | Thu Dec 19 13:20:55 EST 2002 | russ
Your area ratio for this aperture is fine (.78) usually any value greater than .66 will provide a reliable paste release. I would make sure however that the stencil is polished. I agree with other posts regarding your setup and/or paste type is prob
Electronics Forum | Wed Nov 05 13:43:52 EST 2003 | swagner
I just did a bga job with square aperture's, the reasoning is for enhanced print release and additional paste volume. Be careful of the edge to edge clearance between the stencil openings, I don't recommend going below a 8 mil clearance, you could b
Electronics Forum | Wed Jul 13 14:08:13 EDT 2005 | russ
We do have solder balling on occasion but it is usually very minimal. When and if this becomes an issue with us we will then utilize the homeplate aperture. We do not wash boards as a general rule. All of our pb free has been no-clean. We can't f
Electronics Forum | Mon Jan 09 07:50:53 EST 2006 | slthomas
When I had that luxury I always used a double pass, first wet then dry, to reduce the amount of wet solvent left on the stencil. That also gives it some time to evaporate. If you've got suction I don't know how you'd ever get any through the aperture
Electronics Forum | Fri Mar 30 23:09:30 EDT 2007 | mika
We have now ordered a another stencil with square apetures with 20% overprint just because it is so difficult to get the solder paste to stay on the pcb pads without to get it stuck within the apertures. We have set the print speed down, the separati
Electronics Forum | Thu Jul 02 10:52:45 EDT 2009 | dyoungquist
For 0402s we use type 3 paste. We have .006 and .005 stencils. The .006 works okay but .005 seems to give us slightly better results. We use a 1:1 ratio for the aperture to match the pad, round pad not needed. With accurate placement and a correc
Electronics Forum | Tue Jan 31 09:41:06 EST 2017 | emeto
If there is no specific quality reason, stay with paste. More processes you add, more points of failure. They don't need a lot of paste to get attached to the board. The ones I used were 8mil round apertures, so I did cut 1:1 on a 3 mil coated stenci
Electronics Forum | Mon Mar 07 06:44:39 EST 2022 | SMTA-64386201
We previously labelled PCBs after assembly but before AOI. Now we need to trace panels during assembly as well, so have the need to apply labels before the assembly process starts. Our stencils are thus not stepped to accommodate labels. I suppose t
Electronics Forum | Fri Jul 10 10:40:13 EDT 1998 | Todd N
Hi all, We are currently having problems with a laser-cut stencil that is electropolished and nickel plated with 9-mil openings. The paste does not release well from the apertures. We are having to wipe after every print. The board is fixtured well a
