Electronics Forum | Sun Mar 26 19:02:05 EST 2006 | ms
Hi We are running automatic stencil printers, open squeegees, stainless stencil, stainless blades, print speed 25-30mm/sec. We have a frustrating consistency issue printing .37x.3mm apertures on a 45pin LGA (11 pads each side, 1 large ground in mid
Electronics Forum | Mon Mar 27 15:10:48 EST 2006 | ms
Hi Steve Thanks for your reply. Your comments make it sound like it may be the nature of this paste. Any one else agree? Paste control is fairly good. Paste is put in fridge straight after it arrives at inwards goods, (4deg). Removed from fridge
Electronics Forum | Mon Mar 27 10:26:59 EST 2006 | slthomas
It seems highly unlikely that you could actually trap enough air in your paste for it to be releasing air after you've worked it a few times unless it's not rolling properly to begin with. I suppose maybe a contaminant could be present that could b
Electronics Forum | Mon Mar 27 19:32:28 EST 2006 | PWH
You mention "large ground plane pads in the center". Could it be that these large apertures are allowing the blades to "dig" which somehow pulls paste from adjacent apertures as the blades recover?
Electronics Forum | Mon Mar 27 20:34:22 EST 2006 | ms
Thanks for the suggestion. The large ground pad appears as a single large pad on the component and PCB but we print a matrix of 28 small dots of paste to provide the solder for the joint. The inconsistent volume transfer can occur on any of the fo
Electronics Forum | Mon Mar 27 22:20:04 EST 2006 | davef
Mike The air 'contained' in the aperture would prefer to escape between the board and the bottom of the stencil rather than through your paste while you're printing over it.
Electronics Forum | Mon Mar 27 10:28:22 EST 2006 | slthomas
Blasted back button. :/
Electronics Forum | Sun Apr 25 10:28:46 EDT 1999 | Joe Cameron
Hello all, Been doing some comparisons on joints made using the soldering iron versus reflowed solder paste (on a QFP package). The difference is quite significant: the joints made by the soldering iron are inconsistent and in many cases not filled
Electronics Forum | Tue Feb 17 01:15:26 EST 1998 | J.H Kim
| In solder bumping in flipchip technology by solder printing, | the precise control of solder volume and height is very difficult. | Therefore I'd like to know the solution of this problem. | Thanks
Electronics Forum | Tue Feb 24 01:19:01 EST 1998 | Jon Gruett
You are right !!! The exact volume of solder paste onto flip chips is extremely critical. Only one vendor that I know has taken that part of the process to the next level, whereby they can effectively deposit the right amount onto the flip chip exa
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