Electronics Forum | Mon Jan 30 19:27:50 EST 2017 | jgo
Hi all, I'm wondering how does one decide to use flux dipping or solder printing when it comes to be attaching CSPs onto the board? Solder printing has an advantage in that there will be a higher throughput on the mounter as there is no flux dippin
Electronics Forum | Mon Feb 13 01:47:28 EST 2017 | soldertraining
Solder flux and solder paste deposition is a standard step during the chip attach and sphere attach portions of BGA and CSP assembly. A technique called ultra-violet fluorescence intensity mapping (UV FIM) has been introduced that allows flux measure
Electronics Forum | Wed Feb 01 02:39:16 EST 2017 | jgo
80 micrometres (0.08mm)
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 | Wed Feb 01 11:33:37 EST 2017 | emeto
Joshua, 100um is 4mil aperture. You should ask several stencil houses about the possibility to print that small amount of paste(type 6 paste is available now with very small solder spheres 5-15um diameter). Even applying small amount(thin layer of f
Electronics Forum | Tue Jan 31 19:34:11 EST 2017 | jgo
I have solder bumps diameters @ 80um, the board pad size @ 100um. Can this size be printed? How about dispensing?
Electronics Forum | Tue Jan 31 09:10:04 EST 2017 | Rob
Hi Joshua, We've done both, but a lot depends on what soloution your machine vendor has, and how good it is. Can you add it into your machine acceptance criteria? Rob.
Electronics Forum | Wed Feb 01 02:21:26 EST 2017 | rob
80 micrometres (0.08mm) or 80 mil (2mm)? Smallest I've seen reliably printed is around 0.2mm x 0.4mm (01005 pad) and 0.2mm x 0.2mm CSP pad, not seen anything dispensed below 0.35ish, but we are not cutting edge.
Electronics Forum | Wed Feb 01 03:17:10 EST 2017 | rob
Ok, that's small - I think you may need a special semi-conductor printer for this - positional accuracy on a "normal" SMT printer is no more than 20 micrometres from memory. In my semiconductror fab days we were printing with a positional accuracy
Electronics Forum | Tue Jun 02 07:31:55 EDT 2009 | scottp
Early on when we started looking at BGAs we tried dipping. We've done it in production for a couple decades with flipchips. Dip fluxing BGAs worked fine in the lab but we ended up starting production with screen printed flux for cycle time reasons.
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