Electronics > Beginners
Hot Air Reflow with HASL
JustMeHere:
Does anyone have experience hot air soldering HASL boards?
I've read that it is not good because of its uneven surf. When I do solder my ENIG boards, I've found it easiest to pre tin the pads of the small chips, flux, place the chip, then reheat what is there. It seems like HASL would save me a step.
The chips are like 16QFN. I do mostly try to stick to SOIC chips though.
bson:
Depends a lot on the HASL. With some boards and footprints, especially 0.5mm and 0.65mm SOP/LQFP, the pins often end up balancing on top of the tin and are really prone to shifting sideways. Tin and paste is pretty slippery. Also makes it hard to nudge a package to center it since you're effectively pushing uphill. But, yeah, less paste is needed with HASL than ENIG and it's no problem for passives or larger footprints that effectively have flat surfaces. The thickness of the HASL layer also varies.
anvoice:
I've hot air soldered QFN packages with HASL, but I have applied extra solder. HASL is meant to protect the boards, not to provide an alternative for solder paste/solder, so I'm not sure if there's enough to make a good joint. As bson said, probably depends a lot on the HASL thickness.
perieanuo:
--- Quote from: anvoice on September 21, 2018, 04:29:35 am ---I've hot air soldered QFN packages with HASL, but I have applied extra solder. HASL is meant to protect the boards, not to provide an alternative for solder paste/solder, so I'm not sure if there's enough to make a good joint. As bson said, probably depends a lot on the HASL thickness.
--- End quote ---
Meetoo :)
You apply solder evenly on the qfn pads then you place your chip, no matters it is industrial or home edition, iron of hot air or whatever.
Regards,pierre,qfn and bga welder
Envoyé de mon iPad en utilisant Tapatalk
mrpackethead:
If you are hand soldering your boards. then theres not a lot to be gained using ENIG over HASL.
The primary reason for using ENIG Is that it provides a much flatter surface than HASL, and that is very useful when you are doing fine pitch parts were you need to get high precision prints with your solder stencils. Small height variations on the board create variances which in turn result in addition faults. Its also benefical for parts like QFNS, as the center pad wont' sit flat.
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