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linears4 · 11-17-2009, 21:25

i have 100% welding success, with any kind of chip until 35mm, but only at zero time, zero time means after the welding process.

my biggest problem is the long term reliability.

in some cases the chip fails again after about 6 months. in other cases i have some chips working even after one year.

i'm trying to figure the cause, but it is very hard.

i know too that if i fail to do baking i will encounter some problem, but baking process is very time consuming.

a must is to bake the new chips, for 8 hours at 85-95 degrees at least, and then make a moisture barrier package. the theorical floor life of this kind of components is maybe 72 hours, after that a new baking is needed.

but very time consuming process.

even the whole board has to be beaked, to avoid cracks in it during welding.

but all this is a crazy thing...

but a thing is shure, only reflow will never give a long term reliability, cause you don't have flux on the pads, and a reflow can't change the penetration of the soldering alloy to the metal pad, it can only adjust a crack, but if the problem is on the interface a reflow can't change the things too much

11-17-2009, 21:25	#21 (permalink)
linears4 Junior Member Join Date: Mar 2005 Age: 53 Posts: 32 Member: 132074 Status: Offline Thanks Meter: 13	i have 100% welding success, with any kind of chip until 35mm, but only at zero time, zero time means after the welding process. my biggest problem is the long term reliability. in some cases the chip fails again after about 6 months. in other cases i have some chips working even after one year. i'm trying to figure the cause, but it is very hard. i know too that if i fail to do baking i will encounter some problem, but baking process is very time consuming. a must is to bake the new chips, for 8 hours at 85-95 degrees at least, and then make a moisture barrier package. the theorical floor life of this kind of components is maybe 72 hours, after that a new baking is needed. but very time consuming process. even the whole board has to be beaked, to avoid cracks in it during welding. but all this is a crazy thing... but a thing is shure, only reflow will never give a long term reliability, cause you don't have flux on the pads, and a reflow can't change the penetration of the soldering alloy to the metal pad, it can only adjust a crack, but if the problem is on the interface a reflow can't change the things too much Last edited by linears4; 11-17-2009 at 21:32.