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Wave Solder Immersion Depth, Contact length, Dwell Time etc.



Wave Solder Immersion Depth, Contact length, Dwell Time etc. | 15 February, 2001

Hey guys,

I ran a couple of profile in our wave solder machine using wave optimizer and this is what i got:

Parallelism = 0.0 Immersion Depth = 2.1mm to 2.4mm with varying immersion time from 1.1 sec to 3.1 secs. Contact Length = between 5.0 to 6.0 cm Dwell Time = from 2.8 secs to 4.5 secs I ran the above in different conveyor speed; from 80cm/min, 90 cm/min, 95 cm/min and 105 cm/min.

judging from the above wave data results am i correct to conclude the following?

a) our solder pot is too high since even when i reduced our lambda pump lower the immersion depth never changed. b) our contact length is set to 5 centimeters (proven when i measured using a glass plate). Is this too high? No matter how slow i ran the conveyor, my contact length was never below than 5 cm. c) if i lower the solder pot height, will my contact length will be reduced too? d) what's the correct range for contact length, immersion depth and dwell time ?

I'm currently encountering hips of solder shorts after wave soldering.


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Wave Solder Immersion Depth, Contact length, Dwell Time etc. | 16 February, 2001

Dreamsniper, The optimum contact (dwell) time in the wave should be 2 seconds. Contact band width is a function of conveyor speed. For an example, 5cm of contact band width at 150cm/min. conveyor speed will give you 2 seconds of contact time and 2cm of contact band width at 60cm/min. conveyor speed also delivers 2 seconds dwell (contact)time. This data is off a Sandia Laboratories chart and it has been effective for us. The formula goes like this: t= Dwell Time of PCB in Solder Wave t= dx5/V where d= Geometrical length of contact between PCB & Solder Wave v= Conveyor Speed We do not mess with our solder pot height for contact band width. We set the pot to the wave mfg's. specification for the gap between the bottom of the conveyor finger to the top of the baffle. We set band width by adjusting pump RPM. We run the glass plate to check that the pot is level and to measure band width. We run almost all our PCBs at 150cm/min. conv. speed with good results including SMT bottom side w/ SOICW. Of course preheat temp. must be set to deliver the proper top-side board temp. in accordance with the flux mfg's. specification. Hope this helps. PeteC

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Donnie D.


Wave Solder Immersion Depth, Contact length, Dwell Time etc. | 19 February, 2001

One other thing you may want to look at is your nitrgen settings and the difussers. If you don't have them correct, you can also see bridging and icicles.

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