Electronics Forum: double reflow qfp (Page 1 of 93)

double sided reflow

Electronics Forum | Wed Jun 21 22:07:09 EDT 2000 | Jason

We are going to try double sided reflow for the first time. Can we use the same 63/37 paste on both sides? The board also has bare copper pads i'm pretty sure. will this present any challenges? The bottom side has a QFP on it. Should it stay on?

Re: double sided reflow

Electronics Forum | Thu Jun 22 11:01:54 EDT 2000 | Chrys Shea

Jason, Double sided reflow should be no problem. People have been doing it for years. The surface tension of the molten solder will hold the components on the bottom side during your second pass. This is almost always the case, unless you have re

Re: double sided reflow

Electronics Forum | Thu Jun 22 11:02:13 EDT 2000 | Chrys Shea

Jason, Double sided reflow should be no problem. People have been doing it for years. The surface tension of the molten solder will hold the components on the bottom side during your second pass. This is almost always the case, unless you have re

double side reflow soldering

Electronics Forum | Tue May 14 21:07:03 EDT 2002 | ianchan

Hi mates, Yes, the lighter mass is a valid reasoning. in addition to the "lighter (mass) than thou" point of view, 1) the first reason for mounting active Parts (eg. IC, QFP, LGA...) is to minimize the temperature exposure of the Parts to a single

qfp reflow problems

Electronics Forum | Thu Apr 22 14:15:35 EDT 2004 | russ

Well so much for being too hot! Try kicking your max temp up to 220, I wouldn't extend the duration however. I would almost start to think that this QFP has a pb free finish. Let us know what happens Russ

qfp reflow problems

Electronics Forum | Thu Apr 15 16:07:37 EDT 2004 | barry

Hi there all, we are having problems with 2 qfp devices. grainy poorly reflowed solder joints. One 100 pin .5mm pitch, and one 64 pin .5 mm pitch . Both of these devices have a thermo pad on the back of them (pad area soldered to back of device)which

qfp reflow problems

Electronics Forum | Fri Apr 23 12:47:29 EDT 2004 | barry

I have increased my peak to 220, and Flow is better, but it still not quite a good fillet all around. The solder tends to kinda "bunchup" at the toe of the lead. If part is Pb free, would this affect adhesion and or flow?

qfp reflow problems

Electronics Forum | Fri Apr 16 08:49:07 EDT 2004 | Chris Lampron

Hi Barry, Your best course of action is to perform a thermal profile and determine exactly what the times/temps are in these locations. Try to match your profile to the recommendations of your solder paste. (Time between 130-160, Time over 183 and m

qfp reflow problems

Electronics Forum | Thu Apr 22 12:27:47 EDT 2004 | barry

I placed thermo's at 2 of the problem devices. Soak (time 150 to 180) 100 sec. Time above 180 =80 secs with 208 deg. peak. The solder appeared to flow at these pads, but little to no adhesion to the joint.Total time in oven was 5 min. All other joint

qfp reflow problems

Electronics Forum | Thu Apr 15 17:06:08 EDT 2004 | russ

What are your temps at the locations that you are having trouble with. We cannot tell anything by the zone settings of an oven. We need max temp, how long above liquidous etc.. a lot of times this symptom is due to too long of a soak at too high o

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