Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


QFP144 soldering problem

Views: 5901

#51653

QFP144 soldering problem | 5 September, 2007

hi,

I have a big problem with soldering uP QFP144 package.All components in PCB are small, only this chip is big and I can't make good temperature profile.Solder joints of other components are shining and with good wetting, but in QFP leads solder joint look poor and grey.I think, the problem is in the profile, try several profile but nothing.Our reflow have 9zones top znd bottom.Tne paste is kester R256 - Pb.If somebody can halp me I will be very grateful.

reply »

#51656

QFP144 soldering problem | 5 September, 2007

Questions are: * Do not judge the quality of a solder connection by the shineyness or color of the solder connection. Do you have smooth and unform flow, no pitting, and good wetting to the lead and the pad? * What is the temperature of the leads of this problem QFP144? * What do you mean by "QFP leads solder joint look poor."

reply »

#51726

QFP144 soldering problem | 10 September, 2007

Hi, the solder on the pad is not molt.Temperature of the leads is about 220*C( I change this T from 214 to 232) but result is same - solder is granular and not diffuse.I think the T on leads is not enough high,bu I can't increase because the max T on package should be 220*C.

reply »

#51727

QFP144 soldering problem | 10 September, 2007

How are you attaching your thermocouples to measure the temperature of the lead/pad connection?

reply »

#51733

QFP144 soldering problem | 11 September, 2007

HOW did you change the temp? Stay that course till you achieve the temp you need. Try slowing the conveyor as well.

reply »


RDR

#51777

QFP144 soldering problem | 13 September, 2007

switch pastes and see what happens, Kester had issues with their fluxes a little while ago and you may have gotten one of the bad batches.

R

reply »

#51782

QFP144 soldering problem | 13 September, 2007

should have ask the technical support personnel from Kester to come over to your factory and solve the problem on-site. Let them see what is wrong with their product, then they will improve it further....or straight away tell you they do not have solution and change to other paste...please....(I doubt they will say that....:))

reply »


RDR

#51791

QFP144 soldering problem | 14 September, 2007

you using a ramp soak spike or ramp to spike profile? you may be burning out your flux in preheat if you ramp to fast or for too long, most pastes have 2 activation points for their flux one at low temp and one at higher temp. Try a ramp to peak profile if you are not already and see what happens. Take max temp back to 215.

reply »

#51796

QFP144 soldering problem | 14 September, 2007

What is the surface finished of your board and what is the peak temp at your solder joint?

reply »

#51799

QFP144 soldering problem | 15 September, 2007

Hi,

I attach the termocouples with high temperature solder wire, at the QFP pins.Other thermocople I attach at package with high temperature tape.

reply »

#51801

QFP144 soldering problem | 15 September, 2007

220 should be plenty although if they're lead free you might need a little more heat. Is it possible that you've got a paste volume issue (stencil design, clogged apertures), or maybe the footprint isn't right for the part?

I had this same problem with a QFP 100 a while back and it was due to both of those issues, primarily the layout.

reply »

#51803

QFP144 soldering problem | 17 September, 2007

hi,

finishing is lead free HAL, Tpeak=214-232*C in diferent profile, wich we made.

reply »

#51900

QFP144 soldering problem | 25 September, 2007

Hi, we change Kester with Interflux and all it is OK.The problem was paste Regards

reply »

Lead Free Wave Solder - 1 Click SMT

Manufacturing Software