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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Jack Coia

#11790

Discoloured soldermask | 22 April, 1999

On various PCB's after building processes,such as reflow, flowsolder and wash. The soldermask on the PCB's have become discoloured, like a 'marble' effect all along the solder side of the board, it is lighter in contrast than normal, although when other added comps. are assembled and handsoldered afterwards the soldermask seems to return to its normal darker colour around the solder joints where the heat from the iron has been applied. There has been no prominant changes in our processes, not sure where to start trouble shooting or whether it is a PCB manufacturing issue involving problems with curing soldermask.

Your help would be appreciated, thanks in advance.

Jack

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Ben Kirk

#11791

Re: Discoloured soldermask | 22 April, 1999

| On various PCB's after building processes,such as reflow, flowsolder and wash. The soldermask on the PCB's have become discoloured, like a 'marble' effect all along the solder side of the board, it is lighter in contrast than normal, although when other added comps. are assembled and handsoldered afterwards the soldermask seems to return to its normal darker colour around the solder joints where the heat from the iron has been applied. There has been no prominant changes in our processes, not sure where to start trouble shooting or whether it is a PCB manufacturing issue involving problems with curing soldermask. | | Your help would be appreciated, thanks in advance. | | Jack | Sounds to me like the board is delaminating with the heat. But I don't understand why it would return to normal. I would defiantly talk to the manufacturer of the PCB.

B.K.

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#11792

Re: Discoloured soldermask | 22 April, 1999

| On various PCB's after building processes,such as reflow, flowsolder and wash. The soldermask on the PCB's have become discoloured, like a 'marble' effect all along the solder side of the board, it is lighter in contrast than normal, although when other added comps. are assembled and handsoldered afterwards the soldermask seems to return to its normal darker colour around the solder joints where the heat from the iron has been applied. There has been no prominant changes in our processes, not sure where to start trouble shooting or whether it is a PCB manufacturing issue involving problems with curing soldermask. | | Your help would be appreciated, thanks in advance. | | Jack | Jack: I cast my vote for uncured solder mask. TTYL Dave F

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Tom B.

#11793

Re: Discoloured soldermask | 22 April, 1999

| On various PCB's after building processes,such as reflow, flowsolder and wash. The soldermask on the PCB's have become discoloured, like a 'marble' effect all along the solder side of the board, it is lighter in contrast than normal, although when other added comps. are assembled and handsoldered afterwards the soldermask seems to return to its normal darker colour around the solder joints where the heat from the iron has been applied. There has been no prominant changes in our processes, not sure where to start trouble shooting or whether it is a PCB manufacturing issue involving problems with curing soldermask. | | Your help would be appreciated, thanks in advance. | | Jack |

Jack,

Does the discolor have a milky appearence underneath the solder mask? If use hot air or solder iron the color will return (white diappears).

By chance are you using a Kester 2331 zx water soluable flux? Do PCBs have a Taiyo brand soldermask? If so you may be having a chemical reaction with mask, flux, and wash.

Check the archives for "white layer appearance on soldermask"

Happy Hunting!

Tom B.

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#11794

Re: Discoloured soldermask | 22 April, 1999

| | On various PCB's after building processes,such as reflow, flowsolder and wash. The soldermask on the PCB's have become discoloured, like a 'marble' effect all along the solder side of the board, it is lighter in contrast than normal, although when other added comps. are assembled and handsoldered afterwards the soldermask seems to return to its normal darker colour around the solder joints where the heat from the iron has been applied. There has been no prominant changes in our processes, not sure where to start trouble shooting or whether it is a PCB manufacturing issue involving problems with curing soldermask. | | | | Your help would be appreciated, thanks in advance. | | | | Jack | | | | | Jack, | | Does the discolor have a milky appearence underneath the solder mask? If use hot air or solder iron the color will return (white diappears). | | By chance are you using a Kester 2331 zx water soluable flux? Do PCBs have a Taiyo brand soldermask? If so you may be having a chemical reaction with mask, flux, and wash. | | Check the archives for "white layer appearance on soldermask" | | Happy Hunting! | | Tom B. | Tom: I too have seen a lot of boards lately with improper looking solder mask that have turned-out to be Taiyo mask. Most often it has a glossy surface. And you're correct that the lighter color will "disappear," if you heat it. But, this temperature is not sufficient to cure the mask. Send the boards back to the fab house for replacement. TTYL Dave F

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