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White residue after solder mask develope!!!

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Hieu.le

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Hello, my name is Hieu. I'm a process engineer of PCB manufacturing company.

We have an issue about white residue on pad. When we doing solder mask and run developer. We check again see the white residue.

Anybody have an opinions about this issue ?

Picture below
78921959_446217686021435_3293055626044768256_n.jpg 79813617_1134948780230261_6682186784283033600_n.jpg
 

Hi,

What exactly do you mean?

Add some marks on the pictures.

Klaus
 

I think they mean the uneven surface after plating, you can just see it against the gold. I suspect this is the underlying copper being uneven and the gold plating just makes it more obvious. Nothing to worry about.

Brian.
 

Photo resolution is too low to see details. Would prefer a microscope photo with diffuse lighting.

To me, the pad surface looks partly like silver metallic rather than white. What's the gold process? If it's nickel-gold, could it be that the final gold layer is damaged?
 

Hi Klaus

as you can see, on the Annula Ring, we have some white residue, I mark on picture below. It's happen when we do solder mask -> exposure -> cure (enough time) -> develop soldermask -> test (we find the residue at this step.

this residue some time can be cleaned by gently wiping, some time it's can not clean and we have to remove all the solder mask and do it again. Because this white residue, when we do next step (do reflow, it's cannot be welded).

This is the terrible issue that we have met.

78921959_446217686021435_3293055626044768256_n.jpg

Hieu
 

I think they mean the uneven surface after plating, you can just see it against the gold. I suspect this is the underlying copper being uneven and the gold plating just makes it more obvious. Nothing to worry about.

Brian.

Hi Brian

it's not the problem with the plating. As i noted above. I send you picture with a mark, picture below. You can see it's has a white residue on annular ring. The process is : Clean acid -> do Solder mask -> exposure -> cure (enough heat and times) -> develop -> test (we find the white residue at this step).

It's very serious. because if we have this white residue, when we do next step we can not do reflow, can not be welded.

Hieu
 

Photo resolution is too low to see details. Would prefer a microscope photo with diffuse lighting.

To me, the pad surface looks partly like silver metallic rather than white. What's the gold process? If it's nickel-gold, could it be that the final gold layer is damaged?

Hi FvM

Thank you for your reply. Sorry with the picture, I think it's clear enough to see the white residue. I send a picture with a mark, picture below. It's not from plating, we have no damaged with the gold plating.

the process is : Clean with acid -> do solder mask -> exposure -> cure (with enough heat and times) -> develop -> test (we found the white residue at this step)

this is the serious issue. Because if we have the white residue we can not do the next step ( reflow.. it's cannot be welded).

78921959_446217686021435_3293055626044768256_n.jpg


Hieu
 

I think they mean the uneven surface after plating, you can just see it against the gold. I suspect this is the underlying copper being uneven and the gold plating just makes it more obvious. Nothing to worry about.

Brian.

78921959_446217686021435_3293055626044768256_n.jpg

picture with the mark. thank your reply
 

Hi,

Not at all, I fear.
I have to agree.

I see a bright - almost white part at the hole --- I think this just is the reflection of the light.

Klaus
 

Hi,


I have to agree.

I see a bright - almost white part at the hole --- I think this just is the reflection of the light.

Klaus

We have many many prolem with this white residue
it's not a bright
You can see, that white color on the annular ring. That the white residue.
 

Not at all, I fear.

Sorry again about the picture
But we have many many problem with this white residue . You can see, that white color on the annular ring. That the white residue.
 

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