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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


ENIG (thru hole ring turns black after wave soldering)

Views: 6101

#75879

ENIG (thru hole ring turns black after wave soldering) | 15 June, 2016

Anybody see this kind of reject. The thru hole ring turns black (certain area) after wave soldering. The affected area cannot be soldered. Manual touh up is also not possible.

Anybody what is the cause of this?

Any lab test to prove what is the item that prevent soldering?

Attachments:

reply »

#75914

ENIG (thru hole ring turns black after wave soldering) | 27 June, 2016

From the pic, it looks like you have a bad board; ENIG process issue. It used to be called black pad for SMT but I'm sure it's the same condition for T/H.

Any good electronic lab should be able to id the black stuff. I would also send raw boards back to the supplier along with this picture.

my2cents

Good luck.

Mufflerbearings

reply »

#75917

ENIG (thru hole ring turns black after wave soldering) | 30 June, 2016

Looks like "black pad" issue. More about this here:

http://www.ipc.org/feature-article.aspx?aid=Black-pad

Definitly PCB supplier need to improve the process.

reply »

#75934

ENIG (thru hole ring turns black after wave soldering) | 5 July, 2016

As my fellow members are saying this is a bad mfg process, you need to talk to your supplier to see if theres something contaminating the ENIG plating, this is a very critical issue you must act on it before some problems arise in the field where can be problematic to your product.

cheers

reply »

#76098

ENIG (thru hole ring turns black after wave soldering) | 2 August, 2016

ASPIS (Advanced Surface Protection for Improved Reliability PCB Systems) The three year Aspis ‘Research for SMEs’ project has been conducted to address problems found with the nickel gold (ENIG) solderable finishes that are used by the electronics industry to enable components to be soldered to printed circuit boards (PCBs). ENIG has several key advantages over other types of PCB solderable finishes and these are highly significant, making ENIG the preferred choice for many applications. However, while ENIG coatings have a good reputation for excellent solderability, they are also prone to a number of well known reliability problems, such as ‘black pad’, whose formation mechanisms were still poorly understood. [http://cordis.europa.eu/result/rcn/153841_en.html].

reply »

#76099

ENIG (thru hole ring turns black after wave soldering) | 2 August, 2016

On a previous black pad experience we soldered a wire to a fiducial and did a pull test to failure. On the black pad board the wire and solder pulled of clean leaving the fiducial on the board. On good boards the copper came off with the wire. If you have local fiducials you can get a reading near your BGA. Ultimately everything in that board lot will have the issue despite wishful thinking that something can be done to fix things. [Don Adams, Bose Corp, USA]

reply »

#76203

ENIG (thru hole ring turns black after wave soldering) | 22 August, 2016

analysis report is as attached. Pls let me know what you think of the root cause of this issue?

Can i conclude this is a black pad at thru hole ring with a root cause of contaminated gold

Attachments:

reply »

#76204

ENIG (thru hole ring turns black after wave soldering) | 22 August, 2016

i also notice the carbon and oxygen is high on the defect? Why is that?

reply »

#76214

ENIG (thru hole ring turns black after wave soldering) | 24 August, 2016

I'd guess that "black pad" is not the issue that you need to address, because only 2 of your 5 test points has the problem that we seem to be discussing. I'd expect "black pad" problems to be more wide spread. Something is going on at those two locations that is making a mess of things.

Is there a pad at those locations? I'm wondering if the organics that you're seeing are from the bare board.

reply »

#76254

ENIG (thru hole ring turns black after wave soldering) | 29 August, 2016

As an OEM repiar tech I would run into "Black Pad" on occasion, though mostly on surface mount pads.

The only way I could remove the oxidation was to apply water soluble flux and add solder, then wick away the excess. This left me with a suitable surface to solder down parts.

reply »

SMT Equipment

reflow oven profiler