Thank you Inge for the insight.
We are currently running more test on a bare board to try to determine if 
it came from the assembly process or the PCB fabrication process, as you 
have just indicated..
Can you elaborate on what may have occurred to be improper in the copper 
etching process?

Thank you again for your response.

Tom Burek, CID+




Hernefjord Ingemar <[log in to unmask]> 
Sent by: TechNet <[log in to unmask]>
11/22/2007 02:03 AM
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Re: [TN] Green Growth between PCB traces






Puligandla Viswanadham describes this as 'blooming' and/or 'copper 
nodules' in his book 'Failure Modes and Mechanisms in Electronic 
Packages'. The phenomenon is caused by improper copper etching. It's very 
serious a matter. Boards like that should be rejected and never used, 
because the insulation resistance between the traces will sooner or later 
be unacceptable. The green stuff is not pure Copper but Copper salts and 
are highly mobile ions.
/Inge 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Tom Burek
Sent: den 14 november 2007 18:44
To: [log in to unmask]
Subject: [TN] Green Growth between PCB traces


Hello everyone,
Has anyone ever seen or experienced the phenomenon of this green growth 
between the traces and even on some of the pads.
It almost appears as if it is leaching out from under the etchback of the 
traces into the space between the traces. 
Oddly enough it is only on one side of the board, the bottom side, 
opposite the component side.
It will not wash off with DI or Alcohol and a Q-tip, however it will scrub 
off with a stiff bristle brush or very gently with an exacto knife.
The soldermask is very thin in spots, (white solder mask).

The PCB is ENIG with white soldermask.  FR4 material (IPC-1401/21).
The boards had just gone through HALT testing, (Thermal Shock: 2 hrs. @ 
85°C then 2 min. 5 sec. swing to  -40°C for 2 hrs. This was repeated until 
it failed after 136 hrs.) We think this green stuff might have caused the 
failure. 
 With the temperature swings, often there is condensation created so, 
possibly created by humidity? 
Is there something in the PCB fabrication process that could have lay 
dormant until it experienced thermal shock?

I know an analysis of the green stuff is necessary, but I was wondering if 
anyone has ever seen of experienced this type of growth before.

Thank you in advance.

I have attached some pictures, but I know somehow they are suppose to get 
to Steve to post. 



Tom Burek, CID+

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