Dear Lance:

 

My sincere apologies for not getting back to you. It was not intentional. My computer became infected and I had to have the hard drive reformatted while I was away on a training assignment. As a result, I didn’t get a chance to check my email for about a week. I just got back on-line yesterday.

 

I saw your request on TechNet and think you got some very good replies. Both Dave Chapman and Bev Christian I respect their experiences and comments a great deal. I would suggest you go with their opinions.  

 

Some of the responders referred to them as disturbed which would be a defect for Class 1, 2 and 3 per 9.2.4.2. This is where the Standards do become subjective. There is a difference between disturbed “stress lines” and lines of demarcation at the juncture between the existing solder and new solder. I agree with the comments that solder is not required to spread to the very end of the pads/lands.

 

So it comes down to how you interpret the lines in the solder connection whether disturbed or simply “not pretty”. If you have a lot of product being produced this way, you could microsection this connection and have a metallurgist examine it for a final determination. A disturbed solder connection is one where the solder molecules have not had an opportunity to properly align during the cooling process. Therefore, the resulting wetting may be suspect.

 

The down side of solder connections is that we infer the internal wetting to the surfaces being joined (and intermetallic bond between these two surfaces) by simply examining the external surface conditions.

 

I hope these comments have be of some assistance to you.

 

Sincerely,

 

 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Lance Mayes
Sent: Tuesday, September 02, 2003 12:16 PM
To: [log in to unmask]
Subject: [TN] pic's
Importance: High

 

I have attached some pictures of components that always seem to have one joint that is not soldered as the other end.  These happed mainly with this component at various sites on the board.  Is this a contamination a disturbed joint or a cold joint.  This is an SMT process and the problems vary
on the runs.  I would like to know if this is a defect for class 2 or not.

Thanks in advance for your time.


                       P.  Lance Mayes
                       Mfg. Trainer
----- Forwarded by Lance Mayes/CO-GRA/Ametek on 09/02/03 01:07 PM -----

Howard Watson 08/27/03 05:33 PM

To:        Lance Mayes/CO-GRA/Ametek@Ametek         cc:                 Subject:        pic's

Howard Watson
SMT Manufacturing Engineer
AMETEK/Dixson