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November 2010

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Subject:
From:
Guy Ramsey <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Guy Ramsey <[log in to unmask]>
Date:
Thu, 11 Nov 2010 13:14:26 -0500
Content-Type:
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Ed, 
While the apparent hole fill might be 50%, and it is hard to judge the
attributes of the solder connection in the photos, 
I think I see other defects.

In the first image after the x-ray, I don't think there is evidence of
wetting to the lead. And the contact angle of the solder at both the lead
and the PTH appears to be much greater than 90 degrees. 

The second image is harder to evaluate but seems to have the same defects.

The third image, in my judgment, exhibits poor wetting between the lead and
the PTH for more than 90 degrees. Some of the solder joint looks normal. 

The fourth image is really blurry but I would argue that it is close to
insufficient vertical fill. 

Guy


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ed Popielarski
Sent: Thursday, November 11, 2010 11:26 AM
To: [log in to unmask]
Subject: Re: [TN] Pin in paste hole fill

Good Morning,

I've added a few photos at
http://ipc-technet.groupsite.com/galleries/photo/158694 of the resultant
non-wetting that is of concern should this exist on the hole wall.

Any comments?



Regards,

Ed Popielarski

Sr. Mfg. Engr.


NBS Corporation
2950 Patrick Henry Dr.
Santa Clara, Ca. 95054

Ph: 408-654-1100
Fx: 408-654-1107
Cl: 408-234-1497
Cl: 949-581-6601

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ed Popielarski
Sent: Wednesday, November 10, 2010 12:56 PM
To: [log in to unmask]
Subject: [TN] Pin in paste hole fill

 

Greetings 'netlings,

 

I present here http://ipc-technet.groupsite.com/galleries/photo/158694
an x-ray image of a pin-in-paste thru-hole connection, SAC305 with NC on
a .092" OSP SMT both sides assy with some very bothersome ground planes.

 

My concern is we are trying to achieve 50% hole fill and 610 makes an
assumption the hole is full from one side or the other. Our 5DX is happy
with this assumption as well. What we have here is >50% hole fill by
volume, however there is void in the middle of the joint caused by
gassing of the flux.  5DX doesn't like to so well.

 

We have had mixed results with wave and selective as the "techs" tend to
compensate hole-fill difficulties (primary root cause: oxidation) by
overexposure and causing Cu dissolution, sometimes to total annular ring
disappearance. 

 

My question is twofold:

 

Is 610 "interpretable" to accept >50% on Class 2 ground pins if the hole
fill is not continuous, i.e., 26% from top down and 26% from bottom up,
48% void in the center?:

 

I've noticed some holes have a "sausage" shape indicating the
possibility of non-wetted hole wall and we're simply "molding" the
solder into shape and not making an integral connection. If this is
possibly the case, is there any non-destructive test we can do to verify
integrity?

 

Now off subject: History of Electricity was awesome! I think there
should be a subchapter in the section on smoke theory to cover the
electrolytic confetti generator and the noise emitting diode.

 

 

Regards,

 

Ed Popielarski

 

Sr. Mfg. Engr.

 

 

NBS Corporation

2950 Patrick Henry Dr.

Santa Clara, Ca. 95054

 

Ph: 408-654-1100

Fx: 408-654-1107

Cl: 408-234-1497

Cl: 949-581-6601

 


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