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November 2010

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Subject:
From:
Ed Popielarski <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Ed Popielarski <[log in to unmask]>
Date:
Wed, 10 Nov 2010 12:55:49 -0800
Content-Type:
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text/plain (101 lines)
 

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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