Hi Thad,

Q.  Is there an industry term for this type of reflow.  I've heard
     it referred to as "intrusive reflow".  Since I love catchy names, I'm
     soliciting one.
A: This process is commonly called Pin-in-Paste (PIP), Pin-in-Hole or 
Intrusive soldering. The appearance of the solder joint depend on a number 
of factors

Q.  Is the technique in widespread practice in the industry or is
it new?
A: Numerous papers have been published on this subject.
Refer  to  1994 SMI proceeding
     P.363- Bill Barthel from EAC
     P.333- Tom Gervascio from Group Tech.

Q.  Any comments on the reliability of such a solder joint.
A: Provided the hole fill requirements are met per IPC-A-610 & 
J-standard-001 , the reliability of reflow joint should be the same as any 
wave soldering joints.

Q.  Do standards (IPC or otherwise) exist that describe a "good"
joint and a "bad" joint.  I'm interested in IPC Class II product.
A:  Please refer to IPC-A-610

Q.  Are there any tricks of the trade in designing boards for this
      type of assembly.  For example do I need to use modified (i.e.
      smaller) thermals on my through holes to insure good reflow.
A:  The success of this process depends on the following factors:
     * Stencil Design (aperture, thickness)
     * Board Thickness
     * Component Location
     * Component Standoff
     * Hole to lead aspect ratio
     * Thermal constraint of PTH part
     * Retention Mechanism (For double sided reflow)
     * Location of PIP parts
     * Print Parameters

Q.  Are there special processing techniques in assembly that will
produce good joints.  Example - screening paste on both sides or
using special pastes.
A: Depend on the amount of hole fill you can achieve, I don't think the 
solder joint created by this process is rejectable by IPC-A-610B. Screen 
paste on both side is not the best way achieve good hole fill, because the 
air trape in between might cause problem at reflow.

Q.  How can these joints be non-destructively evaluated since they
can't be seen other than microsection.  Do periodic destructive
tests need to be done per an AQL.
A: X-Ray and visual inspection would be a good start.  Based on your 
founding of X-Ray, you will be able to determine the need for microsection.

Q.  I'm aware that any through hole components that use this
      technique must be made of high temperature material to withstand IR,
     but are there any other restrictions regarding what type of
     components this assembly technique can be used for.
A: You need to ensure your PTH part can at least survive the reflow temp.  ( 
Temp.: 220 C for 60 s) Check with your supplier first !

If you have access to Internet, Check out the AMP site:
http://WWW.amp.com

Hope this Helps
Michael Yuen

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