> What kind of hole-fill did you get?   The hole (barrel) was completely
> filled with solder from the top to the bottom side of the PCB (.062"
> thick), and there was good wetting up the sides of the connector pin on
> both sides as well.  The through-hole connector has square leads that are
> .0155" thick.  The hole size on the PCB is .036".  The stencil has .0915"
> oblong apertures and is .006" thick (due to fine pitch parts on the
> board).  When I set-up the screen print process I used a slow squeegee
> stroke (20mm/sec), and extra squeegee pressure (instead of 7kg/in for a
> 14" blade 9kg/in.) in order to force more solder into the hole.  When the
> connector (lead length .0885") is installed the lead protrusion on the
> back side is only about .025" (+/-.001).

      The solder fillet on the top and bottom of the board was 360 degree
solder fillet all                         the way around the lead with
excellent wetting characteristics up all sides of the       connector pin.
      I had no solder balling issues.  The hard part was installing the
through hole       connectors without disturbing the fine pitch surface
mount devices that were       already placed.  This particular through hole
connector has guide pins that snap       into place and if the PCB was not
supported correctly during the connector             installation process
then the fine pitch devices shifted and we had misalignment       problems.
Once proper board support was provided this problem was eliminated.

      I do agree with the other gentleman who mentioned that a small lead
protrusion on                        the back side of the board is critical
in order for PIH to work, but I am not sure             where that cut off
point would be.  All of the boards I have set-up for PIH have the
same lead length/lead protrusion, and our process has always worked without
a                                     glitch.  This could explain my false
sense of euphoria.

      Hope this helps.

       Thanks,
       Kathy Palumbo


> ----------
> From:         Yves Trudell[SMTP:[log in to unmask]]
> Sent:         Friday, April 10, 1998 8:29 AM
> To:   [log in to unmask]
> Subject:      PIH
>
> Kathy, I read your note on the TechNet. You mentioned that you had good
> wetting on both sides when you used paste-in-hole. What kind of hole-fill
> did you get? That is, was all of the barrel filled with solder, where
> solder
> wicked to the tip of the pin on the back side of your pcba?  When we
> switched to PIH, that was one of our concerns, barely being able to see
> the
> solder from the bottom side of the pcba, which fought against too much
> paste
> on the topside which ran the risk of top-side solder balls.
>

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