Browse Prior Art Database

Solder Levelling with TEFLON Squeegee

IP.com Disclosure Number: IPCOM000105334D
Original Publication Date: 1993-Jul-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Kohli, A: AUTHOR [+2]

Abstract

Disclosed is a non contact method of levelling solder on a printed circuit board (PCB) with a precision machined TEFLON* squeegee. The squeegee wiping edge does not contact the PCB. The squeegee wiping edge is positioned at a distance that will allow it to contact only the excess solder bead. Experiments will determine what the optimum distance will be for each product type.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 100% of the total text.

Solder Levelling with TEFLON Squeegee

      Disclosed is a non contact method of levelling solder on a
printed circuit board (PCB) with a precision machined TEFLON*
squeegee.  The squeegee wiping edge does not contact the PCB.  The
squeegee wiping edge is positioned at a distance that will allow it
to contact only the excess solder bead.  Experiments will determine
what the optimum distance will be for each product type.

      A squeegee made out of teflon will be used to level solder on a
printed circuit board.  The wiping edge must be precision machined to
a smooth and straight surface.  Teflon is a material with high
thermal stability.  It will retain its shape even at elevated
temperatures.

      When a PCB is soldered in an immersion wave process, excess
solder remains on the pad in the shape of a sphere.  This is because
of the high surface tension of the solder.  The volume of excess
solder on the pad is dependent on the pad geometry, size, and surface
tension.

      The teflon squeegee which is a non-wettable material, will
knock the excess solder off the pad (see figure).  This is a more
control method since it is independent of the squeegee pressure.
Solder height will be more consistent and solder bridging will be
minimized since the solder will not spread from one site to another
as in a contact wipe system.

*  Trademark of E. I. Du Pont Nemours and Company