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Browse Prior Art Database

Improved Fillets for Solder Ceramic Carrier

IP.com Disclosure Number: IPCOM000106852D
Original Publication Date: 1993-Dec-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Caulfield, R: AUTHOR [+5]

Abstract

Solder columns placed on a ceramic carrier (SCC) are sheared to a uniform height after being attached by eutectic solder reflow. While assuring uniform lengths, this process leaves a less than optimum surface on the pin tip for fillet formation in the ensuing solder operation. A process to provide a spherical tip without sacrificing uniform lengths is provided below.

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Improved Fillets for Solder Ceramic Carrier

      Solder columns placed on a ceramic carrier (SCC) are sheared to
a uniform height after being attached by eutectic solder reflow.
While assuring uniform lengths, this process leaves a less than
optimum surface on the pin tip for fillet formation in the ensuing
solder operation.  A process to provide a spherical tip without
sacrificing uniform lengths is provided below.

      The carrier is placed on a fixture with the columns facing up.
The fixture is made of a suitable material that allows the heat
applied to the column tips to travel to the fixture and be removed by
a water cooled path.  The fixture is placed on a linear motion slide
with a variable speed controller.  A controlled amount of flux is
applied to the column tips using an "ink pad" type fluxer.  A HAT
(hot air thermode) with a nozzle opening slightly longer than the
width of the column array is lowered to allow clearance with the
column tips.  The thermode control temperature was set to
approximately 700ºC and a sufficient gas flow of nitrogen was
set.  By varying the speed control of the linear slide, a process is
established to change the flat column tip to the desired
(hemispherical) shape of the column tip described above.  By varying
travel speed, thermode temperature, thermode separation from the
carrier, and the flow rate of the nitrogen gas, a process can be
tailored for different column lengths.