Browse Prior Art Database

Solder Decal

IP.com Disclosure Number: IPCOM000104733D
Original Publication Date: 1993-May-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 1 page(s) / 52K

Publishing Venue

IBM

Related People

Hayden, TF: AUTHOR [+3]

Abstract

Disclosed is a device for producing controlled amounts of solder which can then be applied to an electronic carrier. This device, termed a solder decal, is particularly well suited for fine pitch patterns such as those encountered with direct chip attach

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This is the abbreviated version, containing approximately 59% of the total text.

Solder Decal

      Disclosed is a device for producing controlled amounts of
solder which can then be applied to an electronic carrier.  This
device, termed a solder decal, is particularly well suited for fine
pitch patterns such as those encountered with direct chip attach

(DCA) or tape automated bonding (TAB) assemblies (e.g., less than 16
mil pitch).

      In the typical process for producing solder decals, a metallic
carrier is chosen which 1) can be plated with the desired solder
metal lurgy composition, typically eutectic tin/lead, and 2) is dewet
by the solder during the time of melting or reflow permitting the
solder to be transferred to the discrete solder-wettable pad patterns
on the circuit carrier.  For eutectic tin/lead, the carrier is
typically stainless steel, aluminum, or titanium.  Photoresist is
then applied to the carrier, imaged with actinic radiation through a
mask, and developed to produce a pattern of holes or openings which
corresponds to the foot print of the electronic device to be
attached.  Solder is then electro plated into these cavities.

      Prior to removal of the photoresist, a planarization or sanding
step is employed to remove solder asperities which extend above the
height of the photoresist.  If not removed, these asperities can
prevent good contact between the decal and carrier, limiting solder
transfer, or causing bridging of solder between pads on the carrier
during solder reflow.

      Once planarized, the p...