Publishing Venue
The IP.com Prior Art Database
Abstract
Disclosed is a method that uses a restrainer clip with an optimized force to help reduce package co-planarity during the underfill epoxy cure process. Benefits include a solution that can be modified for a variety of packages.
A Restrainer Design and Force Definition
for Substrate Warpage Control
Disclosed is a method that uses a restrainer clip with an
optimized force to help reduce package co-planarity during the underfill epoxy
cure process. Benefits include a solution that can be modified for a variety of
packages.
Background
Currently, excessive outgoing co-planarity causes open
contact or high resistance between the substrate and the socket. Intensive design of experiments have concluded that the epoxy
underfill process in the flip chip technology is responsible for the higher
substrate co-planarity, due to high curing temperatures.
General Description
The disclosed method controls and improves package
co-planarity by using a restraining clip during the underfill epoxy cure
process. The disclosed method improves package co-planarity without affecting
the substrate quality or reliability.
Figure 1 shows the restrainer process beginning once the
epoxy dispenser module finishes. The standard Integrated Heat Spreader (IHS)
link attaches the restrainer clip onto the metal carrier. All substrates are
restrained for co-planarity before moving into the epoxy cure oven. Lastly,
restrainer clips are removed using the standard IHS removal link before moving
to the end of the line process (such as test and ball attach). Figure 2 shows
the restrainer clip design, which consists of the restrainer bridge with a leaf
spring pressured onto the restrainer clip. Figures 3 and 4
show two different restrainer cl...