Browse Prior Art Database

Heatsink Attachment for Improved Electro-Magnetic Compatibility and Shock Performance

IP.com Disclosure Number: IPCOM000115136D
Original Publication Date: 1995-Mar-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 4 page(s) / 116K

Publishing Venue

IBM

Related People

Corbin, JS: AUTHOR [+3]

Abstract

Disclosed is a method of attaching an overhanging heatsink to a module (processor) which provides the following advantages: 1. A good thermal path between the heatsink base and module cap is maintained due to a constant preload provided by the spring clip. This compliant attachment of the heatsink to the module also accommodates the dimensional variations of the module height. Additionally, the clip static preload can be sized so as not to overload the card-level solder joints (balls, columns, etc). 2. The attachment design allows easy removal of the heatsink and frame to provide access to adjacent components or devices (e.g., for rework) that are beneath the overhanging portion of the heatsink.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Heatsink Attachment for Improved Electro-Magnetic Compatibility and
Shock Performance

      Disclosed is a method of attaching an overhanging heatsink to a
module (processor) which provides the following advantages:
  1.  A good thermal path between the heatsink base and module cap is
       maintained due to a constant preload provided by the spring
clip.
       This compliant attachment of the heatsink to the module also
       accommodates the dimensional variations of the module height.
       Additionally, the clip static preload can be sized so as not
to
       overload the card-level solder joints (balls, columns, etc).
  2.  The attachment design allows easy removal of the heatsink and
       frame to provide access to adjacent components or devices
(e.g.,
       for rework) that are beneath the overhanging portion of the
       heatsink.  Ease of assembly is also an advantage from a
       manufacturing cost viewpoint.
  3.  The amount of radiated electro-magnetic energy is reduced by
       providing a good ground path between the heatsink and the
ground
       plane of the circuit card.
        The frame restricts lateral motion of the heatsink and
       transmits lateral shock loads through the frame and into the
card,
       thereby increasing its lateral shock tolerance.  Additionally,
       the metal frame provides additional rigidity to the card in
the
       vicinity of the module, which reduces the susceptibility to
shock
       loads that are normal to the plane of the card.

      An exploded assembly drawing is shown in Fig. 1, which consists
of the card, module, frame assembly, anhd heatsink/clip assembly.
The module is surface-mount attached to the card using standard
assembly practices.  After attachment of the module to the card, the
frame assembly is installed by snapping it into the card through four
holes that are drilled in the vicinity of the corners of the module.
These holes are located in pads which are electrically connected to
the ground planes in the card.  the frame assembly is detailed in
Fig. 2, and consists of a stamped and formed metal frame with a
central hole that allows protrusion of the module thr...