Browse Prior Art Database

Thermal Adhesives as Replacements to Mechanical Fasteners in Power Electronics

IP.com Disclosure Number: IPCOM000021892D
Publication Date: 2004-Feb-16
Document File: 3 page(s) / 3M

Publishing Venue

The IP.com Prior Art Database

Abstract

In today's competitive environment, manufacturers need to find out innovative ways to meet market demands of high power densities in shrinking enclosure sizes. These demands require efficient designs for heat transfer and its dissipation, for product life and reliability. Reduction in overall dimensions of enclosures requires engineers to work at higher component frequencies and hence higher power dissipation per unit area. In order to take care of component life when its operating at high cycles per minute, heat needs to be taken out quickly and effectively.

This text was extracted from a Microsoft Word document.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 53% of the total text.

Paper Title:

Thermal adhesives as replacements to mechanical fasteners in Power Electronics

Abstract:

In today's competitive environment, manufacturers need to find out innovative ways to meet market demands of high power densities in shrinking enclosure sizes. These demands require efficient designs for heat transfer and its dissipation, for product life and reliability. Reduction in overall dimensions of enclosures requires engineers to work at higher component frequencies and hence higher power dissipation per unit area. In order to take care of component life when its operating at high cycles per minute, heat needs to be taken out quickly and effectively.

Thermal engineers always prefer to have low thermal impedance interface material for low interface resistance to heat transfer and mechanical fasteners are used for appropriate pressure build up between the two surfaces. For interface material selection choice is available from wide variety like thermal greases, PCMs, thermal adhesives, adhesive tapes, pressure sensitive pads, gap pads etc.

Again these materials can further be subdivided based on their composition. Normally Aluminum Oxide and Boron Nitride are used as fillers for imparting thermal conductive properties to these fillers. Silver, diamond and graphite are used for high end products.

Since there is always a scarcity of room on board, to reduce the footprint of components, components are normally mounted in vertical positions using mechanical fasteners as shown in figure below.

This traditional method of fastening has been in use for overall packaging and mounting the power devices onto heat sink for very long time. Mechanical fasteners provide cheap and simple to install method of assembly along with thermal interface materials (TIM). But the component part count adds to the disadvantage because of use of pins, nuts, clips, washers and screws. Additionally when electrical isolation is required, extra plastic parts are added resulting in further increase in number of components and further scarcity of space. The TIM used are pressure sensitive and minimum pressure needs to be ensured between mating surfaces for full life span of the product. Special care is required for design using mechanical fasteners for automotive applications to make withstand vibrations w...