Thermal/Mechanical Modeling

Thermal Model

Thermal Modeling Software

OVERVIEW

To reduce product size, companies who are developing portable and hand-held electronic products are seeking solutions that will furnish more functionality within each device. Portable or hand-held electronics are a natural target for die usage. Digital cameras and camcorders, for example, must consider ease of use, lighter weight and performance. Telephones, pagers, personal communicators, palm top computers, industrial and automotive electronics, personal GPS, medical and diagnostic products, are all viable candidates for more efficient device miniaturization by using die (unpackaged).

Memory devices are the first commodity type products in the market to adapt CSP in high volume, however, DSP, controllers, CPUs and any number of application specific IC devices are also prime candidates for multiple die packaging.

This demand for smaller, higher density electronic products is increasing, which translates to more heat generation from the electronics and lower heat dissipation capability from the product. For example, a cellular phone's thermal energy is generated from electronic components during a call. The heat dissipation transfers heat to the mounting substrate as well as the housing of the phone. Thermal management becomes even more critical in larger applications. In every case, the critical issue is the operating temperature of any semiconductor junction within the circuit. If any of these device junctions are allowed to overheat, the product is likely to malfunction or fail.

With packaged devices the designer has well-established thermal metrics with which to guide his physical design. The most useful of these is the thermal impedance or thermal resistance of the package . . . expressed as theta junction-to-case or theta junction-to-ambient and rated in terms of 慢/W (degree centigrade rise in junction temperature per watt of dissipation produced by the device). This is convenient when using packaged parts but of little value when attempting to use either individual die or die stacks in the design of a multi-chip-module (MCM). Bare die, wafers or die stacks are not sold with thermal impedance specified.