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Method for a nonconductive restrainer to prohibit solder shorting to surface-mount components in semiconductor assemblies

IP.com Disclosure Number: IPCOM000033141D
Publication Date: 2004-Nov-29
Document File: 6 page(s) / 111K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for a nonconductive restrainer to prohibit solder shorting to surface mount components in semiconductor assemblies. Benefits include improved functionality, improved performance, and improved yield.

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Method for a nonconductive restrainer to prohibit solder shorting to surface-mount components in semiconductor assemblies

Disclosed is a method for a nonconductive restrainer to prohibit solder shorting to surface mount components in semiconductor assemblies. Benefits include improved functionality, improved performance, and improved yield.

Background

              Semiconductor package designers continue to increase package density. However, conductive thermal interface materials (TIMs) typically spread beyond the boundary of the die. Large keep-out zones are required to prevent bridging between the solder TIM material and the surface-mount components. This problem is not solved. Shorting between the TIM and the die-side components is detected during electrical test, resulting in a yield loss.

              Die-side components include surface-mount technology (SMT) devices, such as:

•             Capacitors

•             Resistors

•             Voltage regulators

•             Diodes

              Conventionally, the heat spreader is attached directly to the substrate. The stack includes (see Figure 1):

•             Heat spreader

•             Substrate

•             Silicon die

•             Surface-mount components

•             TIM

              The TIM spread is not limited (restrained). Spread of the conductive material may result in a short to the surface-mount component. The shorting is detectable by electrical testing, acoustic imaging, x-ray imaging, and other imaging techniques or destructive tests.

General description

              The disclosed method is a solder-spread restrainer to prevent the shorting of the electrically conductive TIM to die-side surface-mount components.

              The key elements of the method include a semiconductor assembly package containing:

•             Substrate

•             Silicon die

•             Die-side surface-mount components

•             Integrated heat spreader (IHS)

•             Thermal interface material

•             Retention mechanism

Advantages

              The disclosed method provides advantages, including:

•             Improved functionality due to enabling the placement of surface-mount components closer to the silicon, resulting in a reduction in size of the substrate and/or size of the heat spreader mechanism

•             Improved performance due to limiting solder spread and isolating the surface mount components from the conductive TIM

•             Improved yield due to eliminating the solder shorting of the TIM to surface mount components

•             Improved cost effectiveness due to reducing the size of the substrate and/or size of the heat spreader

Detailed description

 

              The disclosed method adds a dielectric material between two conductive elements to prevent electrical shorting. The method may be compared to the application of a solder resist on a substrate that prevents shorting between adjacent electrical traces or pads, or an insulator that surrounds a copper wire connector, such a...