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Method for mechanical BGA bumps

IP.com Disclosure Number: IPCOM000010174D
Publication Date: 2002-Oct-30
Document File: 4 page(s) / 46K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for mechanical ball-grid array (BGA) bumps. Benefits include improved reliability and improved performance.

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Method for mechanical BGA bumps

Disclosed is a method for mechanical ball-grid array (BGA) bumps. Benefits include improved reliability and improved performance.

Background

� � � � � BGA cracking can cause shorting after reliability testing during temperature cycles, shock, and vibration.

� � � � � Conventionally, a BGA package is connected to the motherboard (MB) through a solder (tin and lead) BGA joint (see Figures 1 and 2).

General description

� � � � � The disclosed method is a mechanical BGA bump. It does not offer any electrical connection, but it is very strong mechanically. Mechanical BGA bumps protect the conventional BGA because the mechanical bumps absorb most of the shear stress due to coefficient for thermal expansion (CTE) mismatch, shock, and vibration of the BGA package assembly.

        � � � � � A mechanical BGA is made of special polymers and can be cured during the BGA reflow process. As a result, the method does not requiring special processing steps.

� � � � � The key element of the method includes the addition of mechanical BGA bumps to the BGA package along with the conventional BGA solder joints.

Advantages

        � � � � � The disclosed method provides advantages, including:

•        � � � � Improved reliability due to defect prevention because of stress absorption

•        � � � � Improved performance due to solid/strong mechanical connections

Detailed description

� � � � � The disclosed method is a mechanical BGA bump (see Figure 3). Mechanical BGAs can be populated as required to different locations. For example, a sample configuration may have random distribution with the conventional BGAs (see Figure...