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Ball Grid Array Pad with Peripherals Via for Air Burst Passage

IP.com Disclosure Number: IPCOM000101563D
Publication Date: 2005-Mar-16
Document File: 2 page(s) / 49K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method that modifies the current via in-pad location and structure to reduce voids in the ball grid array (BGA) during the reflow process. Benefits include improving the ball joint and the solderability between the pad and the ball.

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Ball Grid Array Pad with Peripherals Via for Air Burst Passage

Disclosed is a method that modifies the current via in-pad location and structure to reduce voids in the ball grid array (BGA) during the reflow process. Benefits include improving the ball joint and the solderability between the pad and the ball.

Background

Often when a board passes through reflow, air bubbles are trapped inside the via in the pad, then expand and burst inside the BGA ball. This creates voids which can cause improper connections between the balls and the pad (see Figures 1 and 2). Currently, there is no acceptable solution to the problem; however, a ā€œCā€ shaped solder pad can be used to eliminate the air bubble trapped inside the via in pad. This changes the original ā€œOā€ shape solder pad, and can result in increased costs for changes made to the existing machine setup and configuration.

General Description

The disclosed method moves the current via in-pad location to the edge of the pad itself. This location, with a third of the diameter outside of the pad, provides a passageway to the air bubble so that it can flow freely from the via hole; this will prevent the creation of voids inside the BGA balls. No additional or different solder pad machine configurations are needed for the disclosed method. The only change made to the machine is allowing drilling at the edge of the pad, instead of in the middle of the pad (see Figure 3).

Advantages

The disclosed method improves the ball joint and...