Browse Prior Art Database

Package with Varied Size Back Solder Resist Opening for Solder Ball Co-Planarity Improvement

IP.com Disclosure Number: IPCOM000101545D
Publication Date: 2005-Mar-16
Document File: 2 page(s) / 184K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method that varies the back solder resist opening (B-SRO) to improve solder ball co-planarity. Benefits include a solution that does not require additional process steps or process costs.

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 67% of the total text.

 

Package with Varied Size Back Solder Resist Opening for Solder Ball Co-Planarity Improvement

Disclosed is a method that varies the back solder resist opening (B-SRO) to improve solder ball co-planarity. Benefits include a solution that does not require additional process steps or process costs.

Background

Co-planarity measurement consists of solder ball true position and height. By measuring the height of each ball, the plane of the average ball height is calculated. The maximum deviation of ball height to this plane is called co-planarity.

Component co-planarity is an important issue for components with large form factors, or large die sizes. Insufficient co-planarity prevents the components from meeting outgoing JEDEC specifications, and produces significant yield loss. To avoid this problem:

§         A restrainer solution is implemented during the UF process; however, this increases assembly TPT, equipment purchases and installation, and indirect materials.

§         Potential substrate core material changes are made; however this increases PTH density or micro-via density, which can impact costs and performance.

General Description

The disclosed method uses SRO size to varied the ball height at different sectors of the component. Conceptually, SRO in the center is reduced, while SRO at the peripheral is increased; this is done to the extend component co-planarity. However, taking into consideration solder joint reliability with a reduced SRO size, the minimum size that is recommended...