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Method for a lambda-shaped lead component package

IP.com Disclosure Number: IPCOM000012118D
Publication Date: 2003-Apr-09
Document File: 3 page(s) / 71K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for a lambda-shaped lead component package. Benefits include improved performance, improved reliability, and improved ease of manufacturing.

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Method for a lambda-shaped lead component package

Disclosed is a method for a lambda-shaped lead component package. Benefits include improved performance, improved reliability, and improved ease of manufacturing.

Background

              Bridging defects can occur at fine (<20 mils) pitch gull-wing lead or J-lead frame package solder joints.

              Conventional solutions to resolve fine-pitch lead frame package solder bridging include:

•             Reduce the stencil aperture width opening for 20-mils fine pitch components. Example for 20-mils printed circuit board (PCB) pad width, the stencil aperture opening width is reduced from 18 mils to 17 mils. This solution reduces fine pith solder bridging from ~0.5% to 0.3%, which is unstable and prone to excursion.

•             Utilize an alternate up/down stencil aperture opening with alternate offsets in the length direction to minimize solder bridging.

•             Change all the fine pitch leaded packages 16 mils and less to ball grid arrays (BGAs). This solution does not completely resolve fine-pitch solder bridging and limits the down sizing of fine pitches to less than 20 mils.

General description

      The disclosed method is a lambda-shaped lead component package. The method uses lambda-shaped leads for very fine pitch (16 mils and less) electronic packages with the combination of gull-wing leads and J-leads on the same package. This combination optimizes spacing for the external interconnection of the lead frame package. Solder joint bridging is improved without impacting reliability. The disclosed method is specially designed for lead frame packages at 16-mils pitch and less.

              The key elements of the method include:

•             Lambda-shaped leads for lead frame packages with alter...