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Method for an E-patterned copper surface

IP.com Disclosure Number: IPCOM000130517D
Publication Date: 2005-Oct-25
Document File: 3 page(s) / 88K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for an E-patterned copper surface. Benefits include improved thermal performance and improved yield.

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Method for an E-patterned copper surface

Disclosed is a method for an E-patterned copper surface. Benefits include improved thermal performance and improved yield.

Background

              Board warpage is an identified issue in printed circuit board (PCB) fabrication and assembly. The issue is expected to become increasingly critical as the industry converts to lead-free processes where higher reflow oven temperatures (~260ºC) are required. The expected increase in the use of copper, which requires higher temperatures, is expected to further increase warpage.

               Conventionally, a flat-edge copper surface is created along the board edge. At high processing temperatures in the reflow oven, copper (metal) expands and causes the board to warp. Board warpage is classified as a material defect. Surface mount technology (SMT) machines cannot place SMT components on a warped board, especially at the board edge. Components can be lost from the edge, resulting in defective boards (see Figure 1).

              PCB manufacturers conventionally place nonconnecting dummy copper pads on boards to balance the copper distribution on different sides (such as the top and bottom) to reduce board warpage (see Figure 2).

Description

              The disclosed method replaces the conventional copper flat edge on a PCB with an E-pattern copper surface. The copper dissipates heat from the board quickly, reducing a major factor that causes board warpage. Additionally, the method provides space to...