Browse Prior Art Database

PCB Island for SMT Device

IP.com Disclosure Number: IPCOM000022007D
Publication Date: 2004-Feb-18
Document File: 3 page(s) / 344K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for an SMT device island on a PCB that prevents solder join damage. Benefits include a solution that is easily implemented.

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PCB Island for SMT Device

Disclosed is a method for an SMT device island on a PCB that prevents solder join damage. Benefits include a solution that is easily implemented.

Background

In today’s high volume manufacturing environment, BGA solder ball damages (such as open joints and cracks), are typically caused by uneven surfaces between the PCB and the package during PCB assembly, handling, or the testing process; this introduces additional strains or stresses to the BGA solder ball either through thermal or mechanical forces. When this foreign strain or stress exceeds the solder joint tension limit, the solder balls begin to crack or open. This usually happens at the perimeter of the package, especially on corner BGA balls where the weakest link of the entire BGA ball design exists. In addition, cracks beginning at the outer joint surface of the BGA ball can propagate to the center of the BGA package.

Currently, extra measures are taken to minimize the strain or stress on the PCB board.

 

  • High temperature materials, such as Kevlar, are used to reduce the coefficient of thermal expansion.
  • In the package design, the corners are de-populated to prevent open ball joint issues.
  • In the manufacturing front-end process, the heat profile for reflow and wave solder are optimized.
  • In the manufacturing back-end process, manufacturing and assembly specifications (MAS) are introduced to ensure proper manufacturing handling and testing.

General Description

In the disclosed method, both PCBs are the same size, and have the same material properties and thicknesses. Primary or secondary PCB surface or Both PCB surfaces have the same dril...