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Method for a board deformation measurement on a test fixture through laser displacement sensors

IP.com Disclosure Number: IPCOM000009597D
Publication Date: 2002-Sep-04
Document File: 3 page(s) / 81K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for a board deformation measurement on a test fixture through laser displacement sensors. Benefits include an improved test environment.

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Method for a board deformation measurement on a test fixture through laser displacement sensors

Disclosed is a method for a board deformation measurement on a test fixture through laser displacement sensors. Benefits include an improved test environment.

Background

              Solder-joint cracks due to board deformation during the conventional test process may be induced by several factors, including:

•             Inadequate counter-balance force

•             Probe force

•             Pushdown force

•             Uneven fixture top plate

              In addition to solder-joint cracks, a contact sometimes remains open when a printed circuit board (PCB) is in the test fixture if the board is deformed (see Figure 1). The conventional solution is to use strain gages to measure the compression or tension level of the board to understand the severity of board deformation. Another approach is to use a coordinate measurement machine to compare the Z-axis height between component and the board surface with the fixture actuated and not actuated.

General description

      The disclosed method measures board compression or tension (Z-axis) by using laser displacement sensors.

      The key elements of the method include:

•             Measurement and comparison of the compression or tension level (Z-axis) of two different locations on the board

•             Use of laser displacement sensors with a DAC or an oscilloscope

•             Mounting of a PCB on a test fixture

Advantages

              Th...