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Semiconductor Test Handler Work Press Planarization Method And Jig

IP.com Disclosure Number: IPCOM000174681D
Publication Date: 2008-Sep-17
Document File: 6 page(s) / 119K

Publishing Venue

The IP.com Prior Art Database

Abstract

New high speed devices in BGA packages are sensitive to small changes in voltage on the power supply pins and any voltage drops because of contact resistance between the package ball and the test interface. 4-point crown pogo pins are captured in plastic for the test interface. One of the causes of higher contact resistance is uneven pressure across the device when it is pushed into the pogo pins for test. The total compression for a contactor is 0.020" or less under normal usage. If the work press is not planer with the Contactor Mounting Plate, then there will be uneven deflection of the pogo pins across the device.

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Background:

New high speed devices in BGA packages are sensitive to small changes in voltage on the power supply pins and any voltage drops because of contact resistance between the package ball and the test interface.  4-point crown pogo pins are captured in plastic for the test interface.  One of the causes of higher contact resistance is uneven pressure across the device when it is pushed into the pogo pins for test.  The total compression for a contactor is 0.020” or less under normal usage.  If the work press is not planer with the Contactor Mounting Plate, then there will be uneven deflection of the pogo pins across the device.  

The graph above shows the change in contact resistance for changes in deflection of the pogo pins.  The pins with lower deflection will have a higher contact resistance.  The figure below shows a typical setup for testing BGA devices.

Current Practice for checking planarity:

The Contactor Mounting Plate is replaced with a steel block.  The work-press is lowered until is just touches the block.  Feeler gauges and a mirror are used to check planarity.  This has a couple of problems.  The work press is in a chamber, so it is hard to maneuver around to see if there is any space between the work press and the block.  Feeler gauges are just not good way to check planarity down to 10 thousandth of an in...