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Browse Prior Art Database

ELECTRICAL TEST SOCKETS FOR BGA DEVICES

IP.com Disclosure Number: IPCOM000009006D
Original Publication Date: 1999-Jan-01
Included in the Prior Art Database: 2002-Jul-31
Document File: 1 page(s) / 66K

Publishing Venue

Motorola

Related People

Mack W. Johnson Jr.: AUTHOR [+3]

Abstract

Reliably testing tine pitch BGA (Ball Grid Array 1.0 and .8 mm pitch) devices in initial test software development phase and final manufacturing test environment. There are two problems in testing these new packages. First is that the outside pack- age outline does not allow sufficient accuracy to align the ball grid array to the contacts. The total position accuracy of the solder array with respect to the outside edges is ,275 mm and the solder ball diameter of only .42 mm +/- .08 means you cannot use the package outline to properly position the device in the contacts. Off centered contact causes poor electrical contact or no contact and can cause contact element damage.

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MO7VROLA Technical Developments

ELECTRICAL TEST SOCKETS

FOR BGA DEVICES

by Mack W. Johnson Jr., James Gary Mosier and Darcy Laveau

WHAT IS THE PROBLEM

Reliably testing tine pitch BGA (Ball Grid Array
1.0 and .8 mm pitch) devices in initial test software development phase and final manufacturing test environment. There are two problems in testing these new packages. First is that the outside pack- age outline does not allow sufficient accuracy to align the ball grid array to the contacts. The total position accuracy of the solder array with respect to the outside edges is ,275 mm and the solder ball diameter of only .42 mm +/- .08 means you cannot use the package outline to properly position the device in the contacts. Off centered contact causes poor electrical contact or no contact and can cause contact element damage.

  Secondly, the BGA substrates are thin (.36 mm) and fragile which means they cannot be used to con- trol the contact overdrive. Excessive pressure or uneven pressure on the BGA package can cause plastic molded top to separate from the substrate.

WHAT IS THE PARTICULAR SOLUTION

  The solution to guarantee the correct ball array placement in the contacts was achieved by design- ing a spring loaded guide fixture. This fixture first uses the outside of the package to perform coarse package alignment and then using an array of tapered apertures precisely aligns the solder ball grid array to the contacts probes. After the device is

properly aligned it...