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Browse Prior Art Database

Single sided Selective LGA

IP.com Disclosure Number: IPCOM000016349D
Original Publication Date: 2002-Oct-04
Included in the Prior Art Database: 2003-Jun-21
Document File: 2 page(s) / 61K

Publishing Venue

IBM

Abstract

The present invention provides a structure where the high aspect ratio plated through hole (10:1) is reinforced with a filler material that prevents etchant solutions from entering the pth and the finish Ni-Au is only plated on the top surface and not entering the pth. A pictorial of such structure is shown in Figure (below). where single side hard gold plating structure of LGA in high aspect ratio boards without Ni/Au plating in neighboring PTHs is provided . Such a method and structure eliminates post assembly opens in PTH, high scrap of assembled boards, escapes of such defects in the field eliminates field fails associated with such defects. The following are experiemntal results that demonstrate the concept and the resulting structure. Resin filled vs SM filled, sample size 16/cell

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Single sided Selective LGA

    The present invention provides a structure where the high aspect ratio plated through hole (10:1) is reinforced with a filler material that prevents etchant solutions from entering the pth and the finish Ni-Au is only plated on the top surface and not entering the pth. A pictorial of such structure is shown in Figure (below). where single side hard gold plating structure of LGA in high aspect ratio boards without Ni/Au plating in neighboring PTHs is provided .

Such a method and structure eliminates post assembly opens in PTH, high scrap of assembled boards, escapes of such defects in the field & eliminates field fails associated with such defects.

The following are experiemntal results that demonstrate the concept and the resulting structure.

Resin filled vs SM filled, sample size = 16/cell

Black = Resin filled

RED = SM filled

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Probability Plot for Resin filled-SM filled Lognormal base e Distribution - ML Estimates

Complete Data

c

99

95

90

80

70

60

50

40

30

20

10

5

1

Resin filled SM filled

Location Scale AD* F/C
3.5842 0.09505 1.14 16/0
4.1007 0.07694 0.964 16/0

ent

Per

30

70

40

50

60

Cycles to Fail

References pertaining to this discosure include the following patents. USP Nos. 6,195,883;

6,138,350; 6,127,025; 6,114,019; 5,487,218; 6,000,129; 5, 822,856; 6,156,221.

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