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 .

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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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