IPC-4556 印制板化学镍钯浸金（ENEPIG）规范ENG - 第63页
Figure A7-7 Sn63Pb37 T est Coupon s5&6– T est Coupon 5 (left view) and T est Coupon 6 (right view) are both cross-sections at 500X magnification. Figure A7-8 Sn63Pb37 T est Coupon s7&8– T est Coupon 7 (left view) …
Metallographic Cross-Ssectional Analysis A number of the
non-tested solderball solder joints for each coupon were ran-
domly selected for metallographic cross-sectional analysis.
The purpose of the analysis was to determine if any of the sol-
der joints contained the palladium/tin intermetallic (IMC)
phase PdSn4, which has been shown to cause embrittlement
and degradation of solder joint integrity [1]. The PdSn
4
IMC
structure is a blocky, angular phase in the scanning electron
microscopy (SEM) image of a Sample 19 Sn63Pb37 solder
joint with arrows indicating the PdSn
4
IMC phase illustrated
in Figure A7-4. The Sn63Pb37 solder joints contained more of
the PdSn
4
IMC structure than the SAC305 solder joints. The
difference in the resulting microstructure between the solder
processes is due to the fact that the higher SAC305 reflow
temperature and greater tin composition percentage of the
SAC305 alloy allows for better distribution of the palladium
within the solder microstructure rather than forming the
PdSn4 IMC phase. The thickest palladium plating (Sample
19) also contained the most PdSn
4
IMC phase. Figure A7-5 through Figure A7-16 illustrate typical solder joint microstruc-
tures observed for each of the test coupons for both the Sn63Pb37 and SAC305 solder joints. The arrows shown in the Fig-
ures point to some of the observed PdSn4 IMC phase contained in the solder joints.
Figure A7-4 Sn63Pb37 Test Coupon 19 – 1690X Magnifica-
tion SEM View
Figure A7-5 Sn63Pb37 Test Coupons1&2–Test Coupon 1 (left view) and Test Coupon 2 (right view) are both cross-sections at 500X
magnification.
Figure A7-6 Sn63Pb37 Test Coupons3&4–Test Coupon 3 (left view) and Test Coupon 4 (right view) are both cross-sections at 500X
magnification.
IPC-4556 January 2013
52
０产１７７７７
D:4,738×
P:1,698×
19 DEC 111
４８０８８
18 m
15.B kV AMRAY
Figure A7-7 Sn63Pb37 Test Coupons5&6–Test Coupon 5 (left view) and Test Coupon 6 (right view) are both cross-sections at 500X
magnification.
Figure A7-8 Sn63Pb37 Test Coupons7&8–Test Coupon 7 (left view) and Test Coupon 8 (right view) are both cross-sections at 500X
magnification.
Figure A7-9 Sn63Pb37 Test Coupon 18 – 500X magnification
cross-section view.
January 2013 IPC-4556
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Figure A7-10 Sn63Pb37 Test Coupon 19 – Test Coupon at 200X magnification (left view) and at 500X magnification (right view) and
both are cross-sectional views.
Figure A7-11 SAC305 Test Coupons 1 & 2 – Test Coupon 1 (left view) and Test Coupon 2 (right view) are both cross-sections at 500X
magnification.
Figure A7-12 SAC305 Test Coupons3&4–Test Coupon 3 (left view) and Test Coupon 4 (right view) are both cross-sections at 500X
magnification.
IPC-4556 January 2013
54