IPC-4556 印制板化学镍钯浸金（ENEPIG）规范ENG.pdf - 第73页

Upon completion of the ﬁnal wire bonding and submission of data, the plating ﬁnish sample thicknesses were obtained and summarized. The results are shown in T able A8-III. SUMMARY The tasks identiﬁed through consensus of…

IPC-4556-a8-4

Figure A8-4 (Top) Summary of 1 mil Gold Wire ENEPIG Destructive Pull Test (DPT) Results and (Lower) Comparison of X-Y

Directional DPT Values

Destructive Pull Values (Grams)

Data S

Plating Methodology: Wilrebond Direction

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Summary of NiPdAu Destructive Wire Bond Pull Tes

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t for 1-MIL Gold Wire

I II-SN13-3 II-SN13-4 III-SN7-2 III-SN7-3 III-SN7-4

IVB IXB XXB

VA VIIA VIIIA XB

XIB

XIIA

XXIB XXII2-A XXIVA

Participants

Uyemura - Japan

Uyemura - US

XXR

XXVA

DOW

MacDermid

Cookson-Ethone

OMG

Atotech

Mil-STD 883 Requirement = 3 Grams

ENEPIG Plating Finish 1-mil Gold Wirebond Results X-Y Bond DPT Comparison

Min

Median

Max

IPC-4556 January 2013

Upon completion of the ﬁnal wire bonding and submission of data, the plating ﬁnish sample thicknesses were obtained and

summarized. The results are shown in Table A8-III.

SUMMARY

The tasks identiﬁed through consensus of the IPC 4-14 Plating Processes Subcommittee to evaluate the suitability of Elec-

troless Nickel Electroless Palladium Immersion Gold (ENEPIG) as a ﬁnish for gold ball wire bond bondability included

development of an industry Round Robin with roles and responsibilities, development of a wire bond test vehicle, partici-

pation of commercial ENEPIG plating ﬁnish suppliers, establishment of ENEPIG plating ﬁnish attributes to evaluate the wire

bonding and 1 mil gold ball wire bonding destructive pull testing evaluation per MIL-STD883.

The wire bond test vehicle artwork was supplied by Kulicke and Soffa, fabrication of the test vehicle was conducted by TTM

Technologies, Inc. and the ENEPIG plating ﬁnish was supplied by commercial suppliers, Uyemura, Dow Electronic Mate-

rials, MacDermid, Enthone-Cookson, OMG and Atotech.

The electroless palladium target thicknesses were 4, 8, 12 and 20 microinches. The nickel and immersion gold thicknesses

were not considered variables.

One set of 1 mil gold ball wire bond parameters were selected for testing all six (6) ENEPIG supplier ﬁnishes evaluated in

this study.

All destructive pull testing results for all 6 commercial ENEPIG plating ﬁnish suppliers were in compliance with MIL-STD-

883 requirements.

Table A8-III Summary of Plating Finish Thicknesses for Samples Wire Bonded

Summary of Plating Finish Thickness per Tracking Codes (µinches)

ID Code ID IAu Thickness (µin) EPd Thickness (µin) EN Thickness (µin)

1 I 2.07 3.48 349.32

2 II-SN13-3 2.2 5.49 343.83

3 II-SN13-4 2.54 6.84 371.24

4 III-SN7-2 2.9 1.57 190.3

5 III-SN7-3 2.15 6.38 175.14

6 III-SN7-4 3.3 8.32 182.84

7 IVB 1.64 5.78 176.75

8 IXB 0.77 9.95 190.16

9 XXB 0.72 16.26 176.21

10 VA 1.16 4.46 217.78

11 VIIA 1.82 7.76 212.54

12 VIIB 2.06 10.34 202.79

13 VIIIA 2.22 4.39 280.83

14 XB 1.42 7.48 267.04

15 XIB 1.68 11.01 254.14

16 XIIA 1.35 3.8 181.65

17 XXIB 1.24 5.93 184.07

18 XXII-2A 1.59 6.9 209.22

19 XXIVA 1.48 17.95 196.17

20 XXR 0.56 4.77 219.95

21 XXVA 0.73 7.37 236.76

January 2013 IPC-4556

APPENDIX 9

XRF Thickness Measurements of thin Au and Pd (ENEPIG):

Recommendations for Instrumentation (Detectors) and their Limitations

Michael Haller

Chief Operating Offıcer

Fischer Technology

• The given limitations in Table A9-1 for the minimal measurable thickness is based on measurements of a typical sample

with 50 nm Au and 100 nm Pd plated on 4 µm Ni, over 30 µm Cu on a substrate of ﬁberglass-reinforced epoxy resin with

Br for the given total intensities. Measuring time 120 s.

• Intensities are given for reference. If lower intensities are realized for a certain XRF setup appropriate adjustments should

be made, by either increasing collimator size (while still meeting spot size speciﬁcations) or by increasing the measure-

ment time.

• Detector limits are derived from repeatability precision (standard deviation) of the XRF instruments and based on count-

ing statistics which directly relate to total intensity and measurement time. As a general rule, in order to improve the repeat-

ability precision by a factor of 2 an increase in intensity or measurement time of a factor of 4 is required.

• The minimum measurable thickness for proportional counter detectors is limited due to the strong inﬂuence of the PCB

base material (Br) and Cu thicknesses (background signal and peak overlap).

• The use of calibration standards with similar thicknesses to the speciﬁed ENEPIG thicknesses which are to be measured

is recommended. Tri-layer standards where Au and Pd are plated directly on Ni/Cu/PCB should be used for calibration for

Cu thicknesses >30 µm. Tri-layer foil standards where Au and Pd are plated on a Ni-foil should be used if boards with

varying Cu-thickness are to be measured. The foils allow for great ﬂexibility since they can be placed on various base

materials, therefore achieving optimal accuracy. With decreasing Cu thickness the inﬂuence of the PCB material becomes

more and more signiﬁcant and requires careful calibration.

• For Cu thickness >30 µm a combination of a minimum of two calibration standards with approximate thicknesses as below

should be used.

– Au/Pd/Ni/Base 50 nm/20 nm/3 µ

– Au/Pd/Ni/Base 50 nm/90 nm/3 µ

– Au/Pd/Ni/Base 50 nm/300 nm/3 µ

– Au/Pd/Ni/Base 10 nm/20 nm/3 µ

• For Cu thicknesses <30 µm a combination of a minimum of two calibration foil standards with approximate thicknesses

as below should be used

– Au/Pd/Ni 60 nm/20 nm/4 µ

– Au/Pd/Ni 60 nm/60 nm/4 µ

– Au/Pd/Ni 50 nm/100 nm/4 µ

– Au/Pd/Ni 50 nm/250 nm/4 µ

• To verify accuracy, it is most important after the XRF has been calibrated for the appropriate measurement range, that the

instrument will read Au and Pd values of an uncoated board of the measurement sample as statistically zero. Only in this

way can one ensure that no systematic offset in the calibration and setup exists. (i.e., measure on uncoated Ni/Cu/PCB or

Cu/PCB and record Au and Pd values obtained).

Table A9-1 XRF Detectors and Their Limitations at Typical Count Rates

Detector type

Prop. Counter PIN SDD

Au min ~ 70 - 100 nm ~ 5-10 nm ~ 2 nm

Pd min ~ 100 nm ~ 10 nm ~ 5 nm

Total Intensity 8000 cps 50 000 cps 50 000 cps

PCB and Cu Inﬂuence strong medium medium

Typical Energy Resolution for min Kα 900 eV <200 eV <150 eV

IPC-4556 January 2013