IPC-4556 印制板化学镍钯浸金（ENEPIG）规范ENG - 第68页

APPENDIX 8 Gold Wire Bonding Stephen Meeks St Jude Medical The tasks identiﬁed by a consensus of the IPC 4-14 Plating Processes Subcommittee members to evaluate the suitability of the Electroless Nickel Electroless Palla…

CONCLUSION

The palladium plating thickness range on the test coupons submitted by the IPC 4-14 Plating Processes Subcommittee did

not introduce any loss of solder joint integrity for Sn63Pb37 or SAC305 soldering processes as measured by solderball shear

testing and metallographic cross-sectional analysis.

REFERENCES

1. D. Abbott, Donald, D. Romm, B. Lange, ‘‘Nickel-Palladium-Gold Integrated Circuit Lead Finish and Its Potential for

Solder-Joint Embrittlement,’’ Texas Instruments Application Report SZZA031, December 2001.

2. M. Wolverton, ‘‘Quality, Reliability and Metallurgy of ENEPIG Board Finish and Tin-Lead Solder Joints,’’ SMTAI Con-

ference Proceedings, October, 2011.

3. D. Hillman, P. Bratin, M. Pavlov, ‘‘Wirebondability and Solderability of Various Metallic Surface Finishes For Use in

Printed Circuit Assembly,’’ Surface Mount International Conference Proceedings, pp. 687-701, 1996.

January 2013 IPC-4556

APPENDIX 8

Gold Wire Bonding

Stephen Meeks

St Jude Medical

The tasks identiﬁed by a consensus of the IPC 4-14 Plating Processes Subcommittee members to evaluate the suitability of

the Electroless Nickel Electroless Palladium Immersion Gold ENEPIG) plating ﬁnish for wire bondability were as follows:

• Round Robin Task Group Members Roles and Responsibilities

• Development of a Wire Bond Test Vehicle

• Commercial ENEPIG Plating Finish Supplier Contributions

• ENEPIG Plating Finish Attributes Selected to Evaluate Wire Bonding

• 1 mil Gold Ball Wire Bonding and Destructive Pull Testing Evaluations per MIL-STD-883

Round Robin Task Group Member Roles and Responsibilities

The wire bond test vehicle artwork was supplied by Kulicke and Soffa (K&S).

Fabrication of the test vehicles was performed by TTM Technologies, Inc.

Commercial suppliers provided the ENEPIG plating ﬁnish test vehicles.

St. Jude Medical conducted the auto wire bonding and destructive pull testing evaluations.

Development of the Wire Bond Test Vehicle The artwork

for the round robin wire bond test vehicle was provided by

K&S. The test vehicle/coupon was a double sided Printed Cir-

cuit Board (PCB) with no inner planes. The dimensions of an

individual test coupon were 1 inch by 1 inch square and 0.034

inches thick. The coupon was designed for wire bonding to be

conducted only on one side of the part. Two levels of wire

bond pad surface roughness were selected for the test matrix –

high and low.

FR-4 was the laminate material used for the test vehicle. No

solder mask was incorporated. All coupons were fabricated by

TTM. A tooling hole was added to each coupon within the

panel to provide for a pin #1 location. The wire bonding areas

of each coupon were separated into 4 quadrants for wire bond-

ing and accurate destructive pull data tracking (as shown in

Figure A8-1).

Commercial ENEPIG Plating Finish Suppliers Following the fabrication of the ENEPIG panels by TTM, the panels con-

taining the wire bond test coupons were shipped to the following commercial ENEPIG ﬁnish suppliers who had agreed to

participate in the Round Robin testing:

1. Uyemura

2. DOW Electronic Materials

3. MacDermid

4. Enthone-Cookson

5. OMG

6. Atotech

Figure A8-1 Wire Bond Test Vehicle Showing pin #1, quad-

rants 1, 2, 3 and 4.

Note: The red lines indicate the general wire bond locations and sites

used for Destructive Pull Testing (DPT).

IPC-4556 January 2013

NiPdAu

1 -mil

Gold

Wire

Bonding

The electroless nickel and immersion gold surface ﬁnish thickness metal layers were selected as a control; the electroless

palladium thickness and wire bond pad surface roughness were the variables chosen by consensus of the subcommittee for

evaluation of the suitability of ENEPIG as a plating ﬁnish for gold wire bonding.

The electroless palladium thickness layer varied based upon the following target thicknesses:

a. 4 micro inches

b. 8 micro inches

c. 12 micro inches

d. 20 micro inches

ENEPIG Plating Finish Attributes Used to Evaluate 1-Mil Gold Wire Bonding 1 mil gold ball auto wire bonding for evalu-

ation of the ENEPIG ﬁnish was based upon using the established volume manufacturing wire bond processes used at St. Jude

Medical (Scottsdale, AZ). Experienced and certiﬁed wire bond associates and technicians performed all wire bond setups,

calibrations and conducted the actual wire bonding of the ENEPIG test vehicles.

The wire bond testing was conﬁgured as a blind test. The suppliers, plating thicknesses and other properties were unknown

before and after actual processing. Twenty-one (21) groups of panels were received with special labeling used for designa-

tion of the coupons and wire bonding data collection (Table A8-I).

Development of 1 mil gold wire bond parameters and attributes used for wire bonding onto the coupons with the ENEPIG

plating ﬁnish was consistent with the same approaches used to establish auto wire bonding parameters for standard electro-

lytic gold plating ﬁnish substrates.

Auto Wire Bond Process Design Point Areas of Focus Included:

• Preheat Stage Temperature

• Power / Force / Time

• Visual Inspection Before and After Wire Bonding

• Selection of Coupons within the Panels

• One Set of Parameters to be used for ALL Wire Bond Samples (Standardization Target)

• No Effort would be Placed into ‘‘Making Wires Stick’’

• Wire Bond Equipment was Calibrated Before Processing

• Certiﬁed Wire Bond Operators Used for Wire Bonding

• 1 mil Diameter Gold Wire Used for Bonding

• Destructive Pull Testing per MIL-STD-883 Would be Incorporated

• Pre-conditioning of Test Vehicle Before Wire Bonding

Table A8-I Twenty-one Panels Marked (a) Whole Panel, (b) Array and (c) Hand Cut

January 2013 IPC-4556

１

２

３

４

５

６

７

８

９

１０

１１

１２

１３

１４

１５

SUMMARY OF WIRE BOND Ni-Pd-Au COUPONS RECEIVED

From Whole Panel FRONT

From Arrays

MARK

BACK

MARK

FRONT

MARK

BACK

MARK

＊＊２

SN12-1

O-XX & XXB

13-T

Ⅱ

markings

NONE

Ⅱ

N/A

7-B

7-T

１５

１７

SN13-3

SN13-4

SN7-2

SN7-3

SN7-4

XXIB

XXIVA

NONE I XII A

SN9-3

N/A

9-T

N/A

VIII A

XXV A

VII A

VII B

IXB

２０

XX-R

SN12-4

SN15-3

SN17-3

SN17-4

SN20-1

SN20-3

SN20-4

SN2-1

SN2-4

SN3-2

SN3-4

SN5-1

N/A

MARKING ON ALL

PANELS & ARRAYS

6×8 Card Array

PN ENEPIG IPC MFR

IVB

65916 DC1032

N/A

SN5-3

XIB

SN8-4

N/A

XXII-2A

From Hand Cut

N/A

Ｎ／Ａ