IPC-4556 印制板化学镍钯浸金（ENEPIG）规范ENG - 第24页

APPENDIX 2 Round Robin Test Summary Geor ge Milad Uyemura International Corporation Objective T o determine the appropriate speciﬁcation limits for electroless palladium in ENEPIG for soldering and wire bonding applicati…

depending on the intended application. This bath runs at relatively high temperatures and dwell times. The user should

ensure compatibility of substrate and solder mask, if used. Vendor speciﬁcations for temperature, dwell time, agitation

and bath chemical control should be followed.

7. Rinsing – The purpose of these steps is to remove residual process chemicals from the PWB surface after each chemi-

cal processing step. This may be achieved in either a single step or with multiple rinses. In some instances, pre-dip and/or

post-dip process steps may also be required for optimum process performance. Vendor speciﬁcations for temperature,

dwell time, agitation and turn-over rate should be followed.

8. Drying – The purpose of this step is to ensure the boards are completely dry. This may be achieved by use of either in-line

vertical, or off-line horizontal drying. Off-line horizontal drying should be preceded by a horizontal rinsing step and

should be dedicated to the boards from the ENIG/ENEPIG processes. The time and temperature should be optimized to

suit the type of product.

9. ENIG/ENEPIG Process Combination – Due to the very substantial overlap between the process ﬂows for production of

ENEPIG and ENIG, single process lines can be designed to be capable of producing either product type, by use of dif-

ferent line software control programs.

January 2013 IPC-4556

APPENDIX 2

Round Robin Test Summary

George Milad

Uyemura International Corporation

Objective To determine the appropriate speciﬁcation limits for electroless palladium in ENEPIG for soldering and wire

bonding applications.

Supplier Participation Six suppliers namely: Atotech, Cookson Electronics, Dow Electronics Materials, MacDermid,

OMG and UIC Uyemura, committed to providing samples of the required ﬁnish for the Round Robin testing:

Thickness Measurement Industry capability to accurately measure the thickness of palladium in thickness ranges desired

to be applied to the test vehicle (TV) values was questioned by members of the sub-committee. Prior to the preparation of

the samples for the round robin testing of solderability and wire bonding performance, it was decided to obtain an ENEPIG

test sample to be sent to interested participants with measuring equipment to determine industry capabilities to reproducibly

measure thickness values. The test sample had 16 pads designated for measurement and recorded values were sent to Gerard

O’Brien for compilation. The results are provided in the speciﬁc Appendix 3, authored by Gerard O’Brien. Participants in

this study were able to use this data to conﬁrm their own measurement capability and to identify any need for changes in

their measurement protocols.

Solderabilty and Solder Joint Reliability Testing

The Test Coupon The ‘‘W Coupon’’ described in the IPC-6012 document was used for this phase of the Round Robin. The

coupon is 16.5 cm X 14.0 cm [6.5 in X 5.5 in]. It has 18 sub-units as shown above, as well as 2 detachable BGA coupons.

All submitted samples will be subjected to the stress or conditioning for 8 hours at 72 °C [162 °F] and 85% RH.

Thickness of the ENEPIG to be Tested After additional discussions, the thicknesses of the multiple layers to be tested

were agreed upon and all suppliers targeted the desired thicknesses.

• Electroless Nickel (EN): 5 µm±1µm

• Electroless Palladium (EP): 0.1 µm, 0.2 µm, 0.3 µm and 0.5 µm*

*(from only one supplier).

• Immersion Gold (IG): Supplier preferred immersion gold process (one supplier chose to supply a second ENEPIG sample

set with a very thin immersion gold layer).

All combinations will be tested as follows:

• Soldering with eutectic solder

• Soldering with Lead Free SAC305 alloy

Sample Size Each supplier agreed to provide 6 ‘‘W Coupons’’ per thickness iteration. All samples were shipped to Gerard

O’Brien for coding, prior to being sent to the test locations, to ensure anonymity of the supplier. Gerard will also maintain

a record of the actual thickness plated on each set of coupons, based on measurements made at a single (referee) test

location.

Solderability/Wettability This was evaluated using ‘‘Wetting Balance’’ testing as well as Spread test coupons. Wetting

Balance tests were carried out by G. O’Brien of ST and S Group (see APPENDIX 5). Solder spread testing was conducted

by Brian Madsen of Continental Automotive Systems (see APPENDIX 6).

Solder Joint Reliability Ball Shear testing on the BGA portion of the coupon was used to make this assessment. The testing

was carried out at Rockwell Collins by David Hillman. Both force and fracture mode were recorded. Cross sections of rep-

resentative samples were prepared to examine the composition of the intermetallic compound (IMC) and its conﬁguration.

The data is reported by David Hillman in APPENDIX 7.

Wire Bonding Evaluation

Wire Bonding Coupon The test coupon design was provide by Horst Clauberg of Kulick & Sofa. James Monarchio at TTM

manufactured the test coupons. Jim supplied sets of test coupons at 2 different levels of surface roughness. One to be par-

ticularly coarse (RA ~ 380), utilizing mechanical scrubbing. The surface roughness was measure by proﬁlometrry at Enthone

by Karl Wengenroth.

IPC-4556 January 2013

The Thickness of the ENEPIG to be Tested The thickness is the same as in the solderability test [see (1) above]. All com-

binations were tested as follows:

• Gold wire bonding utilizing ball, wedge or crescent.

• All samples are pre-conditioned for 4 hours at 150 °C [302 °F], before bonding.

• The wire bonding testing was done by Stephen Meeks of St. Jude Medical. For the protocol and results of the wire bond-

ing evaluation, please refer to APPENDIX 8.

January 2013 IPC-4556