IPC-4556 印制板化学镍钯浸金（ENEPIG）规范ENG - 第20页

4.1.2 Sample Test Coupons T est specimens used for qualiﬁcation of printed boards with ENEPIG ﬁnish may be found in IPC-2221 and/or noted in IPC-6010 sectional speciﬁcations. Alternatively , the supplier may create test …

Because of the requirement to test in high density areas, the potential to leave tape residue that could interfere with solder-

ing exists, especially if an incorrect type of tape is used. Veriﬁcation of zero impact to solderability must be demonstrated

for the areas tested, or the area tested shall not be used for ﬁnal product.

3.5 Solderability The thickness speciﬁcation described herein shall meet the Category 3 coating durability requirements of

J-STD-003, i.e., greater than 12 months shelf life.

Note 1: The use of steam exposure (conditioning) is not an applicable accelerated stress test method for ENEPIG.

Note 2: While adherence to the IPC-1601 recommendations for baking prior to assembly may have a negative impact on

solderability performance, the requirements for solderability testing in this speciﬁcation are for samples tested without bak-

ing. Any deviation from this shall be AABUS.

For details of the solder spread testing data from the round robin, see APPENDIX 6. Ball shear data from the same study is

documented in APPENDIX 7.

3.5.1 Force Measurement Testing (Wetting Balance Test-

ing)

The following requirements are based on the use of the

Standard IPC coupon, Figure 3-13, immersed to a depth of

0.6mm at 90 degrees incidence to the solder surface. The

dwell time shall be ten seconds. For details of the wetting bal-

ance data from the round robin study, see APPENDIX 5.

• Force measurement testing of an ‘‘as received’’ sample with

Eutectic SnPb solder, using the prescribed Test Flux#1at

235 °C, shall produce a positive wetting force within 2 sec-

onds and a minimum wetting force of 0.14 mN/mm.

• For force measurement testing of samples stressed for 8

hours @ 72 °C [162 °F] and 85% R.H, the increase in wet-

ting time shall not exceed 1 second. The wetting force shall

be a minimum of 0.12 mN/mm.

• For force measurement testing of ‘‘as received’’ samples with SAC305 solder, using the prescribed Test Flux#2at

255 °C, shall produce a positive wetting force within 1.5 seconds and a minimum wetting force of 0.19 mN/mm.

• For force measurement testing of samples stressed for 8 hours @ 72 °C [162 °F] and 85% R.H., the increase in wetting

time shall not exceed 1 second. The wetting force shall be a minimum of 0.17 mN/mm.

3.6 Cleanliness The surface of an ENEPIG ﬁnish is typically cleaner than most other surface ﬁnishes. Ionic cleanliness

shall be established per the requirements of IPC-5704, which speciﬁes a sample size of 11. It is recommended that solvent

extract conductivity (SEC) testing per IPC-TM-650, Method 2.3.25, also be performed at the same time as the IPC-5704

qualiﬁcation, to establish process control parameters. SIR testing shall be per IPC-TM-650, Method 2.6.3.5. The require-

ments for SIR test performance shall be as speciﬁed in Table 3-1. Failure to meet this cleanliness speciﬁcation should trigger

immediate process control corrective action.

3.7 Electrolytic Corrosion The ENEPIG process contains chemistries that are ionic in nature, but which are readily rinse-

able. Both the quality and volume of water used for the rinsing steps between process baths, and for the ﬁnal rinsing of the

product are critical if the potential for electrolytic corrosion is to be avoided. The use of IPC-TM-650, Method 2.6.14.1,

‘‘Electrochemical Migration Resistance Test’’ is recommended for high reliability applications, or for designs with high fea-

ture density. The resistance values shall not drop more than one order of magnitude after the test has been completed.

4 QUALITY ASSURANCE PROVISIONS

4.1 General Quality Assurance Provisions

These are speciﬁed in IPC-6011 and each IPC-60XX sectional speciﬁcation.

Additional requirements for printed boards with electroless nickel/electroless palladium/immersion gold (ENEPIG) plating

are speciﬁed herein for qualiﬁcation, acceptance, and quality conformance.

Figure 3-13 The Standard IPC Force Measurement

4.1.1 Qualification Recommendations Qualiﬁcation of a printed board supplier, supplying ENEPIG to this speciﬁcation

shall be AABUS (see IPC-6011). The process capability of a supplier of PWB with ENEPIG ﬁnish shall be established by

demonstrating process control over time. Table 4-1 provides a listing of suggested qualiﬁcation elements that should be exer-

cised by the supplier. It includes the associated requirements and/or test methods when applicable.

Coupon

January 2013 IPC-4556

4.1.2 Sample Test Coupons Test specimens used for qualiﬁcation of printed boards with ENEPIG ﬁnish may be found in

IPC-2221 and/or noted in IPC-6010 sectional speciﬁcations. Alternatively, the supplier may create test patterns or process

control coupons to accommodate qualiﬁcation testing and/or lot conformance deposit thickness measurements. Specimen(s)

should be obtained or developed for qualiﬁcation testing to the requirements listed in Table 4-1.

Table 4-1 Suggested Fabricator Qualiﬁcation Plan

Requirement Test Reference Remarks

XRF Certiﬁcation Suitably calibrated XRF instrument with detector

capable of measuring tri-level thin coatings.

Use of certiﬁed national ENEPIG standards as

referenced in Appendices 3, 4, 9 and 10.

Note: Do not use electrodeposited standards or ones

with thicknesses outside the target thickness range

under evaluation.

Perform XRF certiﬁcation by performing a gauge

R&R or equivalent statistical approach. Use of the

correct certiﬁed national standards is critical. This

data may be used as to begin building a suitable

deposit thickness distribution database.

Deposit Thickness

Distribution

Suitable test pattern or production board/panel

having the correct surface area pads as described in

Appendices 3, 4, 9 and 10.

The deposit thickness database to demonstrate 4

sigma distribution should include sample readings

from product processed through the production

baths. Include readings from both front and. back

of the panels. Also, map thickness as a function of

panel position within a basket. It is suggested that

thickness measurements be made at panel locations

that provide as complete panel coverage as possible,

e.g., diagonal, four corners and center, each PWB

within a panel.

Visual Ref. paragraph 3.1 Perform visual inspection per applicable requirements

at a production ﬁnal inspection workstation and

document the appearance of the ﬁnish. It is

recommended to create an inspection checklist.

Solderability

(Wetting Balance)

Use suitable coupon(s) to perform J-STD-003

Category 3 testing.

See paragraphs 3.5 and 3.5.1.

Note: IPC-1601 provides guidance on packaging and

handling of coupons.

It is recommended to qualify to Category 3,

the highest level of storage coating durability

in J-STD-003.

Wire Bondability Test specimen suitable for use with MIL-STD 883,

METHOD 2011.8, or user deﬁned test pattern/

speciﬁcation.

Method 2011.8 of MIL-STD-883 is the most

commonly used test method requirement for

determining wire bond strength. Other user-deﬁned

AABUS measurements may be required. Document a

sufficient quantity of bond pulls to establish capability.

Assistance by the user may be required to support

this method.

Ionic Cleanliness Suitable specimen for IPC-5704

Ion Chromatography (IC) Testing.

IC testing per IPC-5704 is recommended during

qualiﬁcation to conﬁrm that the process and

associated rinses are adequate to ensure that no

contaminates remain that might not meet next level

assembly requirements. Periodic re-qualiﬁcation may

be necessary to account for changes in materials

and processes.

PTH Coverage Suitable Through Hole specimens for

microsectioning.

Microsection a number of ‘‘as received’’ specimen(s)

using darkﬁeld illumination (before solder ﬂoat).

Utilize coupon specimens from a variety of locations,

for example, from the outside and center panels of a

basket load.

Effect on

Soldermask

Adhesion

Para 3.4 - Suitable coupon of IPC-2221 or production

part containing high density features.

Utilizing an appropriate specimen, benchmark

adhesion of solder mask. Inspect to Quality

conformance requirements, or as speciﬁed

by User. Note whether the solder mask was

applied before or after ENEPIG processing.

Repeatability at

Various Stages of

Loading and Bath

Life

Applicable specimens of the Qual Plan. Repeat aspects of the Qualiﬁcation Testing at various

bath life metal turn-over (MTO) stages, as applicable,

looking for any impacts on deposition thickness or

distribution, (for example, for new baths and late

MTO).

IPC-4556 January 2013

the IPC-6010 sectional speciﬁcation.

4.2.1 Thickness Measurements Thickness measurement frequency shall be in accordance with Table 3-1. The number of

readings per panel should be enough to calculate a signiﬁcant standard deviation. A minimum of 20 readings per lot is sug-

gested.

Table 4-2 C=0 Sampling Plan (Sample Size for Speciﬁc Index Value

4.2.2 Qualified Processes If a qualiﬁed process has been established, the requirements of 4.1.1 for a minimum number of

readings and calculation of an associated standard deviation can be waived. For a qualiﬁed process, demonstrating a process

capability (± 4 sigma) within the appropriate speciﬁcation, a sample measurement consistent with Table 3-1 may be used for

lot conformance, provided all readings fall within the Qualiﬁed Process population (± 4 sigma). Alternative thickness inspec-

tion methodologies shall be AABUS.

For gauge capability and GaugeR&R,seeAPPENDIX 10.

)

Lot Size

Class 1 Class 2 Class 3

2.5

4.0

6.5

1.5

2.5

4.0

0.10

1.0

2.5

4.0

1-8 5 3 3 ** 5 3 ** ** 5 3

9-15 533853**1353

16-25 533853**1353

26-50 775877**1377

51-90 11 8 5 13 11 8 ** 13 11 8

91-150 11 9 6 19 11 9 125 19 11 9

151-280 13 10 7 19 13 10 125 29 13 10

281-500 16 11 9 21 16 11 125 29 16 11

501-1200 19 15 11 27 19 15 125 34 19 15

1201-3200 23 18 13 35 23 18 125 42 23 18

3201-10,000 29 22 15 38 29 22 192 50 29 22

10,001-35,000 35 29 15 46 35 29 294 60 35 29

Note 1. Index Value is associated to the A.Q.L. value. If a particular product is determined to be ‘‘critical’’ by the user and a smaller index value is required,the

user shall designate the requirement in the procurement document and should state the ‘‘critical’’ requirement on the master drawing. **Denotes

inspect entire lot.

4.2 Quality Conformance Testing Quality conformance testing shall consist of inspections as speciﬁed in Table 3-1 and

January 2013 IPC-4556