IPC J-STD-003B.pdf - 第16页

4 TEST PROCEDURES 4.1 Test Procedure Limitations The test procedures of this speciﬁcation are applicable to most printed board con- structions typical of the industry . It is recognized that thick printed boards will not…

3.5 Solder Bath Requirements

3.5.1 Solder Temperatures

Tin/lead solderability testing

shall be done at a solder temperature of 235±5°C[473 ±

9 °F]. Lead-free solderability testing shall be done at a sol-

der temperature of 255±5°C[491 ± 9 °F].

3.5.2 Solder Contamination Control The solder in

solder baths used for solderability testing shall be chemi-

cally or spectrographically analyzed or replaced each 30

operating days. The levels of contamination and Sn content

must be within those shown in Table 3-2. The intervals

between analysis may be lengthened if the test results indi-

cate that the contamination limits are not being

approached. The composition of the lead-free solder,

including contamination levels, shall be maintained during

testing per Table 3-2 with the silver and copper element

levels adjusted for alloy requirements.

NOTE: An operating day consists of any eight-hour

period, or any portion thereof, during which the solder is

liqueﬁed and used.

If contamination exceeds the limits speciﬁed in Table 3-2,

then the solder shall be changed and the intervals between

analyses shall be shortened. A sampling plan shall be

developed, implemented, and documented, demonstrating

solder contamination process control.

20 15 10 5 0

IPC-003b-3-2

Figure 3-2 Example Reticle

Table 3-2 Maximum Limits of Solder Bath Contaminant

Contaminant

Maximum

Contaminant Weight

Percentage Limit

Sn Pb Alloys

a, b

Maximum

Contamination

Weight

Percentage Limit

Pb Free Alloys

a,c

Copper 0.300 0.800

Gold 0.200 0.200

Cadmium 0.005 0.005

Zinc 0.005 0.005

Aluminum 0.006 0.006

Antimony 0.500 0.500

Iron 0.020 0.020

Arsenic 0.030 0.030

Bismuth 0.250 0.250

Silver 0.100 4.000

Nickel 0.010 0.010

Lead N/A 0.100

Notes:

a. The tin content of the solder shall be maintained within ± 1% of the

nominal alloy being used. Tin content shall be tested at the same

frequency as testing for copper/gold contamination. The balance of the

bath shall be lead and/or the items listed above.

b. The total of copper, gold, cadmium, zinc, and aluminum contaminants

shall not exceed 0.4%. Not applicable to lead-free alloys.

c. These Maximum Contamination Weight Percentage Limits apply for

solderability testing using the SAC305 solder alloy. The use of other

lead-free solder alloys/maximum contamination weight percentage limits

may be used upon agreement between user and vendor.

March 2007 IPC J-STD-003B

Provided by IHS under license with IPC

Not for Resale

No reproduction or networking permitted without license from IHS

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4 TEST PROCEDURES

4.1 Test Procedure Limitations

The test procedures of

this speciﬁcation are applicable to most printed board con-

structions typical of the industry. It is recognized that thick

printed boards will not act the same as thin printed boards

due to their increased thermal mass, aspect ratio, number of

ground planes and weight of the solder column within the

hole. These factors greatly reduce the likelihood that all

holes will display completely wetted knees with top side

caps.

The test procedures of this speciﬁcation shall be followed.

If determined by an agreement between the user and ven-

dor that changes are necessary due to the physical charac-

teristics of a test specimen and not the solderability of the

test specimen surface, a new procedure shall be docu-

mented and used only for the applicable test specimen.

Changes in test procedures and ﬂux (see 3.2.2) shall take

into account the wetting time and ﬂux issues per 6.6 and

6.7.

4.1.1 Application of Flux The test specimens are to be

dipped in the ﬂux to the full depth to be soldered for 5-10

seconds. The ﬂux shall be maintained at the prescribed

composition deﬁned in 3.2.2. After withdrawal from the

ﬂux, the test specimen shall be allowed to drain vertically

for a maximum of 60 seconds. Excess ﬂux shall be

removed by blotting the surface to be tested with a piece of

absorbent, clean material. The solderability test shall then

be performed in not less than one minute, and not more

than ﬁve minutes, after blotting.

IPC J-STD-003B March 2007

Provided by IHS under license with IPC

Not for Resale

No reproduction or networking permitted without license from IHS

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4.2 Tests with Established Accept/Reject Criteria

4.2.1 Test A – Edge Dip Test Tin/Lead Solder

This test

is for edge dip testing of surface conductors and attachment

lands.

4.2.1.1 Apparatus

4.2.1.1.1 Solder Pot/Bath

A solder vessel that meets the

requirements of 3.3.2 shall be used. The solder shall meet

the requirements of 3.2.1. Solder bath temperatures and

solder contamination control shall be in accordance with

3.5.1 and 3.5.2.

4.2.1.1.2 Dipping Device A dipping device as shown in

Figure 4-1 shall be used. A similar device may be used

providing: the rate of immersion, dwell time, and rate of

withdrawal are within the test limits; perpendicularity of

board and solder surface are maintained; wobble, vibration,

and other extraneous movements are eliminated.

4.2.1.2 Test Specimen The test specimen shall be a rep-

resentative portion of the board, or a full board, whichever

is smaller, not to exceed 50 x 50 mm [1.97 x 1.97 in], or a

test specimen that is representative of the common board

features. Figures 4-2 and 4-3 are suggested test specimen

styles. Test specimen preparation shall be in accordance

with 3.4.

Note: Relative to Figure 4-3, it is imperative that the met-

allization extends to the edge of the test specimen, in order

to guarantee a repeatable and accurate test. This is achieved

by imaging the test specimen larger in the multi-test speci-

men panel format than as it would otherwise have been

done as an individual test specimen. The singulation pro-

cess (removing the individual test specimens from the

multi-image panel) will have the scoring or routing path

pass through the oversize copper image, thus insuring that

the copper is fully present to the edge of the test specimen.

Due to the relative softness of the copper, the rough edge

may need to be ‘dressed’ using 600 grit sandpaper. An

alternate method to ensure that the copper is fully to the

edge of the test coupon is to preroute the test specimen and

edge plate. This latter alternative is generally more costly

and may not be available from all printed circuit board

fabricators.

4.2.1.3 Procedure Dross and burned/residual ﬂux shall

be completely removed from the surface of the molten sol-

der immediately prior to dipping. After ﬂuxing and drain-

ing per 4.1, the test specimen shall be immersed into the

molten solder edgewise to a depth of 25 ± 2 mm [0.984 ±

Flux

Initial Step

Process Flow

Insert

Specimen

Insert

Specimen

Withdraw

Specimen

Withdraw

Specimen

Station

Solder

Station

Final Step

IPC-003b-4-1

Figure 4-1 Edge Dip Solderability Test

March 2007 IPC J-STD-003B

Provided by IHS under license with IPC

Not for Resale

No reproduction or networking permitted without license from IHS

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