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SEMI G59-94 © SEMI 1994, 2002 2 Table 1 Sensitiv ity of Ion Chromatograph Ion Sensitivity( ng/mL) Na + 0.2 NH 4 + 0.5 Cation K + 1.0 Cl - 0.3 PO 4 3- 2.0 Br - 1.0 NO 3 - 1.0 Anion SO 4 2- 1.0 8.2 Chart Recorder 8.3 Ion E…

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SEMI G59-94 © SEMI ,1994, 2002 1
SEMI G59-94 (Reapproved 0302)
TEST METHOD FOR MEASUREMENT OF IONIC CONTAMINATION ON
LEADFRAME INTERLEAFING AND THE CONTAMINATION
TRANSFERRED FROM THE INTERLEAFING TO THE LEADFRAMES
This specification was technically approved by the Global Assembling and Packaging Committee and is the
direct responsibility of the Japanese Assembling and Packaging Committee. Current edition approved by the
Japanese Regional Standards Committee on November 26, 2001. Initially available at www.semi.org
December 2001; to be published March 2002. Originally published in 1994.
1 Purpose
1.1 This test method describes a procedure to
determine the ionic contamination on leadframe
interleafing and the contamination transferred from the
interleafing to the leadframes using a water extraction
method.
2 Scope
2.1 This test method is sensitive to the following ionic
species:
Na
+
, NH
4
+
, K
+
, Cl
-
, NO
3
-
, Br
-
, SO
4
2-
, PO
4
3-
.
2.2 This standard does not purport to address safety
issues, if any, associated with its use. It is the
responsibility of the users of this standard to establish
appropriate safety health practices and determine the
applicability or regulatory limitations prior to use.
3 Referenced Standards
3.1 ASTM Specifications
1
D 4327 — Anions in Water by Ion Chromatography
D 1193 — Specification for Reagent Water
4 Terminology
4.1 eluent — The solvent used to carry the extracted
ions through the ion exchange chromatograph.
4.2 interleaf (for semiconductor leadframes) — A
paper or plastic film which is placed between layers of
semiconductor leadframes strips to prevent tangling.
4.3 regenerant — A chemical solution containing the
ions originally present in the chromatograph column
prior to a test run, used to prepare the column for a new
test.
4.4 retention time — The time required for a particular
ion type to pass from the injection port to the detector.
1 American Society for Testing and Materials, 100 Barr Harbor
Drive, West Conshohocken, Pennsylvania 19428-2959, USA.
Telephone: 610.832.9585, Fax: 610.832.9555 Website:
www.astm.org
Retention time is characteristically different for each
ion type.
4.5 standard solution — A solution containing a
known concentration of the ion to be measured and
used to calibrate the chromatograph.
5 Summary of Method
Ionic contamination is extracted in water at > 95°C for
30 ± 2 minutes. The contamination is quantitatively
analyzed by ion type using ion chromatography, and the
result is presented as nanograms/unit area.
6 Significance
6.1 Contamination on the interleaf may contribute to
semiconductor device reliability problems by
transference of the contamination to the leadframes.
6.2 The method may be used by leadframe
manufacturers for the incoming inspection of the
interleafing material, or by users at incoming inspection
of the leadframes.
6.3 Correlation of device reliability results with
interleaf contamination level measurements may lead to
improved interleaf materials.
7 Interferences
7.1 The interleaf material and the leadframes must only
be touched with cleaned tweezers or while wearing
double-layer gloves with polyethylene outer gloves in
order to avoid additional contamination.
8 Equipment
8.1 Ion Chromatograph for Anion and Cation Analysis
— This equipment is to consist of a concentration
pump, guard column, separator column, and a detector
module.
The minimum sensitivity of the chromatograph for each
ion type is defined in Table 1.
SEMI G59-94 © SEMI 1994, 2002 2
Table 1 Sensitivity of Ion Chromatograph
Ion Sensitivity(ng/mL)
Na
+
0.2
NH
4
+
0.5
Cation
K
+
1.0
Cl
-
0.3
PO
4
3-
2.0
Br
-
1.0
NO
3
-
1.0
Anion
SO
4
2-
1.0
8.2 Chart Recorder
8.3 Ion Extraction Vessels — Polypropylene or
polytetrafluoroethylene containers with sealing caps.
NOTE 1: The contamination level of these vessels must be
less than one fifth (1/5) of the expected contamination level
on the interleaf of leadframes when measured in a control test.
8.4 Water Bath — 300 mm L × 300 mmW × 200
mmH, filled with DI water, and capable of holding
95°C.
8.5 Constant Temperature and Humidity Chamber
8.6 Volumetric Dispenser — (e.g., Pipettes — 10 mL
and 100 mL capacity).
8.7 Quartz Flasks and Pipettes for Cation Standard
Solutions — 100, 250, 500, and 1000 mL capacity
(flasks); 1, 10, and 25 mL capacity (pipettes).
8.8 Borosilicate Glass Flasks and Pipettes for Anion
Standard Solutions — 100, 250, 500, and 1000 mL
capacity (flasks); 1, 10, and 25 mL capacity (pipettes).
8.9 Chemical Balance, Weighing Chemicals
8.10 Scissors, Tweezers, Spatula
9 Reagents and Materials
9.1 Deionized water, resistivity ≥ 15 megohm
centimeters at 25°C per ASTM D 1193.
9.2 Eluents and regenerants for specific chromatograph
columns prepared per chromatograph equipment
manufacturer’s recommendations so that the water peak
can be separated from the ionic peaks.
9.3 Compounds Required for the Preparation of
Standard Solutions
9.3.1 Cations — NaCl, NH
4
Cl, KCl.
9.3.2 Anions — NaCl, Na
2
HPO
4
•12H
2
O, NaBr,
NaNO
3
, K
2
SO
4
.
NOTE 2: All compounds must be reagent grade.
10 Sampling
10.1 Sample Conditioning
10.1.1 In case of measurement of ionic contamination
transferred from the interleaves to the leadframes, select
a stack of ten (10) leadframe strips with their nine (9)
interleaves alternately, from the lot to be tested, and
place them horizontally into a chamber at 85 ± 5°C, 85
± 5% Relative Humidity for 24 hours.
10.2 Sample Selection
10.2.1 Recommended sample size of interleaf used in
interleaf extraction test is 10,000 sq. mm.
10.2.2 In the extraction procedure, do not use the top or
bottom leadframe strips in the stack.
NOTE 3: If a load is used to hold the stack together, it shall
be recorded as part of the conditions of test.
NOTE 4: The leadframe/interleaf contact area shall be
recorded. The vender and customer shall agree on the surface
area of the leadframes.
11 Preparation of Standard Solutions
11.1 Standard Solutions
11.1.1 The single ingredient standard solutions of each
ion (Na
+
, NH
4
+
, K
+
, Cl
-
, NO
3
-
, Br
-
, SO
4
2-
, PO
4
3-
)are
made by dissolving 1.000 g of each ion into 1.000 liter
of DI water, respectively. The stored multi-ingredient
standard solutions shown in Table 2 are then made from
these single ingredient standard solutions by the
dilution method.
Table 2 Concentration of Standard Solution for
Calibration
Standard Solution for
Calibration(ng/mL)
Ion Mixed Standard
Solution
(µg/mL)
I II III
Na
+
10 5 10 20
NH
4
+
10 5 10 20
Cation
K
+
10 5 10 20
Cl
-
4 10 20 40
PO
4
3-
10 25 50 100
Br
-
4 10 20 40
NO
3
-
4 10 20 40
Anion
SO
4
2-
4 10 20 40
11.1.2 Cation and Anion standard solutions for
calibration are made by diluting the stored multi-
ingredient standard solutions as shown in Table 2.
SEMI G59-94 © SEMI ,1994, 2002 3
11.1.3 Store the multi-ingredient standard solution and
the calibration solutions in the correct flasks and label
with the ion type and concentration.
NOTE 5: New Standard solutions for calibration are required
every 24 hours. Ensure that the flasks are cleaned with water
before refilling with a new solution.
11.2 Calibration
11.2.1 Set up the chromatograph and regenerate the
columns according to the manufacturer’s instructions
(ASTM D 4327 provides further details).
11.2.2 Run the eluent through the chromatograph until
a stable baseline chromatograph is obtained.
11.2.3 Select the injection volume recommended by
the manufacturer for each ion type and inject it into the
chromatograph. Record the chromatograph for each ion
type, and make the calibration curve for each ion (ion
concentration versus peak height or area).
NOTE 6: Peak height or area under the ion’s characteristic
curve is proportional to the concentration.
12 Procedure — Container Extraction Method
NOTE 7: The size of the extraction vessels depends on the
expected volume of water and the leadframes. The vessels
must be at least threequarters filled with water and
leadframes.
NOTE 8: The vessels must be from the same manufacturing
batch.
12.1 Extraction Vessels — Cleaning
12.1.1 Fill three vessels three-quarters of the way full
in order to reduce the amount of air in the vessel and
attach the caps.
12.1.2 Place the vessels in a water bath at > 95°C for
30 ± 2 minutes.
12.1.3 Remove the vessels from the bath and rinse out
five (5) times with DI water.
12.2 Interleaf Contamination Extraction
12.2.1 Place the interleaf sample in one of the cleaned
vessels.
NOTE 9: The interleafing may be cut in order to ease loading
into the vessels.
12.2.2 Add 100 mL of DI water and cap the vessels.
Place a similar amount of water into the other cleaned
vessel and attach the cap.
NOTE 10: 100 mL is the recommended volume of water;
however, the samples must be covered with water.
12.3 Leadframe Contamination Extraction
12.3.1 Place five (5) leadframe strips in one of the
vessels cleaned per Section 12.1.
NOTE 11: The leadframes may be cut as required to ease
entry into the vessel.
12.3.2 Cover with DI water and cap.
NOTE 12: 25 mL is the recommended volume of water for a
small volume of leadframe samples, 100 mL for a large
volume. The samples must be covered with water.
12.3.3 Place a similar volume of water in one of the
vessels cleaned per Section 12.1.
12.4 Extration
12.4.1 Place the three (3) vessels into the water bath at
T ≥ 95°C, for 30 ± 2 minutes.
12.4.2 Remove the vessels from the bath and allow to
cool.
12.4.3 Remove the leadframes and interleafing
material from their respective vessel and recap.
13 Measurements and Calculations
13.1 Chromatograph Preparation and Calibration
13.1.1 Prepare the chromatograph for operation by
regenerating the columns according to the
manufacturer’s recommendations.
13.1.2 Run the eluent through the chromatograph until
a stable baseline calibration is established.
13.2 Testing
13.2.1 Inject the recommended sample size of solution
from the interleaf extraction into the chromatograph
and obtain the chromatogram.
13.2.2 Repeat 13.1 and then inject the recommended
sample size from the leadframe extraction and obtain
the chromatogram.
13.2.3 Repeat 13.1 and then inject the recommended
sample size from the water-only vessel and obtain the
chromatogram of the background sample.
NOTE 13: The time from extraction to insertion of the sample
into the chromatograph shall not exceed eight (8) hours.
13.3 Results
13.3.1 Sample concentrations are determined from the
calibration curves for each ion type.
13.3.2 The surface concentration of ionic contaminants
(SCIC) for each ion type is given by the following
equation: