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SEMI G56-93 © SEMI 1993, 2002 1 SEMI G56-93 (Reapproved 0302) TE ST METH OD FO R MEA SU RE ME NT OF SIL VER PLA TING THICKNESS This te st m ethod was tec hnically approv ed by the G lobal Asse mbly and Packag ing Com mit…
SEMI G55-93 © SEMI 1993, 2004 3
NOTE: Specimens were kept in an office and directly exposed to the atmosphere.
Figure 1
Changes of the Brightness Value as Time Goes by
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the contents in whole or in part is for
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idden without express written
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SEMI G56-93 © SEMI 1993, 2002 1
SEMI G56-93 (Reapproved 0302)
TEST METHOD FOR MEASUREMENT OF SILVER PLATING
THICKNESS
This test method was technically approved by the Global Assembly and Packaging Committee and is the
direct responsibility of the Japanese Assembly 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 1993.
1 Purpose
1.1 Use — This test may be used for process control
and outgoing inspection at the supplier or by the
customer for incoming inspection.
1.2 Units — This standard test method uses SI units.
2 Scope
2.1 This method describes the standard method for
measuring the thickness of silver plating on
semiconductor leadframes.
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
ASTM B 568 — Measurement of Coating Thickness by
X-Ray Spectrometry
4 Significance
4.1 The thickness of plating affects assembly processes
such as wire bonding. If the plating is too thin, heat
processes such as die attach cause the surface to
become unbondable due to bleeding of the base
material through the plating.
4.2 Schematic picture for measurement principles is
shown in Figure 2.
5 Summary of Method
5.1 The method is based on the use of fluorescent X-
rays. This method is chosen as the standard because of
the small measurement area requirements, the high
accuracy of the method for typical silver plating
thicknesses used on leadframes, and the non-contact
method.
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
6 Interferences
6.1 Impurities in Plating
6.1.1 Elements with atomic numbers between 42
(Molybdenum) and 52 (Tellurium) cause false readings.
6.2 Measurement Time
6.2.1 At small collimator diameters, the measurement
time is no longer proportional to diameter. X-ray
counting errors may occur for short measurement times.
6.3 Worn or abraded standards will affect calibration.
6.4 Base material variations will affect results.
Standard samples and leadframes must have the same
base material and plating system conditions for accurate
results.
7 Equipment
7.1 Fluorescent X-ray spectrometer.
8 Sampling
8.1 A sampling plan shall be agreed between supplier
and customer.
9 Preparation of Samples
9.1 No special preparation requirements are necessary.
10 Measurement Conditions
10.1 Collimator shall be set at 0.1 mm or 0.3 mm by
agreement between user and supplier.
10.2 Measurement time shall be agreed between user
and supplier.
11 Equipment Setup and Calibration
11.1 Equipment Setup
11.1.1 Set up the equipment according to the
manufacturer’s instructions.
11.1.2 Allow at least 30 minutes for equipment
stabilization before beginning measurements.
SEMI G56-93 © SEMI 1993, 2002 2
11.2 Calibration
11.2.1 Calibration curves shall be generated using
standard samples traceable to the National Institute of
Standards and Technology or equivalent standards
organization.
11.2.2 Calibration curves shall be generated after the
equipment has stabilized per the manufacturer’s
instructions.
11.2.3 The equipment shall be recalibrated every 8
hours.
12 Procedure
12.1 Procedure
12.1.1 Measurements shall be made close to the center
of the die pad, if possible. In those situations where the
die pad is not plated, the measurement site shall be
agreed between user and supplier.
12.1.2 Measure all the selected samples according to
the equipment manufacturer’s instructions.
NOTE: Refer to the equipment manufacturer’s instructions
and ASTM B 568 for safety conditions.
12.2 Results
12.2.1 Thicknesses shall be rounded to the first
decimal place.
13 Report
The report when used by a supplier to certify a user’s
requirements or by the user at incoming inspection shall
contain, at least, the following information. Other
information which is reported shall be agreed between
the user and supplier.
13.1 Supplier’s Lot Number and Date of Shipment
13.2 Test Conditions
13.3 Results from Section 11. (SPC charting
techniques may be used to monitor results for each
leadframe type and plating requirement.)
14 Accuracy and Precision
14.1 Accuracy
14.1.1 Figure 1 shows curves of silver plating
thickness measured by fluorescent X-Ray versus the
percentage error in that measurement for two collimator
settings for a constant measurement time.
15 Related Documents
15.1 SEMI Specifications
SEMI G21 — Plating Integrated Circuit Leadframes
15.2 JIS Specifications
2
JIS H8501 — Methods for Thickness Testing for
Metallic Coatings
JIS H8621 — Electroplated Coatings of Silver for
Engineering Purposes
15.3 Military and Federal Specifications
3
QQ-S-365 — General Requirements for Electro-
deposited Silver Plating
MIL-S-19550 — General Specification for
Semiconductor Devices
15.4 ISO Specifications
4
ISO-3497 — Metallic Coating Measurement of Coating
Thickness X-Ray Spectometry Methods
2 Japanese Industrial Standards, Available through the Japanese
Standards Association, 1-24, Akasaka 4-Chome, Minato-ku, Tokyo
107-8440, Japan. Telephone: 81.3.3583.8005; Fax: 81.3.3586.2014
Website: www.jsa.or.jp
3 Available through the Naval Publications and Forms Center, 5801
Tabor Avenue, Philadelphia, PA 19120-5099, USA. Telephone:
215.697.3321
4 ISO, 1 rue de Varembe, Case postale 56, CH01211 Geneva 20,
Switzerland