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SEMI G20-96 © SEMI 198 0, 1996 1 SEMI G20-96 SPECIFICA TION FOR LE A D FINISHES FOR PLA STIC PACKAGES (ACTIVE DEV ICES ONLY) 1 Purpose This specification defines lead finishes for plastic packages (e.g ., s ingle-in-lin …

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SEMI G19-0997 © SEMI 1980, 19975
Application Note: There is a question regarding the ability of
material suppliers to meet this specification. Revision of this
specification is under review.
6.10.2 Die Attach Pad — Functional side inside 0.508
mm (0.020") border; nothing greater than 0.127 mm
(0.005") diameter × 50% metal thickness in depth; not
more than 2 pits.
6.10.3 Die Attach Pad — Nonfunctional side; nothing
greater than .508 mm (0.020") × 50% of metal
thickness in depth; not more than 3 pits; cannot affect
leadframe strength regardless of size (i.e., pit cannot be
located within 0.127 mm (0.50") of pad support bar
attachments).
6.10.4 Internal leadframe areas where design width is
0.635 mm (0.025") or more, must be less than 0.381
mm (0.015") × 50% metal thickness in depth; if design
width is less than 0.635 mm (0.025"), area must be 50%
of design width. Cannot affect leadframe strength
regardless of size.
6.10.5 Major Lead Areas (outside dambar) —
Nothing greater than 0.127 mm (0.005") × 50% of
metal thickness in depth; nothing greater than 0.254
mm (0.010") on shoulder above taper. Cannot affect
leadframe strength regardless of size.
6.10.6 Dambar — Pit cannot extend all the way across
the bar.
6.11 Mold Locating Holes — Conventional mold
damage design dictates that gating is opposite pin #1;
therefore, the mold locating holes must be in the rail
adjacent to pin #1. In order to minimize gate flashing
between the mold and the rail edge, a specific tolerance
of ± 0.051 mm (0.002") is required from the centerline
of the mold hole to the opposite rail edge.
6.12 Strip Length — Strip length cut off shall be
within 0.005", lead tip to lead tip centerline (excluding
rails). The rail cut off length shall be within + 0.635
mm (0.025") unless otherwise specified by the user.
7 Sampling
Sampling will be determined between supplier and
purchaser.
8 Packaging and Marking
8.1 Packaging — Leadframes must be packaged in
containers designed and constructed to prevent damage
and/or contamination. Specific protection must be
provided against crushing, exposure to moisture, and
mixture gases.
8.2 Marking — The outer containers shall be clearly
marked to identify the user stock number, user purchase
order number, drawing number, supplier lot number,
and reel numbers within the carton. Additional
information required should be specified by the user.
NOTICE: These standards do not purport to address
safety issues, if any, associated with their use. It is the
responsibility of the user of these standards to establish
appropriate safety and health practices and determine
the applicability of regulatory limitations prior to use.
SEMI makes no warranties or representations as to the
suitability of the standards set forth herein for any
particular application. The determination of the
suitability of the standard is solely the responsibility of
the user. Users are cautioned to refer to manufacturer’s
instructions, product labels, product data sheets, and
other relevant literature respecting any materials
mentioned herein. These standards are subject to
change without notice.
The user’s attention is called to the possibility that
compliance with this standard may require use of
copyrighted material or of an invention covered by
patent rights. By publication of this standard, SEMI
takes no position respecting the validity of any patent
rights or copyrights asserted in connection with any
item mentioned in this standard. Users of this standard
are expressly advised that determination of any such
patent rights or copyrights, and the risk of infringement
of such rights, are entirely their own responsibility.
Copyright by SEMI® (Semiconductor Equipment and Materials
International), 3081 Zanker Road, San Jose, CA 95134. Reproduction o
f
the contents in whole or in part is forbidden without express written
consent of SEMI.
SEMI G20-96 © SEMI 1980, 19961
SEMI G20-96
SPECIFICATION FOR LEAD FINISHES FOR PLASTIC PACKAGES
(ACTIVE DEVICES ONLY)
1 Purpose
This specification defines lead finishes for plastic
packages (e.g., single-in-line, dual-in-line, quad-in-line)
utilizing leadframes with SEMI specified leadframe
materials.
2 Scope
This specification defines the composition, properties,
and limits and refers to the appropriate tests for utility.
3 Referenced Documents
Unless otherwise specified, the following standards and
specifications, with appropriate issue letter at time of
order entry, form a part of this specification to the
extent, and for the purpose, specified herein.
3.1 SEMI Specifications
SEMI G4 — Specification for Integrated Circuit
Leadframe Materials Used in the Production of
Stamped Leadframes
SEMI G18 — Specification for Integrated Circuit
Leadframe Material Used in the Production of Etched
Leadframes
SEMI G55 — Test Method Measurement of Silver
Plating Brightness
SEMI G56 — Test Method Measurement of Silver
Plating Thickness
3.2 ASTM Specifications
1
B 487 — Measuring Metal and Oxide Coating
Thickness by Microscopical Examination of Cross
Section
B 545 — Standard Specification for Electrodeposited
Coatings of Tin
B 567 — Measurement of Coating Thickness by the
Beta Backscatter Principle
B 568 — Measurement of Coating Thickness by X-Ray
Spectrometry
E 1B 571 — Adhesion of Metallic Coatings
E 10 — Standard Test Method for Brinell Hardness for
Metallic Materials
1 American Society for Testing Materials, 100 Barr Harbor Drive,
West Conshohoken, PA 19428-2959
E 384 — Standard Test Methods for Microhardness of
Materials
3.3 Federal Specifications
2
QQ-S-365 — Silver Plating, Electrodeposited, General
Requirements for
QQ-S-571 — Solder, Tin Alloy: Tin Lead Alloy, and
Lead Alloy
3.4 Military Specifications
2
MIL-G-45204 — Gold Plating, Electrodeposited
MIL-P-81728 — Plating, Tin Lead, Electrodeposited
MIL-STD-883 — Test Methods and Procedures for
Microelectronics
MIL-T-10727 — Tin Plating; Electrodeposits or Hot-
Dipped, for Ferrous and Non-Ferrous Metals
4 Application
4.1 Table 1 lists recommended finishes for copper and
nickel/iron alloys.
4.1.1 Silver is approved as a lead finish for all alloys
but only for internal processing. When shipped to a
customer, silver must be removed and replaced by tin
lead.
4.1.2 Gold plate is usable in socketed applications as
well as in soldered applications. Hardness, grain size,
and other properties shall be specified on the
procurement drawing.
4.1.3 Solder, as used in this specification, refers to tin
lead as 63/37 or 60/40 unless otherwise specified and
agreed upon between user and supplier, and stated on
procurement drawings.
4.1.4 “Tinning” is a generic term (pr imarily used in
user industries) and means hot solder dip (near 60/40
tin lead) and not an application of tin.
4.2 Composition, limits, mechanical and physical
properties, and dimensions and tolerances for
leadframes are stated in SEMI G4 and SEMI G18.
4.3 Lead finish details are stated in Section 5.
2 Military Standards, Naval Publications and Forms Center, 5801
Tabor Ave., Philadelphia, PA 19120
SEMI G20-96 © SEMI 1980, 1996 2
5 Lead Finish
5.1 Tin Electroplate
5.1.1 Composition — The tin shall not be less than
99.8% pure tin and shall not contain more than 0.1%
carbon. The deposit is Type I as defined in MIL-T-
10727.
Table 1 Alloys
Finish Iron
Alloys
Finish Copper
Alloys
Tin MIL-T-10727
Tin (over base metal) X X
Acceptable Undercoats
1. Copper X X
2. Nickel X X
Tin Lead (Sn/Pb)
MIL-P-81728
Tin Lead (over base metal) X X
Sn/Pb
Acceptable Undercoats
1. Copper X X
2. Nickel X X
Solder Dip (Sn/Pb)
QQ-S-571
Solder Dip (over base metal) X X
Acceptable Undercoats
1. Copper X X
2. Nickel X X
3. Silver X X
Gold MIL-G-45204
Gold (over base metal) X
Acceptable Undercoats
1. Nickel X X
2. Copper Flash X
Silver QQ-S-365
Silver (over base metal) X X
Acceptable Undercoats
1. Copper X
2. Gold X
5.1.2 Characteristics — The procedure used for
evaluating the tin coating and the general requirements
for the coating shall comply with ASTM B 545 or the
latest current revision, except where noted below.
5.1.3 Thickness — The plated coating as measured on
the major flat of the leads shall be a minimum of 5
micrometers (200 microinches).
5.1.4 Appearance — The surface texture of the tin
shall be non-reflective matte finish.
5.1.5 Hardness — None specified.
5.1.6 Preservation — Preservation coating, if desired
and agreed upon by user and supplier, is acceptable.
(Example: Stearic acid solution in xylol as defined in
MIL-T-10727.)
5.2 Tin Lead (SnPb) Electroplate
5.2.1 Composition — Major constituents shall be tin
lead with minor impurities. Range of major constituents
shall be:
Tin 60%—95%
Lead 5%—40%
5.2.2 Purity and Application — Per MIL-P-81728.
5.2.3 Thickness — Shall be a minimum of 5
micrometers (200 microinches) measured on the major
flat of the leads.
5.2.4 The surface of the tin lead shall be non-reflective
matte finish.
5.2.5 Hardness — None specified.
5.3 Tin Lead Solder-Dip
5.3.1 Composition — 60/40 or 63/37.
5.3.2 Purity — As per Federal Specification QQ-S-
571.
5.3.3 Thickness — Shall be a minimum of 5
micrometers (200 microinches) as measured on the
major flat of the leads.
5.3.4 Process Conformance — Solder coating is
applicable as shown in Table 1. In addition, the coating
is acceptable as follows:
1. Over the electroplated tin or tin lead as per Section
5.1 or 5.2.
2. Over the electroplated silver as per Section 5.4.
3. Over the electroplated gold as per Section 5.5.
5.3.5 Appearance — Surface shall be smooth and
continuous.
5.3.6 Hardness — None specified.
5.4 Silver Electroplate
5.4.1 Composition — Silver electroplate shall be semi-
bright, Type II as per Federal Specification QQ-S-365,
Grade B, (without supplementary tarnish resistant
treatment).
5.4.2 Thickness — Shall be a minimum of 1.25
micrometers (50 microinches) as measured on the
major flat of the leads, in accordance with SEMI G56.