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SEMI G75-0698 © SE MI 1998 2 4.10 t ensile break st rength — T he t e n sile force per unit of orig inal cross section of t he sample at the point of breakag e. 4.11 t ensile modulus — T he ratio o f stre ss to s train o…

SEMI G75-0698 © SEMI 19981

SEMI G75-0698

STANDARD TEST METHOD OF THE PROPERTIES OF LEADFRAME

TAPE

1 Purpose

1.1 This standard describes procedures for measuring

the mechanical, physical, chemical, thermal, and

electrical properties of leadframe tape.

1.2 Equipment, sampling, and procedures are referred

to in the individual test methods.

1.3 The test methods for the indivi dual properties have

been given in this standard.

1.3.1 Ionic impurities (see SEMI G75.1).

1.3.2 Adhesive strength (see SEMI G 75.2).

1.3.3 Peel strength of protective film from leadframe

tape (see SEMI G75.3).

1.3.4 Water absorption (see SEMI G75.4).

1.3.5 Weight loss (see SEMI G75.5).

1.3.6 Shrinkage factor (see SEMI G 75.6).

1.3.7 Thermal decomposition temperature (see SEMI

G75.7).

1.3.8 Coefficient of thermal expansion and glass

transition temperature (see SEMI G75.8).

1.3.9 Tensile strength, elongation, a nd tensile modulus

(see SEMI G75.9).

1.3.10 Volume and surface resistivity (see SEMI

G75.10).

1.3.11 Dielectric constant and dissipa tion factor (see

SEMI G75.11).

1.3.12 Breakdown strength (see SEMI G75.12).

1.3.13 Leakage current (see SEMI G75.13).

2 Scope

2.1 The methods help tape manufacturers, leadframe

manufacturers, and their customers in evaluating

leadframe tapes.

2.2 Units

2.2.1 This standard test method uses SI (metric) units.

3 Referenced Documents

3.1 Referenced documents are list ed in each test

method.

4 Terminology

4.1 breakdown strength — Under the specified test

conditions, the quotient of the minimum r.m.s. voltage

at the breakdown of the test piece (breakdown voltage)

divided by the distance between the two electrodes

(thickness of test piece).

4.2 dielectric constant — The amo unt of electrostatic

energy stored in a unit volume of a substance in a unit

electric field. It is called dielectric constant (εr) and

expressed as the quotient of electrostatic capacity of a

parallel condenser employing the test piece as the

dielectric (C

) divided by that of the same condenser

when air (under the standard condition, the dielectric

constant of air can be taken for that of vacuum) is used

as the dielectric (C

), measured under a specified

frequency.

i.e.,

4.3 dielectric dissipation factor — Dielectric

dissipation factor is the tangent of the complementary

angle of dielectric phase angle (tand). The dielectric

phase angle is the phase difference angle (q) between

sine-wave voltage applied to the test piece and the

current component having the same frequency as the

applied voltage caused by the voltage application.

4.4 HAST — Highly accelerated stress test: For

example, 121° C/2 atm/100% RH.

4.5 leadframe tape — An adhesive coated tape. After

removing protective film, laminated to the inner leads,

which stops lead shift and/or lead lift during the

assembly process.

4.6 protective film —A plastic film to cover the

adhesive on leadframe tapes. This film prevents the

adhesive from becoming contaminated and is removed

from the leadframe tape just prior to taping the lead-

frame.

4.7 strain — The ratio of elongatio n of the sample

length to the original length at the applied stress level.

4.8 stress — The applied force per unit cross-sectional

area of the sample.

4.9 surface resistivity — The quotient of the voltage

gradient parallel to the current along the surface of the

test piece divided by the current per unit width of the

surface.

SEMI G75-0698 © SEMI 1998 2

4.10 tensile break strength — The tensile force per

unit of original cross section of the sample at the point

of breakage.

4.11 tensile modulus — The ratio of stress to strain of

the sample below the yield point, in the elastic region of

the stress/strain curve.

NOTE: Plastic materials may not have a true elastic region in

the stress/strain curve or force/elongation curve. A tangent is

drawn to the maximum slope of the curve in order to

determine the modulus.

4.12 thermal decomposition temperature (base film

and adhesive) — The thermal decomposition

temperature is determined at 5% of the weight loss

when the tape is set to the thermal ramp at 10°

C/minute.

4.13 volume resistivity — The quotient of the voltage

gradient parallel to the current within the test piece

divided by the current density.

5 Significance

5.1 Ionic Impurities

5.1.1 Ionic contamination can adver sely affect the

reliability of semiconductor devices by causing leakage

currents and aluminum corrosion.

5.2 Adhesive Strength

5.2.1 Low adhesive strength may re sult in inner leads

movement of leadframe during the assembly and

packaging process which may result in low yield or

poor device reliability.

5.3 Peel Strength of Protective Film from Leadframe

Tape

5.3.1 If the peeling strength of prote ctive film from

leadframe tape varies in peeling strength, the taping

machines will not operate consistently.

5.4 Water Absorption

5.4.1 If the leadframe tapes absorb a n excessive

amount of water in storage, before or after packaging,

then reliability of devices made by these leadframes

may be affected. Current leakage and corrosion of

device metallization may occur.

5.5 Weight Loss

5.5.1 Weight loss may indicate that devices

manufactured with the leadframe tape may have

reliability problems due to the tape outgassing.

5.6 Shrinkage Factor

5.6.1 Excessive shrinkage at therma l processing may

cause the lead shift and wire bond problems for

automatic bonders.

5.7 Thermal Decomposition Temperature

5.7.1 The devices manufactured with leadframe tape

that decomposes at too low a temperature may have

lower reliability.

5.8 Coefficient of Thermal Expansion and Glass

Transition Temperature

5.8.1 Excessive expansion of the leadframe tape may

cause lead shift and/or lead lift and result in dislocated

bonds from automatic bonders.

5.9 Tensile Strength, Elongation, and Tensile Modulus

5.9.1 If the tensile strength, elongation, and tensile

modulus varies, the taping machines will not operate

consistently.

5.10 Volume and Surface Resistivity

5.10.1 Low volume and/or surface re sistivity is

indicative of potential leakage currents between

leadframe inner leads which can affect the function of

the device.

5.11 Dielectric Constant and Dissipation Factor

5.11.1 High dielectric constant mater ials used in

semiconductor packages may cause transmission

delays. High dielectric loss causes energy loss, which

leads to exothermic problems in semiconductor

packages.

5.12 Breakdown Strength

5.12.1 Very low breakdown strength may cause de-

vices to fail in use.

5.13 Leakage Current

5.13.1 A high leakage current betwee n leadframe

inner leads, which may be exacerbated due to high

moisture test conditions and impurities in the tape, may

result in poor device reliability.

6 Procedure

6.1 Procedures are detailed in the Test Methods

following this document.

7 Reporting Results

7.1 The sample size per lot and the reported items

shall be determined by agreement between user and

supplier.

7.2 The report shall contain the fo llowing information:

7.2.1 Leadframe Tape Material — M anufacturer, type,

and lot number.

7.2.2 Notification of acceptance or rejection.

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’ 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.

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the contents in whole or in part is forbidden without express written

consent of SEMI.