Standard Test Method for Evaluating the Reliability of Surface Mounted Device (SMD) Joints on a Flexible Circuit by a Rolling Mandrel Bend (Withdrawn 2024)

SIGNIFICANCE AND USE
4.1 The existing Test Method F1995, while very useful, is difficult to conduct if an encapsulating dome is applied, and does not reveal the possible failures caused by mechanical stress incompatibility in the overall SMT joint. This mandrel bend test will reveal possible mechanical stress incompatibility between the various adhesives which can result in latent field failures during production handling or with thermal cycling in normal use.  
4.2 The existing Test Method F2750 does not include specifics for SMD attachments and only addresses the conductivity change of the conductive trace.  
4.3 The different combinations of SMD types, attachment medias, circuit substrates and process variation can account for significant variation in test outcome.  
4.4 Bending of printed flexible circuit or their components can affect their visual appearance, mechanical integrity or electrical functionality. This test method simulates conditions that may be seen during manufacture, installation, or use.  
4.5 Bend testing may be destructive, therefore any samples tested should be considered unfit for future use.
SCOPE
1.1 This test method covers a means to test a completed Surface Mounted Device (SMD) joint for bond strength and inter-layer stress compatibility  
1.2 A completed SMD joint includes; SMD (LED, resistor, etc), PTF ink land (typically silver), conductive adhesive (typically silver), staking compound (non-conductive), and encapsulant (non-conductive).
WITHDRAWN RATIONALE
This test method covers a means to test a completed Surface Mounted Device (SMD) joint for bond strength and inter-layer stress compatibility.
Formerly under the jurisdiction of Committee F01 on Electronics, this test method was withdrawn in January 2024 in accordance with section 10.6.3 of the Regulations Governing ASTM Technical Committees, which requires that standards shall be updated by the end of the eighth year since the last approval date.

General Information

Status
Withdrawn
Publication Date
31-May-2015
Withdrawal Date
04-Jan-2024
Technical Committee
Drafting Committee
Current Stage
Ref Project

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ASTM F3147-15 - Standard Test Method for Evaluating the Reliability of Surface Mounted Device (SMD) Joints on a Flexible Circuit by a Rolling Mandrel Bend
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This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: F3147 − 15
Standard Test Method for
Evaluating the Reliability of Surface Mounted Device (SMD)
1
Joints on a Flexible Circuit by a Rolling Mandrel Bend
This standard is issued under the fixed designation F3147; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope tive link circuitry (commonly silver) that will make electrical
contact to the SMD via conductive adhesive.
1.1 This test method covers a means to test a completed
Surface Mounted Device (SMD) joint for bond strength and 3.6 mandrel, n—a cylindrically shaped metal rod, such as a
inter-layer stress compatibility brazing or drill rod.
1.2 A completed SMD joint includes; SMD (LED, resistor, 3.7 SMD, n—abbreviation for surface mount device (that is,
etc), PTF ink land (typically silver), conductive adhesive light emitting diode (LED), resistor, capacitor, etc.).
(typically silver), staking compound (non-conductive), and
3.8 SMD joint, n—the combined interface of silver land-
encapsulant (non-conductive).
pad, conductive adhesive, staking compound (if included), and
encapsulant that holds the SMD in place.
2. Referenced Documents
3.9 SMD-populated flexible printed circuit, n—flexible sub-
2.1 ASTM Standards:
strate with conductive circuitry and electronic components
F1996 Test Method for Silver Migration for Membrane
only—not to include other laminates.
Switch Circuitry
3.10 staking compound, n—a non-conductive adhesive that
F2750 Test Method for Determining the Effects of Bending
is applied at a location directly under the SMD and between
a Membrane Switch or Assembly
conductive adhesive deposits (commonly two or more dis-
pensed dots of conductive adhesive) to provide added bond
3. Terminology
strength and prevent shorting or silver migration.
3.1 bend, v—to force from a straight form into a different
and especially a curved one.
4. Significance and Use
3.1.1 Discussion—In this case, no “hard” or angled crease
4.1 The existing Test Method F1995, while very useful, is
or fold is to occur. The substrate will only be formed into a
difficult to conduct if an encapsulating dome is applied, and
radius.
does not reveal the possible failures caused by mechanical
3.2 bend cycle, n—a bend of a sample around a specified
stress incompatibility in the overall SMT joint. This mandrel
mandrel which is “rolled” in one direction, followed by rolling
bend test will reveal possible mechanical stress incompatibility
in the opposite direction, returning the sample to its original
between the various adhesives which can result in latent field
position (see Fig. 1).
failures during production handling or with thermal cycling in
3.3 conductive adhesive, n—a material used for electrical or
normal use.
mechanical bonding, or both, of the SMD to the substrate and
4.2 The existing Test Method F2750 does not include
land-pad.
specifics for SMD attachments and only addresses the conduc-
3.4 encapsulant, n—a non-conductive adhesive that is ap-
tivity change of the conductive trace.
pliedoveroraround,orboth,theSMDforaddedbondstrength
4.3 The different combinations of SMD types, attachment
and prevention of silver migration (F1996).
medias, circuit substrates and process variation can account for
3.5 land-pad, n—the printed circuit pattern at the location
significant variation in test outcome.
that interfaces with conductive adhesive, in this case conduc-
4.4 Bending of printed flexible circuit or their components
can affect their visual appearance, mechanical integrity or
electrical functionality. This test method simulates conditions
1
This test method is under the jurisdiction of ASTM Committee F01 on
that may be seen during manufacture, installation, or use.
Electronics and is the direct responsibility of Subcommittee F01.18 on Printed
Electronics.
4.5 Bend testing may be destructive, therefore any samples
Current edition approved June 1, 2015. Published July 2015. DOI: 10.1520/
F3147-15 tested should be considered unfit for future use.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

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F3147 − 15
FIG. 1 Bend Cycle
5. Interferences 6. Apparatus
5.1 The following parameters may affect the results of this
6.1 Mandrel, allowed to rotate smoothly around its longitu-
test:
dinal axis, rigid, low friction smooth surface. Diameter to be
specified.
5.1.1 Temperature and humidity,
5.1.2 Mandrel d
...

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