1、Designation: F1995 12Standard Test Method forDetermining the Shear Force of a Surface Mount Device(SMD) in a Membrane Switch1This standard is issued under the fixed designation F1995; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision,
2、 the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of the shearintegrity of materials and procedures used to attac
3、h surfacemount devices (SMD) to a membrane switch circuit.1.2 This test method is typically used to indicate thesufficient cure of conductive adhesive or underfill, or both. Ingeneral, this test method should be used prior to encapsulant.This test may also be used to demonstrate the Shear Force with
4、encapsulation.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to
5、establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Terminology2.1 Definitions:2.1.1 membrane switchA momentary switching device inwhich at least one contact is on (or made of) a flexiblesubstrate.2.1.2 shear loadA force appli
6、ed parallel to the mountingsurface sufficient to shear the SMD from its mounting.2.1.3 SMDAbbreviation for surface mount device (forexample, light emitting diode (LED), resistor)2.1.4 attachment mediaA mounting adhesive used forelectrical or mechanical bonding, or both, of the SMD to thesubstrate.2.
7、1.5 platingA thin metallic coating (that is, gold, nickel)covering the leads of the SMD or circuit, or both, in theelectrical interface area.3. Significance and Use3.1 The different combinations of SMD types, attachmentmedias, circuit substrates, plating options, and process varia-tion can account f
8、or significant variation in test outcome.3.2 The SMD shear strength test is useful to manufacturersand users for determining the bond strength of the componentto the membrane switch circuit.4. Interferences4.1 The following parameters may affect the results of thistest:4.1.1 Temperature and humidity
9、, and4.1.2 Substrate movement during test.5. Apparatus5.1 Device, shall consist of a load-applying instrument withan accuracy of 6 5 % of full scale capable of indicating peakhold.5.2 Mounting Fixture, method to secure specimen to insurestability during test.5.3 SMD Contact Tool, suitable to apply a
10、 uniform distri-bution of force to an edge of the SMD.5.4 Magnification Device, suitable to facilitate visual obser-vation of the SMD and contact tool interface during testing(optional).6. Procedure6.1 Pretest Setup:6.1.1 Attach specimen to the test base to minimize move-ment of the substrate during
11、 test. Ensure that no damage occursduring attachment to the test base that could affect bondperformance.6.1.2 The direction of applied force shall be parallel with theplane of the circuit substrate.6.1.3 The SMD contact tool shall load against an edge of thecomponent, which most closely approximates
12、 a 90 angle withthe base of the circuit substrate. Contact tool should makecontact to SMD at a point equal to or less than12 the total SMDheight, (see Fig. 1).6.2 In-Process Test:1This test method is under the jurisdiction of ASTM Committee F01 onElectronics and is the direct responsibility of Subco
13、mmittee F01.18 MembraneSwitches.Current edition approved Feb. 1, 2012. Published March 2012. Originallyapproved in 1999. Last previous edition approved in 2005 as F199500(2005). DOI:10.1520/F1995-12.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,
14、United States.6.2.1 Bring contact tool into contact with SMD specimen.6.2.2 Gradually increase force, not to exceed 225 g/s, untilbond failure.6.2.3 After initial contact with the SMD edge and during theapplication of force, the relative position of the contact toolshall not move such that contact i
15、s made with the circuit planeor SMD attachment media. If the tool rides over the SMD, anew specimen shall be substituted.6.2.4 Record force measured to shear SMD.7. Report7.1 Report the following information:7.1.1 Temperature.7.1.2 Humidity.7.1.3 Shape and size of contact tool.7.1.4 Orientation of S
16、MD to contact tool.7.1.5 SMD information: SMD part number, plating type,etc.7.1.6 Circuit or substrate type.7.1.7 Attachment media type.7.1.8 Force applied by contact tool when bond failureoccured.7.1.9 SMD size.7.1.10 Type of encapsulant used.8. Precision and Bias8.1 PrecisionIt is not possible to
17、specify the precision ofthe procedure in Test Method F1995 for measuring Shear Forcebecause the test is destructive allowing only limited repeatabil-ity in comparison testing.8.2 BiasNo information can be presented on the bias ofthe procedure in F1995 for measuring Shear Force because nostandard sam
18、ple is available for this industry.9. Keywords9.1 adhesion; bond strength; LED; membrane switch; shearforce; SMD; surface mountASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are
19、expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not re
20、vised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you
21、may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United S
22、tates. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).FIG. 1 SMD ContactF1995 122
