Solder paste is used in the electronics industry to connect surface mount circuit components to printed wiring boards. A printed wire board (PWB) is populated with components by applying solder paste on the PWB, placing components and finally reflowing the solder paste in an oven. Between the time the component is placed on the PWB and the solder paste is reflowed, the components are to be held in position. This is helped by tackiness of the paste. The present paper describes an experimental investigation of the tack strength of three solder pastes with probe size, probe surface roughness, drying time, and surrounding pressure. The results indicate that the probe size has a significant and dominant effect on all the pastes examined. A Mechanistic view of the possible mechanism for this phenomenon is also presented. Measured tack strength is shown not to be simple adhesion, but to include a vacuum under the test probe that increases tack strength (force per unit area) as probe size increases.

Issue Section:
Technical Papers
Topics:
Experimental design, Solders, Probes, Printed circuit boards, Adhesion, Circuits, Drying, Electronics, Ovens, Pressure, Surface mount packaging, Surface roughness, Vacuum, Wire
1.
Ainsworth, P. A., 1986, “Measurement of Tackiness of Solder Paste,” Hybrid Circuits, No. 11, Sept., pp. 27–30.
2.
Anson, S. J., 1995, “An Examination of the Factors Affecting the Measurement of Solder paste Tackiness” Master’s thesis, Binghamton University (State University of New York at Binghamton), Binghamton, NY.
3.
Buttars, S., 1990, “Parameters for Solder Paste Printing,” National Electronic Packaging and Production Conference, Proceedings of the Technical Program, NEPCON EAST, Anaheim, CA, pp. 799–806.
4.
Guillaume, B., Guinet, J., and Hubert, J. C., 1990, “Solder Paste Tackiness: The Influence of the Process Atmosphere and of the Test Results,” 8th International Electronic Manufacturing Technology Symposium, May 7-9, 1990, Baveno, Italy, pp. 375–384.
5.
IPC-TM-650, 1995, ANSI/IPC J-STD-005, 1995, Joint Industry Standard, Requirements for Soldering Pastes, Number 2.4.44, January 1995, Lincolnwood, IL.
6.
Johnson, C., and Kevra, J., 1989, Solder Paste Technology: Principles and Applications, TAB Professional and Reference Books, Blue Ridge Summit, PA, pp. 209–253.
7.
Kevra, J., 1989, “Solder Paste Tack Properties,” National Electronics Packaging and Production Conference, Proceedings of the Technical Program, NEPCON East, Boston, MA, pp. 96–98.
8.
Kevra, J., and Mohoric, D., 1989, “Solder Paste: Tack and Cure,” Microelectronics Packaging and Technology Materials and Processes, Proceedings of the 2nd ASM International Electronic Materials and Processing Congress, Apr. 10–12, 1989, pp. 313–319.
9.
Montgomery, D. C., 1991, Design and Analysis of Experiments, 3rd ed., Wiley, New York, pp. 278–310.
10.
Morris, J. R., Jr., 1988, “Solder Paste Tackiness Measurement,” Brazing and Soldering, No. 14, Spring, pp. 34–37.
11.
Parekh, C., 1990, “Quality of Solder Paste,” Surface Mount Technology, Apr., pp. 40–45.
12.
Thomas, S., 1994, “Measurement of Component Retention Properties of Solder Pastes for Surface Mount Printed Wiring Board Assembly,” Master’s thesis, Binghamton University (State University of New York at Binghamton), Binghamton, NY.
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 by The American Society of Mechanical Engineers
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