Adhesion tests test program

It should be apparent by now that numerous parameters can affect the performance of a joint, and many combinations of those parameters are possible. Therefore, a prime rule in any adhesive or sealant testing program is to standardize and document test variables as thoroughly as possible. The adhesive formulator, supplier, and end user should all utilize the exact same procedures and specimen construction. One should make every effort to ensure that similar tests that are performed at different locations in the company and by different personnel are identical duplicates of one another. 

LARC-TPI was added to the program early in Phase II in anticipation of possible failure in some or all of the other three adhesive systems. Test data confirming LARC-TPI as a suitable candidate adhesive were generated on Boeing Research. 

Peretz and Weitsman (1982) describe an excellent test program to obtain the best results for an epoxy film adhesive (FM-73). Each test was performed in triplicate and each was repeated twice yielding six creep and creep recovery sets of data for each stress level that was then averaged. In this manner experimental scatter was minimized to be less than 2.5%. 

The persistent interfacial failure with 120°C adhesives in actual service forces us to consider that the "standard" FPL etch for aluminum preparation may not be optimum for all bonding conditions. There are many years of outstanding service on this surface, but these surfaces had never before been evaluated with the particular combination of lower bonding temperatures and the unique testing program of combining heat, humidity, and sustained stress. 

It is emphasized that the adhesives tested during this program were not intentionally formulated to withstand these particular test conditions. Consequently, poor performance by an adhesive under the imposed conditions is no indication of the utility of that adhesive for applications under different environmental conditions. 

Tables II and III summarize the total adhesive testing done during the overall program. Since at CEL-NBS both gradual- and rapid-cooling tests were to be conducted at -323 F, the comparative effects of different types of thermal stress could be investigated. For a discussion of thermal stresses in adhesive bonds at low temperatures refer to McClintock and Hiza [2].

The test program should also subject the coating to environmental stress (time, temperature, chemical, mechanical fatigue, etc.) in order to evaluate the stability of the adhesion in the service environment. 

Adhesion test program A program designed to subject the hlm-substrate structure to the stresses (mechanical, chemical, thermal, fatigue) that it might see in subsequent manufacturing and service with adhesion teshng, to ensure the adhesion of the him under those condihons. 

A program name, such as Adhesive 1, is decided by the user and is loaded into the memoiy slot in the YR-1 Rheometer with the test parameters. 

The first specifications for adhesives were generated by the staff of NASA and the DoD who were prompted by the high reliability that was required of microcircuits used in aerospace programs. These specifications covered primarily die and substrate attachments for hermetically sealed integrated circuits, hybrid microcircuits, and multichip modules. Subsequently, with the increased use of surface-mount adhesives in the assembly of commercial printed-wiring boards and underfills for flip-chip devices, industry associations took the lead in generating the requirements and test methods. 

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