An Engineer's Handbook of Encapsulation and Underfill Technology
An Engineer's Handbook of Encapsulation and Underfill Technology
Keywords: Encapsulation, Underfill, Publication
Overall, this is truly a "Handbook" for engineers containing an appropriate level of materials science. In detail, I comment on chapters as follows.
Chapter 1. The scene setting and historical perspective is concise and adequately informative.
Chapter 2. A very useful basic description of organic chemical structures to help electronics packaging engineers grasp the essentials of moulding. It also contains useful comparison tables. The look-up information on fire retardant is a good example. The author could usefully have added comments about the post-mould curing beyond the manufacturers' datasheets, to achieve complete curing and safeguard reliability. The research by the author and compilation into engineering explanations is indeed valuable.
Chapter 3. On failure mechanisms, is the weaker chapter. Aluminium migration(actually electromigration) is not an encapsulation or package related issue. The chapter would benefit from strengthening in a second edition. Section 3.2 and 3.4 can be excluded and explanation of popcorning – which is a manufacturing related failure mechanism – can be improved. The chapter has useful references.
Chapter 4. Again provides a useful overview of essential material properties. The "ideal" amount of encapsulation is debatable, because there is experimental evidence that excessive thickness of silicone encapsulant is less desirable than a thin coating to achieve the desired moisture protection. Totally encapsulating the bond wires is unnecessary. Section 4.5 would benefit from examples of "must have" and "desirable" attributes, as well as "scoring". I understand the author's reluctance to do so, because my own experience in providing such examples is that the novice engineer or inexperienced "manager" grabs the "example" and applies it totally out of context as the definitive statement for all applications in lieu of essential work.
Chapter 5. Has a very useful summary on test methods for encapsulants in Table 5.1. The chapter has very useful materials characterisation procedures and illustrations together with summary explanations. Similarly useful illustrations and explanations are provided for electrical and electronics testing.
Chapter 6. Contains practical guidelines to the precautions and procedures for processing underfills including preparation, cleaning, degassing and dispensing.
Chapter 7. The author sensibly recognised the difficulty of revising all chapters as new developments came along even while writing the book. So, the chapter provides his insight to the newer materials that appeared as the book was put to bed. I found the chapter informative for the engineer in the descriptions of the new types of materials. The "reworkable" thermoset epoxy appears almost a contradiction in terms, but very promising. The increasing availability of self-fluxing underfills from more than one source creates valuable opportunities – meeting the challenges of fluxing,adhesion and protective polymerisation.
Finally, I liked the summary conversion chart – useful to save me having to thumb through standards tables and reaching for my calculator when faced with incomprehensible units such as BTU.ft-1h-1f-1!
Professor Nihal SinnaduraiATTAC, UK
