Lun Hao Tung, Fei Chong Ng, Aizat Abas, M.Z. Abdullah, Zambri Samsudin and Mohd Yusuf Tura Ali
This paper aims to determine the optimum set of temperatures through correlation study to attain the most effective capillary flow of underfill in a multi-stack ball grid array…
Abstract
Purpose
This paper aims to determine the optimum set of temperatures through correlation study to attain the most effective capillary flow of underfill in a multi-stack ball grid array (BGA) chip device.
Design/methodology/approach
Finite volume method is implemented in the simulation. A three-layer multi-stack BGA is modeled to simulate the underfill flow. The simulated models were well validated with the previous experimental work on underfill process.
Findings
The completion filling time shows high regression R-squared value of up to 0.9918, which indicates a substantial acceleration on the underfill process because of incorporation of thermal delta. An introduction of 11 °C thermal delta to the multi-stacks BGA managed to reduce the filling time by up to 16.4%.
Practical implications
Temperature-induced capillary flow is a relatively new type of driven underfill designed specifically for package on package BGA components. Its simple implementation can further improve the productivity of existing underfill process in the industry that is desirable in reducing the process lead time.
Originality/value
The effect of temperature-induced capillary flow in underfill encapsulation on multi-stacks BGA by means of statistical correlation study is a relatively new topic, which has never been reported in any other research according to the authors’ knowledge.
Details
Keywords
The Communist revolution in China has led to the appearance in this country of increasing numbers of Chinese books in Russian translation. The Chinese names in Cyrillic…
Abstract
The Communist revolution in China has led to the appearance in this country of increasing numbers of Chinese books in Russian translation. The Chinese names in Cyrillic transcription have presented many librarians and students with a new problem, that of identifying the Cyrillic form of a name with the customary Wade‐Giles transcription. The average cataloguer, the first to meet the problem, has two obvious lines of action, and neither is satisfactory. He can save up the names until he has a chance to consult an expert in Chinese. Apart altogether from the delay, the expert, confronted with a few isolated names, might simply reply that he could do nothing without the Chinese characters, and it is only rarely that Soviet books supply them. Alternatively, he can transliterate the Cyrillic letters according to the system in use in his library and leave the matter there for fear of making bad worse. As long as the writers are not well known, he may feel only faintly uneasy; but the appearance of Chzhou Ėn‐lai (or Čžou En‐laj) upsets his equanimity. Obviously this must be entered under Chou; and we must have Mao Tse‐tung and not Mao Tsze‐dun, Ch'en Po‐ta and not Chėn' Bo‐da. But what happens when we have another . . . We can hardly write Ch'en unless we know how to represent the remaining elements in the name; yet we are loth to write Ch'en in one name and Chėn' in another.