強化表面黏著電子構裝元件抗振特性之設計方案研究

Design for the Enhancement of Anti-vibration Characteristics of Surface Mount Type Electronic Components

邱柏翔(Po-Shiang Chiou)

指導教授 ： 陳永樹

元智大學/工程學院/機械工程學系/碩士(2009年)

摘要

電子元件封裝之發展，過去由穿孔式(Plated Through-hole Type-PTH)元件演變至今，表面黏著式(Surface Mount Type-SMT)等已佔大宗，其中球柵狀陣列式構裝BGA(Ball Grid Array)更是主流。然而，在振動環境如汽車、軍事、太空衛星上之應用，仍以可靠度較高之穿孔式電子元件為主。但是使用穿孔式元件，在封裝時必須有導線架(Lead Frame)；同時，元件於安裝時，電路板上對應也需鑽微孔。因此，是耗時、耗成本的製程。表面黏著之BGA元件省去上述製程，又提供為數較多之接腳。因此，現已是廣泛應用於最新微小化趨勢下之主流元件如覆晶(Flip-chip)、晶片尺寸(Chip Scale Package - CSP)與晶圓級晶片構裝(Wafer-level CSP)等。礙於這些新式構裝元件之振動可靠度不如穿孔式元件，造成應用上之缺憾。所以，本將針對此問題加以設計改善。
研究發現BGA元件在振動環境下測試，其所損壞之錫球皆為角落之錫球。因而，有些研究將角落錫球加以改變，設計成較大顆之錫球，有些則將之改為錫柱，以能承受較大之應力，或甚至故意擺放一顆單純只用來承受應力之無訊號傳遞功能的錫球。凡此種種設計，在製程上都必須特別處理。如此不但成本增加，且為了少數元件之抗振設計，整個生產製程必須做變動，顯然不是經濟有效之對策。本研究則將利用加強肋與彈性加強片設計，可以增加元件構裝整體之剛性，且抑制電路板之振動變形模態。而彈性加強片之置入，增加了其與晶片背面之接觸壓力，以熱傳觀點而言，增加接觸壓力會大幅改善散熱效果。
本研究所設計之封裝元件，將具備抗振動與散熱改善功能。具體而言，可應用於國內亟待大力發展之汽車電子、以及國家太空科技發展的微衛星之電子元件所需。對產業既有電子產品之擴大應用層面，將有絕對之助力。

關鍵字

球柵陣列封裝 ； 可靠度 ； 表面黏著 ； 抗振動 ； 微衛星

並列摘要

The technology of electronic packaging has evolved from the traditional pin-through-hole(PTH) type into the concurrent surface mount type. Among the latter, ball grid array (BGA) probably dominates the current packaging electronic products. However, under the vibration environments, such as those in the automotive, military, and space industry applications, the PTH products are still chosen as the sole source for the severe vibration environment use. Nevertheless, they have to come with the lead-frame during the packaging processes as well as the requirement of hole-drilling on the printed circuit boards when mounting. These processes are time-consuming and cost intensive. Conversely, the BGA components don’t have to go through the forgoing processes while offering more input/output counts on a single package. It is overwhelmingly used for the new miniaturized electronic components such as flip-chip, chip scale package, and wafer level package. Because BGA’s perform not so well in the vibration environment comparing with those PTH’s, it has limited use in severe vibration conditions. This problem has been set as the goal in this study to solve by having a new design to improve it.
The past research in literatures has shown that the corn solder balls are always failed firstly during the vibration test. Accordingly, some of the designs by enlarging the corner solder balls, or changing them into solder column, or putting dummy solder balls at each corner of the solder balls array to withstand the vibration stresses. Nevertheless, those measures all required major change in the processes thus increasing the manufacturing cost dramatically. Accordingly, this study developed some design improvements on the package for enhancing the anti-vibration characteristics of BGA components. The first improvement was a new design on the existing heat spreaders of the current BGA’s. It changed the contour of the current rectangular heat spreader by including extrusions at each of the four corners to sustain the stresses. Meanwhile, other designs were one with a surface-mountable type square bar and the other with mounting brackets along one of the two opposite edges of the component. A spring metal sheet will be designed and clicked at the bar center for increasing the stiffness and improving the contact pressure while also serving as the heat conducting device(heat spreader). All the effects of these designs were verified experimentally with the sinusoidal and random vibration tests.
The new design not only can resist the vibration induced stresses, it can also improve the functions of current heat spreader by increasing the contact pressure. It can be used for the automotive electronics and the space electronics especially for the miniaturized satellite space program.

並列關鍵字

Ball Grid Array Packaging ； Reliability ； Satellite ； Space ； Anti- Vibration

參考文獻

[33] IPC-9701, "Performance Test Methods and Qualification Requirements for Surface Mont Solder Attachments," Jan, 2002.

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