Environmentally Sound Assembly Processes

Fang, Ting

doi:10.1002/047134608x.w2117

Cited by 3 publications

(2 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Fillets formed after bonding eliminate the use of underfill materials for both ACA interconnect approaches. This self-encapsulation characteristic makes ACA process one of the most environmentally benign process available to date [2].…”

Section: Materials Selectionmentioning

confidence: 99%

Anisotropic conductive adhesive films for flip chip on flex packages

Fang²

4th International Conference on Adhesive Joining and Coating Technology in Electronics Manufacturing. Proceedings. Presented At

View full text Add to dashboard Cite

Miniaturization and high performance demand more and more flip chip and chip scale packages for consumer products. New packages require increased functionality with a reduction in overall size and weight. The traditional flip chip approaches using solder bumps pose an unacceptably high cost for lowend consumer products. Package technologies for integrated circuits with low to moderate I/O counts (below 150) are critical. A low cost and low profile flip chip on flex CSP package using anisotropic conductive adhesive film (ACF) was developed. This package has the flexibility to use the existing wire bonding pad configuration without adding prohibitive redistribution and wafer solder bumping costs, and also eliminates the need for under-chip encapsulation. Figure 1 : Package top and bottom view. Material research and evaluations were conducted to optimize the adhesive material for flip chip on flex applications. Anisotropic conductive adhesive film bonding processes were developed through design of experiments. Critical bonding equipment parameters and process conditions were identified. ACF bonding quality was characterized to adjust the bonding equipment co-planarity. A double layer epoxy film with the second layer loaded with Au plated polymer spheres was identified to be the best ACF material. Contact resistances of the ACF joints were monitored though multiple reflow and thermal-mechanical shock cycles. Various volume production approaches were also explored.

show abstract

Section: Materials Selectionmentioning

confidence: 99%

Anisotropic conductive adhesive films for flip chip on flex packages

Fang²

4th International Conference on Adhesive Joining and Coating Technology in Electronics Manufacturing. Proceedings. Presented At

View full text Add to dashboard Cite

show abstract

“…This technology requires a vacuum deposition system with excellent alignment accuracy for the metal masking procedure during evaporation. Both solder and under bump metallurgy (UBM) are dcposited in a vacuum evaporator so the materials usage efficiency is poor and subsequent removal of the unwanted solder from the evaporator dome is tedious [2,3]. Furthermore, the limited lifc 0-7803-5908-9/00/$10.00 @ZOO0 IEEE 46 cycle of molybdenum masks makcs the cost of C4 humps very high.…”

Section: Introductionmentioning

confidence: 99%

Squeegee bump technology

Lin

Fang²,

Bajaj³

2000 Proceedings. 50th Electronic Components and Technology Conference (Cat. No.00CH37070)

View full text Add to dashboard Cite

An innovative solder bumping technology, termed squeegee bumping, has been developed at Motorola's Interconnect Systems Laboratory that uses baked photoresist as a inask for solder printing to deposit fine pitch solder humps o n , wafers. This process provides much better alignment accuracy and is capable of bumping finer pitch devices than stencil printing technology. Solder paste printing uses a screen printer similar to stencil printing and therefore exhibits better versatility of solder materials selection than the electroplating process.Cost modeling shows that the squeegee bump technology has a significant cost benefit over controlled collapse chip connection (C4) technology. This is because the C4 process has very low efficiency in labor and materials usage. Statistical process control data show au average bump height of 118*3.5im, and a maximum-tominimum bump height range of 17pm over a 150mni-diameter wafer have been produced repeatedly on test wafers with 2 1 0 p peripheral pitch. A 109.6*1.3pm bump height on orthogonal array with 250i1n pitch has been successfully demonstrated with greater than 90% die yield. Bump reliability has been studied using both multiple reflows and extended thermal I humidity storage procedures.No degradation of shear strength was observed after up to 10X reflows and 1,008 hours of a thermal I humidity strcss environment. Bump reliability was also cvaluated by assembling squeegee bumped dice on a plastic chip scale package (CSP). Liquid-to-liquid thermal shock cycling at a temperature range of -55°C to +12S0C had a characteristic life oC 2,764 cycles with a 1" failure at 1,050 cycles. No failures were observed after 432 hours of autoclave stress at 12I0C, 100%RH, 15 psig test condition.

show abstract