Low cost bumping by stencil printing: process qualification for 200 μm pitch

2000 ◽  
Vol 40 (3) ◽  
pp. 497-505 ◽  
Author(s):  
Joachim Kloeser ◽  
Katrin Heinricht ◽  
Erik Jung ◽  
Liane Lauter ◽  
Andreas Ostmann ◽  
...  
1999 ◽  
Author(s):  
Jianbiao Pan ◽  
Gregory L. Tonkay

Abstract Stencil printing has been the dominant method of solder deposition in surface mount assembly. With the development of advanced packaging technologies such as ball grid array (BGA) and flip chip on board (FCOB), stencil printing will continue to play an important role. However, the stencil printing process is not completely understood because 52–71 percent of fine and ultra-fine pitch surface mount assembly defects are printing process related (Clouthier, 1999). This paper proposes an analytical model of the solder paste deposition process during stencil printing. The model derives the relationship between the transfer ratio and the area ratio. The area ratio is recommended as a main indicator for determining the maximum stencil thickness. This model explains two experimental phenomena. One is that increasing stencil thickness does not necessarily lead to thicker deposits. The other is that perpendicular apertures print thicker than parallel apertures.


2010 ◽  
Vol 156-157 ◽  
pp. 10-17 ◽  
Author(s):  
Er Shun Pan ◽  
Yao Jin ◽  
Zhao Mei ◽  
Ying Wang

A stencil printing process (SPP) optimization problem is studied in this paper. Due to the limitation that neural network requires a large number of samples for the accurate model fitting, a two-stage SPP optimization method is proposed. The design interval can be reduced with small sample by using neural network. In this reduced design interval , response surface method is adopted to obtain the accurate mathematical SPP model. The concept of confidence level is introduced to make the proposed model robust. An interactive method is used to solve the model. The proposed method is compared with the one-stage optimization method and the results show that the proposed method achieves a better performance on each objective.


2010 ◽  
Vol 2010 (DPC) ◽  
pp. 000671-000707
Author(s):  
Stephen Kenny ◽  
Sven Lamprecht ◽  
Kai Matejat ◽  
Bernd Roelfs

Electrolytic Solder Deposit for Current methods for the formation of pre-solder bumps for flip chip attachment use stencil printing techniques with an appropriate solder paste. The continuing trend towards increasing miniaturisation and the associated decrease in size of solder resist opening, SRO is causing production difficulties with the stencil printing process. Practical experience of production yields has shown that stencil printing will not be able to meet future requirements for solder bump pitch production below 0.15 mm for these applications. This paper describes a novel approach to replace the stencil printing process by use of an electrolytic deposition of solder. In contrast to stencil printing, use of electrolytic deposition techniques allows production of solder bumps with a pitch below 0.15 mm and with a SRO below 80 μm. Methods for production of electrolytic solder bumps based on pure tin as well as alloys of tin/copper and also tin/silver are shown and in particular a method to control the alloy concentration of electroplated tin/copper bumps. Test results with both alloy systems and also pure tin bumping are presented together with comparison of the advantages and disadvantages. The general advantages of replacement of stencil printing by electrolytic deposition of solder bumps are shown and in particular the improvement of bump reliability and the potential to significantly decrease costs by yield improvement.


2019 ◽  
Vol 19 (19) ◽  
pp. 8597-8604 ◽  
Author(s):  
Kessararat Ugsornrat ◽  
Patiya Pasakon ◽  
Chanpen Karuwan ◽  
Chakrit Sriprachuabwong ◽  
Thitima Maturos ◽  
...  

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