1998 Fiscal Year Final Research Report Summary
Processins Technology of High Density Interconnection Bumps
| Project/Area Number |
09650773
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Material processing/treatments
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| Research Institution | Okayama University |
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Principal Investigator |
KONDO Kazuo University of Okayama, Engineering, Associate Professor, 工学部, 助教授 (50250478)
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| Co-Investigator(Kenkyū-buntansha) |
FUKUI Keisuke Himeji Institute of Technology, Engineering, Associate Professor, 工学部, 助教授 (50047635)
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| Project Period (FY) |
1997 – 1998
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| Keywords | Packaging / Electronics / High density interconnection / Current distribution / Electrodeposition / Bumpping |
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| Research Abstract |
Packaging is the main technology to miniaturize the electronics devices such as personal computer and celler phone. Bump is indispensable interconnection method. The shape evolution mechanism of these bumps has been discussed based on the current distribution.
1 Bump shapes with photo resist angle The mass transfer is controlled by diffusion for the Peclet number of 1.31. The mass transfer is concentrated at the cathode corner. The negative photo resist angle, 0, prevents this mass transfer and decrease current density at the cathode corner. The mass transfer is controlled by convection for the Peclet number of 1407. The vortices form both at upper and lower edge of the cathode corners. The negative 0 enlarges the vortices and decreases the current at the cathode corners.
2 Bump shapes at high Peclet numbers The two vortices start to merge into one for Pe=73 11. A large single vortex form for P=44500. This large single vortex increases the current at the cathode center.
3 Bump shapes with high aspect ratio The current distribution at diffusion control is analyzed with high aspect ratio cavity. The current distribution becomes symmetric with a sharp peak for larger aspect ratio. The convection outside of the cavity does not stir their inside.
4 High aspect ratio bumps for CSP The lower edge of bump enlarges with increase of cathode placement angle for the cavity of 1.0 aspect ratio. A large vortex forms outside of the cavity because of the natural convection at the cathode. The vortex again flows into the cavity and collides with the bump lower edge.
5 Bump shapes with additive and the application -The bumps with hump on the surroundings traps more number of conductive particles and increase the electric properties. An additive of selenic acid is effective and this additive can be explained by the Wagner number and secondary current distribution.
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