Title :
A study about solder bumping process by using the electro-plating method
Author :
Choi, Sung-Chang ; Chi, In-Ho ; Jin, Jeong-Gi ; Bok, Kyoung-Soon
Author_Institution :
Microscale Package Res. Center, Microscale Co. Ltd., Kyunggi, South Korea
Abstract :
Solder bump whose pitch is 150-300 μm was fabricated on Si substrate by electroplating with the medium thickness (~30 μm) photoresist. TiW/Cu/Cu mini bump was used as a UBM (under bump metallurgy) layer. TiW (0.3 μm)/Cu (0.7 μm) was deposited by sputtering and Cu mini bump (5-15 μm) was formed by electroplating. After UBM formation, subsequently, solder bump of mushroom shape was formed by electroplating. In electroplated solder bumping process, the control of the composition is one of the most important key technologies. However, during the formation of a solder mushroom, the composition of solder bump changes due to the variation of plating area. In order to obtain the uniform solder composition with the variance of plating area, applied current was controlled under the consideration of plating area. By controlling the applied current, the composition of solder bump can be controlled within 4%. Solder ball size after reflow could be controlled by calculating the amount of plated solder and measuring the mushroom diameter
Keywords :
electroplating; encapsulation; failure (mechanical); flip-chip devices; photoresists; reflow soldering; shear strength; 150 to 300 micron; 30 micron; 5 to 15 micron; TiW-Cu-Cu; applied current; electroplating method; failure mode; mushroom diameter; mushroom shape; photoresist; plating area; shear strength; solder bumping process; under bump metallurgy; uniform solder composition; Application specific integrated circuits; Assembly; Costs; Flip chip; Integrated circuit technology; Printing; Process control; Radiofrequency integrated circuits; Size control; Surface-mount technology;
Conference_Titel :
Electronic Materials and Packaging, 2001. EMAP 2001. Advances in
Conference_Location :
Jeju Island
Print_ISBN :
0-7803-7157-7
DOI :
10.1109/EMAP.2001.983978
