|Type||Features & uses|
|Bump formation by electroplating||- Costly with large-scale facilities
- Complex process
- Types of bump metals: Gold plating, solder plating, etc.
- For narrow pitches: Straight wall bumps are best suited.
- Suitable for microbumps.
- Uniformity of thickness of bump films is dependent on current distribution.
|Bump formation by electroless plating||- Low facility cost
- Simple process
- Types of bump metals: Limited to nickel-gold plating
- Unsuitable for narrow pitches (possible with resist mask)
- Unsuitable for microbumps (possible with resist mask)
- Uniformity of thickness of bump films is good.
(From “Denshi Buhin no Mekki Gijutsu” by Hidehiko Enomoto, Tsuneshi Nakamura; Nikkan Kogyo Shimbun Ltd.)