| 摘要 |
A method of forming pre-solders on a substrate is provided. Firstly, a substrate is provided. The substrate includes an upper surface and a lower surface. There are several metal circuits and a solder mask both on the upper and the lower surfaces. Each solder mask covers parts of the corresponding metal circuits and parts of the corresponding surface for exposing parts of several pads of the corresponding metal circuits. Then, a patterned photo-resist film is formed on the upper surface. The patterned photo-resist film has several openings for exposing the upper-surface pads. Afterwards, several metal materials are formed in the opening by printing. Thereon, the metal materials are reflown to form several pre-solders on the upper-surface pads. Finally, the patterned photo-resist film is removed.
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