PURPOSE: To prevent Manhattan phenomenon of a chip at the time of printing the chip parts, in a printed circuit board provided with a pair of land patterns with lateral asymmetry for soldering the chip parts.
CONSTITUTION: The structure of a printed circuit board is formed by a land pattern 2 formed by etching a copper foil on a substrate 1, and a resist film 4 which has an open hole having the same shape as the land pattern 2, and another land pattern 7 provided with a cutting part 5 formed by etching the peripheral part of the resist film 4. Therefore, the thermal capacity of the land pattern 2 and the land pattern 7 becomes almost equal and the difference of melting time of cream solder is reduced. As a result, generation of the Manhattan phenomenon can be reduced.
FURUSAWA AKIO
KUMAGAI KOICHI
