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AssigneeNEC Corporation
InventorsNaomi Ishizuka, Akihito Matsumoto, Eiichi Kono, Motoji Suzuki, Akihiro Sato, Hiroshi Matsuoka, Masafumi Kanai
Estimating the term…
In a circuit board having lands 2 each of which has a through hole 4 through which a lead of an electrical part is inserted, the lead 3 and the land 2 being mounted in the circuit board by using lead-free solder 6, the width of the land 2 corresponding to the difference in radius between the land 2 and the through hole 4 is set to about 0.40 mm or more. The width of the land 2 is set to such a value that the land exfoliation due to the solidification/shrinkage of the lead-free solder 6 and the shrinkage of the circuit board in the thickness direction can be prevented. The circuit board 1 has circuit wires at least on both the surface and the back surface.
A circuit board having circuit wires on the surface and back surface thereof, comprising lands having through holes through which conductive members of electrical parts are inserted, said through holes being coated with a conductive film on the side surfaces themselves,
Dependencies are inferred from the claim text.