is comprised of a central portion 60 ac and a ring portion 60 ar located around it a carbon pillar conductive member held by a holding member having plasticity is disposed above the land 60 a and when a key is operated the carbon pillar connects electrically the central portion 60 ac with the ring portion 60 ar this example is the same as the example 1 1 except that no ops layer was formed on a solder pad in which the corrosion resistant layer of the example 1 1 is not formed this example is the same as the example 1 1 except that corrosion resistant layer of nickel palladium gold was formed on the solder pad in which the corrosion resistant layer of the example 1 1 was formed this example is the same as the example 1 1 except that corrosion resistant layer was formed of single layer gold on the solder pad in which the corrosion resistant layer of the example 1 1 was formed in the comparative example 1 1 the corrosion resistant layer nickel gold was formed on all solder pads other matters are the same as the example 1 1 in a group of the example 1 and the comparative example 1 manufactured printed wiring boards were evaluated according to an item a and after the manufactured printed wiring board was accommodated into a casing evaluation on items b and c was performed this evaluation result is indicated in fig1 under the heat cycle condition 130 u00b0 c 3 min and 55 u00b0 c 3 min as a cycle this cycle test was repeated up to 5 000 cycles and every other 500 cycles a test piece was left for 2 hours after the test ended.