| 摘要 |
PROBLEM TO BE SOLVED: To provide a printed wiring board in which good solder joint force can be obtained to an electroless plating layer even when a stress such as thermal stress acts on the electroless plating layer.SOLUTION: A printed wiring board 1A includes a second insulation layer 15B made of an insulation material, a second conductor layer 16B formed on the second insulation layer 15B and partially including a conductor pad 23, a solder resist layer 29 formed on the second conductor layer 16B and having an opening 27 that exposes a part of the conductor pad 23, and an electroless plating layer 51 formed on the exposed conductor pad 23. The electroless plating layer 51 is an electroless Ni/Pd/Au layer formed by successively depositing, from the surface of the conductor pad 23, a Ni layer 52, a Pd layer 53 and an Au layer 54; and the Ni layer 52 contains P by 6 to 8 mass%. An interval P between conductor pads 23 is 100 μm or less.SELECTED DRAWING: Figure 2 |
