| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a forming method of a viahole which reduces thermal damage to insulating material of a lower layer while a laser light is used. SOLUTION: A pulsed laser light is cast on a board from above which has a structure sandwiching a plating layer between resin and an upper insulating layer. In a term A where the laser light is turned on, an irradiated part in the upper insulating layer is violently heated, scattered to make a hole. The heat is conducted to the periphery of the part. In a term B between pulses, heating is not performed and heat is only dispersed, so that the temperature of periphery of the irradiated part does not become excessively high. Thereby resin just below the plating layer is prevented from fusing and vaporizing. Hence the plating layer is not peeled from the resin just below the plating layer.</p> |
