| 摘要 |
PROBLEM TO BE SOLVED: To lessen bad connections by increasing the adhesiveness between a conductor of an inner layer circuit and a conductor of a through connection hole or non-through connection hole. SOLUTION: Inner layer circuits 3a, 3b are formed on an upper and a lower face of a copper clad laminate 2, and then a primer layer 4, an insulating resin layer 5, and an adhesive layer 6 are formed. A non-through hole 7 is made by casting laser beam light and a through hole 8 is made by drilling. The laminate is dipped in an aqueous solution of PH4-9 including ethylenediaminetetraacetic acid and then is put into an electroless plating process. A plating liquid in the electroless plating process is mixed with formalin (37% to the liquid) of the density of 3.5ml/l or above. |
