Abstract: Embodiments of the present disclosure relate to the field of printed circuit boards and particularly to a multi-layer printed circuit board. The multi-layer printed circuit board includes at least two inner-layer circuit boards, each of which has a non-circuit pattern area including a welding area. Each welding area has at least one welding hole. Further, at least one prepreg is used to fill between two adjacent inner-layer circuit boards and is melted to fill into the welding hole in a welding process. In the multi-layer printed circuit board according to the embodiments of the disclosure, a welding area is arranged in a non-circuit pattern area, and one or more welding holes are arranged in the welding area so that a prepreg between two inner-layer circuit boards can be melted filling into the welding hole(s) in a welding process, thus enhancing effectively an adhesive force binding the inner-layer circuit boards.

Abstract: The invention discloses a printed circuit board compensation processing method for fabricating a BGA despite a small distance between a line and a pad of the BGA. The method includes compensating a pad and/or a line under a predetermined condition, and removing a portion of the pad facing the line by a second predetermined width when the shortest distance between the compensated line and pad is smaller than a first predetermined distance. The invention further discloses a device for performing the method and a PCB fabricated using the method.

Abstract: A method of fabricating a printed circuit board is disclosed. The method includes opening a first window in a first base board and opening a second window in a second base board and a resin layer. The resin layer is between the second base board and the first base board. The method further includes bonding the first base board and the second base board through the resin layer; placing a heat dissipating conductor in the first window in the first base board through the second window; placing a resin portion on the first base board in the second window; embedding a sub-board in the second window of the second base board; and bonding the sub-board with the first base board through the resin portion.

Abstract: Disclosed is a method for treating wastewater containing at least one copper complex, comprising: 1) providing the wastewater containing the at least one copper complex, wherein the at least one copper complex is chosen from EDTA-Cu2+ complex and ammonia-Cu2+ complex; 2) adjusting pH of the wastewater containing the at least one copper complex to be within a range from 2.0 to 3.0, and adding ferrous sulfate to convert copper in the wastewater into a form of cuprous ions; and 3) adjusting pH of the wastewater obtained in step 2) to be within a range from 8.0 to 10.5, so that the cuprous ions in the wastewater are converted into precipitates of cuprous hydroxide and/or precipitates of cuprous oxide.