Provided is a wiring circuit board that includes a first insulating layer, a conductive pattern disposed on the first insulating layer, a second insulating layer disposed on the first insulating layer and covering the conductive pattern, and a third protective layer disposed between the conductive pattern and the second insulating layer and protecting the conductive pattern. The third protective layer consists of a metal oxide.

A method for forming a printed circuit board includes: forming on a substrate a first conductive layer for a first edge connector pin and a first conductive layer for a second edge connector pin, wherein the first conductive layer for the first edge connector pin and the first conductive layer for the second edge connector pin are electrically coupled to one another via a first conductive layer for an electrical bridging element; electroplating a second conductive layer onto both the first conductive layer for the first edge connector pin and the first conductive layer for the second edge connector pin via a plating current conductor; and removing at least a portion of the electrical bridging element to electrically separate the first edge connector pin from the second edge connector pin.

The disclosure provides a Sn—In electroplating bath that is Pb-free, environmentally safe, operates at room temperature, and does not require changes in existing plating assemblies. Room temperature aging and limited thermal cycling tests show that the electroplated Sn—In alloy film on a Cu substrate effectively mitigates whisker growth.

The disclosure provides a Sn—In electroplating bath that is Pb-free, environmentally safe, operates at room temperature, and does not require changes in existing plating assemblies. Room temperature aging and limited thermal cycling tests show that the electroplated Sn—In alloy film on a Cu substrate effectively mitigates whisker growth.

A method reduces an area of a mounting electrode provided on a first surface of a multilayer body and connected to a specific component is reduced and decreases a pitch between mounting electrodes. A plating film is formed on the mounting electrodes with the reduced area. The mounting electrodes for connection to specific components are defined by first end surfaces of first via conductors, and hence, the areas of the mounting electrodes are significantly reduced, and the pitch between the mounting electrodes is significantly decreased. Also, the mounting electrodes defined by the first end surfaces of the first via conductors are connected to plane electrodes at end surfaces of second via conductors exposed from a surface of the multilayer body with internal wiring electrodes interposed therebetween. Thus, a plating film is able to be reliably provided on the mounting electrodes.

A multilayer printed circuit board is provided. The multilayer printed circuit board includes a core, a first conductive layer coupled to the core, an insulating layer covering the first conductive layer, and a second conductive layer spaced from the first conductive layer by the insulating layer. The first conductive layer includes a first portion having a first thickness and a second portion having a second thickness greater than the first thickness. The second conductive layer is electrically coupled to the second portion of the first conductive layer by a conductive via extending through the insulating layer.

The disclosure provides an electronic device including a substrate, at least one conductive composite structure, and an electronic element. The at least one conductive composite structure is disposed on the substrate. The at least one conductive composite structure includes a first metal layer, a second metal layer, and a third metal layer. The second metal layer is located between the first metal layer and the third metal layer, and the thickness of the second metal layer ranges from 0.5 μm to 12 μm. The electronic element is disposed on the at least one conductive composite structure and bonded to the at least one conductive composite structure.

The invention relates to a washing solution for a tin plating film after electroless tin plating and before water washing. The invention also relates to a method for forming a tin plating film, the method includes a step of washing step using the washing solution. The washing solution according to the present invention is an acidic aqueous solution containing an acid, a complexing agent, a stabilizer and a chloride ion. The washing solution has a chloride ion concentration of 2 wt % or more, and a tin concentration of 0.5 wt % or less. The washing solution according to the present invention has good washing property for a tin plating film surface, and allows a tin plating film to easily maintain its properties. In addition the washing solution causes little influence on a tin plating film surface even when continuously used and is excellent in temporal stability.

A substrate for a printed circuit board according to an embodiment of the present invention includes a base film having an insulating property, and a metal layer formed on at least one surface side of the base film. In the substrate for a printed circuit board, a plurality of fine particles are disposed between the base film and the metal layer, and the fine particles are formed of a metal the same as a main metal of the metal layer or formed of a metal compound of the main metal. The fine particles preferably have an average particle size of 0.1 nm or more and 20 nm or less. The fine particles are preferably formed of a metal oxide or a metal hydroxide. The fine particles are preferably present between the base film and the metal layer so as to form a layer. The metal layer preferably includes a metal grain layer formed by firing metal nanoparticles.

A substrate for a printed circuit board according to an embodiment of the present invention includes a base film having an insulating property, and a metal layer formed on at least one surface side of the base film. In the substrate for a printed circuit board, a plurality of fine particles are disposed between the base film and the metal layer, and the fine particles are formed of a metal the same as a main metal of the metal layer or formed of a metal compound of the main metal. The fine particles preferably have an average particle size of 0.1 nm or more and 20 nm or less. The fine particles are preferably formed of a metal oxide or a metal hydroxide. The fine particles are preferably present between the base film and the metal layer so as to form a layer. The metal layer preferably includes a metal grain layer formed by firing metal nanoparticles.