Abstract: A hybrid photolithography process for printed circuit board patterning combines two types of photoresist applications to achieve superior protection of printed circuit board (PCB) ‘plated through holes’ (PTH). In a first step, electro-deposited (ED) photoresist (also known as “ED resist”) is applied to a fully copper plated PCB including the ‘plated through holes’ to protect the outer layers and the ‘plated through holes’ from copper etchant solution. In a second step, the electro-deposited photoresist is imaged (exposed) and patterned (developed). In a third step, after developing the circuit image, a layer of Dry Film resist is applied to the panel of the PCB on top of the developed electro-deposited (ED) photoresist. This Dry Film resist layer will ‘tent’ the plated through holes by adding an extra layer of protection to the plated through holes. In a fourth step, the dry film resist is then exposed and developed. At this point, the PCB is etched as normal and all subsequent processing remains unchanged.

Abstract: A hybrid photolithography process for printed circuit board patterning combines two types of photoresist applications to achieve superior protection of printed circuit board (PCB) ‘plated through holes’ (PTH). In a first step, electro-deposited (ED) photoresist (also known as “ED resist”) is applied to a fully copper plated PCB including the ‘plated through holes’ to protect the outer layers and the ‘plated through holes’ from copper etchant solution. In a second step, the electro-deposited photoresist is imaged (exposed) and patterned (developed). In a third step, after developing the circuit image, a layer of Dry Film resist is applied to the panel of the PCB on top of the developed electro-deposited (ED) photoresist. This Dry Film resist layer will ‘tent’ the plated through holes by adding an extra layer of protection to the plated through holes. In a fourth step, the dry film resist is then exposed and developed.

Abstract: A method of making a circuitized substrate having plated through holes free of filler material is provided. The method includes the steps of providing a dielectric substrate having first and second opposite faces. At least one via hole is formed from one face to the other. A first electrically conductive layer is applied onto the top and bottom faces of the dielectric member and onto the side wall of the via. First layers of photoresist are applied to each layer of conductive material and entering at least partially into the via hole. The first layers of photoresist are selectively exposed and developed to remove all of the photoresist, except that photoresist which is disposed in the via holes. Thereafter, a portion of the faces of the metal coatings on the surfaces of dielectric material and any photoresist remaining in the holes extending above the layers of electrically conductive material are removed to form a planar surface thinner than the thickness of the metal in the through hole.

Abstract: A wiring board for mounting an electrical device, which has an array of connectors thereon arranged in a grid pattern, wherein the connectors have at least two levels of criticality of connection to the substrate. The substrate has a plurality of mounting structure or features arranged in the same grid pattern to connect with the array of connectors on the electrical device. The mounting structures or features are divided into a plurality of at least two groups, with each group corresponding to a level of criticality of the connectors on the device. Each group of mounting structures has a discernible feature differing from each other group, to thereby permit different levels of inspection criteria for each group.