Many friends have asked me about the related technology of PCB multilayer board manufacturing. Here I answer this question in great details. The manufacturing process of high-density interconnection (HDI) printed boards by the build-up method, semi-additive method for making precision fine lines (0.08mm/0.08mm line width and line spacing) technology, thermosetting Ink Layering Method (TCD for short) technology, plating and filling blind hole technology (Via Filling); high-end special material printed board manufacturing technology, etc.
1. Add-on method to make high-density inner layer connection (HDI) PCB circuit board technology The build-up method is a new technology that cooperates with the manufacturing of blind holes. The method is to first process the inner layer according to the ordinary multi-layer board processing method, and then superimpose one layer on top of each other, two or more layers, we call It is a build-up layer or SBU layer. The SBU layer and its adjacent layers are connected by micro-vias (ie blind holes). To truly master this technology, you must first master the following technologies:
A. Laser Drilling Technology Although a 2mil-8mil blind hole can be drilled with a laser drilling machine, the laser drilling technology is much more complicated than ordinary mechanical drilling. When the S anti-material is different, the plate thickness is different, and the hole diameter is different, the laser energy required is different. Therefore, we must go through systematic experiments and tests to find out the drilling parameters suitable for various boards, so as to ensure the quality of the drilling.
B. Micro-via Plating Technology HDI boards usually contain buried holes and blind holes, the diameter of the buried hole is about 0.3mm, and the diameter of the blind hole is 0.1-0.15mm. The smallest through hole diameter in ordinary PCBs is 0.5mm, and there are no blind holes. Therefore, to produce HDI boards, blind hole plating is a problem that must be solved. Adopt positive and negative pulse electroplating power supply, and cooperate with the improved electroplating line design, so as to ensure that the thickness ratio of the plating layer in the blind hole to the surface plating layer is close to or higher than 1:1, ensuring that the HDI board has good reliability.
C. Fine Line Production Technology Another feature of high-density circuit boards is that they have very small line width and line spacing. To make lines below 4 mils, it is difficult to achieve the use of traditional stereotypes with stereotypes. It can be realized by using advanced DES (developing, etching, stripping) lines and matching with suitable dry film and exposure technology. The research focuses on the production of 3mil/3mil line width and line spacing, and then studies 2mil/3mil, 2mil/2mil.
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