With the continuous development of printed circuit board technology, the number of layers, the density (especially the density of small pads in the inner and outer layers), the increase in the area of the panel, and the complexity of the structure (coexistence of buried, blind, and through-hole structures), The requirements for the alignment between the layers of multi-layer boards (PCB circuit boards) are getting higher and higher; at present, the requirements for dimensional stability of printed circuit boards have reached an accuracy of no more than 1 mil per 24 inches, and even no more than 0 per 30 inches. 5mil is the standard, and strict accuracy requirements require us to continuously analyze and optimize our process to suit the needs of customers' PCB circuit board design.

　　We know that there are many factors that affect the alignment accuracy between layers of multi-layer boards (PCB circuit boards), mainly including design symmetry, dimensional stability of film negatives, dimensional stability of core boards (substrates), positioning methods in the production process and The accuracy of the positioning system, the accuracy and operation level of the processing equipment, and the production environment conditions (temperature, humidity), etc., are many and extremely complex. In order to effectively control the interlayer misalignment or error caused by the factors related to the interlayer alignment, it is necessary to analyze and study various factors, and formulate corresponding countermeasures from the quality and reliability of the multi-layer board products. Laminate (PCB circuit board) production is strictly controlled and inspected.

　　In order to analyze the influence of different factors on the alignment accuracy of multi-layer boards (PCB circuit boards), and to provide a simple and optimized film compensation coefficient for production control, this paper discusses the control by analyzing the dimensional stability of the core board in the production process. Quality problems caused by sheet shrinkage.

　　Dimensional stability of inner core board of multilayer board (PCB circuit board)

　　1. Principle analysis

　　The shrinkage of the core board will inevitably occur after the multi-layer board (PCB circuit board) is pressed. First, the glass cloth needs to be tightened in the warp direction during the manufacturing process of the prepreg, and at the same time, it needs to be heated so that the epoxy resin changes from A state to B state. The state is the prepreg, so there are different stresses in the warp and weft glass fibers of the processed prepreg. When the hot pressing stage of lamination is performed, it is equivalent to a stress relief process for the glass cloth of the prepreg, that is, shrinkage deformation occurs. , and the warp and weft shrinkage are different. The second is the sheet: after the sheet supplier presses the finished product, the surface is anti-oxidized and then packaged and shipped. The sheets we buy all have stress phenomenon. When we press the multi-layer board (PCB circuit board), the same It is equivalent to performing a stress relief treatment on the core board (substrate), so shrinkage occurs.

　　The internal stress is mainly caused by the different expansion coefficients between the materials. The plate is composed of copper foil, epoxy resin, and glass fiber cloth. After they are pressed together at high temperature, internal stress occurs due to the different expansion coefficients. Among them, copper is: 1.7*10-5K-1, glass fiber is: 1.1*10-4K-1; the size of internal stress is determined by epoxy resin molecular structure, epoxy resin content, dielectric thickness and copper foil thickness It is determined by the interaction with the type of fiber cloth in the production process. When the balance force between them is destroyed during production, the substrate will shrink and deform, causing the inner layer circuit pattern on the substrate to be distorted.

　　2. Experimental background

　　Our company replaced the lamination equipment in the year. The previous film compensation coefficient could not meet the requirements of the current lamination equipment process control after trial. It is necessary to provide a new film compensation coefficient according to the existing production equipment; in addition, the original compensation coefficient was single, It is not conducive to the control of the alignment accuracy between the layers of the multi-layer board (PCB circuit board). It is necessary to refine the original parameters and propose appropriate compensation coefficients.

　　3. experiment procedure

　　In the experiment, the key reference factors of coefficient compensation are confirmed by analyzing four factors including plate thickness, copper thickness, pattern selection and laminated structure, so as to simplify the operability of compensation coefficients.

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