Lamination structure design
(1) Thin core with larger thickness is preferred (relatively better dimensional stability)
(2) PP with low cost is preferred (for the same glass cloth type PP, the resin content basically does not affect the price)
(3) A symmetrical structure is preferred to avoid warping of the PCB after the finished product. The following figure is an asymmetrical structure, which is not recommended.
(4) Dielectric layer thickness > inner layer copper foil thickness × 2
(5) It is forbidden to use PP with low resin content in sheets between 1-2 layers and n-1/n layers, such as 7628×1 (n is the number of layers)
(6) For 3 or more prepregs arranged together or the thickness of the dielectric layer is greater than 25mil, except that the outermost and innermost layers use PP, the middle PP is replaced by a light board
(7) When the second layer and n-1 layer are 2oz bottom copper and the thickness of the 1-2 layer and n-1/n layer insulation layer is <14mil, it is forbidden to use single-sheet PP, and the outermost layer needs to use high resin content PP. Such as 2116, 1080; if the residual copper rate is less than 80%, try to avoid using a single 1080PP
(8) For boards with 1 oz of copper in the inner layer, when one PP is used for the 1-2 layer and n-1/n layer, the PP needs to be selected with high resin content, except 7628×1
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(9) It is forbidden to use a single sheet of PP for boards with inner copper ≥ 3oz. Generally, 7628 is not used. Multiple sheets of PP with high resin content must be used, such as 106, 1080, 2116...
(10) For multi-layer boards with copper-free areas larger than 3″×3″ or 1″×5″, PP is generally not used in single sheets between core boards.
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