Multilayer PCB is mainly composed of copper foil, prepreg, and core board. There are two types of lamination structures, namely, the lamination structure of copper foil and core board and the lamination structure of core board and core board. The copper foil and core board lamination structure is preferred, and the core board lamination structure can be used for special plates (such as Rogess44350, etc.) multi-layer boards and hybrid structure boards.

 1.Design requirements for pressing structure In order to reduce the warpage of the PCB, the PCB lamination structure should meet the symmetry requirements, that is, the thickness of the copper foil, the type and thickness of the dielectric layer, the pattern distribution type (circuit layer, plane layer), the lamination, etc. relative to the PCB vertical Centrosymmetric,

2.Conductor copper thickness

(1) The thickness of conductor copper indicated on the drawing is the thickness of the finished copper, that is, the thickness of the outer layer of copper is the thickness of the bottom copper foil plus the thickness of the electroplating layer, and the thickness of the inner layer of copper is the thickness of the inner layer of the bottom copper foil. On the drawing, the outer layer copper thickness is marked as “copper foil thickness + plating, and the inner layer copper thickness is marked as “copper foil thickness”.

(2) Precautions for the application of 2OZ and above thick bottom copper Must be used symmetrically throughout the stack.

Avoid placing them on the L2 and Ln-2 layers as much as possible, that is, the secondary outer layers of the Top and Bottom surfaces, to avoid uneven and wrinkled PCB surfaces.

3. Requirements for pressing structure

The lamination process is a key process in PCB manufacturing. The more the number of laminations, the worse the accuracy of the alignment of the holes and the disk, and the more serious the deformation of the PCB, especially when it is asymmetrically laminated. Lamination has requirements for stacking, such as copper thickness and dielectric thickness must match.