Multilayer PCB is mainly composed of copper foil, semi-cured sheet, core board. There are two types of press-fit structure, namely copper foil and core board press-fit structure and core board and core board press-fit structure. Preferred copper foil and core lamination structure, special plates (such as Rogess44350, etc.) multilayer board and mixed press structure board can be used core lamination structure. Note that the pressed structure (PCB Construction) and the drilling diagram of the stacked board sequence (Stack-up- layers) are two different concepts. The former refers to the PCB pressed together when the stacked structure, also known as the stacked structure, the latter refers to the PCB design stacking order, also known as the stacking order.
1. Pressed together structure design requirements
In order to reduce PCB warpage phenomenon, PCB pressed together structure should meet the symmetry requirements, that is, the thickness of the copper foil, media layer category and thickness, type of graphic distribution (line layer, plane layer), pressed together symmetrical relative to the vertical center of the PCB.
2. Conductor copper thickness
(1) the conductor copper thickness noted on the drawings for the finished copper thickness, that is, the outer copper thickness for the thickness of the bottom copper foil plus the thickness of the plating layer, the inner copper thickness for the thickness of the inner bottom copper foil. The outer copper thickness on the drawing is marked as “copper foil thickness + plating, and the inner copper thickness is marked as “copper foil thickness”.
(2) 2OZ and above thick bottom copper application considerations.
Must be used symmetrically throughout the laminated structure.
As far as possible to avoid placing in L2 and Ln-2 layer, that is, Top, Bottom surface of the second outer layer, so as to avoid PCB surface unevenness, wrinkling.
3. Pressed structure requirements
Pressing process is the key process of PCB production, the more times the pressed holes and disc alignment accuracy will be worse, the more serious PCB deformation, especially when asymmetric pressed together. Lamination requirements for the lamination, such as copper thickness and media thickness must match.
Post time: Nov-18-2022