The production of PCB high-level circuit boards not only requires higher investment in technology and equipment, but also requires the accumulation of experience of technicians and production personnel. It is more difficult to process than traditional multi-layer circuit boards, and its quality and reliability requirements are high.
1. Material selection
With the development of high-performance and multi-functional electronic components, as well as high-frequency and high-speed signal transmission, electronic circuit materials are required to have low dielectric constant and dielectric loss, as well as low CTE and low water absorption. rate and better high-performance CCL materials to meet the processing and reliability requirements of high-rise boards.
2. Laminated structure design
The main factors considered in the design of the laminated structure are the heat resistance, withstand voltage, amount of glue filling and thickness of the dielectric layer, etc. The following principles should be followed:
(1) The prepreg and core board manufacturers must be consistent.
(2) When the customer requires high TG sheet, the core board and the prepreg must use the corresponding high TG material.
(3) The inner layer substrate is 3OZ or above, and the prepreg with high resin content is selected.
(4) If the customer has no special requirements, the thickness tolerance of the interlayer dielectric layer is generally controlled by +/-10%. For the impedance plate, the dielectric thickness tolerance is controlled by the IPC-4101 C/M class tolerance.
3. Interlayer alignment control
The accuracy of the size compensation of the inner layer core board and the control of the production size need to be accurately compensated for the graphic size of each layer of the high-rise board through the data collected during production and historical data experience for a certain period of time to ensure the expansion and contraction of the core board of each layer. consistency.
4. Inner layer circuit technology
For the production of high-rise boards, a laser direct imaging machine (LDI) can be introduced to improve the graphics analysis ability. In order to improve the line etching ability, it is necessary to give appropriate compensation to the width of the line and the pad in the engineering design, and confirm whether the design compensation of the inner layer line width, line spacing, isolation ring size, independent line, and hole-to-line distance is reasonable, otherwise change engineering design.
5. Pressing process
At present, the interlayer positioning methods before lamination mainly include: four-slot positioning (Pin LAM), hot melt, rivet, hot melt and rivet combination. Different product structures adopt different positioning methods.
6. Drilling process
Due to the superposition of each layer, the plate and copper layer are super thick, which will seriously wear the drill bit and easily break the drill blade. The number of holes, drop speed and rotation speed should be adjusted appropriately.
Post time: Sep-26-2022