Heavy Copper PCB

With the development of automation control and power communication, heavy copper PCB is applied to high current transmission and high connection components, and has gradually become a heavy copper PCB with good market prospects. According to the current market situation, automotive electronics, GBT installation, wind power converter, ignition switch, etc. have a large demand for heavy copper PCB. On the other hand, with the widespread application of PCB in the electronics field, the functional requirements for heavy copper PCB are getting higher and higher! PCB can not only provide the necessary electrical connection and mechanical support for electronic components, but also gradually be given more additional functions, which can integrate power supply to provide large current. High reliability heavy copper PCB has gradually become a new product of ZBPCB.

At present, ZBPCB mostly uses multi-layer solder mask printing auxiliary layer or ultra-thick copper foil that is thickened layer by layer after electroplating copper to manufacture heavy copper PCB, but the above process can only achieve 0.41mm (1202) thick copper PCB, and it is difficult to manufacture heavy copper PCB exceeding 0.41mm (1202). Our company has studied a new method for manufacturing heavy copper PCB. Drawing on the preparation technology of laminated busbars, copper plate embedded bonding technology is used, and through process optimization, heavy copper PCBs above 0.5mm (1402) are manufactured.

The heavy copper PCB board of the power supply is generally a PCB with more than 4 layers, and the copper thickness is generally 1.6mm. The main reason is that the heavy copper PCB board of the power supply has a large current and a high voltage, and a PCB board that is too thin cannot withstand it. Because the heavy copper PCB board of the power supply is a high-voltage power supply board, although they are all made of copper, there are still differences in grades. Ordinary PCB board materials are generally below TG140, and the heavy copper PCB board materials of the power supply are generally above medium TG150, and high TG is above 170. The higher the grade of the PCB material, the better the temperature resistance, and the higher the quality of the board.

However, the thick copper PCB of the power board itself has high current and high voltage, so the design of the PCB is particularly important. Not only the current but also the voltage that needs to pass must be considered. If the design is unreasonable, it is easy to cause the PCB to burn out. Some customers implement the IPC-1 standard, a zero-defect acceptance standard, which is much stricter than general consumer PCBs.

Manufacturing Process of Heavy Copper PCE

1. Laminated structure of Heavy Copper PCB

This board is a thick copper 4-layer PCB, the inner layer copper thickness is 202, the outer layer copper thickness is 202, the outer layer minimum line width spacing is 0.3mm, the surface is FR4 copper board + glass fiber epoxy resin board, the total thickness of the PCB is 1.6mm, single-sided etching treatment, the bonding material is non-liquid PP board (semi-cured board), thickness 0.1mm.

2. Processing method of Heavy Copper PCB

After the thick copper plate is coated and blackened, the blackening of the copper plate can increase the surface area of the copper surface and the resin, increase the wetting ability of the resin on the copper, enable the resin to penetrate into the oxide layer, improve the adhesion after coating, and improve the bonding effect. It can improve the white spot phenomenon during bonding and the whitening and bubbles on the board surface caused by the baking test (287[+16]). The specific blackening parameters are shown in Table 2. Due to the use of traditional lamination methods, there are manufacturing errors. The thickness of the thick copper plate used for bonding and the FP-4 board cannot be exactly the same, which is prone to defects such as aminated white spots and delamination, making bonding difficult. In order to reduce the difficulty of bonding and ensure the quality of bonding, it is recommended to coat the thick copper plate. By testing the lamination structure and plate thickness, the dimensional accuracy of the lamination plate is guaranteed, and a thin plate is used as the intermediate buffer layer. By setting appropriate parameters such as lamination temperature, pressure, and holding time, the lamination effect is achieved, and the technical problems such as white spots and layers in the ultra-thick copper layer are solved. Meet the compression requirements of thick copper PCBs. Since the fluidity of non-fluid Pp resin is low, general covering materials are used. The leather paper cannot make the Pp sheet compressed evenly, resulting in defects such as white spots and wrinkles after lamination. During the lamination process of thick copper PCB products, a conical rubber pad needs to be used as a buffer layer to evenly distribute the pressure during lamination. In addition, in order to solve the compression problem, the pressing pressure parameter in the laminator is changed from 2.1Mpa (22kgicm) to 2.1Mpa (3.1MPa). 3 Adjust to 2.94 Mpa (30 kgcm) 3. Adjust the temperature of the PP board to 170℃. After testing according to Chapter 4.8.5-8.2 of G1B3628-2009, the PcB shall be tested according to 48.2, and shall not exceed the bubbles and cracks caused by 3.5.1.2.3 (subsurface defects). PcB samples that meet 3.5.1.2.3 (subsurface defects) shall be micro-cut and inspected according to 48.3 to 34.2, at the laminar sections, edges and seams

3. Heavy Copper PCB pressure test

Heavy copper plate sample voltage test for each electrode, AC1000V, no impact, no flash, lasting 1 minute

4. Heavy Copper PCB Large Current Temperature Rise Test

Design the corresponding connecting copper plate, connect the poles in the thick copper PCB sample, connect to the high current generator, and test separately according to the test current

The high current temperature rise of the ultra-thick copper PCB is related to its structure, and the temperature change of copper structures with different thicknesses will be different.

5. Thermal stress test of Heavy Copper PCB

Thermal stress test requirements: The samples shall be subjected to thermal stress test according to G13628-209 General Specification for High Temperature Resistant Printed Circuit Boards. Delamination, blistering, pad warpage, white spots and other defects shall not occur. Thick copper plate samples shall be micro-cut after the appearance and size meet the requirements. Since the inner layer of the sample is too thick, metallization cutting cannot be performed. After the sample is subjected to thermal stress test at 287 (+) 6 (+)C, only the appearance visual inspection is performed. The results of the thick copper plate are no delamination, no blistering, pad warpage, white spots