We are a one-stop technical service company mainly doing printed circuit board production, assembly and component sourcing. We have us own circuit board and SMT production line. When initially making PCB/PCBA for customers, one of the first confirmed parameters is the base material, board thickness, copper thickness, surface finishing, solder mask color, etc. One important parameter is the thickness of the copper. Today we will talk about copper and thickness of copper .
The heavy copper pcb is a layer of copper foil bonded on the glass epoxy substrate of the printed circuit board. When the copper thickness is greater than or equal to 2oz, it is defined as a thick copper pcb.
The production of the printed circuit board should first be based on the customer’s design file, and the circuit should be transferred to the board. The raw material is the copper-clad board material, and then through the exposure circuit, etching and other processes, leaving the circuit you want to stay, used to conduct and connect various components.
According to the amount of current, the line width and line spacing need changed. Sometimes, according to needs, a large current will be passed. At this time, not only the scheme of increasing the line width, but also the copper thickness needs to be increased. The copper thickness can increase the current flow in the circuit.So will make heavy cooper PCB boards.
The application of heavy copper PCB board in PCB proofing is almost ubiquitous, and its application field is very broad, including various household appliances, high-tech products, military, medical and other electronic equipment. The thick copper has excellent extension performance, high temperature, low temperature, and corrosion resistance, which allows electronic equipment products to have a longer service life, and also greatly helps the size of electronic equipment to be simplified. In particular, electronic products that need to run higher voltages and currents require heavy copper PCB.
Heavy copper pcb performance:
Thick copper pcb has the best elongation performance and is not limited by processing temperature. At high melting point, oxygen blowing can be used, and it is not brittle at low temperature and other hot melt welding methods, and it is also fireproof. Even in extremely corrosive atmospheric environments, copper plates will form a strong, non-toxic passivation protective layer.
The advantages of heavy copper pcb:
Thick copper pcb are widely used in various household appliances, high-tech products, military, medical and other electronic equipment. The application of thick copper plates makes the core component of electronic equipment products-circuit boards have a longer service life, and also greatly helps the size of electronic equipment to be simplified.
Heavy copper plates are all need copper plated twice. Because the original copper foil thickness of the board is not enough. In the process of secondary copper plating, we need to do a lot of control measures.
The process includes:
1 cutting raw material sheet.
2 Drill holes.
3 Copper plating for the first time.
4 Outer dry film.
5 Second copper etching.
6 First inspection.
7 The first solder mask.
8 Second copper plating.
9 The second outer dry film.
10 Second copper etching.
11 Second inspection.
12 Second solder mask.
13 silk screen text packaging vacuum plastic packaging
Key control 1 Drilling hole control
Since the manufacturing process requires secondary copper plating, the product aperture needs to be compensated accordingly. Before and after the second copper plating, it is necessary to complete the outer layer, solder mask, screen printing text process, and have corresponding control on the hole pin. Therefore, the pin hole should be optimized as follows:
1 Design a pin hole to ensure accurate alignment of the outer layer.
2 Design the secondary alignment pin hole. Since the hole diameter of the pin hole becomes smaller after the second copper plating, the original design needs to be compensated accordingly. Considering that the second copper plating will cause the hole diameter to become smaller. The secondary pin hole directly affects the secondary outer layer, secondary solder resist, text silk screen alignment, and accuracy.
Key control 2 One-time solder mask control
Purpose: Fill the position of the basic material with solder resist ink to ensure a smooth surface with the oil.
Control items and methods.
1 For nail bed production, try to print on both sides at the same time to avoid one-sided printing costing manpower and resources.
2 Line block network production.
3 The viscosity of solder resist ink ≥300dpa.s, to ensure the amount of ink, the height of the substrate and copper foil are consistent.
4 Bake in advance It is required to stand for more than 2 hours after printing, and keep it level when standing to ensure that there are no bubbles in the group.
5-position exposure. Remove the solder resist ink on the circuit for exposure and development, and place 2-3mils on each side of the circuit window to ensure alignment accuracy.
6 After baking Baking in sections. Ensure that the components of the substrate are fully cured.
Key Control 3 Increase copper thickness
Before D / P, roughening of the board surface is required to ensure that the chemical copper layer can be evenly plated with copper throughout the board.
Does not pass the slag tank
D / P copper plating time 20min
Only drying after copper plating to prevent wrinkling
Secondary outer layer
Purpose: To make the actual need to add copper plating area
Key Control 4 Secondary outer layer
Purpose: To make the actual need to add copper area
The pre-treatment of the outer circuit board stops brushing and only pickles to prevent wrinkling of the copper on the substrate
Prevent secondary film electroplating caused by film wrinkling
Alignment accuracy control
Key Control 5 Secondary graphic plating, packaging
Difficulties in thick copper plate production
Difficult to etch
Difficulties in drilling
So in order to overcome the difficulties and produce high-quality thick copper plates, we need to:
Improve the uniformity and symmetry of the inner copper
Increase the inner copper residual rate
Increase line width and spacing
Optimize inner pad design
The heavy copper pcb has the characteristics of carrying large current, reducing thermal strain and good heat dissipation. Increasing copper thickness has become a way for major design manufacturers to seek solutions. Thick copper products are also increasing.
With the continuous development of PCB technology, the requirements of various designs are becoming stricter. The structural problems of thick copper multilayer boards are becoming more and more prominent. This is the continuous progress of these technologies, which promotes the development and innovation of materials. Thick copper products have some difficulties in production, and we still need to find ways to explore and improve them.
As a professional PCBA Manufacturer, we could supply one-stop service, including PCB board making, PCB Reverse Engineering, components sourcing, SMT assembly work, Program+Test, housing making, housing assembly…
We aslo have ERP system to manage every project from production file, quotation, purchase, production, delivery until service after it. Date will be found quickly and precise no matter when client wants to begin project.
If you have related projects, welcome to inquiry us to get free quotation.