China Heavy Copper PCB Manufacturers

What is a Heavy Copper PCB?

A heavy copper PCB is a high-current PCB that contains 3oz or more of copper in the outer and inner layers of the board. If the total amount of copper is less than 3oz, and the copper thickness of the PCB is greater than 4oz, it is also considered a heavy copper PCB. This large amount of copper is used as an alternative to increase the thickness of the traces and is not feasible. Huihe PCB is a professional heavy copper PCB manufacturers In China, many years of heavy copper pcb mass production experience of heavy copper PCB, support heavy copper PCB prototype and heavy copper PCB production. Standard PCB traces for DC motors often require a certain width to provide an appropriate power level, taking into account thermal constraints. Heavy copper PCBs use thicker traces to do the same job, but with a reduced width. 

PCBs can withstand higher temperatures for longer periods of time while handling higher current rates and providing stronger connection points. Heavy copper PCBs can support higher critical current densities than standard circuit boards. While standard circuit boards may only support double-digit amperage, heavy copper PCBs can carry hundreds or thousands of amps and can withstand higher temperatures for extended periods of time. The unique design of these PCBs features thicker, heavier copper layers, giving heavy copper PCBs their durable properties.

Advantages of Heavy Copper PCB

The thickness of PCB holes and through-hole sidewalls may increase on PCBs with heavy copper circuits. The heavy copper PCB manufacturing process is slightly different from that of standard PCBs, using special plating and etching techniques to accommodate the extra thickness of copper. heavy copper PCBs can withstand high temperatures (such as soldering heat) and corrosive environments well. The main advantage of heavy copper PCB is its ability to support high current, high temperature and repeated thermal cycling. These factors often cause problems with standard circuit boards.

Using heavy copper PCB boards allows for higher densities and minimizes the number of layers, resulting in a simple and durable construction. They are able to fit more conductive material in a smaller space and achieve greater mechanical strength for the connector. High current coupled with increased design complexity generates more heat. With the right design, copper's high thermal conductivity enables it to carry heat away from the PCB's temperature-sensitive components, keeping them in better shape. Copper as a material is slightly more expensive, but the overall production cost of heavy copper PCBs is reduced. heavy copper PCBs can be used instead of copper cables, making them more cost-effective. Specific production methods also allow for mixing thick copper with standard features on the PCB, resulting in reduced layer count, smaller footprint and production cost savings.

The Properties of Heavy Copper PCB

1. Heavy copper PCB boards can carry large currents.

In the case of a certain line width, increasing the copper thickness is equivalent to increasing the cross-sectional area of the circuit, so that it can carry a larger current.

2. Heavy copper PCB board reduces thermal strain

Copper foil has a small conductivity, and the temperature rise is small when passing a large current, so the heat generation can be reduced, thereby reducing thermal strain.

3. Heavy copper PCB board has good heat dissipation.

Copper foil has high thermal conductivity (thermal conductivity 401W/mK), which can play an important role in improving heat dissipation performance.

Heavy copper PCBs are not limited by the processing temperature. Hot-melt welding methods such as oxygen blowing can be used when the melting point is high, and they are not brittle at low temperatures. They are also fireproof and belong to non-combustible materials. Copper plates form a strong, non-toxic passive protective layer even in extremely corrosive atmospheres.

Application of Heavy Copper PCB

The vast majority of heavy copper PCBs are high-current substrates (current × voltage = power). The main application areas of high-current substrates are two major areas: power modules (power modules) and automotive electronic components. Some of its main terminal electronic product fields are the same as conventional PCBs (such as portable electronic products, network products, base station equipment, etc.), and some are different from conventional PCB fields, such as automobiles, industrial control, power modules, etc.

Heavy copper PCBs differ from conventional PCBs in efficacy. The main function of a conventional PCB is to form wires that transmit information. The heavy copper PCB has a large current passing through it, and the main function of the substrate carrying the power device is to protect the current carrying capacity and stabilize the power supply. The development trend of this heavy copper PCB is to carry a larger current, and the heat emitted by the larger device needs to be dissipated, so the large current passing through is getting larger and larger, and the thickness of all the copper foil of the heavy copper PCB is getting thicker and thicker. Now the heavy copper PCB made of 6oz copper thickness has become routine.

Heavy copper PCBs are widely used in various high-tech fields such as mobile phones, microwaves, aerospace, satellite communications, network base stations, hybrid integrated circuits, power high-power circuits, and electronic equipment. The application of heavy copper PCBs makes the core components of electronic equipment products - printed circuit boards have a longer service life, and also greatly helps to simplify the volume of electronic equipment, the application field and demand for heavy copper PCB have been rapidly expanding in recent years, and it has become a "hot" PCB variety with good market development prospects.

Difficulties in Processing Heavy Copper PCBs

Heavy copper PCB boards bring a series of processing difficulties to PCB processing due to the thick copper thickness, such as the need for multiple etchings, the insufficient filling of the pressure PCB, the cracking of the inner pads of the drilled holes, and the difficulty in guaranteeing the quality of the hole wall.

1. Difficulties in etching

With the increase of copper thickness, the difficulty of potion exchange increases, and the amount of side etching of heavy copper PCB will also become larger and larger. In order to reduce the large amount of side corrosion caused by potion exchange as much as possible, multiple rapid etching methods are required. To solve the problem, as the amount of side etching increases, the heavy copper PCB needs to compensate for the side etching by increasing the etching compensation coefficient.

2. Lamination Difficulties

With the increase of copper thickness, the heavy copper PCB has deeper circuit gaps. Under the condition of the same residual copper rate, the required resin filling amount needs to increase, and multiple properties are needed to meet the problem of filling; the maximum resin required to be used is the first choice for heavy copper PCB to fill the line gap and other parts to the limit, the prepreg with high glue content and good resin fluidity. The commonly used properties are 1080 and 106. When the inner layer is designed, copper points and copper blocks are placed in the copper-free area or the final milled area to increase the residual copper rate and reduce the pressure of the glue filling.

As the copper thickness and board thickness increase, the more heat is required for thick copper lamination. The actual heating rate will be slower, and the actual duration of the high temperature section will be shorter, which will lead to insufficient resin curing of the prepreg, thus affecting the reliability of the heavy copper PCB; therefore, it is necessary to increase the duration of the high temperature section of the lamination to ensure that the curing effect of the prepreg.

3. Difficulties in Drilling

As the copper thickness increases, the thickness of the heavy copper PCB also increases. Heavy copper PCBs are usually thicker than 2.0mm. When drilling, it is difficult to make due to the factors of thicker PCB thickness and thicker copper thickness. In this regard, the use of new knives reduces the service life of the drill, and segmented drilling has become an effective solution for drilling heavy copper PCBs. In addition, the optimization of drilling-related parameters such as feed speed and retract speed also has a great impact on the quality of the hole.

During drilling, the energy of X-RAY gradually decays with the increase of copper thickness, and its penetrating ability will reach the upper limit. Therefore, for heavy copper PCBs with thick copper, the first PCB confirmation cannot be performed when drilling.

The problem of cracking of the inner layer thick copper pads (mainly for large holes above 2.5mm): the demand for heavy copper PCBs is increasing, the inner layer pads are getting smaller and smaller, and the problem of pad cracking when drilling heavy copper PCBs often occurs.

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