MCPCB

What is MCPCB?

MCPCB (Metal Core Printed Circuit Board) is a kind of metal-based copper clad laminate with good heat dissipation function. Generally, a single panel is composed of a three-layer structure, namely a circuit layer (copper foil), an insulating layer and a metal base layer. For high-end use, it is also designed as a double-sided panel, with a circuit layer, an insulating layer, an aluminum base, an insulating layer, and a circuit layer. Very few applications are multilayer boards, which can be formed by bonding ordinary multilayer boards with insulating layers and aluminum bases.

How MCPCB works？

The power device is surface mounted on the circuit layer, and the heat generated by the device when it is running is quickly transmitted through the insulating layer to the metal base layer, and then the metal base layer transmits the heat out, so as to achieve heat dissipation of the device.

Structure of MCPCB

MCPCB is a kind of metal circuit board material, which is composed of copper foil, a thermally conductive insulating layer and a metal substrate. Its structure is divided into three layers.：

CIREUITL.LAYER circuit layer: equivalent to the copper clad laminate of ordinary PCB, the thickness OF the copper foil of THE circuit is LOZ to 10OZ.

DIELCCTRICLAYER insulation layer: The insulation layer is a layer of low thermal resistance thermal insulation material.

BASELAYER base layer: it is A metal substrate, generally aluminum or copper can be selected. Aluminum-based copper clad laminate and traditional epoxy glass cloth laminate, etc.

The circuit layer (i.e. copper foil) is usually etched to form a printed circuit, so that the various components of the components are connected to each other. Under normal circumstances, the circuit layer requires a large current-carrying capacity, so thicker copper foil should be used, the thickness is generally 35um~280um; the thermal insulation layer is the core technology of the aluminum substrate. It is generally composed of special polymers filled with special ceramics, with small thermal resistance, excellent viscoelastic properties, and the ability to resist thermal aging. It can withstand mechanical and thermal stress.

The thermal insulation layer of a high-performance aluminum substrate uses this technology to make it have extremely excellent thermal conductivity and high-strength electrical insulation properties; the metal base layer is the support member of the aluminum substrate, which requires high thermal conductivity. It is generally aluminum plate, and copper plate can also be used (among them, copper plate can provide better thermal conductivity), which is suitable for conventional machining such as drilling, punching, shearing and cutting.

PCB materials have incomparable advantages over other materials. Suitable for surface mount SMT process of power components. No heat sink is required, the volume is greatly reduced, the heat dissipation effect is excellent, and the insulation and mechanical properties are good.

Performance characteristics of MCPCB

1. Adopt surface mount technology (SMT)；

2. Extremely effective treatment of thermal diffusion in the circuit design scheme；

3. Reduce the operating temperature of the product, improve the power density and reliability of the product, and extend the service life of the product.；

4. Reduce product size and reduce hardware and assembly costs；

5. Replace the fragile ceramic substrate to obtain better mechanical durability.

MCPCB's process capabilities

Explanation of MCPCB's process and process-related vocabulary

Side etching: The etching of the side walls of the wire that occurs under the pattern of the resist layer is called side etching. The degree of lateral etching is expressed in terms of the width of the lateral etching.

Side etching is related to the type, composition and etching process and equipment used in the etching solution.

Etching coefficient: The ratio of the thickness of the wire (excluding the thickness of the coating) to the amount of side etching is called the etching coefficient.

Etching coefficient=V/X

The amount of side etching is measured by the level of the etching coefficient. The higher the etching coefficient, the less side etching. In the etching operation of printed circuit boards, it is desirable to have a higher etching coefficient, especially for printed circuit boards with high-density fine wires. Coating widening When electroplating, the width of the wire is increased because the thickness of the electroplating metal layer exceeds the thickness of the electroplating corrosion-resistant layer, which is called coating widening. The widening of the coating layer is directly related to the thickness of the electroplating resist layer and the total thickness of the electroplating layer. In actual production, the widening of the coating should be avoided as much as possible.

Coating protrusion: The sum of the widening of the metal corrosion-resistant coating and the amount of side corrosion is called the coating protrusion. If there is no widening of the coating, the protruding edge of the coating is equal to the amount of side erosion.

Etching rate: The depth at which the etching solution dissolves the metal per unit time (often expressed in µm/min) or the time required to dissolve a certain thickness of metal (min).

Amount of copper dissolved: The amount of copper dissolved by the etching solution at a certain allowable etching rate. It is often expressed in terms of how many grams of copper (g/l) are dissolved in each liter of etching solution.For a particular etching solution, its copper-dissolving ability is certain.

package of MCPCB

LED packaging mainly provides a platform for LED chips to have better optical, electrical, and thermal performance. A good packaging can make the LED have better luminous efficiency and a good heat dissipation environment, and a good heat dissipation environment can improve the service life of the LED. LED packaging technology is mainly constructed on five main considerations, namely optical output efficiency, thermal resistance, power dissipation, reliability and cost performance (Lm/$).

Each of the above factors is a very important part of the package. For example, the light extraction efficiency is related to cost performance; the thermal resistance is related to reliability and product life; and the power dissipation is related to customer applications. Overall, a better packaging technology must take into account every point, but the most important thing is to think from the customer's standpoint, and to meet and exceed customer needs is good packaging.

Usually a single-layer or double-layer aluminum substrate is used as a heat sink, and a single chip or multiple chips are directly fixed to the aluminum substrate (or copper substrate) with solid crystal glue, and the P and N electrodes of the LED chip are bonded to the thin copper plate on the surface of the aluminum substrate. The number of led chips arranged on the base is determined according to the size of the required power, and can be combined and packaged into high-brightness high-power LEDs such as 1W, 2W, and 3W. Finally, the integrated LED is encapsulated in the shape of the optical design using a material with a high refractive index.

usage of MCPCB

Purpose: Power hybrid IC (HIC)

1. Audio equipment: input, output amplifier, balanced amplifier, audio amplifier, preamplifier, power amplifier, etc.

2. Power supply equipment: switching regulator, DC/AC converter, SW regulator, etc.

3. Communication electronic equipment: high-frequency amplifiers, filter appliances, and transmitter circuits.

4. Office automation equipment: motor drives, etc.

5. Automobiles: electronic regulators, igniters, power controllers, etc.

6. Computer: CPU board, floppy disk drive, power supply device, etc.

7. Power modules: converter, solid state relay, rectifier bridge, etc.

substrate of MCPCB

The commonly used aluminum substrate materials for aluminum substrate plates are mainly 1000 series, 5000 series and 6000 series. The basic characteristics of these three series of aluminum materials are as follows：

1. 1000 series: It represents 1050, 1060, and 1070. The 1000 series aluminum plate is also known as pure aluminum plate. Among all series, the 1000 series is the one with the largest aluminum content, and the purity can reach more than 99.00%. Since it does not contain other technical elements, the production process is relatively single and the price is relatively cheap. It is currently the most commonly used series in conventional industry.

2. 5000 series: represents 5052, 5005, 5083, and 5A05 series. The 5000 series aluminum plate belongs to the more commonly used alloy aluminum plate series. The main element is magnesium, and the magnesium content is between 3-5%. It is also called aluminum-magnesium alloy. The main characteristics are low density, high tensile strength and high elongation. Under the same area, the weight of aluminum-magnesium alloys is lower than that of other series, so they are commonly used in aviation, such as aircraft fuel tanks. In addition, it is also widely used in conventional industries.

3. 6000 series: Represents 6061, which mainly contains two elements, magnesium and silicon. Therefore, it concentrates the advantages of the 4000 series and the 5000 series. 6061 is a cold-treated aluminum forging product, which is suitable for applications with high corrosion resistance and oxidation resistance requirements. It has good applicability, excellent interface characteristics, easy coating and good processability. General characteristics of 6061: excellent interface characteristics, easy coating, high strength, good serviceability, and strong corrosion resistance. Typical uses of 6061 aluminum: aircraft parts, camera parts, couplers, ship parts and hardware, electronic parts and joints, etc.

led aluminum substrate and pcb aluminum substrate

Led aluminum substrate refers to the aluminum substrate used in the specialized led industry. The advent of LED aluminum substrate products has opened up the development of the heat dissipation application industry. Due to the heat dissipation characteristics of the LED aluminum substrate, the aluminum substrate has the advantages of high heat dissipation, low thermal resistance, long life, voltage resistance, etc., thereby expanding the application fields of the LED industry, such as aluminum substrates for indicator lights for home appliances, aluminum substrates for car lights, aluminum substrates for street lights, and large outdoor signage.

The thermal conductivity of the led aluminum substrate is related to the insulating layer in the middle of the aluminum substrate (generally PP, now there are thermal conductive adhesives, etc.). It is one of the three major standards for measuring the quality of the aluminum substrate (thermal resistance and withstand voltage are the other two properties). The thermal conductivity of aluminum substrates can be tested by testing instruments after the plates are pressed together. At present, the high thermal conductivity is generally ceramics, copper, etc., But due to cost considerations, the current mainstream on the market is electronic aluminum substrates. The corresponding thermal conductivity of aluminum substrates is a parameter of concern to everyone. The higher the thermal conductivity, the better the representative performance. One of the signs.

The led aluminum substrate is PCB, which also means printed circuit board, but the material of the circuit board is aluminum alloy. In the past, our general circuit board material was glass fiber.

MCPCB's price

With the improvement of aluminum substrate production technology and equipment, mcpcb's product prices have accelerated rationalization. Usually suppliers will not provide quotations for aluminum substrates directly. You can consult He'an Circuit for quotations for aluminum substrates.

High thermal conductivity aluminum substrate and aluminum substrate thermal conductivity

The thermal conductivity of an aluminum substrate, as the name suggests, is a parameter of the heat dissipation performance of an aluminum substrate. It is one of the three standards for measuring the quality of an aluminum substrate (thermal resistance and withstand voltage are the other two properties). The thermal conductivity of aluminum substrates can be tested by measuring instruments after the plates are pressed together to obtain data. At present, the high thermal conductivity is generally ceramics, copper, etc., But due to cost considerations, most of the current market is aluminum substrates. The corresponding thermal conductivity of aluminum substrates is a parameter of concern to everyone. The higher the thermal conductivity, the better the representative performance. One of the signs.Aluminum substrate is a unique metal-based copper clad laminate aluminum substrate, which has good thermal conductivity, electrical insulation properties and machining properties.

Under normal circumstances, in LED design and various electronic design, there will be the application of aluminum substrate, and LED thermal design is based on fluid dynamics software simulation and basic design, which is very necessary for the production of aluminum substrate.

The so-called resistance of fluid flow is due to the viscosity of the fluid and the influence of the solid boundary, which causes the fluid to be subjected to a certain resistance during the flow process. This resistance is called flow resistance, which can be divided into two types: along-course resistance and local resistance; along-course resistance is in areas where the boundary changes sharply, such as the sudden expansion of the cross-section or the sudden contraction of the elbow and other local locations, it is the flow resistance caused by a sharp change in the flow state of the fluid.

Generally, the heat sink used in the LED aluminum substrate is natural heat dissipation. The design process of the heat sink is mainly divided into three steps.：

1. Design the outline diagram of the radiator according to the relevant constraints；

2. According to the relevant design guidelines of the aluminum substrate radiator, optimize the tooth thickness, tooth shape, tooth spacing and thickness of the aluminum substrate of the radiator.；

3. Check and calculate to ensure the heat dissipation performance of the radiator.

Thermal design of MCPCB

Why thermal design?

The effects of high temperature on electronic products: degradation of insulation properties; damage to components; thermal aging of materials; cracking of welds and shedding of solder joints at low melting points.

The effect of temperature on components: Generally speaking, the resistance value of the resistance decreases when the temperature rises; high temperature will reduce the service life of the capacitor; high temperature will degrade the performance of the insulating materials of transformers and chokes. Generally, the allowable temperature of transformers and chokes should be lower than 95C; too high temperature will also cause changes in the alloy structure of the solder joints—IMC thickening, solder joints become brittle, and mechanical strength decreases; the increase in junction temperature will cause the current magnification of the transistor to increase rapidly, resulting in an increase in collector current and a further increase in junction temperature, which ultimately leads to component failure.

The purpose of thermal design is to control the temperature of all electronic components inside the product so that it does not exceed the maximum temperature specified in the standards and specifications under the working environment conditions.The calculation of the maximum allowable temperature should be based on the stress analysis of the components, and is consistent with the reliability requirements of the product and the failure rate assigned to each component.

MCPCB heat dissipation problem solution

The heat dissipation problem of LED is the most headache for LED manufacturers, but aluminum substrates can be used because aluminum has a high thermal conductivity and good heat dissipation, which can effectively export internal heat. Aluminum substrate is a unique metal-based copper clad laminate with good thermal conductivity, electrical insulation properties and machining properties. When designing, the PCB should be as close to the aluminum base as possible to reduce the thermal resistance generated by the potting glue part.

Repair of MCPCB circuit board

Each circuit board maintenance engineer has its own different judgment methods and maintenance ideas. However, the maintenance steps can be summarized into six steps. To understand the fault of the board for maintenance, first understand the fault condition and set the fault judgment within a smaller range to facilitate the maintenance work. Therefore, understanding the fault condition of the circuit board is very important for starting maintenance.

1. Board observation: Board observation is a preliminary study. The purpose is to understand which input and output interfaces the board has, what functions the board implements, and the distribution of various control parts of the board.

2. Circuit testing: After completing the fault understanding and board observation, preliminary testing of the board is carried out according to the actual situation. Circuit testing may not be able to find the fault point of the board, but experienced circuit board maintenance personnel can eliminate a wide range of faults through testing, paving the way for the next maintenance.

3. Component inspection: For component inspection, most of the components need to be removed from the circuit board through a soldering iron, and then tested by professional equipment. This process will cause damage to the external integrity of the circuit board, so under normal circumstances, maintenance personnel will not remove the components at will.

4. Fault repair: through line testing, component testing and other work, the identified faults are dealt with, including line repair, component replacement, transformation and other work.

5. On-board test: The board that has completed the maintenance work needs to be tested again. After it is determined that there is no fault, it can be tested on-board.

MCPCB waste treatment technology

Printed circuit boards are made of a mixture of glass fiber, epoxy resin and a variety of metal compounds. If the waste aluminum substrate is not properly disposed of, it will contain carcinogenic substances such as brominated flame retardant, which will cause serious pollution and harm to the environment and human health. But at the same time, waste circuit boards also have quite high economic value. The metal grade in circuit boards is equivalent to dozens of times the metal grade in ordinary minerals. The metal content is as high as 10~60\%. The most content is copper. In addition, there are gold, silver, nickel, tin, lead and other metals, many of which are rare metals, and the content of bonanza metals in nature is only 3~5\%.

According to data, an average of 0.9 kg of gold, 270 kg of plastic, 128.7 kg of copper, 1 kg of iron, 58.5 kg of lead, 39.6 kg of tin, 36 kg of nickel, 19.8 kg of antimony are used for 1 ton of computer components, as well as precious metals such as palladium and platinum. It can be seen that waste circuit boards are also a 'gold mine' that needs to be developed. According to a survey of the treatment status of waste circuit boards in most parts of the country, most of the waste circuit boards and frame materials generated by many circuit board companies are now transported to remote areas for treatment by incineration and washing, which has caused extremely serious secondary pollution.

Among them, the incineration method produces a large number of odorous and toxic bromine compounds, which seriously pollutes the atmosphere. It has long been banned by the State Environmental Protection Administration, but in remote mountainous areas, incineration workshops still have room for survival.

The washing method has been widely adopted due to its simple process and low investment. However, the large amount of waste residue generated after washing (that is, 'non-metallic substances', accounting for about 80% of the weight of the aluminum substrate) still causes great harm to the environment, and it is difficult to deal with or eliminate these waste residues. Most washing companies use waste residue as domestic waste to landfill or hand it over to the sanitation department for disposal.

Application and application characteristics of MCPCB

The aluminum substrate is constructed by itself and has the following characteristics: it has very good thermal conductivity, single-sided copper binding, the device can only be placed on the copper binding surface, and the electrical connection hole cannot be opened, so the jumper cannot be placed like a single panel.

SMD devices, tubes, and output rectifier tubes are generally placed on aluminum substrates to conduct heat through the substrate. The thermal resistance is very low and high reliability can be obtained. The transformer adopts a planar SMD structure, which can also dissipate heat through the substrate, and its temperature rise is lower than that of conventional transformers. The same specification transformer adopts an aluminum substrate structure to obtain a larger output power.

Due to the excellent thermal conductivity of the aluminum substrate, it is more difficult to weld manually in small quantities. The solder cools too quickly and is prone to problems. There is a simple and practical method. Turn an ordinary electric iron for ironing clothes (preferably with a temperature adjustment function), turn it over, iron it facing up, fix it well, and adjust the temperature to about 150℃. Put the aluminum substrate on top of the iron, heat it for a period of time, and then paste the components and weld them according to conventional methods. The iron temperature is appropriate for the device to be easy to weld. If it is too high, the device may be damaged, and even the copper skin of the aluminum substrate may be peeled off. The temperature is too low. The welding effect is not good. , Be flexible and master.