Archive for the ‘mcpcb’ Category

Why HASL Surface Treatment Is Not Suitable For Sink Pad MCPCB?

Thursday, January 12th, 2023

Sink Pad MCPCB is a special type of metal core PCB (short for MCPCB), the working principle is through the sink heat pad solder direct to the metal substrate (commonly copper or alumina substrate), so people also call it as Thermal pad MCPCB. Sink Pad MCPCB is popular recently due to its excellent heat dissipation and thermal conductivity. Since the copper is easy to get oxidation, coating a metal film is good for protecting the surface, such as ENIG, ENEPIG or OSP. Lead-free hot air solder leveling (HASL) also is a kind of surface treatment, but why we don’t suggest to apply it? Let me explain with you.

Why is HASL not recommended?

  • Substrate

From the substrate aspect, due to the HASL process is to first dip the solder on the circuit board, then dip the solder flux in the melting, and finally blow off the excess solder on the printed board with the hot compressed air in the air knife through the two air knives, at the same time to eliminate the excess solder in the metal hole, so as to get a bright, smooth and uniform solder coating. Since most of customers prefer choose copper substrate as the base material (Aluminum core sink pad PCB thermal conductivity only could be 235 W/m.k, while Copper core sink pad PCB thermal conductivity could reach to 400 W/m.k). However, copper base is much heavier than alumina core, during the hot air knife scraping tin process, the copper surface is easy to be scratched and get damaged to affect the poor appearance and a short circuit risk. This is one of the reasons why HASL is not suitable for Sink Pad PCB.

  • Structure

From the structure of the Sink Pad MCPCB, the LEDs Chip Thermal Pads solder contact to the copper substrate directly, no dielectric between LEDs heat out pads and the Metal core. As you can see the stack up as below, what Sink PAD PCB laminate is pure film, the adhesion is not very good, so there’s a risk of delamination if do HASL (lead free).

  • Chemical

From the chemical aspect, due to the HASL (lead free) has the process of return the film, the potion will react with the copper chemically, which will bring the poor coating and poor adhesion, so we don’t recommend to use HASL on the Sink Pad MCPCB.

Advances of the Sink Pad MCPCB

  • Thermal conductivity 235 To 400 W/m.
  • Super good heat dissipation
  • Power LED junction temperature
  • Longer LED life
  • Most economical direct thermal path solution
  • Direct thermal path
  • Different structure can be made according different design needs

When can we use Sink Pad MCPCB?

With so many kinds of PCB types, when and where can we use the Sink Pad MCPCB?

  1. The copper metal core has high density, strong thermal conductivity and carries heat effectively. That means, it is possible to dissipate the same heat using a smaller sink-pad MCPCB, as compared to regular MCPCBs. So it is suitable be used in small applications which need to apply in high temperature.
  2. Very popular with high power LED mounting, sink-pad MCPCBs with their thermoelectric separation structure, can minimize the lumens depreciation of the LED, thereby prolonging the life of the LED lamp. Sink-pad MCPCBs are suitable for mounting high-power LED lamps and COB packaged LEDs. Moreover, manufacturers can tailor the sink-pad MCPCB to match the different design requirement needs of any LED.

Best Technology is a professional Sink Pad MCPCB manufacturer for more than 16 years in Asia, we have strong engineering team and specialized sales team can provide most suitable solutions for your applications in a very short time. What we can provide not only include single layer Sink Pad MCPCB, we also can produce 2 layers, double layer and multi-layer Sink Pad MCPCB. View https://www.bestpcbs.com/products/sinkpad-board.htm to know our capability about Sink Pad MCPCB.

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Why it is difficult to make different copper thicknesses on different layers for MCPCB

Friday, October 14th, 2022

With the development of technology, we need the MCPCB to be multi-layer. 1 layer MCPCB is not enough for making some high-quality precision equipment and products.

So now, 2 layers MCPCB becoming more and more popular.

Normally, we make 1OZ, 2OZ and 3OZ copper thickness for each layer for aluminum or copper core/base PCB. The thickness of copper for top and bottom layer are the same.

But recently, more and more customers want the MCPCB to be made with different copper thicknesses on top and bottom layer.

For example, they want 1OZ copper on top layer and 3OZ on bottom layer.

But we don’t suggest to do that, why? Let me do some explanations.

  1. Different copper thicknesses on top and bottom layer will increase the difficulty for production. Because we put the MCPCB into etching liquid to do the etching, we need to use film to protect one side from etching liquid, but if it can’t be protected well completely, it will be etching too, then it is rejected.
  2. Different copper thicknesses on different sided will cause the PCB twist finally if the stack up is double sided (See below double sided stack up)

But if the stack up is 2L (See below 2L stack up), the FR4 PCB is twisted then will affect the lamination for FR4 PCB and aluminum/copper base.

  1. Due to increase the difficulty of production, so the price will be increased too.
  2. Lead time will be longer than normal since the production process is much more completed.
  3. The reliability is not good.

Finally, it is better to do the same copper thickness for each layer for multi-layer MCPCB.

For knowing more knowledge about MCPCB, please email to sales8@bestpcbs.com

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Types of Metal Bases Utilized in MCPCB

Tuesday, May 10th, 2022

What is metal core printed circuit?

Metal core printed circuit board is abbreviated as MCPCB. And namely, the core or the base material of MCPCB is a metal instead of the traditional FR4/CEM1-3.

Types of metal bases used in MCPCB

The metal cores of the thermal PCB can be aluminum, copper and steel alloys. Apart from being cheaper than copper, aluminum is known for its good heat transferring and dissipation abilities, which is the most common used. However, copper is considered to be a better performer. So, why does the aluminum become the first choice for the material of the MCPCB?

Aluminum base—The aluminum PCB offers good heat dissipation and heat transferring ability. Since they are also light in weight, the aluminum core PCBs are widely used in LED products.

Aluminum Core PCB

Copper base—The copper core board features a better performance than aluminum. But customers will usually choose the aluminum instead of copper, for it is relatively expensive. Also, compared with the aluminum, the copper is heavier and involves a tough machining process.

Copper Core PCB

Various base metals and their properties

Metal Base MaterialThermal Conductivity
(W/m-K)
Coefficient of Thermal Expansion
(”m/m-°C)
Aluminum88-25125
Copper38617

Based on the table, it can be known that although the thermal conductivity of the copper is better than that of the aluminum, its ability of thermal expansion does not perform better than the aluminum.

Therefore, there are some reasons why the aluminum is the first choice for the material of the MCPCB, including the lower cost compared to copper, light weight, excellent durability and its heat transferring capabilities.

And these are also the reasons that the MCPCB is widely used in the LED products as we mentioned in the last article.

So, this is the end of this article. In case if you have any questions, you are welcome to contact us via email at  sales@bestpcbs.com. We are fully equipped to handle your PCB or MCPCB manufacturing requirements.

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Thermal Conductivity—Aluminum PCB vs Ceramic PCB Series 2

Tuesday, April 19th, 2022

Last time we have talked about the structure difference between the aluminum PCB and ceramic PCB. So, based on the different structures, whose thermal conductivity is better?

We have known that a single layer aluminum PCB is made up of copper layer, dielectric layer and aluminum layer. Meanwhile, the dielectric layer is the decisive factor affecting the thermal conductivity.

Generally, its thermal conductivity ranges from 0.8 to 3.0 W/m-K, but can up to 8.0 W/m-K. So, in terms of heat dissipation, the aluminum substrate does much better than FR-4 substrate. And it is a good choice for LED lighting products with high power.

Aluminum PCB

However, the heat-conducting property of ceramic PCB is superior to that of the aluminum PCB.

Since ceramic itself is an insulating material with a great heat-conducting property, it does not need a dielectric layer. Therefore, the heat can be dissipated directly through the ceramic.

Because of its excellent performance in heat dissipation, it is particularly suitable for the lighting product with ultra high power and those products which have a high demand of heat dissipation.

Ceramic PCB

To summarize, clearly, we can know from the table below that ceramic PCB does better than aluminum PCB in terms of thermal conductivity and heat dissipation. And this is mainly because of the dielectric layer, which is related to the functions of bonding, insulation and heat conduction.

The better the heat conduction performance of the insulating layer, the more conducive it is to the diffusion of heat generated during the operation to the device, hence it will be more conducive to lower the operating temperature of the device. That is to say, aluminum PCB will be subject to the dielectric layer, while ceramic PCB will not be restricted.    

And, this is the end of the comparison of the thermal conductivity between aluminum PCB and ceramic PCB. If you still have any questions about them, please feel free to contact us.

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Differences in Structure——Aluminum PCB vs Ceramic PCB Series 1

Monday, March 21st, 2022

It is supposed that we are familiar with both aluminum PCB and ceramic PCB. But if juxtaposing them, which one will be better by one tally? So, we are about to talk about some differences between them in terms of structure.

Aluminum PCB

Aluminum substrate namely uses aluminum as substrate, which has a good heat dissipation capacity. Generally, it is single-sided, and also can be double-sided while multi-layer aluminum PCB is a little bit hard to manufacture. Besides, a single layer aluminum PCB is made up of copper layer, dielectric layer and aluminum layer.

Structure of Aluminum PCB

Ceramic PCB

Ceramic PCB namely uses ceramic as substrate. Apart from the material, the structure is the biggest difference between ceramic PCB and aluminum PCB. Since ceramic itself is an insulating material, it does not need a dielectric layer. Its structure is as follows.

Structure of Ceramic PCB

Therefore, whether there is a dielectric layer is the main difference in structure between aluminum PCB and ceramic PCB. And dielectric layer plays an important role in thermal conductivity. So, what is the relationship between dielectric layer and thermal conductivity? And whose thermal conductivity is better between aluminum PCB and ceramic PCB?

We will talk about it next time. And if you would like to know the answer, please feel free to contact us, or you can continuously follow our blog site, we will keep updating more information about the differences between aluminum PCB and ceramic PCB on it.

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What is LED Thermal Management?

Monday, December 20th, 2021

LED lighting (Light Emitting Diodes) can provide more lumens per watt than incandescent bulbs, and the amount of light emitted does not depend on the size or shape of the bulb. It has significantly smaller footprint, higher efficiencies and lasts a long time.

One of the big challenges of LED lighting is LED Thermal Management, since around 70% of the electricity used by an LED becomes heat, and LEDs work best around room temperature, if the heat is not managed with some sort of thermal management solution, it can result in reduced efficiency in the LED, shorten the life of the bulb itself, and possibly causing damage to other components near it. In this context one of the best places to start with would be thermal management within the Metal Core PCB.

Thermal Management in MCPCB

If you are using LED power, there are chances that you would encounter problem at or above 80 watts. For example if you are considering application like the street lighting which might require up to 150 watts per lamp, led thermal resistance at such high power point would be a cardinal concern.

MCPCB can be created using a wide range of heat-dissipating materials without changing the LED component. From copper which offers better thermal conductivity to aluminum which is cheaper to specialized MCPCB using coated steel, ceramics or many other options. To address the LED thermal resistance issues and achieve optimum thermal management using LED, external heat sinks can also be used. This facilitates dissipation of exceptionally large amount of heat.

In fact on an average MCPCBs have several different shapes and degrees of heat dissipation profile. However the most challenging ones are no doubt the types in which the LED applications have to be stored in airtight enclosure to protect from the environment around. Thermal management in this case could be anything from air-to-air heat exchangers to using internal fans to even heat transfer via a series of conduction and convection alternatives.

Thermal Management of MCPCB

Thermal management is important for the electronic systems to encompass the processes along with the technologies.The main objective of thermal management is to ensure the temperature remains consistent for the functional and absolute maximum limits. The temperature exceeding the limit may cause destruction physically or may lead to a system failure. Therefore, MCPCB is essential because efficient thermal management increases the feasibility, enhances durability, and reduces the failure rates.

It also enables the high circuit density design for the users. Basically, thermal conductivity is a specific material from a property with the ability to conduct proper heat management as soon as it enters into the system. The conventional PCB share less thermal conductivity and also not capable enough to meet the increased demand for the thermal constraint required for high power dissipation PCB. The best alternative to solve this problem is the Metal Core Printed Circuit Board.

If you have any questions about MCPCB, welcome to contact Best Technology.

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What kind of MCPCB is suitable for your electronic project?

Saturday, November 13th, 2021

If you need a Metal Core PCB for your project, there are some different types can be selected, the selection of the MCPCB type depends upon the type of application and project you are performing. This blog will provide you information about the metal based PCB, which will also illustrate the construction, uses and distinguishing features of the MCPCB boards, hope it can help you to choose the most appropriate MCPCB for your subsequent projects. 

Types of Metal Clad PCB 

There are many different types of the MCPCB depending upon the type of base material, currently the most common metal used for MCPCB manufacturers are Aluminum, Copper and steel alloy. The selection of the base material depends upon the type and nature of the electronic project.

1) Aluminium core PCB

Aluminium is a better material that we can use for the core of a board. The reason is that it has high heat transfer capability. Moreover, it also shows the heat dissipation capacity to the maximum extent. Aluminium is also relavitively cheaper as compared to the copper material. Therefore, it represents the cheaper and better manufacturing of the printed circuit boards.

2) Copper metal core PCB

Copper is the best material for the core of MCPCB, since this material shows the best heat transfer capability. Moreover, this material is also fit for the excellent heat dissipation during the process. These features save the PCBs from the thermal issues.

The copper core PCB shows the best thermal conductivity as compared to other PCBs. The normal value of the thermal conductivity for these PCBs is 2.0W/mk. However, we can get this value of thermal conductivity up to 12W/mk in the case of insulating layer. Therefore, these types of the PCBs have the tremendous use in the high-power LED lights.

3) Stainless steel PCB

Another important material that has an excessive use in the metal core PCBs is the Stainless steel PCB, which also can provide better capability of connectivity and high performance, and it’s more rigid than both aluminum and copper, but thermal conductivity is lower than them too. 

copper core & aluminum core pcb

Stack up of Metal core PCB

The stack up and construction of the MCPCB depends on the number of layers in the PCB. The PCB with the single layer, two layers and multiple layers have the different methods of stack and construction.

1) Single Layer Metal Core PCB

A single layer MCPCB consists of a metal base, Dielectric Layer, Copper Circuit Layer. The advantage is that it provides a better connection between components of the PCB, and it’s efficient at the heat dissipation in the high-power generator systems. These PCBs have the holes on the board for the mounting process of the electronic components. It can also have the screws around the chassis of the board for the arrangement of the components.

Single Layer Metal Core PCB
  • Two (Double) Layers MCPCB / Double Sided More Core PCB

In some cases, there’s not enough space on the single layer PCB for the mounting of enough electronic components. So we need to use the two layers conducting material to resolve this issue.

Regarding the MCPCBs with two layers of copper conductor, there are two basic types, one is Two (Double) layers MCPCB, the other one is Double Sided More Core PCB, which depends on your demand of the mounting of the electronic components, the components can be soldered on both sides on Double Sided More Core PCB.

If you would like to know more details of the differences between Double Sided MCPCB and Double/Two Layers MCPCB, welcome to click following link.

Double Sided More Core PCB

3) Multi Layers metal core PCB

The Multi Layers MCPCB have the more complex and integrated circuit/construction, which can be populated more components on the boards, put signal and ground layer into seperated layers, to achieve better performance in electrical performance. It’s best for heat transferring from electrical components to the chassis of the board. The use of these boards is tremendous in the digital and analogue devices.

Multi Layers metal core PCB

If you have any questions about MCPCB, welcome to contact Best Technology.

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About the “heat” problem in PCB & MCPCB

Monday, October 18th, 2021

For high-power products, the concept of “heat” is often mentioned, which is especially important in high-power products. It not only determines the service life of the product, but also relates to whether the product can work properly.

We will explain the “heat” problem in circuit board design from three aspects: the generation of heat, the impact of heat on the product and the “heat” in the system layout.

1. Heat generation:

Heat generation in a system takes several paths:

1) Power consumption of the component itself

2) Efficiency of power conversion devices

3) High frequency signal conversion heating

4) Power consumption of contact resistance and wire resistance during signal transmission

2. Impact of fever on products

The operating temperature of components is generally below 80 degree, and the operating temperature of commonly used capacitors and resistors is generally controlled below 50 degree. If the temperature of the system is not controlled, the following conditions may occur:

1) The temperature rise will cause the working parameters of components to change, resulting in the unstable working performance of the whole system.

2) Temperature rise will accelerate the aging of components, affecting the accuracy and life of components.

3) Temperature rise will cause circuit board deformation and poor connection of components.

General heat dissipation components arrangement

3. “Hot” considerations in system layout

1) Selection and layout of the chassis: choose materials with good thermal conductivity, such as aluminum alloy

2) Black heat absorbing material is coated inside the shell to enhance the function of radiation heat absorption

3) The shell is closely combined with the components with high calorific value to conduct heat dissipation

4) A large number of heating components should be placed at the edge of the plate to shorten the heat transfer path. Heat-resistant components should be kept away from light sources.

5) In the design process, the appropriate wire width and copper thickness should be selected, and the influence of wiring density on the current-carrying capacity should also be considered. Copper foil should be filled in the gap of the board surface as far as possible for heat conduction. The heat conduction hole can help effectively heat dissipation and reduce local temperature.

In the design of circuit board, how to effectively control the temperature of the system is a problem that must be considered.

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Why choose MCPCB rather than FR4 PCB for high power LED?

Monday, September 20th, 2021

Compared to conventional LED, high-power LED consume more electricity and require higher currents, but the heat generated in the end cannot be dissipated in time through the ordinary FR4 CPB. And there will be some failures when the heat from a LED is not properly removed, the LED’s light output is reduced as well as degradation when the heat remains stagnant in the LED package.

So if the PCB requires fast cooling, it’s better to use a metal base rather than a traditional FR-4 substrate. The typical LED MCPCB is a single circuitry layer copper foil which is bonded to a layer of thermally conductive dielectric material which is bonded to a thicker layer of metal like Aluminium or Copper base, the purpose of a MCPCB is to efficiently remove the heat from all topical IC’s (not just LEDs). Following are the comparison between FR4 PCB and MCPCB for your reference.

 

1. Thermal Dissipation

FR4 has low thermal conductivity, typically around 0.3W/m.K, while MCPCB has higher thermal conductivity, ranging from 1.0-7.0W/m.K. MCPCB transfer heat 8 to 9 times faster than FR4 PCB, the dielectric layer must be very thin to create the shortest path from the heat source to the supporting metal plate, its thickness is normally between 0.003 and 0.006 inches.

As an example, consider that a test conducted on an MCPCB with integrated 1W LED showed how its temperature remained pretty close to the ambient temperature of 25°C, while the same power LED mounted on a FR-4 board reached a temperature 12°C higher than the ambient one.

2. Better Strength and Stability

Since high power LED chips are usually assembled directly on the PCB, these LEDs can create stability and reliability problems for the circuit. Without adopting the right technique, heat dissipation can hinder the performance of electronic devices that operate at high power. The use of metal PCBs in these applications effectively solves this problem. In addition to ensuring a high durability, aluminum is very light, and adds strength and resilience to the printed circuit board without causing an increase in weight.

3. Dimensional Stability

The size of a metallic printed circuit board remain more stable, as environmental conditions vary, than that of a PCB made with traditional materials, such as FR-4. Subjected to a heating process from 30°C to about 150°C, PCBs with metal layers (such as aluminum) have undergone a very small variation in size, ranging from 2.5% to 3.0%.

If you have other questions about MCPCB, welcome to contact us.

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Baking Time & Temperature Standard of MCPCB

Tuesday, August 17th, 2021

After manufacturing the Metal Core PCB, there is a shelf life, once the shelf life has passed, we need to bake the bare board before assembling the components, otherwise the MCPCB is prone to burst when the SMT line is produced. There are industry specifications for both how long MCPCB can be stored and how long they can be baked.

MCPCB Control Standard

  1. Unpacking & Storage
  2. If the packing bag is sealed, and the manufacturing date is within 2 months, it can be directly used before assembly.
  3. The manufacturing date is within 2 months, and the unpacking date must be marked after unpacking.
  4. The manufacturing date is within 2 months, and it must be assembled and used within 5 days after unpacking.
  • Baking Time
  • If unpacked for more than 5 days within 2 months of the manufacturing date, bake at 120±5°C for 1 hour
  • Two months after the manufacturing date, baking at 120±5°C for 1 hour before assembly.
  • Two to Six months after the manufacturing date, baking at 120±5°C for 2 hours before assembly.
  • Six to Twelve months after the manufacturing date, baking at 120±5°C for 4 hours before assembly.
  • The MCPCB after baking must be used up within 5 days (put into IR REFLOW), and unused board must be baked for another hour before assembly.
  • Over half one year after the manufacturing date, bake at 120±5°C for 4 hours before assembly, and then send it to the production line to do HASL_LF before using.
Baking Machine

Preservation & Baking Standard for in different regions

The specific storage time and baking temperature of MCPCB are not only related to the production capacity and production process of manufacturer, but also have a great relationship with the region.

  1. For areas with heavier humidity, the MCPCB must be used up within 24 hours when exposed to the air, otherwise it is easy to oxidize. After normal opening, it is best to use it up in 8 hours.
  • For areas with a relatively dry climate, the preservation time of PCB will be longer, and the baking time can also be shorter. The baking temperature is generally 120±5°C, and the baking time is determined according to the specific situation.

The MCPCB with OSP or Gold Immersion has a shelf life of 6 months after packaging, and it is generally not recommended to bake for MCPCB with OSP.

PCB board with SMT

If you have other questions about MCPCB, welcome to contact us.

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