An Introduction to IMS PCB - Complete Guide

What is IMS PCB? Why do we need IMS PCB? In this post, you will get an overall introduction to the IMS PCB from the below six parts.

What is IMS PCB?

Insulated metal substrate (IMS) PCB, also known as metal core PCB (MCPCB), is the term for the PCBs constructed with a metallic support plate (usually aluminum), which is separated by a dielectric layer from the copper conductors of the circuit.

The die-electric layer transfers heat from the circuit to the metal substrate. The metal substrate acts as a heat sink and also provides structural support for the PCB. The die-electric layer material has the qualities of excellent heat dissipation and great dielectric strength against high voltages. IMS PCBs are usually found in compact circuits with high heat generation. (ex LED PCBs)

What are the Benefits of Using IMS PCBs

Here are the advantages of IMS PCBs over normal FR4 boards:

• The main advantage of an IMS PCB over a common FR4 PCB is that it has enhanced thermal conductivity. IMS PCB could have thermal conductivities ranging from 1-12 W/(m.K). The metal core thickness could vary between 0.4mm to 3.2mm.
• Thick metal substrates can also be used as structural support or the main structural part of the application. This is another advantage over common FR4 PCBs.
• By taking advantage of the increased thermal conductivity, high heat-dissipating components can be densely packed in IMS PCBs providing overall compactness compared to common PCBs.
• Since the substrate material is metal, IMS PCBs are less vulnerable to fire compared to FR4 material used in normal PCBs. This makes IMS PCBs ideal for high-power applications or applications where the environment temperature is high or flammable.
• The metal substrate also acts as an electromagnetic shield. It can also be used as an active ground plane in the circuit, which indirectly reduces the PCB manufacturing cost by reducing the copper traces required for the ground plane.
• IMS PCBs are surface-mount device (SMD) friendly. This is because the IMS PCB can directly absorb the heat from the SMD components and distribute the heat quickly.

Following is the summary of the above-discussed advantages of IMS PCBs.

• Increased thermal conductivity
• Improved mechanical properties
• Improved fire resistivity
• Increased electromagnetic shield
• More SMD component-friendly

Applications of IMS Boards

IMS PCBs are widely used for LEDs, automotive, power electronics, solid-state relays, etc.

• LED Technology

LED circuits are more and more compact, energy-efficient, and power-dense. These LED circuits widely use IMS PCBs because they can absorb heat generated from LED SMDs and transfer that heat to the heatsink material efficiently.

• Automotive Industry

Modern vehicles consist of dozens of control units (CU). These small computers are placed in or near the engine and are susceptible to harsh temperatures. IMS PCBs provide the necessary thermal conductivity and mechanical properties suitable for these applications.

• Power Electronics

Switching devices in power electronic circuits produce excessive heat. IMS PCBs distribute this heat efficiently without having an individual heatsink per component. This allows for compact designs.

• Solid State Relays

Solid State Relay (SSR) is the modern equivalent of mechanical relays. It consists of an optocoupler driver circuit and a power switching device (MOSFET or TRIAC). All the components are densely packed into a small casing, which acts as the heat sink. These use IMS PCBs to capture heat from all the components and transfer that heat to the enclosure.

Different types of IMS Boards

IMS PCBs or MCPCBs have a few types and differences. Following are the main differences seen in industrial IMS PCBs.

According to the metal substrates, there are three IMS PCB types.

Aluminum metal substrate PCB

This is the most common metal type for the metal substrate material. Aluminum is much cheaper than copper and has moderate thermal conductivity and electrical properties.

Stainless steel metal substrate PCB

Stainless steel is used as a substrate material in applications where mechanical strength is crucial. Stainless steel is the cheapest but has lower electrical and thermal performance compared to aluminum and copper. It is much cheaper than copper and aluminum.

Copper metal substrate PCB

Copper, a substrate material is only used in a handful of applications where excellent thermal conductivity and excellent electrical conductivity are needed. Copper has the best material properties compared to aluminum and stainless steel. The main drawback of having copper is that it is susceptible to corrosion. And the material price — copper substrate PCBs are a bit expensive.

From the advanced PCB manufacturer PCBONLINE, you can avail of copper base PCBs of 1 to 8 layers, which can be both single-sided or dual-sided. Besides, you can design to inlay copper busbars in FR4 PCBs to create high-current PCBs.

According to the PCB layer and component mounting position, there are four IMS PCB types.

Single-Sided Metal Core IMS PCBs

This type of IMS PCB has only one side for components to mount. One copper layer and the bottom side is the metal substrate, which also serves as the heatsink. This type is common for simple circuit arrangements like LED PCBs and Solid State Relay (SSR) PCBs.

Two Layers with Single component mounting side IMS PCBs

This type provides two copper layers, which allows more complex circuits to be integrated. There is an FR4 layer sandwiched between two copper layers which can reduce thermal conductivity. For better thermal conductivity, heat transferring vias are used. These heat-transferring vias touch the bottom side of the SMD components and transfer heat from the top side to the bottom substrate.

Dual component mounting side IMS PCBs

This design comes with two solder mask layers, which can be populated with components. The metal substrate is in the middle. Via is used to transfer heat and current. A resin material is applied around the vias to insulate current-carrying vias. These PCBs have enhanced mechanical properties. Metal substrates have reduced heatsink properties since it sits in the middle but this allows for a more complex circuit.

Multilayer dual component-mounting side IMS PCBs

This is the most complex arrangement of all the variants. It supports dual-side component mounting and has multiple copper layers sandwiched on the top and bottom sides of the metalcore. It supports more complex designs such as single-board computers (SBC), where the processor and all the components are soldered into a compact one PCB. Metalcore acts as a heat conductor to distribute the heat.

Differences between IMS PCBs and FR4 PCBs

Apart from the most obvious differences in thermal conductivity and mechanical properties, there are some other differences between common FR4 PCBs and IMS PCBs.

• In FR4 PCBs, through-hole components can be mounted on single-layer PCBs, but 1-layer IMS PCBs do not support through-hole components.
• IMS PCBs generally have higher thermal conductivity compared to the same layer-type FR4 PCBs.
• IMS PCBs typically have white solder masks, and FR4 PCBs have green, black, or amber solder masks.
• IMS PCB manufacturing uses diamond-coated saw blades to cut the substrate material, while FR4 can use regular machining tools.
• FR4 PCBs support dozens of copper layers, while most IMS PCBs have one layer. It is rare to have IMS PCBs get multiple layers since it requires a complex manufacturing process.
• There is no limit for the thickness of FR4 PCBs since they support dozens of layers, but IMS PCBs have a thickness limit where over that limit their benefits will no longer be valid.

PCBONLINE - Reliable IMS PCB Manufacturer

PCBONLINE is an advanced PCB manufacturer founded in 1999. We provide one-stop IMS PCB manufacturing. You can order all the above-mentioned IMS PCBs from us and enjoy our one-to-one engineering support, free design for manufacturing, and design for excellence.

PCBONLINE is the only manufacturer that has realized fully automatic fabrication so far. Below are our MCPCB capabilities.

Base Material		Aluminum (Larid, Ventec, Yugu Boyu), Iron, and Copper isolation base
Max Dimension		1200mm * 300mm
Copper Foil Thickness		0.5-10oz
Dielectric Thickness		0.075-0.15mm
Finish Thickness		0.5-3.2mm（+/-10%）
Line Width/Space	1oz 2oz 3oz 4oz	0.15/0.12MM 0.18/0.15MM 0.25/0.2MM 0.3/0.25MM
Soldermask Opening		0.05mm
Surface Finish		ENIG, OSP, HASL(LF HASL), Immersion Tin, Immersion Silver
Peel Strength		≥ 1.8 N/mm
Surface Resistance		≥ 1*10^5 M
Volume Resistivity		≥ 1*10^6 M
Solder Float		260℃,10Min, No layering, No sparkling
Permittivity		≤ 4.4
Dissipation Factor		≤ 0.03
Thermal Conductivity		1.0~4.2W/m.k
Hi-pot Withstand		2~6KV
Surface Finish	HASL LF HASL ENIG OSP	SMD 40-2000u", GND 30-800u" SMD 40-2000u", GND 30-800u" Au 1-5u", Ni 80-200u"

We support both online and email quotations. Get an online quote and enjoy $100 off coupons now.

Conclusion

So we have introduced what is IMS PCB, its advantages, and its applications. We've also introduced a trustworthy IMS PCB manufacturer PCBONLINE. If you or your company needs IMS PCBs for your devices, do not miss PCBONLINE to be your IMS circuit board supplier.