An Introduction to IMS PCB – 2022 Updated Complete Guide

IMS PCB- The meaning

Insulated Metal Substrate is sometimes abbreviated as “IMS.”. IMS PCBs, alternately known as MCPCB, is a term that we use to describe printed circuit boards made with a metal plate for reinforcement. It is separated from the copper wires of the circuit by a dielectric substrate.

The circuit’s heat is conducted to the metal substrate via a dielectric layer. The metal base of the PCB serves as a heat sink and a structural backbone. The dielectric layer material has the qualities of top-tier heat dissipation and great dielectric strength against high voltages. IMS PCBs are typically found in compact circuits with massive heat generation, such as LED PCBs.

What are the Benefits of Using IMS PCBs?

The primary advantages of using an IMS board include the following –

• Support (Structural) – Substrates made of thick metal is strong enough to support the structure. They provide a stronger framework for electronic circuits. In addition, IMS PCB boards also act as the primary structure for different applications.

• Electromagnetic Shield- Metal substrates also act as electromagnetic shields. Thus, you can use an IMS PCB board as your circuit’s ground plane, which indirectly reduces the copper traces for the circuit, thereby bringing down the manufacturing cost.

• Better Thermal Conductivity – We all know that metals are good conductors of heat; thus, it only makes sense that the IMS would have high thermal conductivity. An IMS PCB has thermal conductivity capabilities up to 12 W/ (m.K) and a maximum of 3.2 mm metal thickness. In addition, thanks to the metal’s excellent conductivity, IMS PCBs can incorporate many heat-dissipating components for optimal performance. The result is that you get better compactness.

• Fire Resistance – As the substrate material of IMS PCBs is metal, they are less vulnerable to fire. Thus, IMS PCBs are great for high-power applications or applications where the environment temperature is flammable.

• SMD (Surface Mount Device) Compatible – IMS PCBs are also compatible with surface mount devices because they have high thermal conductivity. This means they are capable of dissipating the heat produced by SMD components and preventing damage.

Applications of IMS Boards

IMS PCBs have varied uses. For example, they are integral to LEDs, automotive industries, power electronics, solid-state relays, and more.

• LED Technology – LED circuits are becoming more compact, energy-efficient, and power dense over time. Such LED circuits depend on IMS PCBs because they can absorb heat generated from LEDG SMDs and efficiently transfer that heat to the heatsink material.

• Power Electronics – Power electronic circuits with switching devices generate excessive heat. Without any heatsink er components, IMS PCBs efficiently disperse heat. Thus, the designs become more compact.

• Automotive Industry – IMS boards have pertinent usage in the automotive industry. Modern vehicles comprise dozens of control units (CU). Such small components are placed in or near the engine and are susceptible to high and scorching temperatures. IMS PCBs provide the required thermal conductivity and mechanical properties suitable for these applications.

• Solid State Relays – Another veritable use of IMS boards is in Solid State Relays (SSR). To begin with, SSR is the modern equivalent of mechanical relays. They are made composed of a power switch and a driver circuit for an optocoupler (TRIAC or MOSFET). All components are packed into a small casing, which serves as the heat sink. They must resort to IMS PCBs to encapsulate heat from all the components and forward that heat to the enclosure.

Different Types of IMS Boards

Types of IMS Boards Based on Metal Substrates

Depending on the metal substrate, we have three IMS boards, namely –

1. Copper Metal Substrate PCB – Such IMS boards, are pretty expensive and also rare to find. We can use them for applications that need excellent electrical and thermal conductivity. While copper is one of the best substrate materials, it is not immune to corrosion.
2. Aluminum Metal Substrate PCB – They are commonly available and also quite affordable. However, aluminum substrate PCBs only offer standard electrical properties and thermal conductivity.
3. When compared to copper and aluminum substrates, the price of a circuit board made from stainless steel is significantly lower. Stainless steel substrate IMS boards offer decent thermal and electrical performance. However, they shine bright when it comes to mechanical strength.

Types of IMS Boards Depending on PCB Layer and Position for Component Mounting 

When considering the layer (PCB) and location for component mounting, we have four distinct IMS boards, namely: 

1. IMS Printed Circuit Boards with Dual Mounting Pads for Electronic Components – IMS PCBs with such a design have two solder mask layers. The exciting part is that each layer of solder mask can contain a unique set of features. In addition to the two mounting holes, IMS boards with dual mounting are distinguished by a metal substrate in the center of the board and vias – for transforming current and heat. In addition, there is resin material surrounding the vias and providing insulation. IMS PCBs with such a design render increased mechanical performance and average heat sink abilities. However, they can only create complex circuits.
2. Single-sided Meta PCBs (Core IMS) – PCBs with such an IMS layout only require a single solder mask layer. They also feature a metal substrate and a single copper layer. These layouts shine in the case of elementary circuits, such as LEDs and SSRS. The bottom metal substrate also serves as a heatsink.  
3. Two Layers with Single Mounting Side Component IMS PCBs – IMS PCB with such a design has two copper layers with an FR4 layer in between. These designs enable you to integrate more complex circuits and minimize thermal conductivity. Although the mitigation in thermal conductivity is not up to the mark, the design co=opts heat transferring vias as compensation. These vias can reach the bottom of SMD components and transfer heat to the substrate at the bottom.  

The key distinctions between IMS and FR4 Printed Circuit Boards

It is time to underline the distinctions between IMS and FR4 PCBs. It is worth noting that R4 PCBs and IMS PCBs can be distinguished from one another in a variety of ways, not limited to thermal conductivity and mechanical qualities–

• In FR4 PCBs, we can mount through-hole components on single-layer PCBs. On the other hand, IMS PCBs of one layer do not support through-hole components.
• IMS PCBs generally have higher and better thermal conductivity when compared to the same layer-type FR4 PCB.
• Solder masks for FR 4 PCBs can be either black or green, amber, whereas they are white for IMS PCBs. 
• In the fabrication of IMS PCBs, the substrate material is cut into sections using saw blades that have been coated with diamonds. On the reverse side, common machining techniques can be used for FR4.
• Most IMS PCBs can only handle one layer of copper, while FR4 PCBs can handle dozens. Due to the difficulty involved in producing multilayer IMS PCBs, you will find that they are the exception rather than the rule.
• Lastly, FR4 PCBs do not have any thickness limit, as they can hold many layers. On the contrary, thinner IMS PCBs are not permitted, where anything over that threshold, their benefits are nullified.

Absolute PCB assembly – Reliable IMS PCB Manufacturer

Absolute PCB is your one-stop shop for all IMS PCB manufacturing needs. You can order the PCB boards mentioned above and enjoy our one-to-one engineering support, accessible design for manufacturing, and design for excellence.