Injection Molded Structural Electronics: Creating Smart Surfaces with Electronic Functionality

Watch the session "Injection Molded Structural Electronics: Creating Smart Surfaces with Electronic Functionality," presented by Sini Rytky and Tuomas Heikkilä from TactoTek at Altium Live. In this presentation, they demonstrate how IMSE is redefining electronics integration by enabling smart, functional surfaces that seamlessly merge form and function.

Watch the replay and explore the summary and key takeaways below to learn how IMSE works, where it's being applied, and why it stands out as one of the most exciting innovations in modern electronics design.

Injection Molded Structural Electronics (IMSE): Shaping the Future of Smart Surfaces

Imagine stepping onto the bridge of Star Trek’s USS Enterprise, where control panels react to the swipe of your hand. Navigation, star charts, and warp drive are seamlessly controlled through the sleek, futuristic LCARS (Library Computer Access/Retrieval System) interface. What was once sci-fi fantasy is no longer fiction. Injection Molded Structural Electronics (IMSE) makes this intuitive, integrated technology a reality.

IMSE skillfully embeds printed circuitry and surface-mounted components directly into molded plastics, creating thin, durable, and functional surfaces. Integrating IMSE parts into 3D surfaces requires precise coordination of material and component placement. The process is heat-sensitive, and inexperienced approaches can lead to reliability issues, damaged components, or unnecessarily high manufacturing costs.

While earlier solutions have attempted integration through layering or post-molding assembly, they often trade off performance, durability, or scalability. IMSE enables a single, efficient process that merges electronics and form. In this blog, we’ll break down its core parts, real-world IMSE use cases, and design considerations, such as mold design, part structure constraints, and thermal limitations. 

What Is IMSE?

IMSE, or Injection Molded Structural Electronics, is a technology that fuses printed electronics, decorative surfaces, and components like LEDs, antennas, and sensors into molded plastics.  Unlike traditional electronics, where rigid PCBs are enclosed in separate housings, IMSE enables 3D electronic functionality in curved, space-constrained environments. IMSE opens up a universe where form and function seamlessly coexist, resulting in lightweight, durable, smart surfaces that wouldn’t feel out of place in Tony Stark’s Iron Man suit.

Key Benefits of IMSE

• Ultra-thin structures (2–3 mm)
• Up to 70% weight reduction
• High durability and environmental resistance
• Single-part assembly, eliminating mechanical integration
• Supports complex 3D shapes and design freedom
• Reduces component count and simplifies manufacturing

IMSE Process

IMSE production involves four sequential steps that transform flat films into fully functional smart surfaces:

1. Screen Printing: A plastic film made from polycarbonate (PC) or thermoplastic polyurethane (TPU) receives conductive silver-based inks, dielectric inks, antennas, and decorative graphics. 
2. High-speed machines place electronic components such as LEDs and capacitive sensors onto a flat plastic film. 
3. The film is then heated and formed into a three-dimensional shape using thermoforming, allowing it to conform to the final product’s geometry.
4. The shaped film receives an injection-molded resin (PC or TPU) encapsulation, which seals the electronics while creating a unified, durable structure. The streamlined manufacturing process eliminates the need for multiple assembled parts and hands-on wiring IML film procedures.

IMSE Part Structure

IMSE parts include functional layers seamlessly molded together:

• Decorative A Surface: Printed graphics and finishes on IML films or natural materials (e.g., wood veneer).
  • In-Mold Labeling (IML): A process that applies decorative or functional films (such as wood veneer or printed graphics) to the surface during molding. These films can also include translucent areas for backlighting and remain fully integrated after molding.
• A Surface Electronics: Conductive, dielectric inks, and SMT parts such as LEDs and antennas.
• Plastic Resin Core: Injection-molded polycarbonate or TPU that encapsulates the film.
• B Surface Electronics: Optional second layer of printed circuitry and electronics.
• Functional B Surface: Acts as the internal support and secondary interface.

All layers are fused into a one-piece assembly, enabling sleek and functional smart surfaces.

IMSE Applications

IMSE technology is used in vehicles, wearable electronics, and interactive home devices. Integrating electronic functionality directly into molded plastic parts makes IMSE especially effective in compact, high-performance environments. 

IMSE Applications: Automotive

IMSE has been used in the automotive sector to dramatically simplify and enhance interior parts. For example, a traditional overhead control panel, which typically requires more than 60 mechanical parts and weighs approximately 650 grams, was re-engineered using IMSE into a single molded part weighing only 200 grams and 3 mm thick, reducing part count and complexity while maintaining full performance. 

Another automotive application involves wooden door trim panels, which were once purely decorative; IMSE enhanced them with embedded capacitive touch controls and hidden LED illumination for seat adjustments, all without disrupting the premium surface finish. 

Ashtray covers, once static components, have also been upgraded with IMSE to include touch sliders for AC and seat heating. 

IMSE Applications: Wearables

In wearables, IMSE supports ultra-thin, lightweight designs that endure stress, such as the Suunto smart connector, which is embedded in TPU and survives over 10,000 bends and 50 wash cycles. 

IMSE Applications: Smart Home and Industrial

In smart home and industrial settings, IMSE enables hidden touch controls, gesture-activated lighting, and printed antennas, ideal for sleek, interactive user interfaces in home automation and factory equipment.

IMSE Building Blocks

TactoTek has identified five key building blocks of every IMSE-enabled product to support performance and design flexibility. These blocks give engineers and designers a toolkit for creating responsive surfaces.

Materials and Components

Materials and components are the starting point. IMSE begins with thin, flexible plastic substrates like polycarbonate (PC) or thermoplastic polyurethane (TPU). Onto these films, engineers print conductive inks (often silver-based) and dielectric layers to isolate signals and define touch zones. From there, surface-mounted devices (SMDs) such as LEDs, capacitive sensing chips, and microcontrollers are placed directly onto the printed surface using high-speed pick-and-place machines. These elements are the key to maintaining a lightweight and compact design.

Look and Feel

IMSE supports various finishes, from printed patterns to natural materials like wood veneers. Surfaces can be matte, glossy, textured, or transparent. What's unique about IMSE is that these decorative layers are also functional. Visible surfaces are often design features and interactive.

Example: A woodgrain door panel in a car may look like pure decoration. However, with IMSE, it lights up to show seat adjustment icons and responds to touch when a user interacts with it. The cohesive surface does not require separate buttons or screens.

Touch Elements

Touch elements bring interactivity to the surface. Capacitive buttons, sliders, and custom-shaped touch zones can be printed directly into the structure. Because they're fully embedded, there's no need for mechanical buttons, which means fewer moving parts and better environmental resistance. 

Sense Elements

Sense elements add another layer of responsiveness. IMSE panels can detect a user's presence or hand movement before contact by embedding proximity or gesture sensors. This feature is useful when gloved hands or touchless activation improves safety and hygiene.

Illumination

Illumination is the final layer and is about more than aesthetics. Integrated LEDs are used for ambient lighting, backlit icons, or visual indicators to communicate status or guide interaction. For example, a seat adjustment panel may remain hidden until a hand approaches, icons suddenly illuminate, and controls become visible.

These five building blocks make IMSE a flexible technology for creating responsive, space-efficient, and visually refined surfaces. This modular approach allows product teams to tailor functionality while minimizing complexity.

IMSE System Elements

With IMSE, designers can integrate electronics directly into molded plastic structures to connect to a more extensive system. IMSE parts must communicate with other components within a product's architecture.

Control electronics, microcontrollers, or small printed circuit boards (PCBs) are often housed externally and connected to the IMSE part when in-mold integration of complex chips isn't feasible due to thermal or design constraints.

Flat cables and in-mold connectors bridge the IMSE part with the broader system. These elements are the physical power, signal, and data transfer interface. Because the electronics are embedded inside the molded structure, these connectors must be precisely positioned and sealed during molding.

IMSE technology also supports wireless messaging and communication protocols. IMSE technology works with widely used wireless communication standards like LIN, Bluetooth, NFC, and Wi-Fi, making integrating into connected systems easy without significant hardware upgrades.

IMSE vs. Traditional PCBs

IMSE replaces cumbersome multi-part electronic assemblies with molded parts that combine circuits, components, and surface graphics. To do this, manufacturers form the parts into 3D shapes using polycarbonate or TPU instead of rigid materials like FR4.

Traditional PCBs require designers to assemble circuit boards, casings, connectors, and mechanical switches separately. IMSE combines printed circuitry, parts, and surface graphics into a single molded part, reducing part count and assembly time.

There is also a significant difference in size and weight. An IMSE part is typically 2 to 3 mm thick and can be up to 70% lighter than its traditional counterpart. For example, an overhead control panel that once weighed 650 grams and required over 60 parts was reduced to just 200 grams using IMSE while maintaining the same functionality.

IMSE parts are also more durable by design. The molded structure naturally resists water, dust, and impact, and the electronics are sealed inside. In contrast, traditional PCBs usually require additional enclosures for environmental protection.

Finally, system integration is more straightforward with IMSE. Because it functions as a single, unified component, there’s less wiring and fewer mechanical interfaces to manage, making it easier to design compact, high-performance products.

Comparing IMSE and Traditional PCB Technologies

IMSE Electronics Design Flow

The design of an IMSE part shares basic design principles with traditional PCB design yet has distinct specializations. The materials employed in IMSE need unique attention during the design process. The printed circuitry in IMSE uses silver ink instead of copper, producing a resistance level 100 times higher than copper. The layout optimization needs to be adjusted because of the current flow characteristics. The implementation of dielectric layers stands as a crucial design element. Standard PCB workflows do not require the design and simulation of touch zones and sensor functions, which these insulating materials need for proper implementation.

The design specifications of IMSE require conversion from two-dimensional to three-dimensional space. The three-dimensional nature of the final circuitry requires engineers to verify that trace performance remains intact throughout the forming and molding operations. The design validation requires simulation as a critical step. The layout becomes ready for finalization after engineers check electromagnetic performance together with capacitive sensing behavior and resistance values.

To validate an IMSE design, simulations are essential. Engineers must evaluate electromagnetic performance, capacitive sensing behavior, and resistance values to ensure that the part performs as expected. These extra steps are necessary because IMSE circuits are printed with silver inks and embedded into 3D plastic forms, which behave differently from traditional copper on rigid boards.

While this adds complexity compared to standard PCB workflows, it also opens up far greater design flexibility. Engineers gain the ability to combine form, function, and interface into a single molded structure—something not possible with traditional electronics.

Fortunately, the design tool ecosystem is catching up. Platforms like Altium Designer now include IMSE-specific capabilities, such as automatic dielectric placement, trace resistance simulation, and design rule checks tailored to the unique geometry and materials of IMSE parts. These advancements streamline the process and reduce the risk of design errors.

Explore how Altium Designer supports printed electronics and enables the integration of electrical circuits with three-dimensional mechanical parts.

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