How Electrical Engineers Use In-Mold Electronics to Integrate Circuits Directly Into Functional Surfaces

Imagine pressing a sleek, seamless dashboard control that appears to be part of the surface itself—no buttons, no bezels, just an elegant interface that lights up at your touch. Behind this seemingly magical interaction is a revolutionary approach called In-Mold Electronics (IME), where circuits are no longer attached to the surfaces of printed circuit boards. They have become the surface.

The Problem with Traditional Interfaces

For decades, electronic interfaces have followed the same basic construction: rigid circuit boards populated with components, connected to separate mechanical elements like buttons and switches, all housed within a protective enclosure. This approach creates inherent limitations:

• Design Constraints: Traditional interfaces require cutouts, bezels, and mounting hardware that limit aesthetic possibilities.
• Reliability Issues: Each mechanical connection represents a potential failure point.
• Manufacturing Complexity: Assembly requires multiple steps, components, and processes.
• Space and Weight Penalties: Separate PCBs, buttons, and housings consume valuable space and add weight.
• Environmental Vulnerability: Seams and openings create entry points for moisture and contaminants.

The IME Revolution

In-Mold Electronics (IME) fundamentally changes this paradigm by printing electronic circuits directly onto a flat film, which is then formed into a three-dimensional shape and encapsulated within injection-molded plastic. The result is a single, integrated component where the electronics and structure are inseparable.

The IME process typically follows these steps:

• Printing: Conductive, resistive, and dielectric inks are screen-printed onto a flat thermoplastic film.
• Component Placement: Surface-mount components are attached using conductive adhesives.
• Thermoforming: The printed film is heated and formed into the desired three-dimensional shape.
• Injection Molding: The formed film is placed in a mold, and plastic is injected behind it, creating a solid structure.

This approach delivers transformative benefits:

• Design Freedom: Curved, contoured surfaces can incorporate electronic functionality.
• Part Consolidation: What once required dozens of parts can be manufactured as a single component.
• Enhanced Durability: With no seams or mechanical connections, IME interfaces are inherently more resistant to moisture, dust, and physical damage.
• Weight Reduction: Eliminating separate PCBs, housings, and mounting hardware can reduce weight by 40-70%.
• Manufacturing Efficiency: Fewer parts mean fewer assembly steps and supply chain dependencies.

According to a study by IDTechEx, IME can reduce part count by up to 90% while decreasing manufacturing costs by 20-30% for complex user interfaces.

Real-World Success Stories

Automotive: Ford’s Mustang Mach-E Center Console

Ford’s electric Mustang Mach-E features an innovative center console with integrated controls manufactured using IME technology. 

The design eliminated 50% of dashboard wiring and reduced assembly time by over 30% compared to traditional approaches.

The console integrates capacitive touch sensors, LED indicators, and haptic feedback elements into a single molded component, eliminating discrete parts that would have been required in a traditional design.

Consumer Electronics: Whirlpool’s Smart Appliance Controls

Whirlpool’s premium appliance line features IME control panels that have transformed both aesthetics and functionality. Their dishwasher control panel integrates 15 touch-sensitive controls, status indicators, and a display window into a single, seamless surface that can be wiped clean.

Buyers appreciate appliances that are both beautiful and easy to clean. IME allows manufacturing companies like Whirlpool to eliminate the crevices where dirt and moisture collect in traditional button interfaces.

The IME panels have proven 300% more resistant to cleaning chemicals than mechanical button arrays and have reduced warranty claims related to control failures by 45%.

Medical: Philips Portable Ultrasound Interface

Philips Healthcare’s latest portable ultrasound device features an IME control surface that has revolutionized both usability and infection control. The seamless interface eliminates crevices where contaminants can hide, allowing for complete disinfection between patients.

IME has allowed manufacturers to create interfaces that can withstand hospital-grade disinfectants while maintaining perfect functionality.

The Engineering Process: From Concept to Production

To understand how electrical engineers approach IME design, let’s follow the development of a hypothetical automotive climate control panel from concept to production.

1. Design Conceptualization

Unlike traditional electronics design, which begins with circuit schematics, IME design starts with the physical form and user interaction. Engineers and industrial designers collaborate from day one to define:

• The three-dimensional surface geometry
• User interaction points and feedback mechanisms
• Environmental requirements (temperature range, exposure to sunlight, cleaning chemicals)
• Mechanical performance needs (impact resistance, actuation force)

2. Material Selection

Material selection is critical for IME success. Engineers must consider:

• Base Film: Typically PET or PC, must withstand both thermoforming and injection molding temperatures.
• Conductive Inks: Silver-based inks are common, but carbon inks may be used for cost-sensitive applications.
• Dielectric Materials: Must provide reliable isolation while remaining flexible.
• Injection Molding Resin: Typically PC, ABS, or PC/ABS blends compatible with the base film.

Material compatibility is the foundation of successful IME. Each layer must maintain adhesion and functionality through multiple thermal cycles.

3. Circuit Design with Deformation in Mind

Unlike traditional PCB design, IME circuits must function correctly after being stretched and deformed during thermoforming. This requires:

1. Designing circuits with elongation zones that can stretch without breaking
2. Avoiding component placement in areas of high deformation
3. Using stretchable circuit patterns (serpentine traces) in areas that will undergo significant forming
4. Simulating the deformation process to predict stress points

4. Prototyping and Validation

IME prototyping typically follows a staged approach:

1. Electrical Validation: Testing circuit functionality on flat films before forming
2. Forming Trials: Testing the formability of printed circuits without components
3. Functional Prototypes: Complete assemblies with components, tested for electrical performance after forming
4. Injection Molding Trials: Validating that circuits and components survive the injection process
5. Environmental Testing: Subjecting prototypes to temperature cycling, humidity, UV exposure, and chemical resistance tests

5. Production Engineering

Scaling from prototype to production requires careful process engineering:

1. Screen Printing Optimization: Ensuring consistent ink deposition across production runs
2. Component Placement Precision: Developing fixtures and processes for accurate, repeatable component attachment
3. Forming Parameters: Defining precise temperature, pressure, and timing for thermoforming
4. Injection Molding Setup: Optimizing gate locations, pressures, and temperatures to prevent damage to circuits

Design Tools That Make It Possible

Creating successful IME designs requires specialized tools that bridge the gap between electrical, mechanical, and manufacturing disciplines.

Altium Designer: Enabling the IME Revolution

Altium Designer has developed specialized capabilities for IME design that address the unique challenges of this technology:

• Material-Specific Design Rules: Apply design constraints based on the specific inks and materials being used.
• Manufacturing Output: Generate the specialized outputs required for screen printing, component placement, and forming.

Key features that make Altium Designer ideal for IME development include:

• Printed Electronics Settings: A dedicated environment for printed electronics PCB stack ups in the Layer Stack Manager
• MCAD Aware: Seamless import of 3D models from mechanical CAD systems
• Manufacturing Documentation: Generate the specialized outputs required for IME production

Complementary Tools in the IME Workflow

While Altium Designer handles the electrical design aspects, a complete IME workflow typically includes:

• Mechanical CAD: Tools like SOLIDWORKS or Creo for designing the 3D form
• Forming Simulation: Software like Moldex3D or Polyflow to simulate the thermoforming process
• Injection Molding Simulation: Tools to predict how the injection process will affect the formed circuit

Overcoming IME Design Challenges

Despite its advantages, IME presents unique challenges that engineers must address:

1. Elongation and Trace Integrity

When a flat circuit is formed into a 3D shape, the conductive traces must stretch without breaking. Engineers have developed several strategies:

• Serpentine Trace Patterns: Designing traces with deliberate curves that can straighten during stretching
• Gradient Thickness: Varying the ink thickness in areas expected to undergo significant deformation
• Strategic Routing: Avoiding trace placement in areas of maximum deformation

2. Component Survival

Surface-mount components must withstand both the thermoforming and injection molding processes:

1. Component Selection: Choosing components qualified for the temperature profiles of forming and molding
2. Strategic Placement: Positioning components in areas with minimal deformation
3. Protective Encapsulation: Using additional materials to shield sensitive components during molding

3. Testing and Quality Assurance

Traditional PCB testing methods don’t always translate to IME:

• In-Circuit Testing: Traditional bed-of-nails testing is often impossible with 3D surfaces
• Functional Testing: Developing custom test fixtures that match the 3D geometry
• Optical Inspection: Using 3D scanning to verify trace integrity after forming

Future Possibilities

The IME field continues to evolve rapidly, with several exciting developments on the horizon:

Stretchable Electronics

Next-generation IME will incorporate truly stretchable circuits that can elongate by 100% or more, enabling integration into highly deformable surfaces like automotive airbag covers or medical wearables.

Integrated Sensors

Future IME designs will incorporate printed sensors directly into the molded surface:

• Pressure sensors for touch detection with force feedback
• Temperature sensors for environmental monitoring
• Strain gauges for structural health monitoring
• Gas sensors for air quality detection

Biodegradable and Sustainable IME

As sustainability becomes increasingly important, researchers are developing eco-friendly IME materials:

• Biodegradable substrate films
• Water-based conductive inks
• Recyclable molding compounds

Conclusion

In-Mold Electronics represents a fundamental shift in how we think about electronic interfaces. By integrating circuits directly into functional surfaces, IME eliminates the artificial boundary between electronics and structure, creating products that are more elegant, durable, and efficient.

For electrical engineers, IME requires a new mindset—one that considers electrical, mechanical, and manufacturing factors simultaneously from the earliest design stages. Tools like Altium Designer are evolving to support this integrated approach, enabling engineers to realize the full potential of this transformative technology. To start designing your own IME products, start the Layer Stack Manager in the PCB layout environment in Altium, then select the 3-line icon in the upper right.

You will see multiple options for PCB types, such as Printed Electronics, Rigid-Flex and so on. Go with Printed Electronics. Your PCB stack up changes permanently and then you can define dielectric material between conductivelayers. 

Altium is one of the only SaaS companies addressing this design and development for innovative designs. Altium Designer's native support for printed electronics provides a design environment in which the electrical connections between sequential print runs are understood. It is possible to create insulating areas of dielectric material manually, or automatically at trace crossover locations.

These conductive materials (like copper) are what get printed onto the surfaces of bendable objects.

As IME continues to mature, we can expect to see it expand beyond user interfaces into structural electronics, where entire products become smart, responsive systems rather than passive housings for electronic components.

The future belongs to engineers who can think beyond the circuit board—who can envision electronics not as components to be housed, but as integral elements of the products they create.

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