In-mold electronics (IME) is a combination of in-mold decoration (IMD) and printed electronics. It is an alternative to traditional human-machine interfaces (HMIs) with mechanical switches. IME has strong functionality, light weight and lower cost. It has wide application in automotive, medical devices and household appliances.

 

Advantages of IME

 

IME can integrate film, circuit, electronic components, and LED lights together by injection molding. It integrates traditional mechanical buttons, decorative parts and functional parts into one product. Here are some advantages of IME.

 

1. Light weight

 

IME eliminates bulky printed circuit boards. Take ambient lighting as an example. According to traditional technology, you need to weld a large PCB, on which LED lights are also welded. When using IME, you can take the circuit directly on the back of film, and LED lights can be placed wherever they are needed.

 

2. Optimized design

 

For products with diverse shapes, IME can provide greater design freedom. For example, there is no need to use dead space to accommodate traditional light guide plates. It not only takes up space but also changes shape of the interior.

 

IME reduces the assembly requirements of wiring harnesses such as wires and connectors.

 

Capacitive switches have high design freedom.

 

The design of IME can be modified quickly. You can make optimization easily.

 

3. Low cost

 

The cost of IME is still very high in the prototype production. However, when talking about mass production, IME has low cost.

 

4. Good reliability

 

IME reduces production steps, and reduces the risk of quality control. Various components are integrated through injection molding. There are no moving parts to fail or wear. High variation in capacitance leads to less noise. Additional protection is done from the overall packaging of circuit.

 

Technical difficulties of IME

 

IME integrates circuits into products. It's good for products with lower LED power, such as exterior atmosphere decoration, function prompts, interior atmosphere lights and functional parts.

 

Product surface

 

The surface R angle is ≥ 0.5mm. The angle between the side and the surface is ≥ 100°. Considering the uniformity of light emission, it is not recommended to have large stretching and less flat surface shapes on the surface.

 

Lighting

 

For IME, electronic components are injection molded into the product. LED beads are buried in the product, there is no light guide structure. It is mainly assisted by transparent substrates. So it is brighter near LED beads.

 

Therefore, in styling design, it is necessary to do lighting analysis to achieve uniformity of light emission. There is high requirement for the layout of LED lights. Light uniformity is currently the biggest difficulty for IME.

 

Film forming

 

High pressure film forming requires precise positioning and stretchability. Conductive ink is prone to short circuit. It may cause damage to electronic components during forming.

 

Components welding

 

The electronic components of IME products need to be welded on film, which places high demands on welding precision and firmness. SMT can provide high quality and efficiency.

 

Film injection molding

 

The flow and pressure of the material during injection molding will cause damage to the electronic components on film. There are special requirements for the design of mold and process.

 

Quality inspection

 

You need to check if IME products are good. It's a challenge to do this after injection molding. You must test every electronic component in time.