Patient diagnostics and sensing in real time require new electronic devices that are worn in and outside of a controlled medical environment. Wearables for monitoring vital signs such as respiratory, cardiovascular and glucose levels are becoming more important in patient’s everyday life. This trend of wearable, non-invasive and active patient monitoring continues.
The PCBs, sensors, switches, batteries and connectors on these diagnostic and monitoring devices need to be protected from environmental issues like moisture, temperature and chemicals. Medical devices such as catheters, tube sets, connectors and hearing aids also require gentle encapsulation of sensitive components.
Low pressure molding is a cost-effective process to overmold and encapsulate sensitive components, offering fast cycle times and the advantage of lower pressure compared to traditional injection molding. Low pressure molding also provides design freedom to customize part geometry, surface texture and color, while also enabling complex and intricate assemblies.
Various methods can have limitations
Before explaining how low pressure molding works, let’s review other methods for encapsulation and protection. Traditional materials used for encapsulation and protection include potting and conformal coating. There are limitations with these methods which include:
Potting – this process includes two-part systems so there is mixing required and the solution is non-reworkable. Potting includes a large equipment investment and footprint. This method faces limitations of the housing dimensions and space constraints. The cure schedule can be from 24 to 72 hours with up to 8 process steps which can impact production efficiencies. Potting typically includes 5-7 bill of materials (BOM) part numbers in inventory to manage.
Conformal Coating – material is a thin polymeric film which conforms to the electronic component or connectors and can be applied in various ways including brushing, spraying, dispensing and dip coating. The cure schedule of 4 to 12 hours, is typically less than potting and sealing but provides very limited mechanical strength. There can be up to 8 process steps with this method and 3-4 BOM part numbers in inventory.
The benefits of low pressure molding
Material Compatibility
Hotmelt polymers used in low pressure molding are lightweight and have excellent adhesion to multiple surfaces. They possess high temperature, shock, environmental and solvent resistance and no cure process is required. The material also contains no fillers so mold sets can be made out of less expensive aluminum and still be durable. Materials are suitable for overmolding sensitive electronic components, and many grades are UL 94V0 approved. Henkel materials that have been tested to ISO 10993 biocompatibility standards are also available. Contact us for more information on these materials.
Sustainability
With low pressure molding there is minimal waste as only the parts being protected are encapsulated. It is solvent-free and 80% of raw materials are based on renewables (vegetable oils). There are no harmful fumes from the molding process and it is RoHS and REACH compliant.
Cost Savings
There are fewer physical parts, reducing the number of items on the bill of materials (BOM) and inventory as well as work-in-process. This also results in lower labor cost per part and reduced shipping costs of final products. Fewer steps in the process results in less equipment, reducing production space and lowering capital equipment costs.
Low pressure molding is lower in cost versus conventional injection molding tooling and there is further potential to lower mold costs and reduce lead time by creating molds with Henkel 3D printing materials.
Simplified Manufacturing Process
Part of the appeal of low pressure molding is its ease of processing. Whereas conventional potting can involve as many as eight or more distinct steps and take as long as 24 hours to complete, the low pressure molding process can be achieved in as little as 30 seconds, enabling increased throughput. Compared to mechanical enclosure, low pressure molding can replace a 2+ part housing that may involve gasketing, fasteners and assembly labor.
Choosing a reliable partner
In addition to the advantages of low pressure molding as outlined, there are benefits to partnering with a supplier with material experience that can provide application engineering support for input on product design and mold design for process optimization and product reliability and safety. Contact us if you would like more information on low pressure molding.
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