Henkel’s Low Pressure Molding (LPM) process, which is mainly based on polyamide hot melt adhesives, is increasingly being used to protect electronic components in the fields of medical technology, power generation and industrial automation, heating, ventilation and air conditioning technology, as well as lighting technology. Compared to traditionally used methods, the technology should offer numerous economic, process-controlled, structural and ecological advantages, such as the encapsulation of electronic components with two-component casting resins or high-pressure injection molding.
LPM was invented by Henkel more than 30 years ago, then under the name “Macromelt Molding”. This enables sensitive components to be overmolded with mainly polyamide-based hot melt adhesives in combination with appropriate processing systems and injection molding tools. Since Technomelt products are not abrasive and, compared to conventional injection molding, they are injected with significantly lower pressure, the risk of damaging sensitive components during the LPM process is reduced.
The technology is therefore particularly suitable for protecting sensitive components such as circuit boards or plug-cable connections. Technomelt hot melt adhesives are robust and flexible at the same time, which makes them suitable for this type of application.
“For me, Technomelt’s hot melt adhesives are an exciting part of our portfolio in the field of circuit board protection,” says Matthew Hayward, Global Key Account at Henkel for Power & Industrial Automation. “It has many unique advantages that traditional potting or coating processes cannot. The ability to only apply this material where it’s actually needed is a huge advantage. This makes it possible to ‘skyline’ an application (only to protect the sensitive components) and to significantly reduce the weight by using significantly less material. ”
The material offers a high level of electrical insulation and is also resistant to a wide range of chemical substances, temperature cycles and vibrations. The components are thus protected against external influences such as penetrating water or dust as well as long-term UV exposure. “In contrast to conventional two-component casting resins, the polyamides used in the LPM process are thermoplastics,” explains Michael Otto, Key Account Manager in the Engineering Adhesives division for low-pressure injection molding processes at Henkel. “The cycle times are significantly shorter and no volatile components are released. While with a conventional casting process it can take several hours to days to fully cure, with the Technomelt Low Pressure Molding process a cycle time of a few seconds is achieved. ”
Technomelt hot melt adhesives from Henkel meet the European RoHS (Restriction of Hazardous Substances) directive and REACH (Registration, Evaluation, Authorization and Restriction of Chemicals) regulations. “Another important environmental aspect of these polyamides, which is becoming increasingly important, is the fact that they are largely bio-based, which means that up to 80 percent of their ingredients come from renewable plant sources,” adds Michael Otto.
Henkel offers a selection of Technomelt products for the LPM process, the formulation of which has been developed for specific applications. Some have particularly good heat resistance, while others have increased toughness or adhere particularly well to certain substrates.
One advantage of the LPM process compared to conventional potting systems is the greater economic efficiency in terms of material consumption. With conventional potting processes, the component to be protected is usually placed in a housing and filled until all components are covered. In the Technomelt LPM process, the component is placed in a precisely defined tool and this is then filled with Technomelt. As a result, the components are protected with the least possible amount of mass. This means that you follow the topology of a circuit board, for example. Multi-cavity tools are also possible here in order to overmold several components at the same time.
The molds are usually made of aluminum, which is why production is cheaper than steel tools for “classic” plastic injection molding. In recent years, even more efficient methods from the field of additive manufacturing for mold production have been developed (3D printing).
The Internet of Things (IoT) and the Industrial Internet of Things (IIoT) are based on sensors and the necessary electronic connections and components that connect all types of devices at home, in the office and on the go. This trend has in turn led to increased demands on network connectivity for data and power cables as well as on the connections, which must also function in very harsh environments. In the field of medical care, patient diagnostics and real-time measurements require new electronic devices such as wearables that can work inside and outside medical facilities. The Technomelt LPM process is therefore intended to provide an answer to all of these trends.
For certain medical applications, Technomelt can also be used in areas that go beyond the protection of electronic components. So it is suitable e.g. B. for the attachment of flexible hoses for the supply of liquids, since it does not twist the hoses and offers a permanently tight connection. For this purpose, Henkel has developed Loctite PA 6951. The product has been tested according to the Henkel guidelines, which are based on ISO 10993, the series of standards for biocompatibility. The certificates can be viewed on request. It is planned to qualify further Technomelt products here.
In cooperation with partners who manufacture process systems around the world, Henkel offers a total solution for the Technomelt LPM process: “These partners are extremely important for our success,” says Michael Otto. “Technomelt Low Pressure Molding is an overall system in which materials, machines, molds and technical services as well as engineering are bundled. Our partners have their own sales force, which supports our global market access. ”In addition, Michael Otto emphasizes:“ There are many further developments that increase the requirements for high-quality and cost-effective protection of components. At Henkel, we are convinced that Technomelt Low Pressure Molding technology makes an important contribution to meeting these requirements. ”