Reference Design for Light Projects from 3M Demonstrates Cost and Process Advantages of System Integration
3M has selected the HSMtec pcb of Haeusermann for its integrated lighting concept. 3M combines materials, processes, and technologies recognised in the industry thus reaching a whole new level when it comes to system integration for LED applications. The LED, control electronics, heat sink, case, and reflector blend together to create a single component. A demonstrator with the shape of a hand-held lamp illustrates the diverse possibilities.
The demonstrator looks like an LED torch of the kind we're all familiar with. However, the differences from the standard design are enormous. The case is made from an innovative multi-functional plastic and sparkles pure white. There is no metallic reflector and there are no screw or plug-in connections - instead, the case and heat sink are moulded onto the LED assembly. The insert moulding of the PCB is the innovation that Armin Kayser, Product & Application Development Manager in the 3M Advanced Materials Division in Kempten, showed with the demonstrator.
Plastic compound
The source material is a thermoplastic compound with a high thermal conductivity of 7 W/m·K in comparison with a base material with just 0.3 W/m·K. This remarkable thermal conductivity value is due to the 3M Boron Nitride Cooling Filler. "Boron nitride has a thermal conductivity of up to 400 W/m·K with top electrical insulation values," explains Armin Kayser. In addition to creating the great cooling properties, the filler material boron nitride is responsible for the optical reflection of the plastic body: More than 95% reflection over the entire optical spectrum of the plastic means that a metallic reflector is not needed. LED and control technology is at the heart of the demonstrator. In order to select a suitable circuit carrier for Kayser only one PCB was a contender, meeting all of the criteria: HSMtec by Häusermann.
PCB
Within the pcb embedded copper profiles allow to utilize a high thermal conductivity of 300 W/m·K, so heat is spreaded and dissipated quickly without any bottlenecks in the thermal path from the LED to the heatsink. On the demonstrator, an intelligent combination of copper profiles with different vias ensures fast heat dissipation and directs the heat straight into the moulded-on heat sink with no need for additional thermal interface materials and intermediate layers. Advantage: Using an injection moulding process, the vias are directly filled with thermally conductive plastic, which significantly further reduces the thermal interface resistance and, at the same time, decreases system costs, since there is no need for the expensive plugging of vias with heat paste or something similar.
The high stability and temperature resistance of the HSMtec PCB are basic prerequisites for the injection moulding process. An FR4 PCB without copper profiles tends to bend during insert moulding due to the pressure and heat.
Realisation
The tool design, simulation, and realisation of the injection moulding of the PCB was carried out by RF Plast in Gunzenhausen. Since the plastic can be processed thermoplastically and without abrasion, special technologies are not required. Processing takes place using conventional injection moulding systems and tools.
The following companies are involved in the development and production of the demonstrator in addition to 3M (project management, concept, and realisation) and Häusermann: Plastics specialist Lehman & Voss, RF Plast - a specialist in plastic processing and injection moulding and tool technology, and the EMS provider Dommel Industrieelektronik for the assembly of the PCBs.
About Haeusermann
Haeusermann GmbH specializes in the production of High-Tech-Series of printed circuit boards with special reliability requirements. Besides proven technologies like through-hole plated, multilayer, HDI, and rigid-flexible PCBs, Haeusermann focuses on innovative PCB technologies like “HSMtec” which are well suited for a wide range of diverse applications in the field of LED technology, industrial electronics, renewable energy, electric mobility, etc. Haeusermann aims to further enhance its extensive knowledge and experience in the field of LED applications by means of several research cooperations and development projects together with major players in the LED business sector. Thermal measurements and simulations are our basis to compare and evaluate modern FR4/copper based PCB technologies and to identify the performance of different PCB concepts and layer stack ups. Over the past few years, Haeusermann was able to gain considerable experience in LED applications, participating in numerous research cooperations and research projects with leading LED companies. One of the highlights was the certification for the Osram Opto Semiconductor global expert network “LED Light for you”, comprising of more than 90 notable companies from LED lighting.
Contact:
Haeusermann GmbH
Tanja Reininger
Zitternberg 100
A-3571 Gars am Kamp
Tel. +43 2985 2141-260
tanja.reininger@haeusermann.at
www.haeusermann.at
