Laser-structurable polyamide for electronic components
28 March 2007
Kromberg & Schubert, an automotive supplier based in Renningen, Ger-many, has developed the first 3D-MID electronic components made of BASF’s new laser-structurable polyamide: the conductors are inte-grated directly into the surface of three-dimensional moulded inter-connected devices (MIDs). The new Ultramid T 4381 LDS lends itself extremely well for such mechatronic components. This partially crystalline, par-tially aromatic high-temperature polyamide 6/6T is reinforced with 10 per-cent glass fibres and 25 percent mineral fillers, offering a much broader processing window for the metallization, but without damaging its mechanical properties. This plastic was further improved as to the metal layer adhesion and deposition rates and was optimized with regard to the novel method of laser direct structuring (LPKF-LDS).
First application by Kromberg & Schubert
“Three-dimensional moulded interconnected devices are soldered lead-free. In this process, the component has to withstand a temperature of 245°C [473°F], which calls for a sufficiently heat-resistant plastic,” explains Erik Rega, MID Manager at Kromberg & Schubert. The entire contacting is embedded into the 3D-MID, so that there is no need for any wiring at all. This is a very efficient method, with a vast potential for miniaturization in automotive electronics.
Ultramid T material class
Outstanding properties of the new material Ultramid T 4381 LDS in this application are its high melting point of 295°C [563°F] and its high flexural temperature of about 260°C [500°F] under a load of 0.45 MPa (mega-pascal). Without load, this material can withstand temperature peaks of up to 285°C [545°F]. This means that it is the right choice wherever electronic components have to be soldered; it also allows the use of lead-free solder, clearing the way for even higher soldering temperatures. The base poly-mer Ultramid T, an engineering plastics specialty, is already used in electronics and automotive construction whenever particularly high demands are made in terms of the heat distortion temperature. It offers an optimal compromise between high melt temperature, good processability and low water absorption.
Devices in any shape – MIDs
This new BASF plastic, which is especially suitable for laser direct structuring, incorporates a laser-sensitive additive that contains metal. The laser treatment virtually engraves the conductor tracks into the three-dimensional surface of the component. After that, it is immediately metallized, yielding an optimal adhe-sion. Such MIDs that are directly laser structured allow the integration of electronic circuits straight onto plastic surfaces. In contrast to other meth-ods for producing electronic components, they offer several advan-tages, including greater design freedom, shorter process sequences, a smaller number of different materials needed and flexibility in changing the circuit layouts.
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