Every day the world’s leading medical device companies rely upon laser direct structuring (LDS) to meet their most demanding design and performance requirements. Millions of electronic components with complex geometries are cost-effectively manufactured each year through the use of LDS to create circuit traces on three-dimensional molded interconnect devices (3D-MID).
A single 3D-MID employing LDS consists of multiple components that are incorporated onto a single part. When compared with traditional technologies, LDS enables significant reduction in both manufacturing and assembly steps. The result is an overall reduction in both cost and production time. A position sensor clearly demonstrates these benefits.
This position sensor (see Figure 1) works by transmitting ultrasonic waves to bounce off an object and return to the sensor’s antenna receivers for translation. The signal emitter is located in the center of the molded interconnect device (MID) and is connected to circuitry located on the back with the use of plated through-holes. There is no need for assembly or mounting of the emitter which is one of the many benefits of this design. The emitter is connected to the circuit traces, which reduces current or signal loss due to insufficient bonding of the emitter to the circuit.
There are eight antennas on the front of the MID that surround the emitter (see Figure 2). The antennas receive a portion of the reflected signal, which is used to interpret information about the position and size of the object. The positions of the antennas are exact, consistent, and equidistant from the emitter, reducing error in the objects perceived position due to a variance in antenna placement.
With LDS, there is no need to have a printed circuit board protected by a separate housing; the circuitry can be designed directly onto the plastic housing itself (see Figure 3). This reduces the amount of space needed within the housing and will save time and money during assembly. Soldering or other mounting operations can then be done directly onto the plated circuitry.
Lasering the emitter, the antennas, and the circuit traces onto of the housing also serves to increase their physical strength and durability (see Figure 4). An LDS MID’s overall robustness is much greater than that of a similar part that has been assembled from separate components.
Engineering Plastic Versatility
The technical capabilities of LDS allow the creation of circuitry on a range of engineering plastics, including liquid crystal polymers, nylons or polyamides, polyethylene terephthalate/polybutylene terephthalate alloys, as well as a range of other plastic materials, which provide a mechanical base with outstanding chemical and environmental resistance. In addition to circuits, larger copper landing areas can be created for touch sensor capability. Furthermore, the combination of engineering polymers with noble circuit traces stand up to lifetime corrosion exposure and perform better over time.
In addition to position sensors, LDS is used to manufacture a variety sensors for use in medical devices, including: