LPKF Laser & Electronics has created an interesting video series on the manufacture of a 3D Multi Interconnect Devices, or ‘3D MIDs’, using Laser Direct Structuring (LDS) to create the circuit. A 3D MID is a type electronic device that includes the electrical components and its interconnecting circuits and has a 3 dimensional shape, as opposed to a typical flat circuit board.
Laser Direct Structuring requires the use of specific plastic materials for the molded carrier that have an organic metal complex additive. The additive is activated by the laser to create metallic seeds which allow the metal to form in specific areas in the electroplating process.
Here are the steps to 3D Multi Interconnect Device manufacture using as shown in this series of manual processes:
Step 1 – Design
The circuit and plastic carrier is designed in 3D.
Step 2 – Injection Molding
The plastic carrier is injection molded using materials suitable for Laser Direct Structuring that has an additive in the form of an organic metal complex. LPKF has a list of materials suitable for the process on their website.
Step 3 – Laser Direct Structuring
The circuit structure is etched on the surface with a laser. This activates the areas for the next step, metallization, through a physical-chemical reaction that creates metallic seeds.
Step 4 – Metallization (Electroplating)
The areas of the molding that were activated by the Laser Direct Structuring can now be built up with the metal for the circuit. This is typically a layer of copper followed by either nickel or gold.
Step 5 – Assembly
The solder paste and electrical devices can now be placed on the 3D MID. A pick and place system is typically used to dispense the solder paste and place the electrical devices. You can see a similar process in more detail in the article ‘Assembly On A 3D Molded Interconnect Device’ on Manufacturing Ops.
Step 6 – Soldering
The final step is to set the solder. This process uses Vapour Phase Soldering to set the solder and fix the electrical components to the board.