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3D-MID Overview
Manufacturing Technologies
3D-MID is often associated with the LDS process (Laser Direct Structuring), which was introduced by the German laser equipment manufacturer LPKF Laser and Electronics AG in the late ninetieths. However, the first 3D-MID parts were produced in the early 1980s using a completely different process, namely the two shot molding process.
There are now various methods of manufacturing MID’s. Even tough, LDS is currently the most widespread and mature process, but all other processes have their raison d’être, and it cannot be said that one process is better or worse than the other. However, it is worth to have a look at all processes in order to select the right process for the respective application.
Following is a list of the processes currently on the market that are in different stages of maturity. It should be noted that the state of the art can change quickly due to the rapid pace of technical developmen, which is why this list doesn’t claim to be complete.
1) Two shot molding
Two different resins are molded to build one part, where only one of the two resins is plateable. The plateable material build the circuit, the un-platable material build the insulation between the plated traces
Advantages
+ Simple process
+ High maturity
Disadvantages
– Fine pitch is hardly possible (Line/spacing > 400/400 microns)
– Layout changes require tooling changes (complex and expensive)
2) Laser direct structuring (LDS)
Molding of parts with special additives in the plastic. An IR laser is used to activate the areas of the molded part, which have to be plated. Chemical plating is used to plate the activated areas
+ Very flexible in creating 3D circuits and easy layout changes
+ Small via’s can be easily created during the laser process
– Expensive plastic material in comparison with conventional materials due to the needed special LDS additives
3) Laser substractive structuring (LSS)
Fully plated substrate with a thin layer of copper. Removing of unneded copper by laser and further plating of the remainig copper circuit
+ Advantageous for high ratio of plated to un-plated surface
– Expensive for low ratio of plated to un-plated surface
– Limited choice of substrate materials
4) Laser structuring - chemical activation
The selectivity for the circuit is created by laser structuring followed by chemical activation of the laser structure and plating
+ Independency from additives in the resin (lower costs)
– Achieving the selectivity for the circuit is more difficult in comparison with other processes
5) Film insert molding
A separately manufactured, single or multi-layer flexible circuit pattern film is placed in an injection molding tool and then molded with a plastic material
+ Wide range of standard plastic materials can be used
– Not suitable for complex filigree 3D circuits
6) In-mold structural electronics (IMSE)
It starts with an IML (In-Mould-Labeling) process, on top of the IML substrate, a circuit including electronic components is applied and overmolded by a plastic material
+ Integration of design cosmetical elements, circuit and electronics in one molded part
– too many process steps (difficult to master the whole manufacturing process)
– Not suitable for complex and filigree 3D circuits.
7) Photo-chemical structuring
The to be plated structure is created using speical chemical and UV light. Palladium is used to graminate/activate the structure for subsuquent plating
+ Very smooth nano- surface
+ Easy proccessing
– Limited material choice of substrate materials
8) Photo imaging
Process steps are: full copper plating, photo resist, eching, removing photo resist and than further plating
+ Well known process steps (similar to PCB)
– Only conditionally suitable f6r 3D structures (rather for 2D/2.5D)
9) Primer technology
A platable primer coat applied by e.g. tampon print an a substrate. The primer can be plated in order to creat an electrical circuit
+ Simple process
– Vias and small cavities cannot be activated
– Adhesion is an issue
10) Heated die
Hot embossing of a plated layer on a substrate
+ Simple process
– Only conditionally suitable for 3D structures (rather for 2D/2.5D)
11) Aerosol jet
Conductive materials based on silver or gold nanoparticles can be directly printed on a substrate
+ Printing of capacitors and resistors is possible
+ Fine lines
– Slow
– Expensive
12) Ink jet
Digital inject printing process. Especially suitable for low-viscosity, dissolved materials such as organic semiconductors
+ Different conductive materials can be printed on a broad variety of substrates
+ Fine lines
– Expensive ink
Reports from experts on the above-mentioned processes are welcome to be published in this blog.
Kind regards and best wishes
Nouhad