Molded Interconnect Devices (MID) - Page 1
Forum section: electronics / general

author: branadic
author_rank: Super Contributor
timestamp: June 15, 2013, 12:49:43 pm
content: Hi guys and engineers out there,I was wondering if you ever heard about molded interconnect devices (MID)? If not this a perfect moment to listen. It's not my intention to do commercial but to share a technology with you that is pretty interesting and maybe something new for you even if it's not new at all.Why not combining a part with electrical circuitry without the use of a pcb? Let the case of a cellular phone be the circuit boardAnd that's the way it's done:Hot embossingThis is one of the oldest way to manufactor MIDs. A galvanic copper foil is embossed with a stamper that carries the board layout under temperature and pressure into the surface of a thermoplast. The copper foil can have several finishings: uncoated copper, silver, tin, gold etc.By doing a laser post-cutting also cheaper rolled sheet foils can be used.This methode is only for 2D and 2.5D with small difference of level between two layers.Ready to assemble your parts by using soldering, gluing, bonding...You are not only constricted to solid thermoplastic substrate, you can also use thermoplastic foils.Fully substractive MIDA thermoplastic part is made by injection molding. Afterwards to part is chemically activated to allow a chemical copper deposition. The part is then coated with its finish e.g. Ni/Au. Now a UV-laser cuts out the single traces of the electrical circuit, similar to isolation milling.Ready to assemble your parts by using soldering, gluing, bonding...This methodes allows complex 3-dimensional thermoplastic parts to be added with a complex eletrical circuit on it.Semi additive MIDIt's nearly the same as fully substractive, but the laser cut happens after the copper was deposited and then the finish with Ni/Au is done so the laser cutted edges are passivated too.LPKF-LDS MIDThis methode uses a modified thermoplastic with additives inside its matrix. The plastic part is made by injection molding and the electrical circuit layout is then written by an IR-laser beam onto the surface of the part (direct laser structuring, in german: Laserdirektstrukturierung, short: LDS). Two things happens thereby:1. an ablation of the surface, so the surface is getting rough where the beam met it2. the additives are uncoveredIn a following chemical process again copper is deposited on the laser activated areas, the uncovered additives function as a germ for the copper deposition.This methodes allows fast changes of the circuit layout without a redesign of the complete part, but the laser structuring is a serial process and takes time. The circuit complexity can by very high and you can use laser drilled vias (also made while structuring) to contact to another side of your part. If necessary you can increase trace height using electroplating.Again, ready to assemble your parts by using soldering, gluing, bonding...2k injection moldingThis process uses two thermopastic components while injection molding, one that can be metallized on its surface and a second that can't. With intelligent design you can create a part that uses the first component to create electrical ciruits on the surface of the molded part surrounded by the second component. Circuit complexity on such parts is much lower, but it's a cheap way to produce MIDs in big quantities.Thermoset MIDThis one is rather new. Creating electrical circuits also on thermoset materials has some big advantages because thermosets are dimensionally stable, thermally and chemically robust after the interlacing. The process needs no materials with special additives like LPKF-LDS process does. First researches were done using commercial expoy based thermosets with very promising results, so this introduces a good alternative to thermoplastic MIDs.A good example of where MID is used are the already mentioned cellular phones, in particular the antenna. Live cycle time of such devices are very small and you need a fast way to optimize antenna design without many iterations of the complete phone or pcb.This is why MID is used. In the beginning of the cycle time antenna design is optimized by using LPKF-LDS technics, remember the layout can easily be changed in your CAD and is then written on the parts surface with IR-laser.If antenna layout has reached its final design a tool for 2k injection molding is made and the antenna is fabricated in mass production for a much lower price.But this is just one of many examples where MIDs makes sense. If you want to learn more about it just visit the website of our institutewww.hsg-imat.deor place your question in here.

author: 4to20Milliamps
author_rank: Regular Contributor
timestamp: June 15, 2013, 01:00:55 pm
content: Pretty cool stuff, it probably won't be too long and some smart guy will figure out how to do it with a 3d printer, laser and electroless plating. All of these things should be possible at the hobby level these days.http://www.lpkfusa.com/articles/hdi/laser_activation.pdfAnd could be a great way to re-purpose your saturated etchant:

author: ftransform
author_rank: Frequent Contributor
timestamp: June 15, 2013, 05:49:33 pm
content: make the technology stop advancing so quick

author: branadic
author_rank: Super Contributor
timestamp: June 17, 2013, 07:08:45 pm
content: QuoteI don't believe in that because the most important point is surface roughness, as you don't won't extrinsic deposition of the copper layer. Roughness of printed parts is still very high and therefore unusable.QuoteWhat do you mean by that? MID is nothing new, but mostly unknown.

author: 4to20Milliamps
author_rank: Regular Contributor
timestamp: June 18, 2013, 12:13:23 am
content: I think it would be handy to just burn the circuit pattern on the substrate then deposit copper in the laser tracks, but I guess I have a different visualization of the process."This paper presents a new method for selective micro metallization of polymers. ANd:YAG laser is employed to draw patterns on polymer surfaces that are submerged ina liquid (usually water). After subsequent activation with palladium chloride andfollowed by auto-catalytic electroless plating, copper deposit only on the laser tracks."http://orbit.dtu.dk/fedora/objects/orbit:55401/datastreams/file_3690560/contenthttp://en.wikipedia.org/wiki/Organometallic_chemistryhttp://www.ebay.com/itm/40W-CO2-LASER-ENGRAVING-CUTTING-MACHINE-/160943428206?pt=LH_DefaultDomain_0&hash=item2578f9d26eThe only area that is "rough" or makes carbon/metal bonds is the area activated by the laser, what part is hard to believe?

author: 4to20Milliamps
author_rank: Regular Contributor
timestamp: June 18, 2013, 01:01:07 am
content: This should work:Take a non conductive layer >>>>>>>>>>>>>>>>>>put a thin layer of graphite on it _____________________put a thin layer of material on top >>>>>>>>>>>>>>>>>>then burn your pattern in it and make graphene traces under the top layer, and only expose and activate the areas where the copper pads need to go.https://www.google.com/search?q=lightscribe+graphene&oq=lightscribe+graphene&aqs=chrome.0.57j0l3.9675j0&sourceid=chrome&ie=UTF-8http://www.homedepot.com/p/Blaster-5-5-oz-Graphite-Dry-Lubricant-8-GS/202597501#.Ub-ycOdwqHc

author: amyk
author_rank: Super Contributor
timestamp: June 18, 2013, 10:32:52 am
content: Serviceability not that great?

author: 4to20Milliamps
author_rank: Regular Contributor
timestamp: June 18, 2013, 11:29:43 am
content: Quote from: amyk on June 18, 2013, 10:32:52 amClarification?serviceability of a multilayer board isn't that great either, this is a promising new technology and you have to start somewhere.or get left in the dust......Anyone can think of a million ways and reasons not to do something, only a small handful ignore all that and make breakthroughs.The internet is a huge time waster anyways, I would rather waste it trying to create something rather than figuring out ways to keep from doing it, but that's just me.