Hello Homebrew Printed Circuit Group!
I have successfully modded my Epson Artisan 50 printer Epson Printer
Mod
<
http://groups.yahoo.com/group/Inkjet_PCB_Construction/photos/album/1664\97487/pic/list> to make PCB boards. I did this, as I'm sure as all in
this forum, want to quickly build working devices from all the many
awesome microchips out there (ie: MCU, RFID,WIFI,GSP, etc.)
In my current project, I need to fabricate a "system-in-package" (SIP)
module containing an RFID reader chip (QFN), MCU chip and WIFI
chip(QFN) on two PCB's (1 1/4" x 3/4") including the required discrete
SMD's (resistors, capacitors, inductors, x-tal, etc).
This project requires very small SMD's and a very small and dense
multi-layer PCB with micro vias for fabrication.
This project well exceeds my existing "Homebrew" equipment capability to
fabricate this module.
In assessing the demands for the size and scope of this project (for a
"homebrew" solution) the "show stopper" was all in the fabrication of
the PCB itself.
Here I began my quest for a different "homebrew" solution.
Could I build this module without the complex multi-layer PCB?
Could I interconnect all SMD's (IC's and discrete's) without soldering?
Concept proposal:
Start with a blank substrate (metal, glass, FR4,ceramic,etc) in place of
a conventional PCB.
Apply double sided releasable 3M "micro adhesive" tape covering the top
surface of the substrate.
"Pick and Place" all SMD's onto the top surface of the substrate. Note:
with no PCB traces or vias to contend with, a 50% reduction in SMD
spacing is obtained.
"Epoxy Pot" the top surface embedding all the SMD's.
Flip over the substrate (now working from the bottom side) and release
the tape and substrate from the potted assembly. Clean off any residual
adhesive.
At this point, you should see only the exposed metal contacts of all the
SMD's.
Using the modified Epson Artisan 50 printer (set head height to pass the
1/8" thick epoxy pot assembly depth) and print with special UV curable
conductive ink (Metalon®)
UV cure (need to build a "homebrew" UV source for curing the conductive
ink). The commercial version does it in 3 or 4 seconds.
Subsequent conductive traces (emulating the multi-layers of a
conventional PCB) are first "masked out" by printing with a different
inkjet of NON-conducting ink at the conductive trace crossovers.
DONE! : )
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