Homebrew PCBs

..... an example of the conductive traces "reduction" ratio:

64 pin leadless QFN RFID GEN2 UHF Reader IC with all required SMDs connected (res,caps,inductors,x-tal,etc.)

Conventional multi-layer "PCB"  verses "Flip n' Print"

16 traces reduced to  4
 5 traces reduced to  2
 5 traces reduced to  2
14 traces reduced to  3
 5 traces reduced to  2
23 traces reduced to 10
 7 traces reduced to  4
 5 traces reduced to  2
 6 traces reduced to  3
 8 traces reduced to  3
 5 traces reduced to  2
 6 traces reduced to  3
 5 traces reduced to  2

Totals:
110 traces reduced to 41

Instead of a 5 or 6 layer conventional "PCB" (1.5" by 3/4") only 2 or 3 "printed layers" are needed.

By placing the SMDs "end to end" and "side by side" in combinations, for these connections, you afford essentially a zero "resistive loss",zero "stray inductance and capacitance" and highly conductive soldered connections.

With the now greatly reduced physical length of the "inkjetted conductive traces"(most are only 1/8" to 1/16" long), the higher resistance of the conductive inks now becomes negligible.

In essence, this assembly method uses the SMDs themselves as the majorty of the "wire traces" required.




--- In Homebrew_PCBs@yahoogroups.com, "Richard" <richard.liberatoscioli@...> wrote:
>
> 
> 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!  : )
> 
> 
> 
> [Non-text portions of this message have been removed]
>