[labnetwork] PCB in e-beam evaporator?

[Michael Geiwitz]

Hi Russ,



You should be fine putting PCBs into an ebeam. I think for a basic PCB the
max heat is around 120C. A few nanometers of gold won’t get the substrate
holder anywhere near that hot. I regularly heat them to 100C when attaching
wells to my own chips which again the holder won’t even approach in
temperature.



This may not be necessary, though. I’d be worried that depositing gold
would short a lot of the contact pads unless you meticulously mask them,
which would be a pain. I usually give my PCBs a few minutes soak in IPA and
rinse with DI before mounting and wirebonding and this seems to improve
wirebonding significantly. I use an aluminum wedge bonder. I order them
from JLCPCB <https://jlcpcb.com/> and I make sure the surface finish is
Electroless Nickel Immersion Gold (“ENIG”) to allow for wirebonding.



Best,

Mike

___

Michael Geiwitz, PhD

Boston College Cleanroom and Nanofabrication Facility

Cleanroom Director/Physics Teaching Faculty

245 Beacon, #005

CR: (617) 552-0049

Cell: (845) 514-0708

geiwitz at bc.edu





*From:* labnetwork <labnetwork-bounces at mtl.mit.edu> *On Behalf Of *Russ
Renzas
*Sent:* Wednesday, July 1, 2026 10:11 PM
*To:* Network Fab <labnetwork at mtl.mit.edu>
*Cc:* Lihua Xiao <lxiao at unr.edu>
*Subject:* [labnetwork] PCB in e-beam evaporator?



For a summer lab class we're trying to have students make a chip and
wirebond it to a PCB. We're having trouble wirebonding to the immersion
gold pads though.



Is it okay to put pcbs in our ebeam evaporator to evaporate Au?



We tried a small piece in a Au SEM prep sputter coater and that worked but
it's too small for the class PCBs.



Thanks, also appreciate any tips on how to spec pcb metalization for
wirebonding compatibility. We have both Al ultrasonic wedge and Au ball
bond capabilities.



Russ Renzas

University of Nevada, Reno
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