[labnetwork] PCB in e-beam evaporator?

[Gratuze, Mathieu]

Hello all,

We are performing wirebonding (fully automatic and semi automatic)  on PCBs using either the ball or the wedge of our M17S from FK Delvotek.
>From experience the ENIG finish from JLCPCB or PCBway  is enough to provide adhesion for the wirebonding to be successful. (This is good enough for small series we have not tried doing it at production scale and speed).
However, we do recommend cleaning the PCB using IPA and/or Acetone before wireboding to make sure contaminents have been removed (i.e. fingerprints, traces of flux, epoxy...).
A plasma clean can also be usefull but is not needed.

In my experience, the main reasons why the wirebonding fails on PCB is mostly the improper attachment of the PCB on top of the heater from the wirebonder.
Also large PCBs (10cm+) with multiple areas where to wirebond come with their own set of challenges as the FR4 might warp due to the heat, so the solution might be to concentrate on 1 area at a time.

Best,

Mathieu
LaCIME - École de Technologie Supérieure
Montréal - Canada

________________________________
From: labnetwork <labnetwork-bounces at mtl.mit.edu> on behalf of CELSO RENATO PETER <cepeter at unisinos.br>
Sent: Thursday, July 2, 2026 9:15 AM
To: Russ Renzas <rrenzas at unr.edu>; Network Fab <labnetwork at mtl.mit.edu>
Cc: Lihua Xiao <lxiao at unr.edu>
Subject: Re: [labnetwork] PCB in e-beam evaporator?

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Hi Russ,

For wirebonding on PCBs you will need Soft Gold or ENEPIG metallization (Electroless Nickel, Electroless Palladium, Immersion Gold), many PCB manufactures already offer  ENEPIG metallization.
ENIG finishing is not apropriate for wire bonding, the gold layer is too thin and Nickel is too hard.
ENEPIG is also a good finishing for Tin soldering (solder paste), so it is very flexible.
For Soft Gold finishing the minimum Gold thickness shoul be 200 nm (0,2 um), ideal is 300 nm.


Celso Peter
Coordenador - Instituto Tecnológico de Semicondutores - itt Chip
Unisinos - Somos infinitas possibilidades
www.unisinos.br<http://www.unisinos.br/> - (51) 3591-1122 / Ramal 3180

________________________________
De: labnetwork <labnetwork-bounces at mtl.mit.edu> em nome de Russ Renzas <rrenzas at unr.edu>
Enviado: quarta-feira, 1 de julho de 2026 23:10
Para: Network Fab <labnetwork at mtl.mit.edu>
Cc: Lihua Xiao <lxiao at unr.edu>
Assunto: [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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