Milling vs. Etching
Application: multilayer boards with standard prepregs for etching
Construction: 0,035mm copper 0,2mm inner layers 0plus 0,1mm separation prepreg
Application: Cotherm boards
Copper coated alumimium PCBs as normally used in LED ap-plications
Construction: 0,035mm copper plus 0,1mm separation prepreg plus 1,5mm aluminium carrier
Application: thin FR4 boards
Construction: 0,035mm copper double sided plus plus 0,2 mm FR4 carrier
Isolation Milling Statement
Please consider the following as an open minded
statement that shall help you at the true starting point to
decide how to make your in-house prototype PCBs.
The Bungard CCD was introduced in 1991 to fill
the gap of (hand-) drilling, milling and routing of PCBs and
Aluminium front panels in prototype labs, but was soon compared
to machines from LPKF or T-Tech in terms of "quick"
prototyping by isolation milling.
No doubt, this machine is well suited for that
technique, and we developped it further to meet particular
issues of that application. Anyhow, we do not consider this
way of making prototypes to be a professional standard. We
say: Only in-house wet processing allows to create circuit
boards that really match industry standards.
As a proven matter of fact, even though our
machine is one of the fastes of that kind in the world, isolation
milling is many times slower and much more expensive than
chemical etching. Even more, data preparation and machine
operation require that engineers instead of executive staff
invest their valuable time.
On the other hand, isolation milling creates
boards that differ heavily in their electrical / RF performance,
as compared to etched PCBs. This is an important aspect that
RF designers do have to consider - and that cannot be overcome
with even the highest priced, extremly short living special
To say it sharply to the point, isolation milling
is a slow, expensive, almost 30 years old attempt to be different
by someone who had a paranoia against chemical etching. This
technique indeed created strong public interest (and a hand
full of competing suppliers), but has never reached industrial
I repeat, the machine is well suited for isolation
milling, and the cons of that technique are general, not particular
to us. Only it seems we are one of the few suppliers in the
world that allow you a choice, so we need to inform you that
there is a choice!
At any time, you may start making prototypes
with the Bungard CCD, but at any time you feel the above statement
becomes true for you, please remember:
The name Bungard stands for Professional Prototyping by wet
Can I make RF / Microwave
circuits by isolation milling?
Yes, you can, but these prototypes will show heavily differentelectrical
properties than an industry-made PCB.
Can I use a CNC plotter
to create multilayered PCBs?
That is not possible for sure. The inner layers of such a
board are too thin (0.2mm). They will be destroyed by the
penetration of the isolation milling tool. The air inclusions
in the milling channels will cause delamination of the layers
under the smallest thermal stress, i. e. during soldering.
Why else has this technique never found any acceptance in
Can I do through-hole
plating with just the CNC plotter?
That is again big nonsense. We know what you might have been
told, but here comes the truth: conductive pastes have a too
high electrical resistance. They cannot be soldered, as they
decompose under application of heat, and they are mechanically
too weak. We understood that LPKF stopped promoting this technique
in Europe. Of course, we have optional accessories to use
our machine for dispense application, but what we mean there
is for example to apply solder creams or SMT adhesives.
Can I place rivets for
vias or multilayer PCBs?
No. To connect the inner layers, rivets or pins will not work,
as they do not establish the necessary electrical contact
to the very thin lateral edges of the 35 µm copper pads.
With the BUNGARD CCD,
can I cut a PCB in any shape without using a seperate shear?
Yes, that is one of the applications that we designed it for.
You can also mill / route aluminium or other material like
plastics or even wood. And please ask our competitors if they
have a motor driven Z axis that would allow a defined depth
and stroke speed.
How do I mount the boards
on the machine?
The Bungard CCD comes with a universal clamp fixture system
where you can put your board or your ready-cut front panel
in a predefined Zero position. Secondly you are free to prepare
any drill base sheet with two or more fixing holes that you
may use with reference pins. This way of mounting the boards
is essential if you have to mount a board on the machine more
than once or if you have to turn it over for double side milling.
Motor driven versus electro-magnetic
/ pneumatic Z axis
Only with a motor driven Z axis you have control over the
actual penetration depth and Z stroke speed, which are both
indispensible parameters if you want more than stamping the
holes in the board. We understood that LPKF machines cannot
even drill / cut deeper than 2 mm, and in absence of a defined
drill speed, we even heard about problems with PTH due to
poor wall quality of the drill holes. With our motor driven
Z axis you have an active stroke length of more than 30 mm,
and the board penetration depth is limited only by the type
of tool being used. And if we tell our software to cut 3.0
mm deep with 5 m/min stroke speed, (maybe in 3 iterations
of 1.0 mm per turn) then it will cut exactly this depth at
that speed, without fiddeling around on mechanical adjustment