ProtoLaser S. It’s the real deal.
Design your circuit, load virtually any type of substrate, send your file, and you’ll have
real working circuit boards in minutes. So real in fact, you’ll achieve consistent, high
resolution geometries that chemical etching can’t even touch. From prototypes to
medium-run production, the ProtoLaser S will liberate you from the board house.
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where the origin is considered the
bottom of the circuit where the bend
radius is applied. Parameter Ei is the
modulus of each layer within the circuit while Ai is the area of each layer.
The neutral axis location, R0, is the
distance from the origin or bottom of
the circuit, as shown in Figure 3b.
If performing calculations for different PCBs and different materials,
it might be useful to have some strain
values as guidelines or reference
points. For example, studies have been
done in the flexible circuit industry
that give a correlation of strain to copper fracturing and when using smooth
rolled copper the maximum strain is
2 percent. PCBs with rolled annealed
copper handle bending and forming
much better than PCBs with standard
electrodeposited (ED) copper. Still,
some confusion exists between these
two copper types because of the way
they are tested. PCB copper is typically tested for elongation within a plane,
where a copper foil is pulled apart in a
planar manner but without any bend.
When a bend radius is applied, rolled
copper will perform much better than
standard ED copper due to its copper
surface roughness and copper grain
structure. Figure 4 offers an exaggerated and simple drawing to explain
this issue. When a bend is applied to
standard ED copper, the peaks of the
surface will be pulled apart from each
other and a crack will easily form.
( )( )
with Yi being the mean distance from
the origin for each layer of material,
To calculate values for the neutral
axis and the percent strain, an Excel®
worksheet can be created to predict
those values. Predictions can be made
based on the following equations for
the neutral axis, R0, and the percent
strain (% strain):
s Fig. 4 An exaggerated, simple comparison of standard ED copper and rolled copper.
The red lines show potential for crack initiation and propagation for the different types
ROLLED ANNEALED COPPER