Microvia_-_pouziti

Plan ahead. If microvias might be needed to complete a design, plan

ahead. Microvias are not a last-minute design addition. Rather than
using just 40 or 50 microvias to complete a design, considering
using 1,000. Reason: Once the system and maintenance cost, system
drill time and operator expenses are accounted for, the overall cost to
produce microvias can run anywhere from about 8 to 10 cents per
100 holes.2 Therefore the cost and processes to produce 50 microvias
will be about the same as to make 1,000.

Communicate with the fabricator. Communication with the board vendor is

probably the most critical step in creating a design that uses microvias.
It is essential that the designer understand the limits and capabilities of
the fabricator in order to prevent designing a board that either cannot
be produced or done so only in low yields. The vendor will provide
information that is critical to their production process, such as drill
sizes, pad diameter, layer stacks, material thicknesses and types, and so
on. Such information allows the designer to make the correct decisions
and generate a set of artwork that can easily be produced.

Do your homework. One of the keys to the cost-effective use of

microvias is to shop around for pricing and source a manufacturer
with a track record in producing microvia boards. Depending on the
volume of microvia designs produced, some shops may not charge a
premium. Microvias can be affordable, and time-saving during the

design cycle, especially on boards that have a very high compo-
nent/routing density or a very tight pad-to-pad spacing.

Depending on the fabricator, microvias can add as little as 5% to

the overall cost of a bare board. If the fabricator selected is familiar
with the technology and has been producing microvia boards for a
few years, chances are the premiums charged will be on the low end
of the scale. Other board shops may charge 20% per microvia layer
pair, which could drive the board price up to a point where it’s no
longer feasible to use microvias.

Microvia technology can achieve an increase in overall route den-

sity, a reduction in the number of layers required to complete a pro-
ject and in some cases functionality gains, while reducing board real
estate. Microvias are becoming a mainstream technology, and more
board manufacturers will invest in the equipment necessary to pro-
duce them.

I remember when 0.010˝ lines and spaces were considered a lead-

ing-edge technology. Now some shops produce boards with 0.002˝
and 0.003˝ lines and spaces. Maybe in 10 or 15 years, we’ll look back
at the early days of microvia technology and chuckle.

References1. Kevin Arledge and Tom Swirbel, “Microvias in Printed Circuit Design,” IPC