Alumina (Al2O3)
Alumina or multi crystalline Al2O3 comes in 3 common forms for dicing.
99.6% alumina is the purest form and the hardest. It is normally
used for thin film microwave circuits operating at high frequencies
because it can be polished to a 1 microinch or better surface finish.
This lets the circuit designer obtain precise values for thin film
resistors such as tantalum nitride (TaN) or nichrome (NiCr). 99.6%
alumina is also useful for capacitor fabrication because of its dielectric
constant ( 9.9).
96% alumina has a higher filler content and consequently is somewhat
easier to cut with a diamond saw. It is normally used for thick film
fired circuits because the thick film pastes do not adhere as well
to purer alumina. The surface is frequently lapped for circuit applications,
but can be polished if required.
92% alumina has even more filler and is useful for packaging applications
where multiple layers of ceramic and conductive layers are built
up. While softer than the previous types of alumina, it can present
challenges for accurate dicing because of the thicker layers and
pattern distortion during firing.
Back to Top of Page
|
Aluminum nitride (AlN)
Aluminum nitride (AlN) is useful for high power circuits
which require a lot of heat dissipation. The thermal conductivity
is 80-100 W/m-K compared to alumina which is 30 W/m-K. It can be
polished with a finish similar to alumina and is generally easier
to dice than 99.6% alumina. Alkaline solutions such as many detergents
can form a surface oxide which may be detrimental to the performance
or appearance of the circuit. Kadco’s
engineers will discuss the proper processing techniques to assure
our customers circuits have the optimum performance.
Back to Top of Page
|
Beryllium oxide (BeO)
Beryllium oxide (BeO) is useful for circuits which must dissipation
large amounts of heat. The thermal conductivity is 248 W/m-K which
is higher than alumina or aluminum nitride. It has a fairly low dielectric
constant for a ceramic circuit substrate, 6.5. The primary limitation
is the potentially hazardous dust. Kadco’s
engineers are prepared to discuss tradeoffs in the properties of
various ceramics in the design of circuits requiring heat dissipation
Back to Top of Page
|
Ceramic
 Ceramic
materials include many hard metal oxides and nitrides. The term is
derived from the Greek keramos which means “pottery” which
comes from an older Sanskrit root meaning “to burn”. Certain
materials like silicon carbide (SiC) stretch the definition somewhat
but can be considered in the ceramic family. Whatever your requirement
is for precise ceramic machining, the engineers at Kadco will be happy
to discuss your needs and ways we can help manufacture your device.
Ceramic substrates are typically wax mounted on glass and cut
with a diamond blade using a directed flow of water.
Back to Top of Page
|
Copper (Cu)
 Copper
(Cu) is a metal that is typically machined with metal cutting tools
instead of diamond saws. However many electronic applications require
precise cuts or unique coatings on copper plates or wires. Kadco can
plate copper with nickel/gold (Ni/Au) for example and then diamond
machine it to burr free shapes for submounts and other applications.
Copper submounts have a burr after dicing due to smearing of the soft
copper and gold. Kadco's exclusive process will remove the burrs, resulting
in a submount that will lie flat in the package.
Back to Top of Page
|
Gallium arsenide (GaAs)
Gallium arsenide (GaAs) is useful to the electronics industry for its
semiconductor properties. Gallium arsenide wafers are typically diced
on tape or wax mounted on glass depending on the final requirements
for chipping and cleaning. Tape cutting simplifies handling but can
cause more edge chipping than wax mounting on glass. Wax mounting
on glass will allow more precise thru cuts and grooves, but requires
more handling during demounting and cleaning. Kadco’s
engineers will discuss your requirements based on our experience
machining gallium arsenide to help you reach a cost effective solution
to your problem.
Back to Top of Page
|
Garnets
Garnets are metal silicates such as calcium aluminum silicate (Ca3Al2(SiO4)3)
which are better known as gemstones than substrates. However garnets
do have applications in electronics and optics. The engineers at
Kadco have experience machining hard materials
including garnet and are anxious to discuss your requirements.
Back to Top of Page
|
Lithium Niobate
Lithium niobate (LiNbO3) is useful in photonics for its nonlinear optical
properties. Switches, multiplexers and waveguides made on lithium
niobate substrates may require the intricate machining and singulation
that Kadco ’s capabilities include.
Back to Top of Page
|
Piezoceramic and Piezoelectric
materials (PZT)
Piezoelectric materials produce a voltage proportional to the mechanical
pressure applied to them. For electronic applications lead zirconate
titanates (PZT) or barium titanates (BaTiO3) are frequently used
in substrate form. All of these tend to be very fragile and friable
compared to other electronic substrates. Kadco
has experience metalizing, dicing and machining these materials to
minimize chipping and maintain proper adhesion of metal on the surfaces.
Back to Top of Page
|
Plastics
Plastics are not normally thought of as substrates for dicing because
of their softness. However laminates of ceramics or metals and Kapton
for example may require diamond machining. Two critical issues that
require expertise in processing are mounting the substrate and avoidance
of stringers. Since many plastics don’t adhere well to dicing
tape or wax, the engineer must plan for appropriate fixturing. Plastic
stringers can form if the dicing parameters are not carefully investigated.
Discuss your project in its early stages with the engineers at Kadco
to avoid difficult problems later.
Back to Top of Page
|
Pyrex
Pyrex or borosilicate glass is occasionally used as a substrate because
of its low coefficient of thermal expansion. The dicing parameters
must be carefully determined to minimize chipping and fracturing.
Kadco will be very interested in discussing
your particular requirements to provide a product which meets your
needs.
Back to Top of Page
|
Quartz (SiO2)
Quartz (SiO2) is useful in electronics for its piezoelectric and dielectric
properties and has many and varied photonic applications. As a substrate
it is very hard and comes in a number of different crystal orientations.
This can present problems for diamond dicing and machining if the
cutting parameters aren’t carefully selected initially and
monitored during the course of cutting. Kadco
has processed quartz substrates larger than 6” square and thicker
than 0.150”. Call and let us discuss your requirements.
Back to Top of Page
|
Sapphire (Al2O3)
Sapphire (Al2O3) is a single crystal alumina as opposed to alumina
substrates which are multi crystalline. Sapphire comes from the Persian
safir which means “beloved of Saturn” While sapphire
has many desirable optoelectronic applications, it is not beloved
of engineers who have to machine it because of its hardness. Kadco
has developed techniques to machine sapphire and our engineers would
like to discuss your requirements.
Back to Top of Page
|
Silicon (Si)
Silicon (Si) is famous for its semiconductor properties and primarily
comes in the form of wafers for electronic applications. Wafers
can be tape mounted for ease of handling the die after cutting
or can be wax mounted on glass to minimize chipping. Kadco can
apply a resist coating before dicing to prevent silicon dust from
adhering to critical surfaces. This can be easily removed with
acetone or photoresist developer. Our engineers have experience
diamond machining silicon as much as 0.5” (13 mm) thick.
Although many different geometries can be etched into silicon,
deep trenches with straight sidewalls usually must be done by diamond
machining. The application engineers at Kadco are anxious to apply
their experience to your problems.
Back to Top of Page
|
Tungsten
(W)
Tungsten (W) is a hard metal that has electronic applications
as a submount for soldering chips into packages. Kadco can plate
metals such as nickel and gold (Ni/Au) on tungsten shapes and then
diamond machine submounts which are burr free and ready for soldering.
We have many different sizes in stock. Call Kadco
to discuss your particular requirements.
Back to Top of Page
|
Yttrium aluminum garnet
(YAG)
Yttrium aluminum garnet (YAG) is well known for its optical applications.
Diamond machining may be required for isolation cuts on the surface
or other patterning. Kadco’s engineers
have experience with controlled depth grooves to give you high
yields on your product.
Back to Top of Page
|
