Chip Scale Review May • June • 2018[ChipScaleReview.com]
There are many issues that would need to be
addressed before any potential material could
be used commercially in a semiconductor
package. Due to the heterogenous nature
of IC package technology, changes in one
component may result in unintended effects
or consequences to the entire system. Many of
these issues have been alluded to earlier in this
paper, but described next is an example with
epoxy molding compounds. Epoxy molding
compounds are generally an epoxy thermoset
resin filled mostly with fused silica and some
additives like catalysts and hardeners. In
the past, small amounts of bromine (Br) and
antimony (Sb) were added to the mixture as
flame retardants but RoHS declared those
elements as harmful to the environment and,
therefore, needed to be eliminated.
The unintended consequences discussed
above resulted from the alterations to
molding compound formulations to make
the end package RoHS-compliant. Those
changes also made the molding compound
“stickier” during the molding process, and
thereby harder to remove the excess material
from the mold surfaces and subsequently
increased wear on metal mold platens and
for an illustration of a
transfer mold press) during production. This
means that more time must be devoted to
cleaning the mold press to prevent defective
packages. Additionally, the working life
of the mold surfaces in contact with the
molding compound are all reduced, which in
turn reduces manufacturing efficiency and
increases operation costs .
Therefore, perhaps the lesson here is that
the path to a more environmentally-friendly
end product may be filled with unanticipated
costs and issues. That should not preclude
pursuing research and development to find
such materials to be used in semiconductor
packaging, but researchers should be
aware of the risks and issues that can come
from altering a stable system. Reducing
e-waste and harm to the environment are
all admirable goals, but they do not come
without risks or a price.
Die shear strength readings for re-workable thermosetting underfill materials .
Transfer mold press .
Materials used in semiconductor packaging .
Materials used in semiconductor packaging 
This section lists different types of materials used in semiconductor packaging.
Influence of molding compound ingredients on physical properties .
Molding compounds, die attach adhesives and underfills
A molding compound’s properties are a balance between ease of use in a high-
volume manufacturing environment and its relationship to the overall package’s
performance and reliability.
shows how much effect each ingredient in
a molding compound has on its manufacturing performance and reliability.
Die attach adhesives are similar to molding compounds, usually consisting of
a liquid epoxy resin, a filler material, reactive epoxy diluent or solvent, catalyst,
Finally, chip underfill materials are similar to both die attach adhesives and
molding compounds, typically being a liquid epoxy resin filled with fused silica
and additives such as catalysts, hardeners, and coloring agents.