Advancing
Interconnect
Solutions for
Modern Electronics

Subtractively Formed
Interconnects (SFI)

The conventional method of manufacturing Interconnects (popularly known as PCBs) relies on subtractive technology. This traditional method begins with a fully copper-clad laminate. A structured photoresist covers the desired copper structure, protecting the underlying copper during the etching process.

After stripping the photoresist, only the intended copper traces remain. While this method remains prevalent, the increasing demand for miniaturization has highlighted its limitations, particularly regarding the minimum spacing between copper traces.

The traces have a trapezoidal cross-section because the etching process removes copper from the top and sides of the traces. This leads to wider traces at the base than at the top.

The minimum conductor spacing achievable also depends on the height of the copper used, the subtractive method is limited to line and spaces of 20 micrometers with a copper foil thickness of 10 micrometers.

Explore Our
Capabilities (FPC)

Description
Capabilities
Layer Count
1-12
Copper Thickness (type)
9um - 35um (ED/RA/EP)
Line/Space (as per copper thickness)
20/20 ~ 100/100um
Min Via, Diameter
25um
Filled Via (Via in pad, capping)
Epoxy and Copper filling
Layer to Layer, Registration
25um
Converlay / SM, Resigtration
50um - 100um
Finishing
OSP, Electrolytic Ni Au (Hard & Soft), Electrolytic Direct Au, Electrolytic NiPdAu, ENIG, ENEPIG
Materials
  • Adhesive & Adhesive less FCCL, Sputtered FCCL PI, PET, PEN based (Dupont, Taiflex, Ube, Shengyi)
  • Coverlay PI, PET, PEN; Solder Mask DFSM, LPISM
  • Shielding films (Tatsuta, Aplus)
  • Stiffener PI, PET, FR4, SS, Alu (PSA/TSA)
Assembly
SMT, ACF, Hot bar, Selective soldering
Electrical Test
4 Wire, Flying probe
Supporting the Future of
Electronic Innovation
Through a strategic blend of additive and conventional manufacturing technologies, SQAI supports both legacy electronic designs and next-generation high-density interconnect requirements.
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