Laser-activatable PEEK plastic in wafer production

The market for sensor applications is constantly growing. In many industries such as telecommunications, automotive, aviation and mechanical engineering sectors, microsystems are required with increasing frequency and are therefore important, crucial components of several products. Depending on the purpose of the application, there are numerous different sensors: PT sensors, magnetic field sensors, eddy current sensors, coil applications and optical sensors are only a small selection.

The basis of these sensors are formed from what are known as wafers. This term is used in the microelectronics, photovoltaic and semiconductor industries to describe circular or square ‘slices’, generally of silicon and with a thickness of about a millimeter. They are manufactured from mono or polycrystalline blanks and provide the carrier substrate for electronic components.


NEW AND INNOVATIVE WAFER PRODUCTION

The production and further processing of these silicon wafers is very labour-intensive and costly. A new method for the production of sensor applications on the basis of thermoplastic materials permits a cost-efficient, simplified alternative.

The starting point for this is a wafer substrate made from laser-activatable PEEK (PEEK LDS), to which it is possible to apply very fine conductor path structures. Usually, sensor structures are generated on silicon substrates using lithographic and coating processes, under cleanroom conditions. This places high demands on the infrastructure and operating costs.
With the newly developed approach, the sensor structures are incorporated onto the PEEK wafer using injection moulding, thus removing the complex and costly process stage of lithography. Subsequently, the PEEK wafers are coated with a magnetoresistive layer and finally, using CMP, the cavity exposed and the defined sensor structures generated.

The following graphics compare the conventional method with the new manufacturing process.

Wafer production (Step 1)

Wafer manufacturing process based on silicon

Wafer production with silicium The production of silicon wafers is very complex and highly expensive.

Wafer manufacturing process based on PEEK LDS

Wafer production with PEEK LDS In wafer production based on PEEK LDS, only three instead of seven process steps are required.

Packaging (Step 2)

The subsequent packaging process (for surface mounting and installation of the wafer chip on the PCB) is also eliminated with the new process, as the PEEK wafer can be attached directly, unlike the silicon wafer.
 

Packaging process with a silicon wafer

packaging processwith silicium

Packaging process with a PEEK wafer

Packaging process with PEEK LDS

Connection (Step 3)

In the conventional process with the silicon wafer, the connection to the PCB is made by soldering the bonding wires. The PEEK wafer, on the other hand, can be attached by solder pads placed at the bottom.

Connection process with a silicon wafer

Connection process with silicium Wafer-Chip package soldered to PCB

Connection process with a PEEK wafer

Connection process with PEEK LDS Wafer-Chip on PCB, direct soldered to PCB

ADVANTAGES OF PEEK WAFERS

  • Complexity of production and packaging reduced from seven to three process steps
  • No cleanroom environment and photolithography required
  • In-house production possible
  • The use of laser-activatable PEEK as a substrate can bring cost advantages in production, as PEEK is significantly cheaper than silicon
  • Faster production through shorter process chain
  • Less machines required

Savings potential of 90% possible!


approved Materials

The LDS method has been developed by LPKF Laser & Electronics AG. These Ensinger materials have been approved for this application by LPKF:

  • TECACOMP PEEK LDS black 1017665
  • TECACOMP LCP LDS black 1014978
  • TECACOMP LCP LDS black 1049426
  • TECACOMP PPA LDS black 1014979 (thermal conductive)
  • TECACOMP PPA LDS black 1014980 (thermal conductive )

More information about the LDS process and LPKF can be found here: Laser-Direct-structuring (LDS) of 3D-MIDs


Business Case

Compounds: Business Case – AMR Sensors

Alternative manufacturing methods for sensor applications have been investigated and reveal that modified polyetheretherketone (PEEK) can replace high-priced substrates such as silicon.