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LPKF TGV Process

LPKF TGV Process

Precise Through-glass vias

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LPKF Vitrion 5000
The LPKF Vitrion 5000 can process wafers as well as panels
The newly developed LPKF TGV process combines the advantages of a glass substrate with the precision of a laser process. Holes could previously only be either produced with insufficient quality at reasonable throughput or with acceptable quality, but far too slow for mass production. By means of this TGV process, combining both, perfect holes can even be made at five times the speed of today's fastest method - and it’s getting faster all the time.

Overview of LPKF TGV Process

Base material is an industrial standard glass for interposers.
Ultrashort pulse laser
An ultrashort pulse laser modifies the glass structure.
Laser Induced Deep Etching Process
The modified holes are opened in a standard wet etching process.
Interposer with many vias
Each interposer has a large number of precisely generated vias.
Standard glass wafer with numerous interposers.
Numerous interposers are produced on a standard glass wafer

Additional Process Steps for Interposer Production

Metallization and structuring
Metallization and structuring of the interposer.
Circuitry on glass interposer
Example: Circuitry on glass interposer.
Interposer connection
The interposer connects very fine contacts from integrated circuits to the tracks on the PCB.
Electronic modules on chip
One single chip combines different electronic modules.

Variable Processes

Glass interposers are mainly manufactured using two processes, both of which can be implemented with the LPKF TGV technology. Thus, the TGV process can be smoothly integrated into existing production chains. In the wafer-based process, blind holes are first produced in the glass. Then the wafer is polished down to the desired glass thickness. This creates conical through-glass vias with constant taper angles and aspect ratios (hole diameter to glass thickness) of up to 1:10. The panel-based process generates classic vias, usually in thin substrates. The glass is processed over the entire thickness by laser modification. Subsequent etching is performed uniformly on both sides to produce the desired hourglass shape. Here, too, aspect ratios of up to 1:10 can be achieved.

Process Parameters

Conical blind vias
The laser and etching steps generate conical blind vias in the glass. Subsequent polishing opens the holes of the bottom side.
Through-glass via exhibits pinched waists
The vias exhibit pinched waists. The top diameter adjusts itself in relation to the extent of material reduction.
Hour-glass shaped through via
Hour-glass shaped through via.
SEM tapered through-glass via with metal in the hole
Tapered through-hole via with metal in the hole.

Variable Hole Geometries

Both processes can be used for glass with a thickness of up to 300 μm. Hole diameter is primarily a function of the etching time. Currently holes with diameters down to 5 μm can be made in 50-micron-thick glass in mass production operations. Through control of the etching duration, the hole diameter can be adjusted precisely. The etching process reduces the overall thickness of the glass wafer by approximately 20 %.

  • Glass as interposer
  • Efficient ultrafast laser process
  • More than 5 000 holes per second
  • Panel or wafer format


LPKF Process for High-Speed TGV Formation

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