PCB Preparation and Probing

Microwave measurement and calibration

(Source: TET, TUHH)

  • SMA connector for 50 ohms
  • Two-pole probes for SG or GS
  • Mounting adapter – finest adjustment
  • Accurate measurement up to 65 GHz
  • Microprobes in micrometers scale
  • Microprobe separation down to 50 µm

For very accurate measurement with the network analyzer it is necessary to remove the parasitics caused by cables and probes or connectors by performing calibrations. Such calibrations can be done using calibration standards based on SMA connectors or it can be done using specific probes and calibration substrates. Such calibrations substrates contained several calibrations structures which show a well-defined electromagnetic behavior even at high GHz frequencies. Therefore, their dimensions are in the µm range. To contact these calibrations structures and for accurate measurement microprobes are used. For accurate probing these microprobes are mounted on micro positioners. Additionally, a microscope is used for exact probe placement. With this technique, it is possible to provide a good contact with the devices under test. After the calibrations, the system is ready for very accurate high frequency measurements. For example, it is possible to perform measurements on vias and other interconnects on multilayed printed circuit board. Also antennas and other devices can be characterized. Due to a very small mechanical stress of the probes, multiple measurements can be performed on the same device under test.

Circuit board plotter

(Source: TET, TUHH)

  • Range of speeds up to 60.000 rpm
  • Milling structures as small as 100 μm
  • Resolution ± 0.5 µm (0,02 Mil)
  • Up to 15 tool holder positions
  • High processing speed of 150 mm/s
  • Optical fiducial recognition (camera)

The circuit board plotter is suitable for easy and fast manufacturing of multilayer printed circuit boards. Prototypes or small series can be manufactured easily. Fast milling of finest trace contours possible for up to eight stacked layers. Often, the milling machine is used for milling and drilling RF-substrates. Special hard metal tools allow an exact processing of special base materials such as ceramics. Sharpengravings on plates and films are possible as well as contour routing and milling on aluminium and plastics. For stencil printing the milling data are being inverted.

The Protomat S63 can easily be operated from a PC. The software sends all milling data and required settings to the machine. First, the magazine is equipped with milling tools. Before milling, the vacuum table must be started. The workpiece can be positioned on the vacuum platform. Then the milling head is switched on and the transparent protection cover must be closed. Now the PC should show a notification that the machine is ready. All milling data and settings are entered in the PC and then the process can be started. The machine executes the whole milling. After editing, the workpiece is removed.