VELO pitch adaptors

Critical to the success of the VELO are pitch adaptors which connect the silicon modules to the electronic readout chips. The silicon detectors have 172,032 channels which must be routed to the readout electronics. This is done using pitch adaptors that match the profiles of the silicon wafers and the readout chips on each end. Pictures of some pitch adaptors are shown above.

In the sequence of photographs below, you can see: the pitch adaptors being glued to the hybrids (left); the pitch adaptors being wire-bonded to the silicon and to the readout chips (centre); a close-up of those bonds (right).

In collaboration with the Tyndall Institute, UCD is responsible for manufacturing and testing the pitch adaptors for the VELO replacement due to be installed at CERN in two years. Unlike the current VELO, we will be making the pitch adaptors on a thin glass substrate in order to improve the bonding, the glass providing a more rigid surface than kapton.
A picture of the layout we will be manufacturing is shown to the left, and the files can be accessed in LGX, GDS, PS or PCB format.

After manufacture we will be testing the pitch adaptors for continuity and shorts. Further details of those tests will appear here.

First set of prototypes

Second set of prototypes