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ATLAS Semiconductor Tracker Upgrade Hybrid

    

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Introduction

A preliminary attempt at what an SCT Upgrade hybrid might look (based on the ABC-N ASIC).  As of now, what we don’t know:

 

· No footprint of the ASIC exists, but one can maybe assume that it will be similar to the present ABCD3T (with minor modifications).

· Useful to try to remove the chip-to-fan-in bonding i.e. remove the need for fan-ins altogether.

· Powering scheme (serial or DC-DC regulation) not yet included.

 

 

The first two points are intimately linked. If the assumption is made that it is indeed possible to wire-bond directly from the readout ASIC to the sensor then this will give a good starting point to what the bonding pad arrangement (for the front-end) might look like. From this one can then, tentatively, define the width of the device, so making the following assumptions:

 

· Sensor bond-pad pitch is 75.6µm

· ASIC readout bond-pad pitch is 60µm

 

And, furthermore

 

· Maintaining a 1.5mm gap between the ASICs it is still possible to retain the Power and Ground bonding towards the sides of the ASICs. It will require the use of wire-bondable decoupling capacitors, for example a 100nF, X7R type capacitor is available from Presidio Components Inc. (this has a footprint of  0.75mm x 2mm; http://www.presidiocomponents.com/products/vl.htm)

 

Using the above information one could envisage a bonding arrangement for the Sensor-to-ASIC as shown below:

 

 

 

 

 

 

 

 

 

 

 

                     

 

                      (Click to zoom)

 

 

ASIC Wire-Bonding

Enhancements could also be made to the existing ABCD3T ASIC bonding-pad arrangement which would lead to easier routing of the hybrid:

· Moving the “TokenIn + DataOut” and “TokenOut + DataIn”  pairs from the back of the ASIC (shown in RED) to the sides will enable direct chip-to-chip wire-bonding without the use of traces on the hybrid. See below

 

 

 

(Click to zoom)