1 Module and stave interconnect Rev. sept. 29/08

2 Outer Stave layout … End of stave card serves 8 modules (half a stave) along Z Stave has 32 modules total, 16 on each face. 8 modules connected to 1 stave card via stave cable. Cable is pre-assembled on stave (4 cables per stave). Modules are loaded on top of cable and connected down to it with a connector similar to present PP0 connector, but smaller. Module on back

3 4-chip outer stave module Active area Flex pigtail (connector plugs into page)‏ Pixel orientation Flex down to chip w-bonds Flex hybrid on top of sensor (vertical inter-chip gap 0.1mm)‏

4 Loaded module side view 20 position connector would be used. Replace dimension by 6.52 glue chips sensor flex connector Compressed scale 1.0 mm stiffener Hirose DF30 series 0.4mm contact pitch

5 12mm1.5mm X8 HV-ret HV-1-2 HV-3-4 HV-5-6 NTC Out-1 Out-2 HV-7-8 Multi- drops Layer 1: Signals (1/4 oz copper)‏ Layer 2: Power and return (25um aluminum)‏ ground ref. +LV x8 DC-DC 2-layer Stave cable layout -LV x8 (trace width varies such that each module sees the same cable resistance)‏...

6 LV voltage drops For the case of parallel power each module has 2 aluminum traces, supply and return By making the traces fill the complete stave width (see figure previous page) each module can “see” the same number of squares to the end of stave For an 8-module stave (4-chip modules per slide 3) each module would see 200 squares (one-way)‏ Using chip current of 0.6A, and 1.5mW/square (typical for 25um Al foil) this gives a round trip voltage drop of 0.6V for direct power distribution. The relative cable power loss is 0.6/1.5 = 40%. => thicker conductor needed If x2 DC-DC converters are used inside the chip, the current is reduced in half. The voltage drop becomes 0.3V and the relative cable power loss 0.3/3.3 = 9% (note that there is an additional 10% loss from the converter efficiency, so the cable + DC-DC power overhead is 19%). => 25um Al is OK

7 Stave cable notes All copper traces are 100um wide. To keep to one copper layer, for bias voltage one supply per 2 modules is assumed with common return (note for serial power common return would not work)‏ The differential strip-line geometry makes use of the stave carbon facing (bottom) and the aluminum power layer (top)‏ With 75um layer-layer spacing and dielectric constant ~4, the expected impedance is ~75ohms. Carbon fiber ¼ oz. copper Al power layer 75um

8 Stave section (not to scale)‏ showing cable copper (red) and aluminum (blue)‏ Center line glue Polyimide substrate inter-layer cover layer aluminum copper chips sensor glue facing foam Flex hybrid