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BTOF demonstrator/mechanics meeting
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Description
https://ucsc.zoom.us/j/98299273347?pwd=HHm9tGM6hD7aZaIVWWaF16ueAT3gVu.1
Quick recap
The meeting focused on updates and discussions related to the assembly and design of the FCFD demonstrator, including the gluing and testing of chips and sensors on the interposer, and challenges with UV glue leading to a switch to silver epoxy. Takashi presented the FPC connector design, addressing pin assignments, high voltage connections, and temperature monitoring, while participants raised concerns about the number of I2C buses, fast command lines, and temperature sensor placement. The group discussed the need for resistance per unit length data to calculate power losses and the implications of design changes, such as increasing the number of sensor channels, on the ASIC and FPC. There were detailed exchanges about sensor grounding, alignment marks, and the importance of testing ASICs before assembly, with suggestions for probe cards and QA plans. The possibility of delaying sensor production to finalize design details was discussed, along with the need for simulations to assess the impact of design changes. The conversation ended with a review of open questions for Hamamatsu regarding sensor design and alignment, and a brief mention of upcoming presentations and meetings.
Next steps
- Simone Mazza: Try assembling the demonstrator using silver epoxy tomorrow and attempt wire bonding to test glue coverage.
- Takashi: Provide the resistance per unit length of the power lines on the FPC to Tonko.
- Takashi: Update the pin assignment and number of temperature lines based on the discussion (upper bound of 28 sensors).
- Takashi: Investigate the possibility of including high voltage pins in the main connector.
- Takashi: Send out the previous presentation showing the IR drop calculations if it can be found.
- Takashi: Explore different connector options for the stavelet testing setup, considering reliability.
- Tonko: Discuss with Arthur (ASIC designer) the requirement for ASICs to have an internal, I2C-readable temperature sensor.
- Elke: Post the link to the QA plan webpage in the chat.
- Simone Mazza: Share the silicon sensor design file with the group.
- Satoshi: Contact Taku and negotiate with Hamamatsu regarding the sensor production, aiming to converge on open questions (e.g., number of strips) by October.
- Satoshi: Compile a list of all questions for Hamamatsu (e.g., grounding pads, alignment crosses, slim edge) and distribute it to the group.
- Satoshi: Organize a special meeting for the simulation results regarding the sensor hole and detection efficiency, beginning of next week.
- Simone Mazza: Check with Arthur about the grounding scheme for the ASICs.
- Simone Mazza: Start exploring and testing different ZIF connector options for the stavelet testing.
Summary
Demonstrator Development and Connector Updates
Simone Mazza provided an update on the demonstrator development, explaining that they have assembled chips on an interposer and conducted tests with UV glue for sensor gluing, but encountered issues with complete curing through gaps. They plan to switch to silver epoxy for assembly and will test wire bonding with the new glue coverage. Takashi presented details about an FPC connector design, specifying a 5mm height, maximum 400 pins, and 1.28mm pin pitch, with ongoing discussions about signal routing and power connections. The team agreed to proceed with testing the connector setup and prototype assembly.
System Parameter and Sensor Requirements
Tonko raised concerns about critical system parameters, specifically requesting the resistance per unit length of power lines to perform calculations, and recommended increasing the number of I2C buses from two to four due to the increased number of ASICs. He also suggested increasing the fast command pairs from seven to fourteen to avoid overloading a single fiber fast command line when driving multiple ASICs. The team discussed temperature monitoring requirements, with Tonko advocating for external sensors focused on sensor performance rather than ASIC temperature, while Wei and Grigory suggested alternative approaches including using temperature dissipation simulations to reduce the number of required sensors.
High Voltage Connector Integration Planning
The team discussed integrating high voltage pins into a connector, with Takashi and Tonko confirming there are enough pins available for approximately 10 power connections. Wei proposed a solution for temperature monitoring where multiple temperature sensors could be connected in series using I2C communication, eliminating the need for a separate MAC64 chip. Tonko agreed this approach was elegant and decided to add it as a requirement for the AIC designers when speaking with Arthur.
LDO Power Dissipation Discussion
The team discussed power dissipation calculations for the LDO, with Tonko explaining that the exact power loss cannot be determined without knowing the resistance per unit length of the FPC. They agreed that the power loss would be less than 486 and likely less than what would be dissipated by 4 ASICs. The group also addressed testing procedures for the silicon module, with Takashi confirming that testing could be done using connectors on the FPC rather than requiring wire bonding. Simone Mazza presented a slide showing a potential connector configuration for testing stavelets before placement on the stave.
ASIC and Sensor Testing Approach
The team discussed the design and testing approach for ASICs and sensors, focusing on the need for flexibility and reliability in mounting and testing components. Rachid emphasized the importance of evaluating and potentially replacing ASICs before sensor mounting, while Simone Mazza suggested using a probe card for electrical testing, which was deemed feasible and cost-effective. Elke recommended referring to existing QA plans for similar projects and suggested collaborating with Arthur to develop a tailored QA plan for FCFD, with the testing potentially done at Fermilab. Dan advised exploring multiple ZIF connector options due to potential reliability issues. The group agreed to further investigate these options and review the provided QA documentation.
Service Hybrid Design Modifications
The team discussed modifications to the service hybrid design, focusing on adjusting the width of components including the stay width, service hybrid width, and power board width. Simone Mazza emphasized the need for simulations to determine optimal dimensions, particularly regarding magnetic field effects at different measurements, while noting that current simulations don't fully account for magnetic fields. The group also discussed potentially increasing the number of channels in the ASIC from 32 to 40 channels, which would require redesigning the front end but would only slightly impact the overall form factor and not affect the FPC or service hybrid components.
Sensor Dimensions and Prototyping Concerns
The team discussed sensor dimensions and spacing concerns, with Rachid expressing concerns about the 1 millimeter gap between ASICs and suggesting a minimum of 2 millimeters would be better. Satoshi announced the purchase of 300 new baseline sensors (64 strips total) expected in March, but Rachid requested to hold the prototyping until October to converge on open questions about the number of strips needed and address concerns about detection efficiency. The team acknowledged that changing the number of strips would require new masks and significant time from Hamamatsu, with Simone Mazza suggesting they could also discuss producing additional health sensors at the same time.
Silicon Sensor Design Discussion
Satoshi reported receiving the first results from the simulation team but noted that the presenter is unavailable this week due to a workshop, proposing a special meeting next week. Rachid requested the silicon sensor design from Satoshi, specifically asking about grounding pad locations and sizes, to which Satoshi confirmed they have multiple grounding paths next to the strip but noted that adding alignment crosses would require a new mask and additional costs. The team discussed the need for proper sensor alignment on the interposer for future production, with Simone Mazza suggesting that adding alignment marks might not require significant extra cost since it would only need one modified metal layer in the mask.
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