Thermal Modelling and Mechanical Integration of WFEE Electronics

(R2) Application Deadline: 30 Nov 2026 - 23:59 (UTC) Country: France Type of Contract: Temporary Job Status: Full-time Hours Per Week: 35 Offer Starting Date: 1 Jan 2027 Is the job funded through the EU Research Framework Programme? Not funded by a EU programme Is the Job related to staff position within a Research Infrastructure? No Offer Description MISSION OF THE POSTDOCTORAL RESEARCHER Thermal Modelling and Mechanical Integration of WFEE Electronics The main mission is to develop and validate an analytical thermal model of the WFEE Engineering Model (EM) to predict the operating temperatures of active components, quantify thermal gradients and identify the principal heat transfer paths. The model will rely on a simplified thermal network representing the main heat sources, components and effective thermal conductances between ASIC dies, ceramic packages, interposers, printed circuit boards (PCBs) and the mechanical structure. The objective is to provide a physically meaningful and reusable engineering tool without requiring exhaustive modelling of the mechanical geometry. The work will include experimental thermal characterisation of existing WFEE boards and new designs under development, as well as the preparation and execution of thermal tests using the APC cleanroom's space environment simulator. Measurements will be used to characterise component temperatures, identify thermal gradients and validate or refine the analytical model. The researcher will contribute to verifying compliance with applicable CNES requirements and relevant space engineering standards, including ECSS. Particular attention will be paid to the integration of ASICs in JLCC and CQFP ceramic packages using interposers to consolidate electrical interconnections, minimise bonding-wire lengths and optimise heat dissipation and temperature gradients. The researcher will also produce technical reports and scientific publications describing the modelling, characterisation and integration methodology developed to ensure optimal thermal operating conditions for WFEE circuits. MAIN ACTIVITIES 1. Analytical thermal modelling of the WFEE Identify the main heat sources, thermal nodes and heat transfer paths. Establish a simplified thermal network based on power dissipation and effective interface conductances. Estimate the conductances of PCB-to-mechanical structure, component-to-PCB and ASIC-to-package interfaces, as well as other relevant interfaces. Predict the operating temperatures of ASICs, buffer amplifiers, voltage regulators and other active components. Quantify thermal gradients and assess their sensitivity to integration parameters and boundary conditions. Account for the space environment, particularly vacuum conditions, conduction and radiation. Use existing mechanical CAD data, including STEP files, to identify relevant interfaces. 2. Mechanical and thermal integration of ASICs and electronic boards Study thermal paths between ASIC dies, packages, interposers, PCBs and the mechanical structure. Develop and evaluate interposer-based integration solutions for JLCC and CQFP ceramic packages. Optimise electrical interconnections, bonding-wire lengths, thermal resistance and temperature gradients. Assess the influence of materials, geometries and mounting conditions on thermal performance. Ensure compatibility with applicable CNES requirements and space engineering standards. 3. Experimental characterisation and thermal testing Perform thermal measurements on existing WFEE boards and new designs. Define appropriate test configurations, instrumentation and measurement procedures. Prepare and conduct thermal tests using the APC cleanroom's space environment simulator. Analyse experimental results and compare them with model predictions. Contribute to thermal performance verification and compliance assessment. 4. Technical reports and scientific publications Document the thermal model, assumptions, limitations and results. Produce technical reports describing characterisation methods, test procedures and WFEE integration choices. Publish scientific and methodological results on the thermal integration of electronic assemblies, particularly ASICs, ceramic packages, interposers and PCBs. Present results and recommendations at project meetings, design reviews and scientific conferences. EXPECTED RESULTS AND DELIVERABLES At the end of the postdoctoral appointment, the team is expected to have: A documented and reusable analytical thermal model of the WFEE EM. Estimates of the thermal conductances of the main interfaces. Predictions of active component operating temperatures and thermal gradients under representative space conditions. Experimental characterisation results and a comparison between measurements and model predictions. Quantitative recommendations for improving the mechanical and thermal integration of electronic boards and components. A proposed integration solution for ASICs in JLCC ceramic packages using interposers, addressing electrical, thermal and mechanical objectives and applicable requirements. Technical reports and scientific publications describing the methodology developed and the results obtained. SCIENTIFIC AND STRATEGIC CONTEXT The APC contribution to the WFEE is part of the Detection Chain Working Group of the X-IFU instrument consortium. APC is responsible for the design and development of the Warm Front-End Electronics (WFEE) for the ATHENA X-ray astronomy mission. The WFEE incorporates custom-designed low-noise ASICs and electronic boards that must meet stringent electrical, thermal, mechanical and space qualification requirements. The project is entering a critical phase involving the development, integration and delivery of successive engineering models. The thermal management of electronic assemblies is essential to ensure appropriate operating conditions in the space environment, where heat transfer is primarily governed by conduction and radiation. This postdoctoral position will strengthen the APC team in instrumentation, thermal modelling and mechanical integration, with the objective of developing and validating a predictive thermal model of the next WFEE engineering models. WFEE X-IFU ATHENA PROJECT TEAM AT APC The WFEE contribution at APC covers: ASIC design and characterisation. Design and integration of electronic boards for space applications. Mechanical and system engineering. Electrical, thermal and environmental testing. Product assurance, quality and technical documentation. Project management. The postdoctoral researcher will work closely with the WFEE team, particularly the electronics designers and mechanical engineering partners. The successful candidate will join the APC instrumentation team involved in the development of the ATHENA X-IFU WFEE. The position lies at the interface between scientific instrumentation, microelectronics, mechanical integration and thermal engineering, in close collaboration with the WFEE technical lead and relevant engineering partners. Where to apply Website: https://emploi.cnrs.fr/Offres/CDD/UMR7164-GEODIA-004/Default.aspx Requirements Research Field: Mathematics Education Level: PhD or equivalent Research Field: History Education Level: PhD or equivalent Languages: FRENCH Level: Basic Research Field: Mathematics Years of Research Experience: 1 - 4 Research Field: History » History of science Years of Research Experience: 1 - 4 Additional Information Eligibility criteria SCIENTIFIC AND TECHNICAL KNOWLEDGE Scientific instrumentation and electronic readout systems. Electronic components, PCB integration and power dissipation. Heat transfer by conduction and radiation. Thermal resistances, conductances and thermal network modelling. Mechanical and thermal integration of electronic assemblies. Thermal constraints of space instruments operating in vacuum. Knowledge of cryogenic detectors and their readout electronics would be particularly valuable. OPERATIONAL SKILLS Develop and use analytical thermal models. Estimate thermal conductances and identify dominant thermal resistances. Perform and analyse thermal measurements. Prepare and conduct thermal and vacuum tests. Interpret mechanical CAD data and identify relevant thermal interfaces. Compare integration solutions and formulate quantitative recommendations. Produce technical reports and scientific publications. Experience in scientific programming or numerical simulation would be an asset. No specific thermal simulation software is required. SOFT SKILLS Strong analytical and problem-solving abilities. Scientific and methodological rigour. Autonomy in conducting technical studies and tests. Ability to connect modelling, measurements and design decisions. Ability to work within a multidisciplinary team. Strong technical writing and scientific communication skills. RECRUITMENT LEVEL PhD in scientific instrumentation, electronics, mechanical engineering, thermal engineering or a related discipline. Experience in scientific instrumentation and a good understanding of electronic readout systems are sought. Experience in analytical thermal modelling or thermal management of electronic assemblies would be desirable. Experience in mechanical design, CAD, ceramic packages, interposers or wire-bond integration would be an asset. Knowledge of cryogenic detectors, CNES requirements and space engineering standards would also be valuable. Website for additional job details: https://emploi.cnrs.fr/Offres/CDD/UMR7164-GEODIA-004/Default.aspx Work Location(s) Number of offers available: 1 Company/Institute: Astroparticule et Cosmologie Country: France City: PARIS 13 Contact City: PARIS 13 Website: http://www.apc.univ-paris7.fr/APC_CS/