High Density Interposer – Challenges and Opportunities

Within "More than Moore" concepts interposer based packaging technologies, know as 2.5 D/3D Wafer Level System Integration, open up a wide range of minaturized multi-functional sytem Solutions. Pending of the final application dedicated interposer concepts have beend developed for grabbing multiople active components, fabricated by different suppliers, using different Technologies and materials, e.g. sensors, logic, Radio frequency (RF) and momory-ICs, as well as passive devices, including antennas. In many cases the application of high density wiring, miceo pillar (µ-pillar) interconnectsa as well as Through Silicon Vias (TSVs) are required. Finally the interposer needs to provide the mechanical basemente for system packages. In order to support system miniaturization and extension of system performance on one hand and to meet costs an time to market challenges on the other hand the development of modular interposer concepts as well as the application of dedicated basic interposer technologies is of high interest for R&D, prototyping and small volume manufacturing. A short outline of high density interposer technologies developed and available at Fraunhofer IZM on 300 mm substrates will be presented. Starting with a brief discussíon of basic elements of interposers, several technology concepts dveloped and validated for high density wiring will be addressed and generic results will be presented. A high level comparsion of challenges and opportunities will be shown and discussed. A brief outlook of future development work for system applications will be given

Rapid scan in-situ FT-IR curing studies of low-temperature cure thin film polymer dielectrics in solid state

Rapid scan in-situ Fourier Transform Infrared Spectroscopy (FT-IR) was used to characterize the cure process of two common low-temperature cure thin film polymer materials for wafer-level packaging applications. Beside a discussion of the spectral changes during the cure reaction, aspects of quantification the degree of cure will be shown. First, a photosensitive low-temperature cure ester-type polyimide precursor was investigated. As this material is a negative working photosensitive polyimide precursor, the impact of the photo-crosslinking on the imidization rate will be discussed in comparison to unexposed films. It will be shown, that at certain temperature / time conditions the exposure dose should be carefully adjusted to yield fully imidized films with minimized cure temperatures. Second, the thermosetting process of a low-k polymer dielectric based on divinyl siloxane bis-benzocyclobutene (DVS bis-BCB) was studied. Due to the chemical nature of the DVS bis-BCB resin a highly crosslinked network is formed during the cure process. Especially above 80% degree of cure at temperatures below 210°C a significant reduction of the reaction rate was measured. A two step cure process was developed, which can minimize the process time at elevated temperatures and yield a rather high degree of conversion in a reasonable process time. Both polymer cure reactions are characterized by a chemically-controlled and a diffusion controlled region with significant different reaction rates. Based on the aforementioned results a time, temperature and conversion dependent kinetic / diffusion model was used to describe the experimental data quantitatively. This model allows calculating very precisely the conversion in dependence on both, temperature and time, which will help to optimize the cure process for the two thin film polymers with respect to thermal budget and / or process time. Therefore this paper shows a method, which will help comparing different thin film polymer formulations regarding cure kinetics. Modeling of the data allows optimizing the process conditions to meet the temperature requirements in the area of wafer-level packaging and 3D integration

Active Lower Limb Prosthetics: A Systematic Review of Design Issues and Solutions

This paper presents a review on design issues and solutions found in active lower limb prostheses. This review is based on a systematic literature search with a methodical search strategy. The search was carried out across four major technical databases and the retrieved records were screened for their relevance. A total of 21 different active prostheses, including 8 above-knee, 9 below-knee and 4 combined knee-ankle prostheses were identified. While an active prosthesis may help to restore the functional performance of an amputee, the requirements regarding the actuation unit as well as for the control system are high and the development becomes a challenging task. Regarding mechanical design and the actuation unit high force/torque delivery, high efficiency, low size and low weight are conflicting goals. The actuation principle and variable impedance actuators are discussed. The control system is paramount for a “natural functioning” of the prosthesis. The control system has to enable locomotion and should react to the amputee’s intent. For this, multi-level control approaches are reviewed

A methodological approach to integrate psychological factors to lower limb prosthetic functional design

As user-centered development (UCD) involves users for an understanding, objective assessment and utilization of their needs, it represents a promising approach to develop improved user-friendly prostheses. Hence, human factors have to be identified and integrated into development. To identify relevant factors and assess the amputees’ requirements, a literature review, questionnaire results and interviews are considered. Further, models of the identified factors’ impacts on the development and Quality Function Deployment (QFD) for the translation from the human understanding to technical design are prepared for evaluation with amputees. The important body scheme integration (BSI) is examined in experiments with unharmed subjects exploring a Rubber Leg Illusion similarly to the Rubber Hand Illusion. Besides BSI, satisfaction and feeling of security (FOS) show to be important factors for UCD. Satisfaction is linked to quality of life (QoL) and time of daily use and influenced by appearance, usability and functional properties of prosthetic components. FOS seems to be an issue of the overall system leading to reliability and balance during use. BSI also affects QoL and might lead to more user-friendly prostheses. Technical functions (enabling) contrary to characteristics from the user’s view (predisposing) seem to be perceived as different properties. The first ones are utilized: Functional units are identified and assessed. Models and QFD are used for their evaluation and translation to technical development. The technical functionality is reviewed and extended based on a comparison of functional and psychological aspects of the units and the overall concept. The elaborated approach should enable to involve users during the whole development process. Yet, it is not validated with a sufficient number of users. Substantiating this approach with sufficient data is necessary – e.g., a comparative analysis to solve conflicting goals. It is promising for the development of future user-friendly prostheses

A methodological approach to integrate psychological factors to lower limb prosthetic functional design.

As user-centered development (UCD) involves users for an understanding, objective assessment and utilization of their needs, it represents a promising approach to develop improved user-friendly prostheses. Hence, human factors have to be identified and integrated into development. To identify relevant factors and assess the amputees’ requirements, a literature review, questionnaire results and interviews are considered. Further, models of the identified factors’ impacts on the development and Quality Function Deployment (QFD) for the translation from the human understanding to technical design are prepared for evaluation with amputees. The important body scheme integration (BSI) is examined in experiments with unharmed subjects exploring a Rubber Leg Illusion similarly to the Rubber Hand Illusion. Besides BSI, satisfaction and feeling of security (FOS) show to be important factors for UCD. Satisfaction is linked to quality of life (QoL) and time of daily use and influenced by appearance, usability and functional properties of prosthetic components. FOS seems to be an issue of the overall system leading to reliability and balance during use. BSI also affects QoL and might lead to more user-friendly prostheses. Technical functions (enabling) contrary to characteristics from the user’s view (predisposing) seem to be perceived as different properties. The first ones are utilized: Functional units are identified and assessed. Models and QFD are used for their evaluation and translation to technical development. The technical functionality is reviewed and extended based on a comparison of functional and psychological aspects of the units and the overall concept. The elaborated approach should enable to involve users during the whole development process. Yet, it is not validated with a sufficient number of users. Substantiating this approach with sufficient data is necessary – e.g., a comparative analysis to solve conflicting goals. It is promising for the development of future user-friendly prostheses