A Manufacturing Process for Producing Thick Films with Controlled Microstructures

生产具有受控微结构的厚膜的制造工艺

• 批准号: 1435949
• 负责人: Desiderio Kovar
• 金额: $ 46.46万
• 依托单位: University of Texas at Austin
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-01 至 2018-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1435949&HistoricalAwards=false
• 关键词: Manufacturing; Process; Producing; Thick; Films

Patterned thick films are used in the manufacture of integrated circuits and sensors for applications ranging from camera sensors, to medical implants, to computer networks. Currently, most thick films are produced by a screen printing process, which involves deposition of pastes containing fine metal particles which are then heated to high temperatures to bond the particles so that the conductivity is increased to an acceptable level. The need for high processing temperature limits the choices of substrates upon which the films can be deposited, and often requires expensive and rigid glass or ceramic substrates. This award supports research towards advancing a new method for depositing thick films that can dramatically reduce processing temperatures and would allow deposition on lower-cost and flexible substrates, while also allowing novel material structures that have the potential to produce films with superior properties. Such patterned films that exhibit improved properties would have applications in many devices including high power electronics and solar cells, and other applications that could advance US competitiveness in manufacturing. The multidisciplinary approach which involves a combination of computer simulations and experiments will enable the education of graduate students, and the outreach activities will integrate this research with a proven program that enables high school teachers to effectively teach engineering to encourage and prepare their students to enter engineering and science careers.The laser ablation of microparticle aerosol process is a relatively new process for depositing patterned, micro-scale thick films with nanostructured features. Nanoparticles are produced from commonly available and inexpensive powders via an aerosol ablation and then impacted at high velocities onto a substrate. High production rates allow direct writing of inorganic (metallic, semiconductor, or ceramic) thick films without a mask at room temperature onto polymeric, metallic, or ceramic substrates. The grain size and porosity in the films can be controlled through the ablation and deposition parameters. The current process, however, is limited to producing polycrystalline or amorphous films with a maximum as-deposited relative density of about 70 percent. A combination of predictive molecular dynamics computer simulations and experimental studies of the nanoparticle impaction and film growth processes are planned to develop an understanding of how processing parameters influence deposition efficiency, the film morphology, and film structure on a nano- to-micro scale. Computer simulations will be used to systematically study the influence of particle size, impaction energy, substrate temperature, material composition and crystallinity, defect orientation and concentration, and particle/substrate misorientation on the resulting films. In combination with the computer simulations, the experimental apparatus will be modified to allow experiments to be conducted under conditions in which the simulations can be validated. The experimental data will be used to modify the computer simulations as needed so that accurate predictions of the resulting film microstructures can be made. It is expected that by studying the factors that control deposition and film growth will lead to a much larger range of microstructures and densities than is currently possible, including single crystal patterned films with relative densities approaching 100 percent.

图案化厚膜用于制造集成电路和传感器，其应用范围从相机传感器到医疗植入物到计算机网络。目前，大多数厚膜是通过丝网印刷工艺生产的，该工艺涉及沉积含有细金属颗粒的浆料，然后将所述浆料加热至高温以粘合颗粒，使得导电率增加至可接受的水平。对高处理温度的需要限制了可在其上沉积膜的基底的选择，并且通常需要昂贵且刚性的玻璃或陶瓷基底。该奖项支持研究推进一种沉积厚膜的新方法，该方法可以显著降低加工温度，并允许在低成本和柔性基板上沉积，同时还允许具有生产具有上级性能的薄膜的潜力的新型材料结构。这种具有改进性能的图案化薄膜将应用于许多设备，包括高功率电子和太阳能电池，以及其他可以提高美国制造业竞争力的应用。涉及计算机模拟和实验相结合的多学科方法将使研究生的教育成为可能，而推广活动将把这项研究与一个经过验证的计划相结合，使高中教师能够有效地教授工程学，以鼓励和准备他们的学生进入工程和科学职业生涯。微粒气溶胶过程的激光烧蚀是一种相对较新的沉积图案的过程，具有纳米结构特征的微米级厚膜。纳米颗粒由通常可获得且廉价的粉末经由气溶胶烧蚀产生，然后以高速冲击到基底上。高生产率允许在室温下将无机（金属、半导体或陶瓷）厚膜在没有掩模的情况下直接写入到聚合物、金属或陶瓷基底上。薄膜中的晶粒尺寸和孔隙率可以通过烧蚀和沉积参数来控制。然而，目前的工艺仅限于生产具有约70%的最大沉积相对密度的多晶或非晶膜。结合预测分子动力学计算机模拟和纳米粒子碰撞和薄膜生长过程的实验研究，计划开发一个理解的工艺参数如何影响沉积效率，薄膜形态，和薄膜结构的纳米到微米尺度。计算机模拟将被用来系统地研究颗粒尺寸，冲击能量，衬底温度，材料成分和结晶度，缺陷取向和浓度，以及粒子/衬底取向差对所得薄膜的影响。结合计算机模拟，将修改实验装置，以允许在可以验证模拟的条件下进行实验。实验数据将被用来修改计算机模拟需要，使所得的薄膜微观结构的准确预测可以。预计通过研究控制沉积和膜生长的因素将导致比目前可能的更大范围的微结构和密度，包括相对密度接近100%的单晶图案化膜。