【作者】 郑英松；

【导师】 王晓东；

【作者基本信息】 大连理工大学 ， 机械电子工程， 2009， 硕士

【摘要】 键合是制造微流控芯片的关键环节之一,基片上的微结构只有通过键合才能形成封闭的微通道网络,键合在很大程度上决定了芯片的制作质量。将聚合物超声波焊接技术引入到聚合物微流控芯片的键合能大大提高微流控芯片的键合效率,超声波的局部加热使得微结构以及芯片整体键合前后变形很小,此外该方法还具有不需要中间介质、键合强度高、生物兼容性好等优点。但是目前采用超声波键合聚合物微器件尚停留在小面积封接微阀、连接导管等应用上,微流控芯片整体键合尚无报道。此外,将传统的聚合物超声波焊接运用于关键尺寸在微米量级的微流控芯片的键合时,键合精度难以满足要求。因此本文基于聚合物在超声波作用下的分段产热机理,提出键合过程非熔融控制方法,实现高精度的聚合物微流控芯片非熔融整体键合。首先,本文从聚合物微流控芯片超声波键合相关理论和实验研究出发,提出一种聚合物微流控芯片超声波微熔融键合方法,设计了适用于该方法的面接触导能筋结构,以延缓熔体产生速率,通过对聚合物超声波键合过程进行分阶控制,实现微熔融键合目的,避免熔融物堵塞微通道。超声波微熔融键合方法采用振幅较高,输入到焊接区域的能量较大,局部容易因过热出现气泡等质量问题,因此提出基于局部溶解性激活和热辅助两种聚合物微流控芯片超声波非熔融键合方法。基于局部溶解性激活的超声波键合方法是利用超声波局部产热原理和溶剂的温变溶解特性来实现对微流控芯片的封接,导能筋在焊接过程中起到能量引导和集中作用,因此导能筋存在的部位将是键合过程热源产生的部位,通过对导能筋的设计达到使热量产生在需要键合的部位的目的。所用溶剂在常温下对芯片基体材料不产生溶解作用,而在低于材料玻璃转化温度的某温度段对基体材料产生溶解,这样才会随着超声作用下键合界面温度的升高,溶剂对材料的溶解性被激活来实现芯片的有效键合。热辅助超声波键合方法是利用材料在玻璃转化温度附近键合界面分子的扩散作用,在压力作用下界面分子运动并相互缠结达到使界面联接的目的。键合前通过热板加热聚合物材料到玻璃点转化温度Tg以下的某温度值,并在外部压力的作用下使得联接表面紧密接触,然后开始超声键合过程,随着键合界面温度的升高,聚合物材料的大分子链具有了一定的活性,能够跨越界面而形成联接,实现对微流控芯片的键合。利用必能信2000XF超声波焊接机进行了上述几种微流控芯片超声波键合实验,通过实验方法对键合工艺参数进行优化,得到了很好的微流控芯片键合质量。更多还原

【Abstract】 Bonding is one of the key procedures of manufacturing microfluidic chips. The micro structure on the substrate can form seal micro channel net only by bonding. The bonding process decides the quality of manufacturing chips. The bonding efficiency can improve a lot by introducing ultrasonic polymer welding technology to the bonding of microfluidic chips. The ultrasonic bonding process has some advantages, such as the chips have little distortion after bonding, external substance free, higher bonding strength, shorter bonding time, have no limitation in biological compatibility, etc. Ultrasonic welding technology often used to bond micro pump or valve, it is seldom used to bond microfluidic chips. Traditional ultrasonic welding technology is suit to macro polymer material, when it is used to the bonding of microfluidic chips which key dimension is in the level of micron, there are some problems about bonding quality and precision. By researching on the ultrasonic micro-melting or non-melting bonding method of polymer microfluidic chips, we can resolve this problem and get good bonding quality.First, this paper introduces the relate ultrasonic bonding theory and experiment research of polymer microfluidic chips, it proposed a ultrasonic micro-melting bonding method of polymer microfluidic chips and design a area contact micro energy director structure that is suit to this method, it can control the ultrasonic bonding process according to every bonding phase and finish the micro-melting process without melting material flow into the channel of microfluidic chips. But this bonding method must adopt very high amplitude, then some quality problems such as cavitations will be produced on some place of the chip for overheat. So a local solubility activated method and a thermally assisted non-melting method for ultrasonic bonding of polymer microfluidic chips are proposed. A local solubility activated method is based on ultrasonic local heating and temperature dependent solubility of PMMA in isopropanol (IPA). Energy director place a important role during ultrasonic bonding process, because it can make the ultrasonic vibration and the heating energy produced on special place that need it. The solvent should have no solubility for the substrate material at room temperature, but it have solubility for the substrate material when the temperature is below the material’s glass transition temperature, only that can the two substrate be bonded for the solvent’s solubility when the temperature of the bonding area is raised to a certain level. A thermally assisted method for ultrasonic bonding of polymer microfluidic chips take advantage of the material’s molecule movement when the temperature of bonding area get to near the glass transition temperature. Under certain bonding pressure, the molecule of the bonding surface entwist with each other and form the strength between the two substrate as a result. Before the bonding process begin, the material should be heated up to a certain temperature which is below the glass transition temperature, the bonding surface is compact closely under external bonding force, the bonding surface’s total temperature can rise up to the glass transition temperature after the ultrasonic vibration is placed on the bonding surface, then the big molecule is activated, they twist each other and form the bonding strength. The PMMA substrate and cover are bonded on Branson ultrasonic 2000xf assembly system successfully and the bonding process is optimized by using some experimental method. Last, the microfluidic chips are bonded very well.更多还原