申请人:CELANESE CORPORATION
公开号:EP0135310A2
公开(公告)日:1985-03-27
(D An improved thermoplastic moulding composition is provided which is particularly suited for use in the impervious void-free encapsulation on a relatively expeditious basis of an electronic component wherein the preformed electronic component is positioned in a mould cavity prior to the introduction of the moulding composition via injection moulding. The moulding composition comprises a melt processable thermotropic liquid crystalline polymer which is of a relatively low weight average molecular weight of approximately 4,000 to 25,000 (e.g. approximately 4,000 to 10,000) and which is substantially incapable of further chain growth upon heating. Uniformly dispersed within the liquid crystalline polymer is approximately 40 to 80 percent by weight (e.g. approximately 50 to 75 percent by weight) of a particulate inorganic material (preferably of silicon dioxide) which serves advantageously to decrease its volumetric coefficient of thermal expansion and advantageously to increase its thermal conductivity. In a preferred embodiment the electronic component which is encapsulated is a semiconductor device, such as a relatively delicate quad or dual-in-line integrated circuit device which is assembled onto a flat prestamped lead frame or other conductive device having a plurality of leads which extend outside the area which is encapsulated. The resulting encapsulated electronic component is well protected in spite of the relatively low molecular weight of the liquid crystalline polymer and is capable of satisfactory service for an extended period of time even if adverse environmental conditions are encountered. A rugged commonly non-burning and relatively inexpensive package is provided.
(D) 提供了一种改进的热塑性模塑组合物,该组合物特别适用于在相对较快的基础 上对电子元件进行不透水无空隙封装,其中在通过注塑成型引入模塑组合物之 前,将预制电子元件置于模腔中。模塑组合物包括一种可熔融加工的热致性液晶聚合物,其平均分子量相对较低,约为 4,000 至 25,000 (例如约为 4,000 至 10,000),并且在加热时基本上不能再发生链增长。均匀地分散在液晶聚合物中的颗粒状无机材料(最好是二氧化硅)的重量百分比约为 40%至 80%(例如约为 50%至 75%),可降低其体积热膨胀系数并提高其热导率。在一个优选的实施方案中,被封装的电子元件是一个半导体器件,如一个相对精致的四线或双线集成电路器件,它被装配在一个扁平的预冲压引线框架或其他导电装置上,该导电装置有多条引线,这些引线延伸到被封装区域之外。尽管液晶聚合物的分子量相对较低,但封装后的电子元件仍受到很好的保护,即使遇到不利的环境条件,也能在较长的时间内提供令人满意的服务。这种封装坚固耐用,通常不会燃烧,而且成本相对较低。