SPT’s wire bonding capillaries utilize a state-of-the-art Ceramic Injection Molding (CIM) technology to achieve reproducibility from the first piece up to the nth piece with excellent consistency to meet customers’ tighter dimensional tolerance and robust bonding performance requirement in a cost effective way.
|Block diagram of state-of-the art- ceramic injection molding (CIM) for capillary
Small Precision Tools’ injection molding process is a combination of powder, injection molding, and sintering technologies. To obtain the necessary chemical and physical properties, powders are selected by size and shape and complemented with additives. Every particle of the powder is coated with binder components, which transport the powder for molding and gives the final form rigidity.
The ceramic injection molding is very suitable for high volume production of complex design with tight tolerances like bonding capillaries. It is an effective way of manufacturing complex precision components with the highest degree of repeatability and reproducibility.
Process flow for capillary manufacturing process
The characteristics of the ceramic powders, such as grain size distribution and morphology play a vital role not only in the achievement of the desired product properties, but also in the success of the different stages of the process. The ceramic powders used for the manufacturing of capillaries are selected by size and shape and complemented with additives to obtain the necessary chemical and physical properties.
Stage 2 - 3
Before the injection molding, the powder is mixed with binder to form a homogeneous mixture that is used to form the shape of the capillary. The binder is used for the artificial plasticisation of the ceramic powders and for the formation of the desired shape through injection molding. Consideration for binder selection includes the flow characteristics for injection molding, the ease of binder removal and binder-powder interaction.
Stage 4 - 5
Subsequently, the mixture is feed to the mold for injection molding. The molding process is a significantly affected by the temperature, pressure and time envelope and it is essential to have the correct temperature and pressure sequence together with the time sequence.
The binder is removed by evaporation and exothermic reaction, leaving only a small fraction behind. Removal of the binder is a critical step between the molding operation and the sintering process. The extent of the binder removal requires careful monitoring and control to retain the shape of the capillary.
The formed part is then sintered in an oxidizing or reducing atmosphere, or in a high vacuum at temperature of up to 1800°C. During sintering, the parts become more dense and shrink. Depending on the raw material properties, shrinkage ranges from 15% to 25% of its molded dimensions. Repeatably attaining the required dimensional tolerances on the sintered parts requires that the green density of the part be uniform within each part and consistent from part to part, and that the shrinkage during sintering be repeatable and predictable.
Small Precision Tool’s injection molding process offers a high degree of reproducibility. Complex parts in ceramic can be shaped in one operation with diverse geometry, different profiles, undercuts, sharp edges, and different wall thickness.
The Application Horizon:
Today, the Small Precision Tool’s injection molding process is applied in the instrumentation, textile, automobile, printing, electronic assembly, communications, aerospace, optical, medical, dental and chemical industries. Cost effective applications are found in relatively small parts demanding complex machining operations, and where volume production requires a large investment in machine tools
Market: Medical, Dental, Industrial, Mechanical