Micro Injection Molds

Recently, the telecommunication industry has undergone rapid expansion, and a strong consumer trend towards smaller and lighter telecommunication devices, such as cellular phones and notebook computers, is indicated. Small connection sockets and chip carriers are micro-injection-molded parts requiring the high flowability, high mechanical properties and dimensional stability of LCPs. These merits are now thought to be another application field for LCPs in the electronics industry. 

The special issue of micro injection molding applied for polymer heat exchangers will not be considered here. Additionally, for MEMS-like systems discussed above, other techniques, mostly based on etching, e.g. deep reactive ion etching (DR1E), are applied [20, 71, 86]. These techniques allow for future mass production of the small-scale (sub-watt fuel processors) devices to which they are applied. 

A 7] The fiber-coupled spectrometer is actually designed for applications with hand-held devices. A combination of micro injection molding and an electroforming process allows the production of a high-performance but low-cost device. The optical grating is, for example, replicated in plastic to reduce costs. 

The first device integrated a microstructured multichannel plate fabricated by micro-injection molding from a two-component liquid silicon rubber material (Silopren LSR 4070) with an appropriately interfaced and temperature-controlled housing, as shown in Figure 3.1a. 

Zhang N, Chu JS, Byrne CJ, Browne DJ, Gilchrist MD (2012) Replication of micro/nano-scale features by micro injection molding with a bulk metallic glass mold insert J Micromech Microeng 22 065019... 

Shen YK, Wu WY (2002) An analysis of the three-dimensional micro-injection molding, hit Commun Heat Mass Transf 29(3) 423 31... 

Micro-injection molding scaled-down version of injection molding (cmitraction flow). 

For specid applications micro components with high temperature stability or small thermal expansion coefficient are necessary. Hence, further process developments like micro casting as well as metal and ceramic micro injection molding targeted to the fabrication of metal and ceramic microstructures are under investigation. (11,12)... 

The addition of P-nucleating agent raised the onset crystallization temperatnre and the relative crystallinity of the P-crystals of the micro-injection molding specimens becanse of its strong heterogeneons nncleating effect in the iPP matrix. Introdnction of UHMWPE increased thickness of the shish-kebab stractnre in the skin layer and indnced the formation of perfect P-cylindralites. Similar effect was observed with the addition of polyolefin elastomer. ... 

Finally, polymer heat-exchangers may be fabricated by injection molding, and microchannels have been produced by micro-injection molding [642] for numerous applications. 

Shen YK, Yeh SL, Chen SH (2002) Three-dimensional non-newtonian computations of micro-injection molding with the finite element method. Int Commun Heat Mass Transf... 

The present edition is not only updated, but modernized and renewed. This is also indicated by the fact that only six of the old authors are still involved, and there are new chapters such as micro injection molds, molds for the rubber industry, or rapid prototyping, while others are no longer applicable. Otherwise, as it was already stated in the preface of the 4th German edition, it still applies that this compilation does not intend to serve as a textbook for the detailed design of an injection mold or to replace the catalogue of a manufacturer of standard mold units, and it is also not the long version of a lecture manuscript either. Rather, the brief description of the basic facts and the latest state of the art for the individual mold types and their manufacture allow a direct comparison in a compact form. 

In micro injection molding, two major groups of components can be differentiated ... 

Micro injection molding parts, in other words, small parts with low weight (mass in mg) and the smallest dimensions and structures (Eigure 1.256). 

In either case, different tolerance, surface features, and accuracy may be required. Eor the micro injection molded parts themselves, the same rules apply (e.g., avoidance of sink points, etc.) as for normal plastic parts. Experience in micro-mold making and preliminary testing is mostly necessary. Here, the collaboration with the customer is a priority, much more so than in the area of standard shapes. 

In certain cases it will be necessary to provide for preliminary experiments. Programs for the computer-aided simulation of the micro-injection molding can be helpful in the early stages of part development and mold design. Under certain circumstances, such programs are overwhelmed by the size of the parts or structures. The programs available on the market should therefore be subjected to a detailed evaluation and testing phase. 

FIGURE 1.262 Guiding principle for micro injection molds (source z-werkzeugbau-gmbh, A)... 

Especially in micro injection molded parts, the question of further processing always arises. The smallest parts are often difficult and cost-intensive to further process. Through the use of multi-component injection molding, such assembly operations can be prevented. In this method, two or more different materials can be injected either simultaneously or sequentially and thereby create a composite part. 

The micro injection molding process is similar to the conventional injection molding in terms of environment and continuing processes. The size of the parts has an additional influence on the MST process. Here are some examples ... 

Handling systems that combine several injection molding machines in micro or standard and micro injection combination. The micro injection molded parts are positioned precisely in the mold and placed in a precisely defined position. This circumstance can be used very well. Handling units remove and further transport the parts to testing, inspection, control, packaging, and assembly processes. 

In addition to continuing processes, the issue of cleanliness is also an important part of the environment. Clean rooms or clean room cabins are used or are mandatory in many fields of the micro injection molding technique. 

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