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The size issue
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Accurate component placement is essential in implantable cardioverter defibrillators. |
As products become increasingly smaller, component size is reduced to a minimum. Once components of 0.6 mm x 0.3 mm were considered to be the smallest components possible. Today, these have been superseded by those measuring 0.4 mm x 0.2 mm. This continual reduction in component size affects several aspects of the production process. It particularly requires innovative placement solutions to feed these small components carefully, reliably and repeatedly.
The challenge has been met by combining placement heads with a digital vision system that is located directly opposite the placement position. This ensures that even the smallest components are centered optically and placed precisely, and at potential speeds of 20000 components/h. Time and cost savings are possible because the components can be adjusted while the placement head is in motion and taken to the placement position.
Greater complexity
Another trend in electronics products is the increase in performance requirements, which means their development becomes increasingly complex. Mult-ilayer circuit boards with integrated components have been designed as well as (sub)modules offering the latest circuitry and connection technologies. Submodules with an average size range of 10 mm x 10 mm are frequently used, and these are also getting smaller. In general, modules contain between 10 and 20 passive components and one or two bare chips. Manufacturing submodules, therefore, requires placement systems that are able to precisely and repeatedly place large and small passive components and bare chips with chip-on-board or flip-chip technology. Today’s equipment is able to seamlessly place 1000 components that are usually arranged on a single cluster during submodule production, with an expected actual output rate of better than 90% of the theoretical output figures.
Package density
Advanced component package technologies are being utilised with the aim of increasing package density and electrical performance. The chip-scale package (CSP) is the standard component with Random Access Memory packages. One of the difficulties with these components is that no solder can be printed onto the bottom CSP after it has been placed. In a standard flip-chip process this is solved by the top CSP being dipped into flux as an in-line operation, thus flip-chip capability is a main requirement of placement systems.
Maintaining productivity
Apart from machine performance, it is also important to keep nonproductive time to a minimum by providing offline programming, offline setup and offline optimisation. This is the only way for companies to realise fast production runs, during which components for several models need to be loaded simultaneously. The optimal solution consists of a modular machine platform that is easy to adjust, supplemented by software, service and support to provide a complete line and production solution that focusses on the overall concept.
For more information, contact Angelika Wright, Siemens Automation and Drives Ltd, Electronics Assembly Systems, Sir William Siemens House, Princess Road, Manchester M20 2UR, UK, tel. +44 161 446 5291, e-mail: angelika.wright@siemens.com, www.siplace.com.
