Special manufacturing demands require the use of a stepped stencil. Unlike a standard stencil without steps, a stepped stencil is able to provide the right amount of paste for every component. A mix of components comprising connectors, large and small elements, µBGA and QFN placed together on one PCB requires different stencil strengths. This can only be achieved through step technology.
In view of the growing proportion of mixed assemblies, stepped stencils have become increasingly popular in the manufacture of electronic PCB assemblies. Mixed assemblies describe a variant that feature both very large and very delicate components on the same PCB. Large components require more solder paste volumes while small components require less. If the quantity of applied paste can no longer be sufficiently controlled by adapting the pad size, stepped stencils are used to optimally adjust the solder paste volume.
Stepped stencils can also be used in other areas of application, e.g. to compensate for excessively high via-hole pluggings. As part of this process, plugs that are not on the exact same level as the PCB surface are covered by a recess on the underside of the stencil. This prevents unintended snap-off during the printing process and subsequent print smearing. Any number of recesses of different depths can be integrated into the stepped stencil here.
The development of an innovative, patented manufacturing process allows the steps to be integrated accurately and efficiently into the stepped stencil. To begin with, the stainless steel blank is manufactured. At this stage, different plug recesses, step heights and step depths can be arranged on the squeegee and/or the PCB side. Next, the blank is precisely put in position thanks to the camera system integrated into the cutting laser, before the stepped stencil is cut and processed further. Another advantage offered by stepped stencils made from solid material is the smooth gradient between the steps, which prevents the paste from depositing and hardening.
As the European technology and market leader in the manufacture of high-precision metal stencils, Christian Koenen GmbH offers its customers not only a precision tool, but also comprehensive process support. The company is the only stencil manufacturer to operate its own in-house laboratory for research and development activities – the Application Center. The Application Center is equipped with sophisticated printing and measuring technologies and is staffed by experienced process engineers. New technologies are developed, existing products perfected and customers supported with their process evaluation needs. In addition, the company conducts fundamental research in the field of technical printing. Customers and partners alike therefore have access to a platform for training, running print tests and conducting research tasks.
Well over twenty parameters have an effect on production line quality and performance during the stencil printing stage. The printing process can cause up to 65% of the defects that come up during electronic assembly production. A correctly configured layout combined with optimal release behavior is crucial for production as only a stable production line is cost-effective. Our technical setup allows customers to outsource any research and development work needed to improve the printing process. This frees up valuable production time as our production line performance is in no way affected. The experts at Christian Koenen GmbH are also happy to provide customers with in-depth process advice: Our experts adapt processes using parameters and materials provided by the customer. Continuous product development places our customers ahead of the competition in the long run.
The Application Center has the equipment needed to implement and assess applications for screen and stencil printing.
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Europe’s largest manufacturer of precision stencils.