Development of thin-film coating process and equipment for heat-resistant resin applicable to reflow soldering

SHOWA SHINKU has developed a new anti-reflection coating process and its equipment for the heat-resistant resin lens applicable to reflow soldering instead of former resins, responding to the transition in the production of mobile phone camera modules to the reflow soldering process and wafer-level packaging process. The related patents are pending.

So far camera lenses are coated by methods such as deposition with an anti-reflection film, which prevents reflection in the visible spectrum and increases transmittance. These antireflection films have been indispensable as the camera for a mobile phone heightens its resolution.

The anti-reflection film on a lens cracks by stress in a 270 deg C of reflow oven in the former process because of the different coefficients of thermal expansion between both materials, a heat-resistant resin and antireflection film.

We have developed the coating process and its equipment for the reflow soldering in addition to the usual environment-resistant performance necessary for resin lenses.

The manufacturing process of camera modules for a mobile phone has been shifted from the injection molding with conventional resin lenses to the reflow soldering and wafer-level packaging with heat-resistant resin lenses, which are expected to become more widespread.

Why mobile phone camera modules require the reflow soldering process

RoHS restricts the use of lead in electrical and electronic equipment. As soldering without lead needs to pass a resin lens through a reflow oven at about 270 deg C higher than usual, the camera modules for a mobile phone are assembled in a different process from other modules so far. The high-heat-resistant resin developed by a material maker has made the reflow soldering process available also to the camera modules of a mobile phone.

Why mobile phone camera modules require the wafer-level packaging process

The high-heat-resistant resin has made it possible to pass an assembly through a reflow oven in the same process as other parts. And in order to further increase the productivity, wafer-level packaging has been available, which can produce high-heat-resistant resins from hundreds to thousands of pieces on a wafer while the former injection molding can produce from several to dozens at once.