Vitronics Corp. v. Conceptronics, Inc.

Vitronics Corp. (Vitronics) (plaintiff) held a patent for a method of soldering devices to printed circuit-board surfaces by passing the boards through ovens, which maintained the devices below the solder reflow temperature. A preferred embodiment of the invention was disclosed in the patent specification describing the solder as having a liquidus temperature, or the temperature the solder begins to melt, of about 190 degrees Celsius and a peak reflow temperature of about 210 to 218 degrees Celsius. The embodiment also described heating the board and solder up to about 210 degrees Celsius to achieve the method. Vitronics sued Conceptronics, Inc. (Conceptronics) (defendant) for patent infringement in district court. The district court delayed claim construction until the conclusion of testimony, when Vitronics argued solder reflow temperature should be construed to mean peak reflow temperature and Conceptronics argued it should mean the liquidus temperature. Vitronics relied on the specification for its construction, and Conceptronics relied on a paper written by a former employee and testimony from an expert witness. The district court construed the term to mean liquidus temperature without indicating which evidence it relied on. Vitronics conceded, in accordance with the district court’s claim construction, that Conceptronics was entitled to judgment as a matter of law. Vitronics appealed.