| 摘要 |
An instrument and a method for measuring a duration at or above a predetermined temperature, such as a solder reflow temperature, are disclosed. The instrument includes a capillary tube and an indicator material that is solid at temperatures below the predetermined temperature and a liquid that will move into and through the capillary tube at and above the predetermined temperature. In the method according to the invention, an instrument according to the invention is heated, then cooled. The amount of indicator material in the capillary tube indicates how much time the instrument spent at temperatures at or above the predetermined temperature. The instrument and method are useful, for instance, for indicating the length of time an integrated circuit package is at or above a solder reflow temperature during manufacturing processes.
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