DIP packages are usually made from an opaque molded epoxy plastic pressed around a tin-, silver-, or gold-plated lead frame that supports the device die and provides connection pins. Some types of IC are made in ceramic DIP packages, where high temperature or high reliability is required, or where the device has an optical window to the interior of the package. Most DIP packages are secured to a printed circuit board by inserting the pins through holes in the board and soldering them in place. Where frequent replacement of the parts is desired, such as in test fixtures or where programmable devices must be removed for changes, a DIP socket is used.