In recent years, with the improvement of the requirements for miniaturization of electronic devices, NTC thermistors and electronic components embedded in the built-in substrate of components are becoming miniaturized and thinner. It’s configured on built-in substrate of the component, filled with insulating resin and embedded in the substrate. In general, the electrical connection of the embedded NTC thermistor and wiring are carried out through the through-hole electrode. For example, face to external electrode of NTC thermistor, irradiating laser on an insulating resin to form a through hole and fills the through hole with metal conductor, thus making electric connection for the external electrode and wiring of the NTC thermistor.
However, in the case of using the traditional NTC thermistor, when the through hole is formed by laser, the laser must be irradiated on the external electrode accurately in order not to damage the thermistor billet of the NTC thermistor. Therefore, when laser irradiating, the NTC thermistor requires very accurate position accuracy, thereby, it made the manufacturing process of electronic equipment more complicated. As a result, we provide an NTC thermistor and its manufacturing method for substrates that do not require very accurate position accuracy when using lasers to form through holes.
The characteristics of NTC thermistor for substrate are:
1. A thermistor billet consisted by a ceramic sintering body and having two opposite main surfaces, two opposite side surfaces and two opposite end surfaces;
2. A plurality of internal electrodes are formed in the thermistor billet; two external electrodes are formed on the outer surface of the thermistor billet and making electric connection with the plurality of internal electrodes.
The external electrode comprises a first electrode layer covering an end surface of the NTC thermistor Billet; The second electrode layer formed on a main surface of the NTC thermistor billet, one end is connected with the first electrode layer, the other end is extended along the direction of the other end surface and the second electrode layer is composed of at least one layer; and third electrode layer covering at least one layer of the first electrode and the second electrode layer.