Laser-induced selective heating for microLED placement and bonding

摘要

A laser is used to induce bonding of LED contact pads with corresponding substrate contact pads on a display substrate. The wavelength of the laser light and the material used for the contact pads are both selected so that the laser light is capable of melting the contact pads. For example, the laser light has a wavelength of between 220 nm and 1200 nm, and the contact pads are formed of a copper-tin oxide (CuSn). Furthermore, the system may be configured to shine the laser light through a number of other components, such as the pick-up head and the LED itself. These materials can be formed of materials that do not absorb the energy of the laser light. Bonding the contacts with a laser in this manner allows for faster heating and cooling times, avoids reheating of previously bonded contact pads, and reduces thermal expansion of the display substrate.