TAGS: Electrical & Electronics
Researchers at the Japan Science and Technology Agency (JST) have developed a precision joining device through heat sink laser welding based on a new accurate thermal-welding technique that welds only the joints for high-quality products.
Overcoming the Limitations of Traditional Joining Methods
Methods for laminating and sealing resins include welding, which melts the joining faces, in addition to adhesives. Traditional methods of welding include hot-plate/hot-air welding and ultrasonic welding; however, precise heating of the joining faces is difficult, which makes these methods not easily applicable to small parts. For products where burning or vaporization of parts due to excessive heating is problematic, quality assurance of welded product was a major issue.
In this development, a new technique that accurately welds only the joint was put into actual use. This technique uses a laser as a heat source and pressure-welds a radiator that transmits light (heat sink) to a tip of the outlet of the laser while in contact with the surface of the part to be welded. This prevents temperature increase in the surface and the inside of the part.
Improved Appearance and Accuracy with New Technique
As a result, the researchers successfully completed a welding device for three types of target parts. For small electrical parts, spot-scanning laser welds irregular outline of PPS (polyphenylene sulfide) while avoiding terminals and the like. For microchannel, spot-scanning laser accurately welds outline of the flow path of COP (cycloolefin polymer) without burning or vaporization. For flat panel, shaped laser beam is sequentially irradiated to seal the whole PET (polyethylene terephthalate) material.
By cooling the resin with heat sink, it was made possible to weld together olefin-based resin and fluorine-based resin that were difficult to weld because of high laser absorption and heat generation. The developed technique is anticipated to contribute greatly to improved appearance and accuracy of the finish, and welding and assembly of precision devices, such as resin casing, medical microchip, and LCD panels, for which reliability is a requirement.
Source: Japan Science and Technology Agency