| 摘要 |
#CMT# #/CMT# The method involves dispensing at least one solder portion (3) on surface of substrate (1) e.g. leadframe, lowering pin (5) into solder portion until pin touches substrate surface, applying predetermined force to pin so that pin presses against the substrate. The ultrasonic sound is applied to pin in such a way that ultrasonic waves are produced in pin which are directed perpendicularly or angularly in relation to substrate surface. The pin is moved along a predetermined path which extends parallel to the substrate surface. The pin is lifted until pin has been severed from solder portion. #CMT# : #/CMT# An independent claim is included for a method for mounting semiconductor chips on a substrate. #CMT#USE : #/CMT# Soldering method for dispensing solder on substrate used in mounting of semiconductor chips on metallic substrate such as leadframe. #CMT#ADVANTAGE : #/CMT# Reduces undesired bleeding of the solder since processing of substrate with ultrasonic sound improves the wettability locally on the area on which solder is desired. Improves wettability of surface that should be covered by solder since ultrasonic sound is transmitted by the pin onto the substrate and causes by cavitation a destruction and removal of any oxide layers which were formed on the surface of substrate. Increases viscosity of solder portion since cooling of the pin ensures that the pin removes heat from solder portion so that temperature of solder portion decreases at least locally in the environment of pin. #CMT#DESCRIPTION OF DRAWINGS : #/CMT# The drawing shows a schematic diagram of view of the method for applying solder to a substrate. 1 : Substrate 3 : Solder portion 4 : Head 5 : Pin 6 : Contact surface. |
