Metal working – Means to assemble or disassemble – Means to assemble electrical device
Reexamination Certificate
1998-12-23
2001-01-23
Young, Lee (Department: 3729)
Metal working
Means to assemble or disassemble
Means to assemble electrical device
C029S832000, C029S833000, C029S840000, C029S843000, C029S854000, C029SDIG004, C228S180220, C228S212000, C269S021000, C269S903000
Reexamination Certificate
active
06176008
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a jig for mounting metal balls, particularly metal balJs smaller than 1 mm, to a semiconductor chip substrate or a circuit board for soldering.
It has been customary to mount metal balls to electrode pads arranged on a substrate and connect an LSI (Large Scale Integrated circuit) or similar semiconductor to the substrate via the metal balls. The metal balls are as small as about 0.6 mm in BGAs (Ball Grid Arrays) currently predominant in the semiconductors art or as small as 0.3 mm to 0.4 mm in CSPs (Chip Size Packages) recently put to practical use. Future metal balls for such applications are expected to have diameters even smaller than 0.15 mm.
Metal balls to be mounted to the electrode pads of a substrate are usually implemented by solder balls. Japanese Patent Laid-Open Publication No. 5-299424, for example, discloses a method of mounting solder balls to electrode pads formed on a semiconductor substrate. However, the method taught in this document has a problem that a guide plate, or transfer mask, formed with holes for receiving metal balls cannot be reduced in thickness. Further, when the dimensional accuracy of the contour of a container storing metal balls and the contour of a suction head is low, the balls cannot be accurately mounted to the electrode pads. In addition, the guide plate is not replaceable.
Technologies relating to the present invention are also disclosed in, e.g., Japanese Patent Laid-Open Publication No. 8-167611.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a jig implementing a thin configuration of a guide plate formed with holes for receiving metal balls.
It is another object of the present invention to provide a jig capable of accurately mounting metal balls to electrode pads even when the dimensional accuracy of the contour of a container storing the balls and that of a suction head is low.
It is a further object of the present invention to provide a jig allowing a guide plate thereof to be replaced.
In accordance with the present invention, a jig for mounting metal balls to electrode pads formed on a substrate includes a tray having an open top and storing the metal balls therein. A first mask is positioned on the open top of the tray and formed with a plurality of holes each being sized to pass one of the metal balls therethrough. A frame accommodates the tray and is spaced from the tray by a clearance in the horizontal direction. Resilient members constantly bias the tray toward the first mask away from the bottom of the frame. A suction head faces the first mask and includes a second mask formed with holes facing the holes of the first mask and each having an inside diameter smaller than the diameter of the balls. Distance regulating members regulate the distance between the frame and the suction head such that when the first and second masks contact each other, the tray sinks into the frame against the action of the resilient members.
Also, in accordance with the present invention, a jig for mounting metal balls to electrode pads formed on a substrate includes the tray having an open top for storing the metal balls therein. A transfer mask is positioned on the open top of the tray and is formed with a plurality of holes each being sized to pass one of the metal balls therethrough. A frame accommodates the tray and is spaced from the tray by a clearance in the horizontal direction. Resilient members constantly bias the tray toward the transfer mask away from the bottom of the frame. A regulating device regulates the amount by which the resilient members bias the tray toward the transfer mask. A suction head faces the transfer mask and includes a suction mask formed with holes facing the holes of the transfer mask and each having an inside diameter smaller than the diameter of the balls. Distance regulating members are provided on either one of the surface of the frame and the surface of the suction head facing each other for regulating the distance between the frame and the suction head such that when the transfer mask and suction mask contact each other, the tray sinks into the frame against the action of the resilient members.
REFERENCES:
patent: 2-278831 (1990-11-01), None
patent: 5-299424 (1993-11-01), None
patent: 8-167611 (1996-06-01), None
patent: 9-298356 (1997-11-01), None
patent: 11-97486 (1999-04-01), None
Chang Rick Kiltae
McGuireWoods LLP
NEC Corporation
Young Lee
LandOfFree
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