Metal working – Method of mechanical manufacture – Electrical device making
Patent
1998-10-02
2000-05-02
Arbes, Carl J.
Metal working
Method of mechanical manufacture
Electrical device making
29740, 29832, H01R 4300, B23P 1900
Patent
active
060557249
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method and device for sealing an IC chip mounted on a substrate by a flip-chip mounting method.
BACKGROUND ART
In a flip-chip mounting method or multi-chip mounting method which has become more and more popular in recent years, sealing of the IC chip, after it has been mounted on a circuit board, according to a conventional method, was performed generally as shown in FIG. 3.
In FIG. 3, a circuit board 3, on which an IC chip 2 is mounted, is fixedly set by suction force on a block 1 which is heated to a prescribed temperature, for example 60.degree. C., and inclined at a predetermined angle .theta., for example 15.degree.. A sealing material (epoxy phenol resin) 5 is applied onto an upper surface 2a of the IC chip 2 by a dispenser 4 so as to let the sealing material 5 to run into between the IC chip 2 and the circuit board 3 by the 15.degree. inclination of the block 1, thereby accomplishing the sealing of the IC chip 2.
FIG. 4 shows the positional relationship between an application nozzle 4a of the dispenser 4 and the circuit board 3. As shown, the application nozzle 4a is positioned at a location where there is a gap h of, for example 0.2 mm, between the circuit board 3 and itself, before discharging the sealing material 5.
However, with the conventional sealing method as described above, when the discharge of the sealing material is started under such a condition that said gap h between the application nozzle 4a and the circuit board 3 is wider due to variation in dimensions such as thickness of the block 1 or the circuit board 3, the sealing material 5 is discharged on the IC chip 2 as shown in FIG. 5, which causes imperfect sealing.
In view of the problem in the prior art as described above, it is an object of the present invention to provide a method and device for sealing an IC chip by which the occurrence of imperfect sealing can be eliminated by surely feeding a sealing material onto the upper surface of a circuit board.
DISCLOSURE OF INVENTION
The method of sealing an IC chip of the present invention is characterized by having the steps of: providing a first gap between an application nozzle and a board on which an IC chip has been mounted before sealing the IC chip; discharging a sealing material; providing a second gap which is greater than the first gap between the application nozzle and the board; and discharging the sealing material so as to seal the IC chip. The sealing material is discharged in a state where the first small gap is provided, making sure that the sealing material will contact the upper surface of the board, after which the sealing is performed with the second gap appropriately formed. Therefore, the sealing material is surely applied onto the upper surface of the board, preventing it from being discharged onto the upper surface of the IC chip, by which the occurrence of imperfect sealing is prevented.
By discharging the sealing material for a certain period of time in a state that the application nozzle is positioned at a location where there is provided the first gap until the discharge of the sealing material is stabilized, the sealing operation can be stably performed. Further, by detecting the upper surface of the board before the sealing operation and determining the first gap and the second gap based on the detected position of the upper surface of the board, these gaps can be precisely determined, thereby preventing even more certainly the occurrence of imperfect sealing.
Also, the device for sealing an IC chip of the present invention is characterized in that a sealing material application head having an application nozzle and a position control means is provided with a contact detecting means for detecting a position where the tip of the application nozzle comes into contact with an upper surface of the board on which an IC chip is mounted, and that a gap which is to be provided between the application nozzle and the board is determined by making reference to the positional data detected by the contact detect
Enchi Kohei
Kanayama Shinji
Nishino Kenichi
Otani Hiroyuki
Yoshida Hiroyuki
Arbes Carl J.
Matsushita Electric - Industrial Co., Ltd.
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