Chip device bonding machine

Abstract: The invention provides a chip device bonding machine in which bubbles can be effectively prevented from remaining in an adhesive (7) or the like. A flexible board (1) is moved on a base (14) at every unit by the rotation of reels (15S, 15T). In accordance with the movement of the flexible board (1), a new portion of a tape (16) made of a film, a paper or the like is moved above the base (14). The tape (16) is located between the flexible board (1) and the base (14). A thermosetting adhesive (7) is deposited on the flexible board (1) on the base (14) by an adhesive nozzle (20). An IC chip (3) is placed on the flexible board (1) on the base (14) by an IC chip supply arm (18). A pressing arm (22) including a heater (23) presses and heats the IC chip (3) toward the base side to interconnect the IC chip (3) to the flexible board (1). When the IC chip (3) is heated and pressed by the pressing arm (22), the tape (16) is concaved at its portions corresponding to bumps and consequently the flexible board (1) is deformed, whereby bubbles produced within the adhesive (7) are pushed out to the outside. Thus, the bubbles can be effectively removed from the adhesive (7).

Description: BACKGROUND OF THE INVENTION Field of the Invention The present invention relates generally to chip bonding machines and, e.g. a flip chip device bonding machine for bonding chip-shaped electronic assembly parts such as ICs or the like to a flexible board, and a method thereof. Description of the Prior Art IC cards in which an IC chip is housed in a plastic card are proposed. When the IC card is manufactured, an electrode of IC chip must be interconnected to a wiring pattern of the board. Fig. 1 of the accompanying drawings shows an example of a conventional interconnection method which utilizes a wire bonding technique. In Fig. 1, reference numeral 1 depicts a flexible board and 2 a wiring pattern formed on the flexible board 1. An IC chip 3 is secured to the flexible board 1 by an adhesive 4 and then an electrode 3a of the IC chip 3 and the wiring pattern 2 are interconnected by means of a gold wire 5. According to the prior-art wire bonding interconnection method, the gold wire 5 occupies a predetermined space, which unavoidably increases the thickness of the product (IC card). In order to solve this problem, an interconnection method utilizing a flip chip bonding (face-down bonding) technique, which is one of the wireless bonding techniques, is proposed. Figs. 2A and 2B of the accompanying drawings show a conventional interconnection method utilizing the flip chip bonding technique. in Figs. 2A and 2B, like parts corresponding to those of Fig. 1 are marked with the same references and therefore need not be described in detail. Bumps 6 are interconnected to the wiring pattern 2 at its positions corresponding to the electrodes 3a of the IC chip 3. A thermosetting adhesive 7 are deposited on the flexible board 1 at its position corresponding to the position at which the IC chip 3 is set, as shown in Fig. 2A. Then, the IC chip 3 is set on the flexible board 1 such that the electrodes 3a are faced to the bumps 6. The IC chip 3 is heated at a thermosetting temperature of the adhesive 7 and applied with a pressure so that the adhesive 7 between the electrode 3a of the IC chip 3 and the bump 6 may be removed. Thus, the IC chip 3 is secured on the flexible board 1 and the electrodes 3a of the IC chip 3 are interconnected to the wiring pattern through the bumps 6 as shown in Fig. 2B. In the above-mentioned flip chip bonding process, when the adhesive 7 is heated, it is frequently observed that bubbles (chemical gas or air) are produced from the adhesive 7 and remain in the adhesive 7 between the flexible board 1 and the IC chip 3. Figs. 3A and 3B show the condition such that bubbles 8 remain in the adhesive 7 between the flexible board 1 and the IC chip 3. Fig. 3A is a longitudinal cross-sectional view and Fig. 3B is a bottom view with the flexible board 1 being omitted. When the bubble 8 remains between the flexible board 1 and the IC chip 3, the bubble 8 is expanded and contracted in response to the change of temperature, thereby causing the interconnection portion to be cracked or peeled off. As a result, reliability of the interconnection is deteriorated. Therefore, according to the conventional technique, in order to remove the bubbles 8, the amount of the adhesive 7 is increased or a lot of time is spent for the heating and pressing process, which uselessly consumes the adhesive 7 or deteriorates the efficiency of manufacturing. OBJECTS AND SUMMARY OF THE INVENTION Therefore, it is an object of the present invention to provide an improved chip device bonding machine in which the aforesaid shortcomings and disadvantages encountered with the prior art can be eliminated. More specifically, it is an object of the present invention to provide a chip device bonding machine which can effectively prevent bubbles from remaining in the adhesive between a flexible board and an IC chip. It is another object of the present invention to provide a chip device bonding machine in which efficiency of manufacturing can be increased. It is still another object of the present invention to provide a chip device bonding machine in which reliability of interconnection can be improved. For a chip device bonding machine for bonding a chip device on a flexible board, comprising: board supplying means for supplying said flexible board having first and second surfaces, a wiring pattern being arranged on the first surface, including a plurality of bumps for connection with the chip, adhesive deposition means of depositing a thermosetting adhesive on said first surface of said flexible board, chip device mounting means for mounting a chip device on said first surface of said flexible board on which said thermosetting adhesive is deposited, said chip device having electrodes to be connected with the bumps of the wiring pattern, tape putting means for putting a tape on said flexible board, pressing means for pressing said chip device on said flexible board and heating said chip device on said flexible board, this problem is solved in that the tape putting means is provided to put the tape on said second surface of said flexible board, to cooperate with the pressing means to concave the tape at its positions corresponding to the bumps, so that the flexible board is deformed at a portion between the bumps, whereby bubbles produced within the adhesive are pushed out. Furthermore, a method for bonding a chip device on a flexible board is defined in claim 3. The above and other objects, features, and advantages of the present invention will become apparent from the following detailed description of an illustrative embodiment thereof to be read in conjunction with the accompanying drawings, in which like reference numerals are used to identify the same or similar parts in the several views. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a diagram used to explain an interconnection method utilizing a wire bonding technique according to the prior art; Figs. 2A and 2B are respectively diagrams used to explain an interconnection method utilizing a flip chip bonding technique according to the prior art; Figs. 3A and 3B are respectively a longitudinal cross-sectional view and a bottom view in which the flexible board is omitted, and illustrating the condition such that bubbles remain in the adhesive between the flexible board and the IC chip; Fig. 4 is a schematic diagram showing an arrangement of a chip device bonding machine according to an embodiment of the present invention; and Figs. 5A and 5B are longitudinal cross-sectional views used to explain how to push out bubbles. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A chip device bonding machine according to an embodiment of the present invention will hereinafter be described in detail with reference to Fig. 4. Also in Fig. 4, like parts corresponding to those of Figs. 1 through 3 are marked with the same references and therefore need not be described in detail. Referring to Fig. 4, there are provided a supply reel 11S for supplying the flexible board 1 and a take-up reel 11T for taking up the flexible board 1. These supply and take-up reels 11S and 11T are rotated under the control of a system controller 13. The flexible board 1 is composed of a plurality of successive units in each of which the wiring patterns 2 and the bumps 6 are fixed in advance (see Figs. 2A and 2B). The flexible board 1 is moved on a base 14 at every unit in accordance with the rotation of the reels 11S and 11T. In Fig. 4, reference numerals 15S and 15T respectively depict a supply reel and a take-up reel for a tape (sheet-like member) 16 made of a film, a paper or the like. The rotation of these reels 15S and 15T is controlled by the system controller 13., The tape 16 is located between the base 14 and the flexible board 1. As a new unit of the flexible board 1 is moved on the base 14, a new portion of the tape 16 is moved on the base 14 by the rotation of the reels 15S and 15T. An IC chip supply arm 18 is adapted to place the IC chip 3 (see Figs. 2A and 2B) on the flexible board 1. Operation of the IC chip supply arm 18 is controlled by the system controller 13. An adhesive nozzle 20 is adapted to deposit a thermosetting adhesive 7 (see Figs. 2A and 2B) such as an epoxy resin or the like on the flexible board 1. Operation of the adhesive nozzle 20 is controlled by the system controller 13. A pressing arm 22 houses therein a heater 23. Pressing operation of the pressing arm 22 is effected by a plunger 24 which is controlled by the system controller 13. According to the above-mentioned arrangement, a new unit of the flexible board 1 is moved on the base 14 by the rotation of the reels 11S and 11T. Also, a new portion of the tape 16 is moved on the base 14 by the rotation of the reels 15S and 15T. Then, the adhesive nozzle 20 is moved above the unit of the flexible hoard 1 on the base 14 and the thermosetting adhesive 7 is deposited on the unit. In the next process, the IC chip 3 is placed on the unit of the flexible board 1 on the base 14 by the IC chip supply arm 18. At that time the electrode 3a of the IC chip 3 is opposed to the bump 6 interconnected on the wiring pattern. The pressing arm 22 is moved toward the base 14 side by the plunger 24 and the IC chip 3 is pressed to the base 14 side while it is being heated. As a consequence, the electrode 3a of the IC chip 3 is brought in contact with the bump 6 and then interconnected to the wiring pattern 2. Under this condition, the IC chip 3 is secured to the flexible board 1 when the adhesive 7 is heated and then cured. The above-mentioned bonding operation is effected each time the unit of the flexible board 1 is sequentially moved on the base 14. According to this embodiment, the tape 16 is located between the base 14 and the flexible board 1. Thus, when the IC chip 3 is heated and pressed by the pressing arm 22, as shown in Fig. 5A, the tape 16 is concaved at its portions corresponding to the bumps 6 so that the flexible board 1 is deformed so as to project a central portion thereof corresponding to a portion between the bumps 6, 6. As a result, the bubbles 8 produced within the adhesive 7 are pushed out to the outside and no bubbles 8 remain within the adhesive 7 at the completion of the bonding operation as shown in Fig. 5B. As described above, according to the flip chip bonding machine of this embodiment, the bubbles 8 can be effectively prevented from being left within the adhesive 7 and therefore reliability of the interconnection can be improved. Further, as compared with the prior-art technique in which the amount of the adhesive 7 is increased and the adhesive 7 and the IC chip 3 are heated and pressed during a long period of time, according to the present invention, the adhesive 7 can be more efficiently utilized and efficiency of manufacturing can be increased. While the IC chip 3 is interconnected to and secured to the flexible board 1 in the above-mentioned embodiment, the present invention is not limited thereto and the flip chip bonding machine of the present invention can be similarly applied to the case such that other chip-shaped electronic parts are interconnected to and secured to the flexible board. According to the above-mentioned embodiment, the flexible board 1 is moved and the tape 16 also is moved, thereby new portions of the tape 16 being utilized sequentially. When the concaved portion of the tape 16 has sufficient force of restitution, the same portion of the tape 16 can be utilized a plurality of times, before being advanced. While the flexible board is composed of a plurality of units, supplied by the supply reel and taken up by the take-up reel as described above, the present invention is not limited thereto and such a variant is also possible. That is, for example, the flexible board might be formed of a single unit, or plural flexible boards might be supplied one by one. Having described the preferred embodiment of the invention with reference to the accompanying drawings, it is to be understood that the invention is not limited to that precise embodiment and that various changes and modifications thereof could be effected by one skilled in the art without departing from the invention as defined in the appended claims.

Claims: A chip device bonding machine for bonding a chip device on a flexible board, comprising: (a) board supplying means for supplying said flexible board having first and second surfaces, a wiring pattern (2) being arranged on the first surface, including a plurality of bumps (6) for connection with the chip; (b) adhesive deposition means of depositing a thermosetting adhesive (4) on said first surface of said flexible board; (c) chip device mounting means for mounting a chip device on said first surface of said flexible board on which said thermosetting adhesive is deposited, said chip device having electrodes (3a) to be connected with the bumps (6) of the wiring pattern; (d) tape putting means for putting a tape on said flexible board; (e) pressing means (23, 14) for pressing said chip device on said flexible board and heating said chip device on said flexible board; characterized in that the tape putting means is provided to put the tape on said second surface of said flexible board, to cooperate with the pressing means to concave the tape (16) at its positions corresponding to the bumps (6), so that the flexible board (1) is deformed at a portion between the bumps (6), whereby bubbles (8) produced within the adhesive are pushed out. A chip device bonding machine according to claim 1, characterized by control means for controlling the operation of said board supplying means, said adhesive depositing means, said chip device mounting means, said tape putting means and said pressing means. A method for bonding a chip device on a flexible board, comprising the steps of: (a) supplying said flexible board having first and second surfaces to a basic stand, a wiring pattern being arranged on the first surface, including a plurality of bumps for connection with the chip; (b) depositing a thermosetting adhesive on said surface of said flexible board; (c) mounting a chip device on said first surface of said flexible board on which said thermosetting adhesive is deposited, said chip device having electrodes to be connected with the bumps of the wiring pattern; (d) putting a tape on said flexible board; (e) pressing said chip device on said flexible board and heating said chip device on said flexible board, characterized by putting the tape on the second surface of said flexible board, to operate with the pressing means to concave the tape at its position corresponding to the bumps, so that the flexible board is deformed at a portion between the bumps, whereby bubbles produced within the adhesive are pushed out. The chip device bonding machine according to claim 1, wherein said board supplying means comprises a board supply reel for supplying said flexible board and a board take-up reel for taking up said flexible board. The chip device bonding machine according to claim 2, wherein said board supplying means comprises a board supply real for supplying said flexible board and a board take-up reel for rolling said flexible board, in which said control means controls a rotation of said board supply and board take-up reels. The chip device bonding machine according to claim 1, wherein said sheet putting means comprises a sheet supply reel for supplying said sheet and a sheet take-up reel for taking up said sheet. The chip device bonding machine according to claim 2, wherein said sheet putting means comprises a sheet supply reel for supplying said sheet and a sheet take-up real for taking up said sheet, in which said control means controls rotation of said sheet supply and sheet take-up reels. The chip device bonding machine according to claim 1, wherein said pressing means comprises a heater for heating said chip device on said flexible board and heater shift means for shifting said heater between first and second positions, said heater shift means contacting said heater at said first position. The chip device bonding machine according to claim 2, wherein said pressing means comprises a heater for heating said chip device on said flexible board and heater shift means for shifting said heater between first and second positions, said heater shift means contacting said heater at said first position, and said control means controlling operation of said heater and said heater shift means.

Inventors: HORI TAKESHI, HORI, TAKESHI
Applicants: SONY CORP, SONY CORPORATION
Application year: 1992
Main classification: H05K3
IPC codes: H01L21