JP2549412B2 - Bonding method and device - Google Patents

Description

The present invention relates to a bonding technique, and more particularly to a technique effectively used for bonding a semiconductor element to a lead frame in manufacturing a semiconductor device.

[Conventional technology]

As a conventional technique, JP-A-53-102671 discloses a method of pelletizing a lead frame in manufacturing a semiconductor device.

The outline is that a dispenser (a device that drops a fluid from a syringe-like device by air pressure) drops a small spherical silver paste into multiple parts on the pellet mounting surface of the lead frame, and then the pellets are placed on top of it. It is placed and attached with pellets (hereinafter referred to as adhesion).

[Problems to be Solved by the Invention]

The present inventor has revealed that the following problems occur when the pellets as the adherends are adhered to the lead frame as a member in the manufacture of the semiconductor device by using the above-described technique.

That is, even if the silver paste is dropped onto a plurality of places on the pellet bonding surface, when the pellet is placed, the spherical silver paste spreads from the inside toward the circumference. Is difficult to spread, and the silver paste does not adhere to the entire pellet-bonding surface.

As a result, the present inventor has also clarified that there is a problem in that pellets cannot be reliably adhered to a predetermined position of the lead frame, resulting in defective pellet adhesion.

It is also apparent by the present inventors that even if the pellets are successfully adhered, there is a problem that the pellets may peel off due to various impacts in the subsequent manufacturing process (for example, heat and vibration) at first glance. Was done.

An object of the present invention is to provide a technique capable of uniformly adhering a silver paste to the entire pellet-bonding surface.

Another object of the present invention is to provide a technique capable of reliably adhering the pellet to a predetermined portion of the lead frame.

Another object of the present invention is to provide a technique capable of reliably adhering a pellet to a predetermined portion of a lead frame, thereby improving the reliability of pellet adhering.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[Means for solving the problem]

The outline of a typical one of the inventions disclosed in the present application will be briefly described as follows.

That is, in a range larger than the adhesive surface of the pellet, a silver paste having a desired thickness was applied on a flat plate, and the pellet was pressed relatively to the silver paste, so that the silver paste was applied to the adhesive surface of the pellet. After that, the pellet is adhered to a predetermined portion of the lead frame.

[Work]

According to the above-mentioned means, the silver paste has a desired thickness and is larger than the adhesion surface of the pellet, and is applied on the flat plate, and the pellet is pressed toward the silver paste. A silver paste of the desired thickness will be applied to the surface over the adhesive surface of the pellet.

Therefore, if the pellet is placed on a predetermined portion of the lead frame and adhered, the entire adhesive surface of the pellet can be adhered to a predetermined portion of the lead frame via silver paste, and the spherical paste is adhered to a plurality of places separately. The pellets can be bonded to each other more reliably than the ones that do.

〔Example〕

FIG. 1 is a schematic front view showing a paste adhered portion of a pellet bonding apparatus which is an embodiment of the present invention.

FIG. 2 is a schematic front view showing a state in which a silver paste is applied on a glass plate in a paste adhered portion of a pellet bonding apparatus which is an embodiment of the present invention.

FIG. 3 is a schematic side view showing a bonding portion of a pellet bonding apparatus which is an embodiment of the present invention.

FIG. 4 is a schematic front view showing a semiconductor device manufactured by using an adhesion technique which is an embodiment of the present invention.

FIG. 5 is a schematic plan view showing the appearance of a pellet bonding apparatus which is an embodiment of the present invention.

In FIG. 1, reference numeral 1 indicates a paste adhered portion. Two
Is a paste tank for storing a silver paste as an adhesive and supplying the silver paste to a glass plate described later. Reference numeral 3 denotes a roller, which is a cylindrical member and has a role of accumulating the silver paste and a role of applying the silver paste to a glass plate described later. The roller 3 is rotatable in the circumferential direction by a motor provided in the head 4, and is provided so as to project from the head 4. Reference numeral 5 denotes a plate, which is a plate-shaped member having a width similar to the width of the roller 3 in the direction of the cylinder height, which is close to the circumferential surface of the roller 3 from the side of the roller 3 with an inclination. The silver paste can be stored in the concave portion formed by the roller 3 and the roller 3. The proximity (gap) between the plate 5 and the roller 3 is a gap (slightly larger) close to (slightly larger than) the desired thickness of silver paste to be attached to pellets described later. Reference numeral 6 denotes a shield plate, which is a substantially rectangular plate-shaped member, of the roller 3,
One plate is attached to each end face in the cylinder height direction to support the plate 5 (the roller 3 rotates but the shield plate 6 does not rotate) and the silver paste 7 is prevented from leaking from the side. It is for doing. Reference numeral 8 denotes a shaft, which is attached to a motor (not shown) in the head 4 to rotatably support the roller 3. Reference numeral 9 denotes a scraping plate, which is a plate-like member having a tapered tip end directed downward, and is attached to the head 4 upright with respect to a glass plate described later. The scraping plate 9 has a function of leveling the thickness of the silver paste applied on the glass plate described later as desired. Reference numeral 10 denotes a glass plate, which is a rectangular flat plate-shaped object and is for applying a silver paste having a thickness to be attached to a pellet described later once to a range larger than the adhesive surface of the pellet, and is vertically moved,
It is supported so that it can move in the horizontal direction. 11 is
A guide body, which engages with the side surface of the glass plate 10 and supports the glass plate 10 so as to be horizontally movable. A ball screw 12 is arranged below the glass plate 10 in parallel with the moving direction of the glass plate 10. 13 is a support member,
The ball screw 12 is for supporting it on a base plate described later, and the ball screw 12 is supported by two supporting members 13. 14 is a moving member, attached to the glass plate 10, by the forward and reverse rotation of the ball screw 12,
The ball screw 12 can reciprocate in the longitudinal direction.
That is, the glass plate 10 can be moved back and forth along the guide body 11 by the forward and reverse rotations of the ball screw 12. A motor 15 is mounted on a base plate described later and can rotate the ball screw 12 forward and backward. 16 is a base plate, and the guide body 11
Alternatively, the motor 15 or the like can be mounted. Reference numeral 17 denotes a shaft, which is vertically attached to the back surface of the base plate 16 (the surface opposite to the surface on which the guide body 11 is placed),
The two shafts 17 support the base plate 16. 18 is a bearing, the shaft
The shaft 17 (base plate 16) is guided by the bearing 18 so that it can move up and down. Reference numeral 19 denotes a bearing, which rotates or moves up and down along a cam described later, that is, the base plate 16 moves up and down as the bearing 19 moves up and down. 20 is a support member,
It is attached to the back surface of the base plate 16 and rotatably supports a bearing 19 via a shaft 21. 22 is
The cam is in contact with the bearing 19, and the rotation of the cam 22 moves the bearing 19 (base plate 16) up and down. Reference numeral 23 denotes a shaft, which is attached to the cam 22 and is driven by a motor (not shown).
It can rotate 22. Reference numeral 24 denotes a suction head as a support member, which is capable of suctioning a pellet, which will be described later, and can be moved up and down, and can be moved in parallel. 25 is a collet, which is a quadrangular prism, for adsorbing pellets,
A trapezoidal recess 26 and a through hole (not shown) penetrating the recess 26 from the opposite surface are formed. 27 is an air pipe, which is mounted upright on the opposite surface of the collet 25 different from the surface on which the recess 26 is formed.
Is supported, and a negative pressure can be applied to the collet 25. In other words, a negative pressure from a negative pressure mechanism (convum or the like) not shown acts on the recess 26 through the air pipe 27 and through a not shown through hole of the collet 25. It will be adsorbed. 28 is a pellet as an adherend, which is the heart of the semiconductor device.

In FIG. 2, the silver paste 7 is placed on the glass plate 10.
After being applied to a desired thickness, the pellet 28 adsorbed by the adsorption head 24 is pressed against the silver paste 7 and the surface of the pellet 28 to which the silver paste 7 is to be adhered is shown.

FIG. 3 shows a bonding portion, and shows a state in which the pellet 28 to which the silver paste 7 is attached is carried to a bonding station described later. Reference numeral 29 denotes a bonding station, which is a portion for positioning a lead frame described later at a predetermined position, heating the lead frame to a predetermined bonding temperature, and bonding the lead frame. Reference numeral 30 denotes a guide rail whose cross section in a direction orthogonal to the longitudinal direction is a U-shaped rail, and two guide rails 30 are arranged so that their U-shaped cross sections face each other. . 31 is a heat block,
A lead frame, which will be described later, is heated to a predetermined temperature and is lowered when the lead frame is conveyed so as not to hinder the lead frame conveyance. 32 is a lead frame as a member.

By the way, when the lead frame is carried, it is carried intermittently by a rectangular motion of a carrying claw (not shown).

In FIG. 4, reference numeral 33 is a tab, which is a square-shaped portion on which pellets are placed (bonded) and which constitutes a lead frame. Reference numeral 34 is a lead, which serves to establish continuity between the inside of the pellet 28 and the outside thereof, and constitutes a lead frame. Reference numeral 35 is a wire for connecting the pellet 28 and the lead 34 to each other. 36 is a virtual line indicating a package. Reference numeral 37 denotes a semiconductor device, and in the present embodiment, an example applied to a DIL (dual in line) type semiconductor device in which the leads 34 project from two side surfaces of the package (36) is shown. .

In FIG. 5, reference numeral 38 indicates a bonding device. Reference numeral 39 is a loader, which houses lead frames (not shown in the figure before pellet adhesion) as members in multiple stages in a rack to be described later, and uses an elevator mechanism (not shown) to reach the lead frame conveyance level (conveyance height). , Which can be sequentially increased (or decreased). Reference numeral 40 denotes a rack, which is a frame-shaped object having a rectangular cross section in a direction orthogonal to the lead frame storage surface, and grooves for accommodating lead frames are formed in multiple stages on both sides in the storage surface direction. . The guide rail 30 described above is arranged in front of the loader 39 (on the left side in the figure), and the rack of the loader 39 is mounted by a take-out tab (not shown).
The lead frame taken out from 40 is conveyed to the unloader described later through the bonding station 29. 41
Is an unloader, and the lead frame, which is arranged so as to face the loader 39 with the guide rail 30 in between, and whose pellets have been adhered, can be stored in multiple stages in a rack 40 that can be vertically moved by an elevator mechanism (not shown). It is like this. Reference numeral 42 denotes a tray, which is a plate-like member in which concave portions on which pellets are placed are formed in a plurality of rows and a plurality of columns in the XY direction, and a plurality of pellets to be bonded to the lead frame are placed. ing. The tray 42 is placed on an XY table (not shown) and is movable in the XY directions. Reference numeral 43 is a positioning pocket for aligning the pellet with respect to a portion to be bonded of a lead frame (not shown) so that the inclination in the plane direction and the inclination in the thickness direction are aligned with each other. A trapezoidal recess (not shown) is formed so as to be narrowed. 44 is an adsorption arm, the air pipe 27 to which the collet 25 is attached,
It is attached to the tip thereof, and can be reciprocated further up and down by a cam mechanism (not shown) from the positioning pocket 43, through the glass plate 10, to the bonding stage 29.

Incidentally, although not shown, the pellets (not shown) from the tray 42 are transported to the positioning pocket 43 by an arm similar to the suction arm.

The operation of the embodiment of the present invention having the above-described structure will be described below.

 First, the operation of the paste adhered portion will be described.

In FIG. 1, the silver paste 7 is supplied to the concave portion formed by the plate 5, the roller 3 and the shield plate 6. The gap between the plate 5 and the roller 3 is
It is set to about 50 μm (it is better to increase the size by several μm). By the way, in this embodiment, the pellet 28 is attached with a silver paste having a thickness of 50 μm. In this state, the roller 3 rotates in the direction of the arrow in the figure. Then, the silver paste 7 adheres to the circumferential surface of the roller 3 as shown in FIG. The silver paste 7 is formed from the gap between the plate 5 and the roller 3, and the silver paste slightly thicker than 50 μm (hereinafter about 50 μm) is attached to the circumferential surface of the roller 3. Therefore, while the roller 3 is rotating, the silver paste 7 having a thickness of about 50 μm is always adhered to the circumferential surface of the roller 3 which has passed through the plate 5.

On the other hand, in FIGS. 1 and 2, the glass plate 10 is
The rotation of the cam 22 raises the base plate 16 to raise the clearance between the tip of the scraping plate 9 and the glass plate 10 to 50 μm. After that, the glass plate 10 moves from the left side to the right side in the figure by the rotation of the motor 15. (The figure shows a state where the glass plate 10 has completed moving to the right.) The moving speed at this time is the same as the rotation (circumferential speed) of the roller 3, and the silver paste attached to the roller 3 7 is applied on the glass plate 10. When the glass plate 10 continues to move (moves to the right), the scraping plate 9 levels the silver paste 7 on the glass plate 10 to a thickness of 50 μm. In this way, the silver paste 7 having a thickness of 50 μm is supplied (applied) onto the glass plate 10. After that, the pellets 28 adsorbed by the collet 25 of the adsorption head 24 become the silver paste 7 on the glass plate 10.
The silver paste 7 on the glass plate 10 adheres to the pellet 28. At this time, since the silver paste 7 having a thickness of 50 μm is adhered on the glass plate 10 wider than the silver paste adhering surface of the pellet 28, the silver paste 7 is uniformly applied to the pellet 28.
However, it adheres with a thickness of 50 μm.

When the silver paste 7 on the glass plate 10 to be adhered to the pellets 28 disappears, the cam 22 rotates, the glass plate 10 descends, and the glass plate 10 is rotated by the motor 15 in the opposite direction. Move to the center left. After that, the glass plate 10 is lifted by the rotation of the cam 22 again, and the silver paste is applied to the glass plate 10 by repeating the above-described operation.

Next, the overall operation of the pellet bonding apparatus, which is an embodiment of the present invention, will be described.

In FIG. 5, first, a lead frame (not shown) before pellet adhesion is taken out from the rack 40 of the loader 39 by a take-out claw (not shown) and is conveyed onto the guide rail 30. Thereafter, the lead frame is intermittently transported to the bonding station 29 by the rectangular motion of the transport pawl (not shown). At the time of this transportation, when the transportation of the lead frame is stopped, the heat block 31 is raised so that the lead frame can be heated to the temperature at the time of pellet bonding.

On the other hand, in the paste adhered portion 1, FIG.
As shown in FIG. 2, the silver paste 7 having a thickness of 50 μm (desired thickness) is applied onto the glass plate 10 by rotating the roller 3 and moving the glass plate 10. In synchronization with this, pellets (not shown) to be adhered are taken out from the tray 42 shown in FIG. 5, placed in the positioning pocket 43 and positioned. Next, the pellet in the positioning pocket is taken out by the collet 25 of the suction head 24, the adhesive surface thereof is brought into contact with the silver paste 7 on the glass plate 10, and the pellet 28 has a silver paste 7 of 50 μm.
However, the pellet 28 can be evenly attached to the entire adhesive surface. After that, the pellet 28 to which the silver paste 7 is uniformly attached is conveyed by the suction head 24 as it is as shown in FIG. 3, and is adhered to a predetermined portion of the lead frame 32 positioned at the adhering station 29.

As described above, according to the present embodiment, the silver paste 7 having a desired thickness can be adhered to the entire bonding surface of the pellet 28 so that the pellet can be adhered, and the pellet can be reliably adhered. Therefore, as shown in FIG. 4, the semiconductor device 37 assembled according to the present embodiment is affected by various impacts in various steps after pellet adhesion and even for a long period thereafter. Poor adhesion of pellets and peeling of pellets can be reduced.

By the way, in this embodiment, the silver paste is applied on the glass plate by using the roller and the scraping plate, but another mechanism may be used.

Further, in the present embodiment, the silver paste was applied to the glass plate before the silver paste was attached to the pellets, but a material other than the glass plate may be used.

Further, although not described in detail in the present embodiment, if the glass plate coated with the silver paste at a desired thickness is made considerably larger than the pellets, the silver paste for a plurality of pellets can be obtained as desired. After being applied, the pellets can be continuously bonded to the lead frame one after another.

In this example, a silver paste having a desired thickness (thickness desired for pellet adhesion) was applied on a glass plate.
When the adhesion of the silver paste to the pellets is not good at the time of adhesion to the pellets (when the silver paste remains on the glass plate with a small thickness left), the silver on the glass plate is previously prepared. The silver paste may be applied thickly on the glass plate in consideration of the rest of the paste. The same can be said when the silver paste is attached to the glass plate from the roller.

By the way, in this embodiment, by lowering the pellet side,
I attached silver paste to the pellet, but on the silver paste side,
That is, the glass plate side may be lifted up.

(1) Applying a silver paste of a desired thickness on a flat plate within a range larger than the adhesive surface of the pellet, and pressing the pellet relative to the silver paste makes it uniform over the entire adhesive surface of the pellet. The effect that the silver paste can be attached to is obtained.

(2) A silver paste having a desired thickness was applied on a flat plate in a range larger than the adhesive surface of the pellet, and the pellet was pressed relatively to the silver paste to attach the silver paste to the pellet. After that, by bonding the pellets to the lead frame, the entire bonding surface of the pellets will be bonded via the silver paste, and the pellets will be bonded to the predetermined parts of the lead frame more reliably than when using a dispenser. The effect of being able to be obtained is obtained.

(3) A silver paste having a desired thickness was applied on a flat plate in a range larger than the adhesive surface of the pellet, and the pellet was pressed relatively to the silver paste to attach the silver paste to the pellet. After that, by bonding the pellets to the lead frame, the entire bonding surface of the pellets will be bonded via the silver paste, and the pellets will be bonded to the predetermined parts of the lead frame more reliably than when using a dispenser. it can. Therefore, the effect of improving the reliability of pellet adhesion can be obtained.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the above embodiments and can be variously modified without departing from the scope of the invention. Nor.

In the above description, the invention mainly made by the present inventor is applied to the pellet bonding technique in the manufacturing of the semiconductor device, which is the field of application which is the background of the invention, but the invention is not limited thereto.

〔The invention's effect〕

The following is a brief description of an effect obtained by the representative one of the inventions disclosed in the present application.

That is, after evenly applying the silver paste on the flat plate, the pellet is pressed against the silver paste on the flat plate, and the silver paste is attached to the pellet. The silver paste can be applied uniformly.

[Brief description of drawings]

FIG. 1 is a schematic front view showing a paste adhered portion of a pellet bonding apparatus that is an embodiment of the present invention, and FIG. 2 is a paste adhered portion of a pellet bonding apparatus that is an embodiment of the present invention. FIG. 3 is a schematic front view showing a state in which a silver paste is applied onto a glass plate, FIG. 3 is a schematic side view showing a bonding portion of a pellet bonding apparatus which is an embodiment of the present invention, and FIG. FIG. 5 is a schematic front view showing a semiconductor device manufactured by using an adhesion technique as an embodiment, and FIG. 5 is a schematic plan view showing an overview of a pellet adhesion device as an embodiment of the present invention. 1 ... Paste adhered area, 2 ... Paste tank, 3 ...
Roller, 4 ... Head, 5 ... Plate, 6 ... Shield plate, 7 ... Silver paste, 8, 17, 21, 23 ... Shaft,
9 ... bare board, 10 ... glass plate, 11 ... guide body,
12 …… Pole screw, 13,20 …… Support member, 14 …… Movement member, 15 …… Motor, 16 …… Base plate, 18,19 …… Bearing, 22 …… Cam, 24 …… Suction head, 25 ...... Collet, 26 ...... Concave, 27 ...... Air pipe, 28 ...... Pellet,
29 …… Adhesion station, 30 …… Guide rail, 31 ……
Heat block, 32 …… Lead frame, 33 …… Tab,
34 ... Lead, 35 ... Wire, 36 ... Package, 37 ...
… Semiconductor device, 38 …… Adhesive device, 39 …… Loader, 40 ……
Rack, 41 ... Unloader, 42 ... Tray, 43 ... Positioning pocket, 44 ... Suction arm.

Claims (6)

(57) [Claims] 1. A stage that reciprocates horizontally and vertically between one side where the adhesive is supplied and the other side where the adhesive is applied to the adherend, and a state in which the stage is lowered. , A stage moving mechanism that moves the stage to one side in the horizontal direction and moves the stage to the other side in the horizontal direction while the stage is raised, and a lower peripheral surface on one side of the stage. A roller provided in close proximity to the roller, a plate provided in close proximity to the side circumferential surface of the roller, and a rake plate provided in the middle of the one side and the other side of the stage with the lower end close to the stage A space formed by the roller and the plate, which uses an adhesive device that supports an object and includes a collet that presses the object to be adhered to the adhesive applied on the stage on the other side of the stage. The accommodated adhesive adheres to the roller by the rotation of the roller, the film thickness is regulated by the gap between the roller and the plate to make it uniform, and is transferred, and when the stage moves to the other side in the horizontal direction. This adhesive is applied on the stage, and with the movement of the stage, it is regulated by the gap between the scraping plate and the stage to be uniformized and moves to the other side, and the stage moves to a position close to the collet on the other side. At this time, the object to be adhered supported by the collet is pressed against the adhesive on the stage, and the adhesive is applied to the object to be adhered. 2. The bonding method according to claim 1, wherein the adherend is a semiconductor pellet, and the adhered adhesive is used for bonding the semiconductor pellet and the lead frame. 3. The bonding method according to claim 1, wherein the peripheral speed of the roller outer peripheral surface due to the rotation coincides with the moving speed of the stage. 4. A stage that reciprocates in the horizontal and vertical directions between one side where the adhesive is supplied and the other side where the adhesive is applied to the adherend, and a state in which the stage is lowered. , A stage moving mechanism that moves the stage to one side in the horizontal direction and moves the stage to the other side in the horizontal direction while the stage is raised, and a lower peripheral surface on one side of the stage. A roller provided in close proximity to the roller, a plate provided in close proximity to the side circumferential surface of the roller, and a rake plate provided in the middle of the one side and the other side of the stage with the lower end close to the stage A collet that supports an object and presses the object to be adhered to the adhesive applied on the stage on the other side of the stage, and the adhesive accommodated in the space formed by the roller and the plate. Is adhered to the roller by the rotation of the roller, the film thickness is regulated by the gap between the roller and the plate to be uniformized and transferred, and is applied onto the stage when the stage moves to the other side in the horizontal direction. When the stage moves, the adhesive is regulated by the gap between the scraping plate and the stage and uniformized and moves to the other side, and when the stage moves to a position close to the collet on the other side, the collet An adhesive device, characterized in that an object to be adhered supported by a substrate is pressed against an adhesive on a stage, and the adhesive is applied to the object to be adhered. 5. The adhering device according to claim 4, wherein the adherend is a semiconductor pellet, and the adhered adhesive is used for adhering the semiconductor pellet and the lead frame. 6. The bonding apparatus according to claim 4, wherein the peripheral speed of the roller outer peripheral surface due to the rotation coincides with the moving speed of the stage.