JP2001156092A - Method for mounting solder ball and apparatus therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for mounting a solder ball simple in procedure, suitable to small-scale operation for mounting a solder ball, free from displacement or deformation of the solder ball in soldering, excellent in quality for a terminal, and simple and exact in removing a solder ball screen. SOLUTION: In the first step, a flux is coated on the side of an electrode film 12 in a semiconductor chip 10. In the second step, the semiconductor chip 10 is set to a holder 13, a solder ball screen 21 is placed on the flux 24 of the semiconductor chip 10, and a solder ball 20 is mounted via a solder ball positioning hole 23. In the third step, the solder ball screen 21 is released while its one end is raised up with lower end of the solder ball screen 21 as a fulcrum. In the fourth step, the solder ball is mounted by heating to fit the solder ball 20 to the electrode film 12 while inserting the semiconductor chip 10 into the holder 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a BGA (Ball)
Grid Array), CSP (ChipScal)
e Package), MCM (Multi Chip)
The present invention relates to a method and an apparatus for mounting a solder ball, which is used as a lead terminal of an LSI in a module or the like.

[0002]

2. Description of the Related Art With the increase in the number of pins of an LSI constituting a CPU and the miniaturization of packages, such as miniaturization of portable communication terminals and notebook computers, solder balls 20 are used as lead terminals.
The method of adopting is increasing. A conventional method for mounting the solder balls 20 on the electrode films 12 of the semiconductor chip 10 will be described with reference to FIG. (1) As shown in FIG. 6 (a), the electrode film 12 formed on the electrode film 12 of the semiconductor chip 10 is set in the semiconductor chip set recess 15 of the holder 13 so as to face upward. This semiconductor chip 10 is detached from the substrate,
Solder balls 20 in which a part or all of the solder balls have disappeared are neatly sucked by a solder cleaner. Of course, it may be a new semiconductor chip 10 on which the solder balls 20 are not yet mounted.

(2) As shown in FIG. 6 (a), a cream solder screen 17 stretched on a lower surface of a screen frame 18 is fitted into a shallow screen alignment recess 14 on the upper surface of a holder 13 to form an electrode. Place on the membrane 12. Since the mesh of the screen for cream solder 17 is completely aligned with the electrode film 12 in advance, the cream solder 19 is applied from above the screen for cream solder 17 with a brush or a spatula, so that the upper surface of the electrode film 12 is formed. Then, a layer of cream solder 19 is formed.

(3) As shown in FIG. 6B, a screen 21 for solder balls is used instead of the screen 17 for cream solder.
Into the screen positioning recess 14 of the holder 13. Then, a large number of solder balls 20 are put into the screen frame 22, and the solder balls 20 are supplied to the solder ball alignment holes 23 of the solder ball screen 21 while lightly rolling the solder balls 20 on the solder ball screen 21 with a brush or the like. . The remaining solder balls 20 are discharged from the discharge holes 29 of the screen frame 22. Solder balls 20 with cream solder 1
9, the solder ball 20 is sucked by a vacuum suction device instead of the cream solder screen 17, and X
In some cases, the Y-axis device is accurately positioned and transported and mounted.

(4) With the solder ball screen 21 mounted on the holder 13 together with the semiconductor chip 10, the solder ball screen 21 is placed in a reflow device, and hot air is sent from the upper or lower side to heat at a set temperature of 220 ° C. for about 2 minutes. 20 is melted and fixed on the electrode film 12 as shown in FIG.
(5) The solder ball screen 21 is removed, and the screen is cleaned with an ultrasonic cleaner to complete the reproduction.

[0006]

The above conventional methods have the following problems. (1) Semiconductor chips 10 such as BGA, CSP, and MCM
In order to print the cream solder 19 on the package, a cream solder screen 17 for printing adapted to each semiconductor chip 10 is required, and the work process is complicated. (2) A device for carrying and mounting the solder balls 20 by a vacuum suction device is large and difficult to work, and is not suitable for small-scale solder ball 20 mounting operations such as remounting. (3) When the solder balls 20 are mounted with the solder ball screen 21 serving as a guide and hot air is sent from above or below the semiconductor chip 10 to solder the solder balls 20, the solder balls 20 are made of a material having a large temperature deformation such as stainless steel. In the solder ball screen 21, the mounting position of the solder ball 20 is shifted from the electrode film 12. Further, the solder ball 20 hits the solder ball screen 21 so that the solder ball 20
Is deformed.

(4) With the solder ball 20 of ordinary solder (melting point: 183 ° C.), the temperature differs between the outside and the inside of the solder ball 20 with the solder ball screen 21 attached, and the surface of the solder ball 20 is distorted such as wrinkles. As a result, the quality of the terminal deteriorates. (5) To remove the solder ball screen 21 from the solder ball 20 before the soldering by heating, the semiconductor chip 10 is fixed to the lower side so that the solder ball 20 is not displaced from a fixed position, and the solder ball screen 21 is removed. It requires a device to be lifted right above, the work is complicated, and a dedicated device is required. (6) The diameter of the cream solder 19 tends to increase when the solder ball 20 is melted, so that a sufficient pitch interval cannot be obtained, or an oxide film is formed when the solder ball 20 solidifies, and the surface of the solder ball 20 can be wrinkled. Cheap.

The present invention has a simple work process, is suitable for small-scale solder ball mounting work, has no displacement or deformation of the solder ball during soldering, has excellent terminal quality, and has a solder ball screen. It is an object of the present invention to provide a method and an apparatus for mounting a solder ball in which the operation of removing the solder ball is simple and accurate.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a semiconductor chip 10 employing solder balls 20 as lead terminals and a solder ball having a solder ball alignment hole 23 for mounting the solder balls 20 on the semiconductor chip 10. Screen 21, a semiconductor chip setting recess 15 for setting the semiconductor chip 10 in the lower stage, and a screen positioning recess 14 for setting the semiconductor chip 10 on the set semiconductor chip 10 with a gap equal to or less than the diameter of the solder ball 20. The solder ball screen 21 is fixed so that the entire periphery is surrounded by a screen frame 22, and the solder ball screen 21 is fixed to a screen alignment recess 14 at one lower end of the screen frame 22. That the handle 25 for lifting the other end side is formed integrally with the fulcrum as a fulcrum. Is a solder ball mounting apparatus according to symptoms.

In the above configuration, in the first step,
A flux 24 is applied to the electrode film 12 side of the semiconductor chip 10, and in a second step, the semiconductor chip 10 is
The solder ball screen 21 is placed on the flux 24 of the semiconductor chip 10, and the solder balls 20 are mounted through the solder ball alignment holes 23.
In the step, the solder ball screen 21 is removed while lifting the other end side with the lower end of the one end of the solder ball screen 21 as a fulcrum. In the fourth step, the semiconductor chip 10 is heated while being fitted to the holder 13 and soldered. The solder balls are mounted by fixing the balls 20 to the electrode films 12.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The solder ball mounting method and apparatus according to the present invention are based on the following steps. First step: A flux 24 is applied to the entire surface of the semiconductor chip 10 on the electrode film 12 side. Second step: the semiconductor chip 10 is fitted and set on the holder 13, the solder ball screen 21 is placed on the flux 24 of the semiconductor chip 10, and the solder is placed in all the solder ball alignment holes 23 of the solder ball screen 21. The ball 20 is mounted. Third step: The solder ball screen 21 is removed while the other end is lifted by pushing down the lower end of the one end of the solder ball screen 21 as a fulcrum. Fourth step: With the semiconductor chip 10 set in the holder 13, the solder ball 20 is fixed to the electrode film 12 by heating, and after fixing, the semiconductor chip 10 is taken out of the holder 13.

By performing the above-described steps, complicated printing of the cream solder 19 on the cream solder screen 17 is omitted to simplify the work, and the solder ball screen 21 is pushed down by using the lower end of one end as a fulcrum. By removing the solder ball screen 21 while lifting the other end, the solder ball screen 21 can be removed from the solder ball 20 and the entire semiconductor chip 10 can be uniformly heated and soldered. It is possible to easily and surely mount the solder balls 20 by eliminating factors such as deformation and deterioration of quality.

An embodiment of the present invention will be described below with reference to the drawings. The solder ball mounting apparatus according to the present invention includes a holder 13 for positioning and setting the semiconductor chip 10 and the solder ball screen 21 and a solder ball screen 2 for correctly positioning the solder ball 20 on the electrode film 12.
1 and a flux 24 applied to the electrode film 12 side of the semiconductor chip 10.

Generally, the solder ball 20 is formed as shown in FIG.
As shown in (c), the diameter d = 0.89 mm, 0.76
mm, 0.5 mm, 0.4 mm, etc., and the melting temperature is
183 ° C, 290 ° C and the like. The solder ball screen 21 is made of a stainless steel plate, and its thickness t is
The size is 0.15 mm, 0.13 mm or the like, and the size is made about 10 to 20 mm larger depending on the size (6 × 6 to 50 × 50 mm) of the semiconductor chip 10. The diameter h of the solder ball positioning hole 23 formed in the solder ball screen 21 is the diameter d of the solder ball 20.
About 10% larger than the solder ball 20 so that the solder ball 20 can be easily dropped. This solder ball alignment hole 2
The pitch of 3 depends on the semiconductor chip 10, but is 0.5 to
It is about 1.5 mm. The solder ball screen 21 thus formed is fixed to the lower surface of the rectangular screen frame 22 with an adhesive or the like, as shown in FIG. Also,
A handle 25 is integrally provided on one side of the screen frame 22 for attachment to and detachment from the holder 13 and for pushing down. By making the portion of the outer periphery of the solder ball screen 21 thus formed without the solder ball alignment hole 23 sufficiently large, it becomes a space for storing the extra solder balls 20.

The holder 13 is heated by being put into a reflow soldering apparatus with the solder balls 20 mounted on the semiconductor chip 10, so that heat-resistant aluminum, magnesium, carbon resin or the like is used. This holder 1
2, a screen positioning recess 14, a semiconductor chip set recess 15, and an extrusion hole 16 are formed from the top side as shown in FIG. The screen positioning concave portion 14 has a depth substantially equal to the thickness of the solder ball screen 21. Semiconductor chipset recess 1
5 sets the semiconductor chip 10 fixedly and maintains a gap g of about half the diameter d of the solder ball 20 between the solder ball screen 21 and the electrode film 12 of the terminal plate 11 in the semiconductor chip 10. The solder balls 20 in the solder ball positioning holes 23 of the solder ball screen 21.
It is intended to be dropped and mounted. The extrusion hole 16 is for extruding the semiconductor chip 10 from the holder 13 after reflow soldering.

The operation of the solder ball mounting apparatus configured as described above will be described for each process. First step: BGA, CSP, MC without ball terminals
As shown in FIG. 1A, an aerosol type flux 24 is sprayed on the surface of the electrode film 12 (round) in the semiconductor chip 10 of M or the like. At this time, instead of coating the electrode film 12, the electrode film 1 is not used without using a screen or the like.
The flux 24 is applied to the entire surface of the terminal plate 11 on which the second 2 is formed.

Second step: As shown in FIG. 1 (b), the semiconductor chip set concave portion 1 of the holder 13 with the electrode film 12 side of the semiconductor chip 10 coated with the flux 24 facing upward.
5 is fitted and set. Further, a screen 21 for solder balls is provided in the screen positioning recess 14 of the holder 13.
Put. Then, a gap g is generated between the electrode film 12 and the solder ball screen 21. In this state, solder balls 20 which are sufficiently larger than the number of solder ball alignment holes 23 (about several times the total number of terminals) are supplied onto the solder ball screen 21, and the holder 13 and the screen frame of the solder ball screen 21 are supplied. The solder ball 20 is dropped into all the solder ball alignment holes 23 of the solder ball screen 21 by shaking the solder ball 20 several times in the front / rear, left / right, horizontal directions, etc. while holding down 22. When all the drops are confirmed,
With the solder ball screen 21 integrally held down, the remaining solder balls 20 sloping so that the handle 25 side of the screen frame 22 is lowered are brought to a space in the solder ball screen 21 where there is no solder ball alignment hole 23. .

Third step: As shown in FIG. 1 (d), with the holder 13 placed on a horizontal table or the like, the lower end of the screen frame 22 on the handle 25 side is cut from the corner of the screen positioning concave portion 14. By pressing down so as not to move, the solder ball screen 21 is lifted up at the other end with the lower end of one end of the solder ball screen 21 as a fulcrum.
From the solder ball 20. By removing the solder ball screen 21 by rotating with one point as a fulcrum in this manner, the excess solder ball 20 is removed together with the solder ball screen 21 without the solder ball 20 being displaced.

Fourth step: placing the semiconductor chip 10 on the holder 13
The solder ball 20 is fixed to the electrode film 12 by heating with a reflow soldering apparatus while the solder ball 20 is set in the above-mentioned manner, and the solder ball 20 is formed on the electrode film 12. After the formation, the semiconductor chip 10 is taken out of the holder 13.

In the above embodiment, when the solder ball screen 21 is detached from the solder ball 20 while being rotated about the lower end of one end of the solder ball screen 21 as a fulcrum and lifting the other end, the solder ball screen 21 is temporarily moved. The screen positioning recess 14 is formed to have a thickness of approximately the same thickness as the solder ball screen 21 in order to rotate while being fixed to the surface. However, the present invention is not limited to this example.
As shown in (1), projections 26 are provided on the lower surfaces of the one end and the other end of the screen frame 22, respectively, and the screen positioning concave portion 14 may be formed in a groove shape in which these projections 26 are fitted. Conversely, the projection 26 may be formed on the upper surface of the holder 13 and the groove-shaped screen positioning concave portion 14 may be formed on the lower surface of the screen frame 22. In short, the lower end of the screen frame 22 on the side of the handle 25 is pushed down so as not to move, and the lower end of the screen 21 for the solder ball is rotated and the other end is lifted to remove the screen 21 for the solder ball from the solder ball 20. Anything should do.

In the above embodiment, the terminal plate 11 is provided integrally with the semiconductor chip 10 and the electrode film 12 is formed on the terminal plate 11. However, the present invention is not limited to this example. Is a terminal plate 1 as shown in FIG.
1, the solder balls 20 can be mounted on the electrode film 12 in the same manner as described above, even when the electrode film 12 is formed directly on the semiconductor chip 10. In this case, the size and the depth of the semiconductor chip set concave portion 15 are of course formed according to the shape of the semiconductor chip 10. Further, as shown in FIG. 5, the semiconductor chip 10 may be provided with a heat dissipation substrate 27 via an insulating film 28, and the insulating film 28 may be formed with the electrode film 12. In this case, a relief hole 30 through which the semiconductor chip 10 protrudes is formed in the center of the solder ball screen 21.

[0022]

According to the present invention, since the flux 24 is applied to the entire surface of the semiconductor chip 10 on the side of the electrode film 12, a conventional cream solder screen 17 for printing that matches the semiconductor chip 10 is required. And the working process is simplified.

The solder balls 20 can be mounted on the solder ball screen 21 without the need to carry and mount the solder balls 20 with a vacuum suction device. It is suitable for such a small-scale solder ball 20 mounting operation.

After the solder ball screen 21 is removed, the solder ball 20 is heated by a reflow soldering apparatus.
Is fixed to the electrode film 12, so that the solder ball screen 21 does not undergo thermal deformation, so that the solder balls 20 can be accurately mounted for a long period of time. The screen 21 can be used for a long time.

Since the solder ball screen 21 is removed and then heated and melted by a reflow soldering apparatus, even if the solder balls 20 are made of normal solder (melting point: 183 ° C.), there is no difference in temperature between the outside and the inside, so It is an excellent terminal.

Since the handle 25 for lifting the other end side is formed integrally with the locking point of the lower end of the screen frame 22 with the screen positioning recess 14 as a fulcrum, before the solder ball screen 21 is heated and soldered. The solder ball 20 can be removed without being shifted from a fixed position without using a special device for removing the solder ball 20 from the solder ball 20.

Flux 24 instead of cream solder 19
Is applied, there is no change in the diameter when the solder ball 20 is melted, and the above of the flux 24 covers the surface of the solder ball 20 during heating, and it becomes difficult to form an oxide film when solidifying.

[Brief description of the drawings]

FIG. 1 shows an embodiment of a method and an apparatus for mounting a solder ball according to the present invention, wherein (a) shows a semiconductor chip 10;
(B) is an explanatory view of a step of applying a flux 24 to the electrode film 12 side, (b) is an explanatory view of a step of mounting a solder ball 20 through a solder ball alignment hole 23 of a solder ball screen 21, and (c) is an explanatory view of the step. FIG. 4D is a partially enlarged view of the solder ball 20 and the solder ball screen 21, and FIG. 4D is a diagram illustrating a process of removing the solder ball screen 21 while lifting the other end side with the lower end of one end of the solder ball screen 21 as a fulcrum.

FIG. 2 is a perspective view showing one embodiment of a solder ball mounting device according to the present invention.

FIG. 3 is a sectional view showing another embodiment of the solder ball mounting device according to the present invention.

FIG. 4 is a cross-sectional view showing an example in which solder balls 20 are mounted on semiconductor chips 10 of different shapes by the solder ball mounting device according to the present invention.

FIG. 5 is a sectional view showing another example of mounting a solder ball 20 on a semiconductor chip 10 having a further different shape by the solder ball mounting apparatus according to the present invention.

FIG. 6 shows a conventional solder ball mounting method.
(A) is an explanatory view of a step of applying cream solder 19 to the electrode film 12 of the semiconductor chip 10 by the cream solder screen 17, and (b) is a solder ball screen 21 applied to the semiconductor chip 10 to which the cream solder 19 has been applied. FIG. 3C is a partially enlarged view of a state in which the solder ball 20 is fixed to the semiconductor chip 10.

[Explanation of symbols]

10 semiconductor chip, 11 terminal plate, 12 electrode film, 1
3. Holder, 14 Screen recess, 15 ...
Semiconductor chip set recessed part, 16: extrusion hole, 17: cream solder screen, 18: screen frame, 19: cream solder, 20: solder ball, 21: solder ball screen, 22: screen frame, 23: solder ball alignment Hole, 24: flux, 25: handle, 26: ridge, 27: heat dissipation board, 28: insulating film, 29: discharge hole,
30 ... escape hole.

Claims (4)

[Claims] A step of applying a flux to the electrode film of the semiconductor chip; setting the semiconductor chip in a holder; and placing a solder ball screen on the flux of the semiconductor chip. Mounting the solder balls 20 through the solder ball alignment holes 23, removing the solder ball screen 21 while lifting the other end side with the lower end of one end of the solder ball screen 21 as a fulcrum, Fixing the solder balls 20 to the electrode film 12 by heating while being fitted to the holder 13. 2. A semiconductor chip 10 in which ball terminals are not formed.
Spraying an aerosol type flux 24 on the surface of the electrode film 12 and applying the flux 24 on the electrode film 12 side, and the semiconductor chip of the holder 13 with the electrode film 12 side of the semiconductor chip 10 coated with the flux 24 facing upward. The solder ball screen 21 is set in the set recess 15, and the solder ball screen 21 is placed on the screen alignment recess 14 of the holder 13 with a gap equal to or less than the diameter of the solder ball 20 on the electrode film 12. Supplying the balls 20, dropping the solder balls 20 into the solder ball alignment holes 23, and bringing the remaining solder balls 20 to a space where the solder ball alignment holes 23 are not formed in the solder ball screen 21; Is fixed horizontally, and the lower end of the screen frame 22 on the handle 25 side is Removing the solder ball screen 21 from the solder balls 20 while pushing down the corners of the clean alignment recess 14 so as not to move and lifting the other end side with the lower end of the solder ball screen 21 as a fulcrum; Heating the solder ball 20 to the electrode film 12 by heating with a reflow soldering apparatus while being set in the holder 13 to form the solder ball 20 on the electrode film 12, and then taking out the semiconductor chip 10 from the holder 13; A solder ball mounting method, comprising: 3. A semiconductor chip 10 employing solder balls 20 as lead terminals, a solder ball screen 21 having a solder ball alignment hole 23 for mounting the solder balls 20 on the semiconductor chip 10, and the semiconductor chip Semiconductor chip set recess 15 for setting 10 in the lower stage
And a holder 13 having a screen positioning recess 14 formed on the set semiconductor chip 10 with a gap equal to or less than the diameter of the solder ball 20. The solder ball screen 21 has an entire circumference. The screen frame 22 is fixed so as to be surrounded by the screen frame 22, and a handle 25 for lifting the other end side is formed integrally with the screen frame 22 at a lower end of the screen positioning concave portion 14 as a fulcrum. A solder ball mounting device, comprising: 4. A semiconductor chip 10 employing solder balls 20 as lead terminals, a solder ball screen 21 having solder ball alignment holes 23 for mounting the solder balls 20 on the semiconductor chip 10, and the semiconductor chip Semiconductor chip set recess 15 for setting 10 in the lower stage
And a holder 13 having a screen positioning recess 14 on which the semiconductor chip 10 is set with a gap of about half the diameter of the solder ball 20. The solder ball screen 21 is formed of a solder ball. A large number of solder ball positioning holes 23 are formed so as to be about 10% larger than the diameter d of the balls 20 so that the solder balls 20 can be easily dropped, and the entire periphery of the screen frame 2 has a rectangular shape.
2 and a portion of the outer periphery of the solder ball screen 21 where there is no solder ball alignment hole 23 is a sufficient space for storing an extra solder ball 20. A solder ball mounting device comprising a handle 25 for integrally lifting a lower end of the screen frame 22 at a lower end of the screen frame 22 with the screen positioning recess 14 as a fulcrum.