JP2001044239A - Method of mounting mixture of electronic component and member for use in mixture mounting process - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and precisely conduct mixed mounting of a semiconductor bare chip and a surface mount component, even when a flexible film is used. SOLUTION: After a semiconductor bare chip 50 is mounted on a flexible film 30, it is subjected to cream solder printing. At this time, a screen mask 70, having a projected portion 75 at a portion corresponding to a mounting region of the semiconductor bare chip 50, is placed on the flexible film 30. A squeegee 80, formed such that a portion 85 corresponding to the projected portion and other main body portion 86 can be deformed independently, is brought into contact with the screen mask 70. A cream solder supplied on the screen mask 70 is scraped off by this squeegee 80. Then, a surface mounted components is mounted on the cream solder printing portion. The cream solder is melted by a reflow process to mount the surface mounted component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of mounting heterogeneous electronic components on a circuit board, and more particularly, to a method of mounting electronic components for mounting a semiconductor bare chip and a surface mounting component on a strip-shaped flexible film serving as a circuit board. The present invention relates to a mounting method and a member used in a mixed mounting process.

[0002]

2. Description of the Related Art When heterogeneous electronic components including a semiconductor chip and other circuit elements are mixedly mounted on a circuit board, a semiconductor bare chip is conventionally mounted on a QFP (Quad Flat Package).
Is mounted on a circuit board printed with cream solder, together with other surface mount components (SMD), and then electrically and mechanically connected and assembled by a reflow process. Was used. In recent years, however, in the electronics industry, devices have become increasingly smaller and lighter, and in response to this, a flip-chip mounting method for mounting a semiconductor bare chip face down on a circuit board has been used.

[0003]

In the above-mentioned conventional flip-chip mounting method and the like, with miniaturization, management of mounting accuracy by narrowing the pitch between terminals of a semiconductor bare chip or the like and management of foreign matter inclusion must be stricter. Because of the necessity and the use of a sealing resin, it has not been easy to mix and mount a semiconductor bare chip and a surface mount component on a circuit board. In particular, when a flexible film having low rigidity is used as a circuit board, it is difficult to handle the flexible film, and it is very difficult to mount the flexible film with high precision.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is possible to reliably and precisely mount a semiconductor bare chip and a surface-mounted component together, and to easily carry out mixed mounting even when a flexible film is used as a circuit board. It is an object of the present invention to provide an electronic component mounting method and a member used in the electronic component mounting process.

[0005]

According to the present invention, there is provided a hybrid mounting method for electronic components, comprising: a first step of mounting a semiconductor bare chip on a circuit board; and, after the first step, a portion corresponding to a mounting area of the semiconductor bare chip. A substantially flat screen mask is mounted on the circuit board except for a part having a convex portion on the circuit board, and the flat portion corresponding to the convex portion and another main body portion are formed so as to be independently deformable. A second step of performing cream solder printing on the circuit board by contacting a screen-shaped squeegee with the screen mask and scraping the cream solder supplied onto the screen mask with the squeegee; and after the second step. And a third step of mounting another electronic component corresponding to the cream solder formed on the circuit board.

Preferably, in the first step, a strip-shaped flexible film is used as the circuit board, a predetermined tension is applied to the flexible film, and a mounting area of the semiconductor bare chip is kept flat. Then, the flexible film is pressed by a pressing jig except for the mounting area and is brought into close contact with a flat receiving table, and a semiconductor bare chip is assembled in the mounting area.

[0007] Preferably, in a state where the screen mask is mounted on the circuit board, an interval in a height direction between a top surface inside the convex portion of the screen mask and a top surface of the mounted semiconductor bare chip is set to 100 μm or less. I do.

Preferably, in the circuit board, a resist is formed in a layer before mounting the semiconductor bare chip, and a resist opening is provided in a portion of the resist corresponding to a mounting region of the semiconductor bare chip.

A screen mask for a mixed mounting process of electronic parts according to the present invention is used in a step of performing cream solder printing in mixed mounting of electronic parts on a circuit board.
A screen mask that is placed on the circuit board and covers the circuit board. The screen mask is formed in a substantially planar shape except for a part, and has a convex shape on a portion corresponding to a mounting area of a semiconductor bare chip mounted on the circuit board. Part is provided. Further, preferably, the height from the contact surface of the screen mask to the circuit board to the upper surface inside the convex portion is 100 μm higher than the height of the top surface of the semiconductor bare chip mounted on the circuit board.
Set high within.

The squeegee for the mixed mounting of electronic components according to the present invention is used in the step of performing cream solder printing in the mixed mounting of electronic components on a circuit board. A squeegee for scraping cream solder supplied on a mask, wherein, in a squeegee main body formed in a flat plate shape, a convex portion corresponding portion corresponding to a convex portion formed on the screen mask and another main body portion. It is formed so as to be independently deformable.

As described above, by providing the projections on the screen mask, the stress generated at the time of cream solder printing is not applied to the semiconductor bare chip, and the semiconductor bare chip mounting portion is prevented from being adversely affected. Reliability is ensured. Further, in the squeegee, for example, a slit is provided at a boundary between a convex portion corresponding portion of the screen mask and another main body portion so that the convex portion corresponding portion can be independently deformed, so that the squeegee can cover the entire surface of the screen mask. Since the contact is made so that a force is evenly applied to the contact, uniform and good cream solder printing is possible, and a cream solder having a uniform and stable thickness is formed. In addition, when the screen mask is placed on the circuit board, the height-direction interval between the upper surface of the inside of the convex portion of the screen mask and the uppermost surface of the mounted semiconductor bare chip is set to 100 μm or less, so that the height of the convex portion is reduced. By monitoring the solder soldering, it is possible to detect an abnormality such as foreign matter in the mounting portion of the semiconductor bare chip at the same time as the cream solder printing.

In addition, when the semiconductor bare chip and other electronic components such as surface mount components are mounted in a mixed manner, the mounting of the semiconductor bare chip is performed first, thereby facilitating the management of foreign matter in the mounting portion. Can be alleviated. Note that a semiconductor bare chip is mounted by a flip chip mounting method, a mounting method using an anisotropic conductive film, or the like. Further, when a strip-shaped flexible film is used as a circuit board, a predetermined tension is applied to the flexible film, and the mounting area of the semiconductor bare chip is kept flat by a pressing jig, and the semiconductor bare chip is assembled, whereby rigidity is improved. Problems such as bending and bending that occur in a low flexible film are prevented, and deterioration of productivity is suppressed. In addition, a resist is formed in a layer on the circuit board before mounting the semiconductor bare chip, and a resist opening is provided in a portion corresponding to a mounting area of the semiconductor bare chip. Since the conductive film is blocked by the resist and the sealing resin does not protrude from the resist opening and spread, the floating of the screen mask and the adverse effect on other electronic components are prevented.

According to such an electronic component mounting method, the semiconductor bare chip and the surface mounting component can be mounted in a reliable and accurate manner and easily and accurately even when a flexible film is used as a circuit board. Be able to implement.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory view showing a process for assembling a semiconductor bare chip on a flexible film by a hybrid mounting method of an electronic component according to an embodiment of the present invention, and FIG. 2 uses a screen mask following the process shown in FIG. FIG. 3 is an explanatory view showing a step of performing cream solder printing on a flexible film, FIG. 3 is a perspective view illustrating a structure of a squeegee used in the step shown in FIG. 2, and FIG. It is explanatory drawing which shows the example of implementation of.

In this embodiment, a mounting method is described in which a flexible flexible film is used as a circuit board, and a semiconductor bare chip and a surface mount component are mixedly mounted on the flexible film.

First, the semiconductor bare chip 50 is mounted on the flexible film 30. In FIG.
(A) and (B) are views when the mounting process is viewed from the side, and (C) are views when the state where the semiconductor bare chip is mounted is viewed from above.

As shown in FIG. 1A, a pedestal 10 having a flat upper surface is set horizontally. A flexible film holding means (not shown) made of a reel or the like pulls the strip-shaped flexible film 30 serving as a wiring board to both sides to apply a predetermined tension, and allows the flexible film 30 to be supported by the two support portions 21 and 22. It is held at a predetermined distance from the upper surface of the cradle 10 in the state of being held.
In this case, the part where the semiconductor bare chip is assembled is
It is desirable that the positioning is performed so as to be located at an intermediate portion between the two support portions 21 and 22.

Next, as shown in FIG. 1 (B), a pressing jig 40 having a flat bottom pressing surface is attached to two support portions 21 and 21.
2, the flexible film 30 is pressed against the tension from the flexible film holding means,
The flexible film 30 is brought into close contact with the cradle 10 while being kept flat. The pressing jig 40 has an assembling opening 4 for assembling the semiconductor bare chip 50 at substantially the center of the pressing surface for pressing the flexible film 30.
1, a through hole is formed.

Then, the bare chip assembling device 60 holding the semiconductor bare chip 50 is lowered into the assembling opening 41 of the pressing jig 40, and as shown in FIG.
The semiconductor bare chip 50 is mounted on the flexible film 30 by a known mounting method. Semiconductor bare chip 5
Various methods can be applied as the mounting method of the semiconductor bare chip 50, such as a flip-chip mounting method in which projecting electrodes are formed as shown in the drawing, a mounting method using an anisotropic conductive film, or the like. The terminals and the conductive pattern of the flexible film 30 are electrically connected.

Thereafter, the assembled semiconductor bare chip 50
Is sealed with a sealing resin 55 (see FIG. 2). In this example, the semiconductor bare chip 50 forms a spherical bump by melting an Au wire by using a bump bonder in which a wire bonding apparatus is improved, and the bump is formed by ultrasonic waves, heat, or the like.
It is formed to have a protruding electrode 51 (see FIG. 2) by bonding to a bare chip by pressure or the like.

In the process shown in FIG. 1, since the flexible film 30 is always in tension, the flexible film 3 is
There is no problem such as warping or waving in 0, and by using the pressing jig 40, it is possible to mount the semiconductor bare chip accurately and reliably in a state where the flatness of the mounting area is sufficiently ensured. . Further, by using the flexible film processed into a belt shape, the mounting process can be continuously performed, and the productivity is also improved.

After the semiconductor bare chip 50 is mounted on the flexible film 30 as described above, cream solder printing is performed to mount the surface mount components. After the assembly of the semiconductor bare chip 50 is completed (including the sealing),
As shown in FIG. 2, a substantially flat flexible film 30 except for a part is placed on a flat receiving table 15, and a screen mask 70 is placed thereon. Opening patterns 71 and 72 for cream solder printing are formed on the screen mask 70. In the screen mask 70, the portion corresponding to the semiconductor bare chip 50 mounted on the flexible film 30 is the assembled semiconductor bare chip 50 (if the sealing resin 55 is around the semiconductor bare chip 50, the sealing resin 55 (including 55).

After placing the screen mask 70 in this manner, a cream solder (not shown) is supplied thereon, and the cream solder is scraped off by a squeegee 80, thereby passing through the opening patterns 71 and 72 to be flexible. Only the cream solder placed on the film 30 remains on the flexible film 30 as cream solder prints 71a and 72a. By the above-described steps, unnecessary cream solder is not applied to the assembled semiconductor bare chip 50, and the screen mask 7
By providing the protruding portion 75 at 0, unnecessary stress is not applied to the semiconductor bare chip 50 when the semiconductor bare chip 50 is scraped off by the squeegee 80. Can be prevented.
Therefore, it is possible to prevent a failure of the mounting portion, and to secure reliability.

As shown in FIGS. 2 and 3, the squeegee 80
Is formed of a square plate member having elasticity, and at the boundary between the convex portion corresponding portion 85 corresponding to the convex portion 75 of the screen mask 70 and the other main body portion 86, both are independently formed. A slit 87 is provided so as to be deformable. Therefore, in this step, when the squeegee 80 is set up vertically on the screen mask 70 and the cream solder on the screen mask 70 is scraped in the direction of the arrow DR, the convex portion corresponding portion 85 is moved to the screen mask 70. 2 and elastically bends and deforms as shown in FIG. 2 so as to smoothly pass over the convex portion 75 and scrape the cream solder on the screen mask 70 satisfactorily. Thereby, the squeegee 80
Contact the entire surface of the screen mask 70 evenly,
A stable scraping action by the squeegee 80 is obtained, and the flexible film 30 under the opening patterns 71 and 72 of the screen mask 70 is printed with even and good cream solder.

At this time, a predetermined gap is secured between the convex portion 75 of the screen mask 70 and the semiconductor bare chip 50, and the stress from the squeegee 80 is not directly applied to the semiconductor bare chip 50. The space between the gaps, that is, the space in the height direction between the upper surface inside the convex portion 75 and the uppermost surface of the mounted semiconductor bare chip 50 in a state where the screen mask 70 is mounted on the flexible film 30 is (semiconductor) (From back of bare chip) For example 1
It is set within 00 μm.

When a semiconductor bare chip is mounted, the height of the back surface of the semiconductor bare chip differs depending on the mounting method.
It has been empirically found that the variation does not exceed at most 100 μm. For this reason, in the case where the back surface height of the semiconductor bare chip varies by 100 μm or more and the semiconductor bare chip 50 floats on the convex portion 75 of the screen mask 70, it is considered that foreign matter has entered the semiconductor bare chip mounting portion. . Therefore,
If the mounting portion of the semiconductor bare chip 50 has an abnormality such as floating or adhesion of foreign matter, it can be easily determined by monitoring the height of the convex portion 75 when the screen mask 70 is mounted. It is possible to check the connection abnormality of the bare chip mounting part.

Furthermore, in this embodiment, since the mounting of the semiconductor bare chip is performed first and then the cream solder printing is performed to mount the surface-mounted components, the management of the contamination with foreign substances is facilitated, and the management standard is improved. Can be alleviated. In addition, by using a screen mask and a squeegee, cream solder printing can be performed without any trouble even after the semiconductor bare chip is mounted, and the semiconductor bare chip and the surface mount component can be easily mixed and mounted.

FIG. 4 shows another example of mounting when a resist is provided on a flexible film. 4A is a diagram of the resist on the flexible film as viewed from above, and FIG. 4B is a diagram of the relationship between the resist, the semiconductor bare chip, and the screen mask as viewed from the side.

In this example, in addition to the semiconductor bare chip mounting area and the cream solder printing area on the flexible film 30, the insulating and sealing resin are prevented from spreading.
For example, a resist 31 having a thickness of about 10 μm is formed in a layer. That is, the semiconductor bare chip mounting area and the like are formed as the resist openings 32, and the mounted components, the sealing resin, and the like are provided here. When the thickness of the resist 31 is increased, the effect of preventing the expansion of the sealing resin is improved. However, the thickness of the resist 31 is determined according to the type of the sealing resin used for mounting the semiconductor bare chip or the anisotropic conductive film for connection. desirable.

In this case, the semiconductor bare chip 50 is mounted on the flexible film 30 on which the resist 31 is formed, and the sealing resin 55 is supplied to the resist opening 32 for sealing. Then, as in FIG.
The screen mask 70 and the squeegee 80 are placed on the “0” and cream solder printing is performed.

In the example of FIG. 4, a resist 31 is formed around the semiconductor bare chip 50 at a slight distance from the side surface of the mounted semiconductor bare chip 50, and a sealing resin 55 is formed in the resist opening 32. Injected. At this time, the sealing resin 55 is blocked by the resist 31, and the sealing resin 56 does not flow beyond the resist 31. Problems such as adverse effects can be prevented. Also in this case, if the gap between the semiconductor bare chip 50 and the convex portion 75 of the screen mask 70 is regulated, it is possible to judge whether or not the semiconductor bare chip 50 is assembled at the same time as the cream solder printing.

As described above, after mounting the semiconductor bare chip and performing the cream solder printing, a surface mount component (not shown) is mounted as another electronic component corresponding to the cream solder printing portion, and the cream is formed by a reflow process. The mounting is performed by melting the solder and electrically and mechanically connecting and fixing the surface mount components. Also in mounting the surface mount components, as in the case of mounting the semiconductor bare chip, the assembly is performed while being held down and fixed by the jig.

As described above, according to the hybrid mounting method of the present embodiment, the hybrid mounting of the semiconductor bare chip and the surface mounting component can be performed easily and reliably, with good productivity and with high accuracy.
A high-quality heterogeneous electronic component mixed mounting structure can be manufactured.

In the above-described embodiment, the semiconductor bare chip and the surface mount component are taken as the heterogeneous electronic components. However, the present invention is not limited to this. Obviously, it may be applied to parts. 2 to 4
Although the process relating to cream solder printing indicated by is performed using a flexible film as a circuit board, it is apparent that the process can be applied to other circuit boards.

[0035]

As described above, according to the present invention, a semiconductor bare chip and a surface mount component can be reliably and accurately mixedly mounted, and mixed mounting can be easily performed even when a flexible film is used as a circuit board. There is an effect that it is possible to provide a mixed mounting method of a possible electronic component and a member used in the mixed mounting process.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a process for assembling a semiconductor bare chip on a flexible film by a mixed mounting method of an electronic component according to an embodiment of the present invention.

FIG. 2 is an explanatory view showing a step of performing cream solder printing on a flexible film using a screen mask, following the step shown in FIG. 1;

FIG. 3 is a perspective view illustrating a structure of a squeegee used in the process shown in FIG.

FIG. 4 is an explanatory diagram showing another example of mounting when a resist is provided on a flexible film.

[Explanation of symbols]

 10, 15 Receiving stand 21, 22 Supporting part 30 Flexible film 40 Pressing jig 41 Assembling opening 50 Semiconductor bare chip 51 Projecting electrode 55 Sealing resin 60 Bear chip assembling device 70 Screen mask 71, 72 Opening pattern 71a, 72a Cream solder printing 75 Convex part 80 Squeegee 85 Convex part corresponding part 86 Body part 87 Slit

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05K 3/34 505 H05K 3/34 505C (72) Inventor Tomio Ema 4-chome Tsunashima Higashi, Kohoku-ku, Yokohama, Kanagawa Prefecture No. 3 No. 1 Matsushita Communication Industrial Co., Ltd. F term (reference) 5E319 AA03 AB05 AC03 BB05 CC33 CD29 5E336 AA04 BB12 CC31 EE01 5F044 KK03 LL01 LL04

Claims (7)

[Claims] A first step of mounting a semiconductor bare chip on a circuit board; and after the first step, a substantially planar shape except for a part having a convex portion in a portion corresponding to a mounting region of the semiconductor bare chip. A screen mask is placed on the circuit board, and a plate-shaped squeegee in which a portion corresponding to the convex portion and another main body portion are independently formed so as to be deformable is brought into contact with the screen mask. A second step of performing cream solder printing on the circuit board by scraping off the cream solder supplied on the screen mask; and after the second step, another step corresponding to the cream solder formed on the circuit board. And a third step of mounting the electronic component. 2. In the first step, a strip-shaped flexible film is used as the circuit board, a predetermined tension is applied to the flexible film, and a pressing jig is performed so as to keep the mounting area of the semiconductor bare chip flat. 2. The method according to claim 1, further comprising pressing the flexible film except for the mounting area with a tool to adhere the flexible film to a flat receiving table, and assembling a semiconductor bare chip in the mounting area. 3. 3. The method according to claim 1, wherein, in a state where the screen mask is mounted on the circuit board, a height-direction interval between the upper surface of the convex portion of the screen mask and the uppermost surface of the mounted semiconductor bare chip is set to 100 μm or less. 3. The method according to claim 1, wherein the electronic component is mounted on the electronic component. 4. The circuit board according to claim 1, wherein a resist is formed in a layer before mounting the semiconductor bare chip, and a resist opening is provided in a portion of the resist corresponding to a mounting area of the semiconductor bare chip. 3. The hybrid mounting method of the electronic component according to 1 or 2. 5. A screen mask, which is used in a step of performing cream solder printing in the mixed mounting of electronic components on a circuit board, and is mounted on the circuit board and covers the circuit board, except for a part. A screen mask for a mixed mounting process of an electronic component, wherein the screen mask is formed in a substantially planar shape and a convex portion is provided in a portion corresponding to a mounting region of a semiconductor bare chip mounted on the circuit board. 6. The height from the contact surface of the screen mask to the circuit board to the upper surface of the inside of the protruding portion is one more than the height of the top surface of the semiconductor bare chip mounted on the circuit board.
6. The method according to claim 5, wherein the height is set within a range of 00 .mu.m.
6. A screen mask for a mixed mounting process of an electronic component according to 4. 7. A squeegee for use in a step of performing cream solder printing in the mixed mounting of electronic components on a circuit board, wherein the squeegee contacts a screen mask covering the circuit board and scrapes the cream solder supplied onto the screen mask. In the squeegee main body formed in a flat plate shape, a convex portion corresponding portion corresponding to the convex portion formed on the screen mask and another main body portion are formed so as to be independently deformable. A squeegee for mixed mounting of electronic components.