JPH0832296A - Positioning method for mounting electronic device - Google Patents

Abstract

PURPOSE:To obtain a method for positioning an electronic device simply and surely without requiring any expensive and intricate apparatus, e.g. an image recognition unit. CONSTITUTION:The positioning method at the time of mounting an electronic device comprises a first step for superposing a positioning mask 3 having an opening 7 at a position corresponding to the mounting area of a circuit board, i.e., a ceramic board 2, a second step for engaging an electronic device, i.e., a bare chip 1, having a plurality of solder bumps 4 on the bottom face into the opening 7 of the mask 3 from the top face side, a third step for holding the bare chip 1 by means of a tool, and a fourth step for drawing out the mask 3 from between the ceramic board 2 and the bare chip 1 and then thermocompressing the bare chip 1 using a tool.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of aligning electronic parts. More specifically, the present invention relates to a semiconductor package having a plurality of bumps or the like on the bottom surface of a circuit board on which a semiconductor chip is mounted, and a method for aligning a semiconductor chip or the like having the same bumps or the like on the bottom surface. is there.

[0002]

2. Description of the Related Art With the recent miniaturization and higher performance of electronic equipment, a semiconductor package or the like having a semiconductor chip (bare chip) or the like is often surface-mounted on a mother board.

A surface mounting type package of this type is a QFP (Quad flat gullwing-leaded package).
Those having an external connection terminal using a lead frame, such as the above, occupy the current mainstream. However, as semiconductor chips become highly integrated and the number of pins and the pitch thereof become narrower, it becomes difficult for a lead frame formed by stamping or the like to sufficiently meet the demand. Therefore, as a package suitable for high pin count and narrow pitch,
BGA (Ball) with many bumps formed on the bottom of the circuit board
grid array) etc. are receiving attention.

A similar tendency exists in a method of mounting a bare chip on the circuit board itself. That is, instead of the conventional wire bonding connection method, the number of packages adopting a connection method using bumps formed on the bottom surface of a bare chip (so-called flip chip) is increasing.

By the way, when mounting a BGA or a bare chip by bumps, it is necessary to preliminarily align the bumps on the electronic component side and the connection pads, etc. on the mounted side with accurate positions. The alignment at this time is performed by, for example, an image recognition device or the like provided additionally to the mounting device.

[0006]

However, in order to carry out the above-mentioned alignment method, it is necessary to purchase an expensive and complicated image recognition device or create an arithmetic program for the device. Become. Therefore, it becomes difficult to achieve cost reduction.

Further, in the case of the alignment method by image recognition, if the bumps or the connection pads are dirty or deformed, the alignment accuracy may be deteriorated or the alignment may become impossible. Further, in the case of this method of aligning each electronic component, if the number of mounted components in one board increases, the time required for mounting inevitably increases accordingly.
Such a reduction in mounting efficiency leads to a reduction in overall productivity.

The present invention has been made to solve the above problems, and an object of the present invention is to easily and surely perform alignment without using an expensive and complicated device such as an image recognition device. An object of the present invention is to provide a method for aligning electronic components that can be used.

[0009]

In order to solve the above problems, according to the invention of claim 1, the alignment mask has an opening formed at a position corresponding to a mounting area on the circuit board. The gist is a positioning method for mounting an electronic component having a step of engaging an electronic component having a plurality of external connection terminals on the bottom surface from the upper surface side in the opening.

According to a second aspect of the present invention, in the first aspect, when the external connection terminal of the electronic component is a bump, the position is determined by using the side surfaces of the plurality of bumps and the inner wall surface of the opening of the mask. The point is to make a match.

[0011]

According to the first aspect of the present invention, for example, when the mask is superposed on the upper surface of the circuit board in the first step, the opening is positioned on the mounting area. When the electronic component is engaged with the opening in the second step, the relative positions of the external connection terminal on the electronic component side and the external connection terminal on the circuit board side are substantially matched. By holding the electronic component with the tool in the third step, a suitable relative positional relationship between the circuit board and the electronic component is maintained. When the mask is pulled out from between the circuit board and the electronic component in the fourth step, both can be connected.

Alternatively, when the electronic parts are engaged with the openings in the first step and then the mask is overlaid on the circuit board in the second step, the external connection terminals on the electronic part side and the external connection on the circuit board side are connected. The relative position with the terminal is almost the same.
Holding the electronic component with the tool in the third step maintains a suitable relative positional relationship between the circuit board and the electronic component. When the mask is pulled out from between the circuit board and the electronic component in the fourth step, both can be connected.

Further, first, at least one of the electronic component and the circuit board is moved in the thickness direction of the circuit board to temporarily separate the electronic component and the circuit board. Even at this time, since the electronic component is held by the tool, the preferable relative positional relationship between the electronic component and the circuit board (specifically, the relative positional relationship in the X, Y, and θ directions excluding the Z direction) is maintained. To be done. Then, the mask that has finished its function is pulled out from between the electronic component and the circuit board. After this,
At least one of the moved electronic component and the circuit board is returned to the original position. Then, the external connection terminals of the electronic component and the external connection terminals of the circuit board are in contact with each other, and the respective external connection terminals can be connected.

According to the second aspect of the invention, since the alignment method uses the bumps formed at relatively accurate positions as a reference, the error in alignment is further reduced. Furthermore, since thermocompression bonding is performed while holding the aligned electronic component by the tool, the electronic component can be reliably mounted on the circuit board without causing a positional shift or the like.

[0015]

【Example】

[Embodiment 1] An embodiment in which the present invention is embodied in a method of mounting a bare chip on a ceramic substrate constituting a semiconductor package (so-called MCM: Multi-chip module) will be described in detail with reference to FIGS. 1 to 7. explain. First of all,
The configurations of the bare chip 1, the ceramic substrate 2 and the alignment mask 3 will be briefly described.

As shown in FIGS. 3 and 6, the bare chip 1 as an electronic component is made of a substantially square silicon wafer (5.0 mm square, thickness 0.7 mm). A large number of spherical solder bumps 4 as external connection terminals are regularly formed on the bottom surface of the bare chip 1. In the case of this embodiment, the height of the solder bump 4 is about 70 μm to 80 μm.
μm.

As shown in FIGS. 1 and 6, mounting areas for mounting bare chips 1 are provided at a plurality of locations on the surface of a ceramic substrate 2 as a circuit board.
Is provided. In this embodiment, there are three mounting areas R1. In each mounting area R1, a connection pad 5 as an external connection terminal is provided with the solder bump 4
It is formed regularly as well. Ceramic substrate 2
An unillustrated wiring pattern or the like is also formed on the surface of the. In addition, alignment marks 6 are silk-screen printed on two of the four corners of the ceramic substrate 2.

As shown in FIGS. 1 and 3, the alignment mask 3 is a plate member made of a metal (for example, stainless steel or the like) having substantially the same outer shape as the ceramic substrate 2. Mask 3
Is approximately equal to the height of the solder bump 4. This mask 3 has three substantially square openings 7.
I have one. Each opening 7 is a ceramic substrate 2
It is provided at a position corresponding to the upper mounting area R1.

The size of the opening 7 is slightly smaller than the outer size of the bare chip 1. Instead, FIG.
As shown in FIG. 7, the distance L1 between the inner wall surfaces of the opening 7 facing each other and the distance L2 between the side surfaces of the solder bumps 4A located in the outermost row of the solder bumps 4 are substantially equal. Further, through holes 8 having a circular cross section are formed in two of the four corners of the mask 3.

Next, the alignment method using the mask 3 will be described step by step. In performing the first step, first, the ceramics substrate 2 is surely fixed in advance on the table (not shown) of the mounting apparatus. Next, while irradiating the spot light 9 or the like toward the two marks 6 from directly above (the thickness direction of the ceramic substrate 2 = Z direction),
The mask 3 is transferred above the ceramic substrate 2. Then, as shown in FIG. 1, alignment is performed while finely moving the mask 3, and when the alignment is achieved, the mask 3 is superposed on the upper surface of the ceramic substrate 2. Then, each opening 7 is located on each mounting area R1,
In addition, the connection pad 5 is located in the opening 7.

In the second step, as shown in FIGS. 2 and 3, an operator or the like engages the bare chip 1 with the opening 7 from the upper surface side of the mask 3. At this time, as shown in FIG. 3, the peripheral edge of the bottom surface of the bare chip 1 is supported by the peripheral edge of the upper surface of the opening 7 of the mask 3. On the other hand, the solder bumps 4 on the bottom surface of the bare chip 1 are not supported by the peripheral edge of the upper surface of the opening 7, and are all located inside the opening 7. Then, the side surfaces of the solder bumps 4A located in the outermost row and the inner wall surfaces of the openings 7 are in contact with each other, and the relative positions of the solder bumps 4 and the connection pads 5 are substantially the same. That is, the lower surface of each solder bump 4 is in contact with the upper surface of each connection pad 5.

In the third step, as shown in FIG.
The tool 10 provided on the head (not shown) of the mounting apparatus is lowered, and the bare chip 1 is securely held by the vacuum suction means (not shown) of the tool 10. Therefore,
A suitable relative positional relationship between the ceramic substrate 2 and the bare chip 1 is still maintained. The head of the mounting apparatus of this embodiment is provided with a plurality of tools 10 as described above. Each tool 10 adsorbs the individual bare chips 1 almost simultaneously.

In the fourth step, as shown in FIGS. 5 and 6, the tool 10 holding the bare chip 1 is moved upward to separate the bare chip 1 from the ceramic substrate 2 once. Even at this time, since the bare chip 1 is held by the tool 10, a suitable relative positional relationship between the bare chip 1 and the ceramic substrate 2 (specifically, a relative positional relationship in the X, Y, and θ directions excluding the Z direction). Is maintained.

Here, the mask 3 having finished its function is pulled out from between the bare chip 1 and the ceramic substrate 2. After that, the tool 10 that has been moved upward is lowered to return the bare chip 1 to the original position. Then, as shown in FIG. 7, the solder bumps 4 and the connection pads 5 are brought into contact with each other, and the alignment of the bare chip 1 and the ceramic substrate 2 is completed.

Further, pulse heat is applied to the tool 10 holding the bare chip 1 so that the solder bumps 4 and the connection pads 5 are thermocompression bonded. Through the above procedure, the mounting of the bare chip 1 on the ceramic substrate 2 is completed.

The alignment method of this embodiment basically requires only the alignment mask 3 and does not require image processing. Therefore, it is not necessary to purchase an image recognition device or create an arithmetic program for the device. Therefore, cost reduction can be achieved as compared with the related art. Further, unlike the case of the image processing, even if the solder bumps 4 and the connection pads 5 are slightly soiled or deformed, the alignment accuracy is not deteriorated or the alignment is not disabled. That is, according to the method of this embodiment, there is an advantage that the alignment can be performed easily and surely without using an expensive and complicated device.

Particularly, in this alignment method, since the solder bumps 4 formed at relatively accurate positions are used as a reference, the alignment error is extremely small. Therefore,
Even though it is a simple method, there is an advantage that accurate positioning is possible.

Further, according to this method in which the positions can be collectively adjusted, even if the number and types of bare chips 1 to be mounted on one board increase, the time required for mounting does not become so long. Therefore, there is no fear of reducing the overall productivity.

According to the mounting method of this embodiment,
Thermocompression bonding is performed while the bare chip 1 that has been aligned is held by the tool 10. For this reason,
The bare chip 1 can be reliably mounted on the ceramic substrate 2 without any displacement of the bare chip 1. [Embodiment 2] Next, Embodiment 2 in which the present invention is embodied as a method of mounting a BGA on a printed wiring board which is a mother board will be described in detail with reference to FIGS. First, the configurations of the BGA 11, the printed wiring board 12, and the alignment mask 13 will be briefly described.

As shown in FIGS. 8 and 10, the BGA 11 as an electronic component is a so-called semiconductor mounting device. A bare chip 15 is mounted on the upper surface of the ceramic substrate 14 that constitutes the BGA 11. The bare chip 15 side and the ceramic substrate 14 side are electrically connected via a bonding wire 16. The wire-bonded bare chip 15 is sealed by a cap 17.

On the bottom surface of the BGA 11, a large number of spherical solder bumps 4 serving as external connection terminals are regularly formed. In the case of this embodiment, the height of the solder bump 4 is about 70 μm to 80 μm.

As shown in FIGS. 9 and 10, mounting areas for mounting the BGA 11 are provided at a plurality of locations on the surface of the printed wiring board 12 as a circuit board.
Is provided. In each of the mounting areas R1, connection pads 5 as external connection terminals are regularly formed similarly to the solder bumps 4.

As shown in FIGS. 8 and 10, the alignment mask 13 is made of a stainless steel plate material that is substantially the same as the outer shape of the printed wiring board 12. This mask 13
Similar to the mask 3 of the first embodiment, three substantially square opening portions 18 are provided. Each opening 18 is provided at a position corresponding to the mounting area R1 on the printed wiring board 12.

As shown in FIG. 10, a step portion 18a is formed on the inner wall surface of the opening 18 over the entire circumference. Separation distance L3 between the inner wall surfaces of the opening 18 facing each other
And the length L4 of one side of the BGA 11 are substantially equal.

As in the case of the first embodiment, the printed wiring board 12 has the alignment mark 6 silk-screen printed thereon, and the mask 13 has the through hole 8 formed therein.

Next, the alignment method using the mask 13 will be described step by step. In performing the first step, first, the printed wiring board 12 is securely fixed in advance on a table (not shown) of the mounting apparatus.

In the first step, as shown in FIGS. 8 and 10, an operator or the like engages the BGA 11 with the opening 18 from the upper surface side of the mask 13. At this time, BGA1
The peripheral portion of the bottom surface of 1 is supported by the upper surface of the stepped portion 18 a of the mask 13. On the other hand, the solder bumps 4 on the bottom surface of the BGA 11
Are not supported by the upper surface of the stepped portion 18a, and are both positioned inside the opening portion 18. At this time, the upper portion of the inner wall surface of the opening 18 and the side surface of the BGA 11 are in contact with each other.

In the second step, as shown in FIGS. 9 and 10, the mask 13 is aligned while irradiating the spot light 9 or the like toward the mark 6 as in the first embodiment. Then, when the positions are aligned, the mask 13 is superposed on the upper surface of the printed wiring board 12. Then, the openings 18 are located on the respective mounting areas R1, and the relative positions of the solder bumps 4 and the connection pads 5 are substantially the same. That is, the lower surface of each solder bump 4 is in contact with the upper surface of each connection pad 5.

The third and subsequent steps are basically the same as in the first embodiment. That is, in the third step, as shown in FIG.
As shown in FIG. 1, the plurality of lowered tools 10 hold the individual BGAs 11 securely and almost simultaneously. Fourth
In the step (2), the BGA 11 and the printed wiring board 12 are once separated from each other by moving the tool 10 upward as shown in FIG. Here, after removing the mask 13 that has finished its role, the tool 10 is lowered to return the BGA 11 to the original position. Then, as shown in FIG.
As shown in FIG. 3, the solder bumps 4 and the connection pads 5 are brought into contact with each other, and the alignment between the BGA 11 and the printed wiring board 12 is completed. Further, when pulse heat is applied to the tool 10 holding the BGA 11 and the solder bumps 4 and the connection pads 5 are thermocompression bonded, BGA1
Implementation of 1 is completed.

Even with the method of the second embodiment as described above, the same effect as that of the first embodiment can be obtained. That is,
For the reason that basically only the alignment mask 13 is required and no image processing is required, the alignment can be performed easily and surely without using an expensive and complicated device.

In particular, in this embodiment, the BGA 1 which is an electronic component is used instead of the alignment based on the solder bump 4.
Positioning is performed with reference to the side surface of 1. Therefore, even if the solder bumps 4 are not provided on the BGA 11 side, there is an advantage that the alignment can be performed.

The present invention is not limited to the above embodiment, but can be modified as follows. (1) The alignment method according to the second embodiment is not limited to the case where the solder bumps 5 are provided on the BGA 11 side, and is similarly applicable to the case where the solder bumps 5 are provided on the printed wiring board 12 side.

(2) Instead of the solder bumps 4 of the first and second embodiments, bumps made of another metal such as gold may be used. Further, the shape of the bump is not necessarily limited to the spherical shape, and may be, for example, a straight wall shape.

(3) In the fourth step, instead of moving the tool 10 side holding the electronic components 1 and 11 in the Z direction, the table side fixing the circuit boards 2 and 12 is moved in the opposite direction. It may be moved (lowered). Of course, both the tool 10 and the table may be moved.

(4) In Embodiments 1 and 2, when the masks 3 and 13 are superposed on the circuit boards 2 and 12, the alignment may be performed by, for example, engaging the through hole 8 with the alignment pin. Good. With this method, it is not necessary to irradiate the spot light 9, so that the configuration of the device can be further simplified.

(5) An alignment method using the alignment mask 19 as another example shown in FIGS. 14 and 15 may be used. The mask 19 has the same basic structure as the mask 3 described in the first embodiment. However, in the case of this mask 19, a part of the opening 7 is cut out. Therefore, in the third step, the mask 1 as shown in FIG.
It is possible to pull out 9. Therefore, the vertical movement of the bare chip 1 can be omitted. Also,
It is also possible to pull out the mask 19 after performing thermocompression bonding with the tool 10.

(6) When electronic components 1 and 11 of different sizes and types are mounted on one board, the masks 3, 13 and 19 are selected according to the electronic components 1 and 11 to be mounted.
The thickness of may be partially changed. Further, in one mask 3, 13, 19, for example, the opening 18 having the step 18a and the opening 7 having no step 18a may be mixed.

Here, in addition to the technical ideas described in the claims, the technical ideas grasped by the above-described embodiments and other examples will be listed below together with their effects. (1) When mounting an electronic component according to any one of claims 1 and 2, wherein a step is formed on an inner wall surface of the opening of the mask, and alignment is performed using a side surface of the electronic component and an upper portion of the inner wall of the opening. Alignment method. With this method, the alignment can be performed without the bumps on the electronic component side.

(2) In claims 1 and 2, thermocompression bonding is performed collectively using a head provided with a plurality of tools. According to this method, the mounting can be efficiently performed in a short time, and the overall productivity is improved.

The technical terms used in this specification are defined as follows. "Electronic component: In addition to a semiconductor chip having a plurality of external connection terminals formed on the bottom surface, for example, a package such as BGA or butt joint PGA having a plurality of external connection terminals formed on the bottom surface, and a semiconductor mounting device such as MCM, Furthermore, it also refers to passive components such as surface mount type connectors with multiple external connection terminals formed on the bottom surface. ”

[0051]

As described in detail above, according to the first and second aspects of the present invention, since the alignment is performed by the mask, an expensive and complicated device such as an image recognition device is used. Without this, the electronic components can be easily and reliably aligned.

According to the second aspect of the present invention, since the bump is used as a reference, it is possible to realize accurate alignment.

[Brief description of drawings]

FIG. 1 is a bare chip mounting method according to a first embodiment,
It is a schematic perspective view which shows a 1st process.

FIG. 2 is likewise a schematic perspective view showing a second step.

FIG. 3 is likewise an enlarged schematic sectional view of an essential part showing a second step.

FIG. 4 is likewise a schematic perspective view showing a third step.

FIG. 5 is likewise a schematic perspective view showing a fourth step.

FIG. 6 is likewise an enlarged schematic perspective view of an essential part showing a fourth step.

FIG. 7 is likewise a schematic perspective view showing a state where the bare chip is returned to the original position.

FIG. 8 shows a first example of the BGA mounting method according to the second embodiment.
It is a schematic perspective view which shows the process of.

FIG. 9 is likewise a schematic perspective view showing a second step.

FIG. 10 is likewise an enlarged schematic sectional view of an essential part showing a second step.

FIG. 11 is an enlarged schematic sectional view of an essential part showing the third step.

FIG. 12 is likewise an enlarged schematic sectional view of an essential part showing a fourth step.

FIG. 13 is also a schematic perspective view showing a state where the BGA is returned to the original position.

FIG. 14 is a schematic perspective view showing a third step in the bare chip mounting method of another example.

FIG. 15 is likewise a schematic perspective view showing a fourth step.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Bare chip as an electronic component, 11 ... BGA as an electronic component, 2 ... Ceramic substrate as a circuit board,
12 ... Printed wiring board as circuit board, 3, 13, 1
9 ... (for alignment) mask, 4 ... Solder bumps as external connection terminals, 5 ... Connection pads as external connection terminals, 7, 18 ... Openings, R1 ... Mounting area.

Claims (2)

[Claims] 1. An electronic component having a plurality of external connection terminals on a bottom surface is engaged with the opening of a positioning mask having an opening formed at a position corresponding to a mounting area on a circuit board from an upper surface side. A positioning method for mounting an electronic component having steps. 2. The electronic component according to claim 1, wherein when the external connection terminals of the electronic component are bumps, the alignment is performed using the side surfaces of the plurality of bumps and the inner wall surface of the opening of the mask. Positioning method when mounting.