JP2002203872A - Method for mounting electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cost-effectively provide a method for a highly reliable mounting which does not require an expensive equipment but removes a solder oxide film with relatively easy method. SOLUTION: A method for mounting electronic components to mount a bare chip on a mounting substrate 1 with solder bumps comprises the step of mechanically and physically removing an oxide film 5 formed on a surface of the solder bumps 2 using a abrasive type cleaner.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for mounting an electronic component, which handles, for example, a high-speed / high-frequency signal, on a substrate via a solder bump by a flip chip method.

[0002]

2. Description of the Related Art In recent years, practical use of a high-speed and wide-band communication system has begun widely, and application to a communication field that handles signals in a microwave frequency region such as public communication has been attempted and put to practical use. For example, in an electronic device such as a transmitting device or a receiving device used in such a communication system, the LS is used to configure a circuit of the electronic device.
Various electronic components mounted face-down on a substrate such as I have been put to practical use. As a mounting method of such an electronic component, for example, the following flip chip method is known, and thereby, the mounting density and the high frequency characteristics are improved.

Incidentally, as an electronic component used in this mounting method, for example, a bare chip, that is, a bare chip (semiconductor chip) is used. Specifically, a microwave monolithic integrated circuit (hereinafter, referred to as MMIC) is used. )
A mounting method of a bare chip using such a method is known. Then, according to this mounting method, the bare chip is mounted and integrated on the ceramic mounting substrate (see FIG. 6C).

That is, in this mounting method shown in FIG. 6, first, in a first step (see FIG. 6A), a solder bump 2 is formed at a predetermined position on a ceramic mounting substrate.
It is connected to a circuit pattern (not shown) on the mounting board 1.

Next, in a second step, as shown in FIG. 1B, an MMIC chip as a bare chip 3 is mounted on the mounting substrate 1.
Mount on top. The MMIC chip is provided with an electrode 4 for connection with the solder bump 2, and the electrode 4 and the solder bump 2 are aligned, and are arranged in a state where the mutual positional relationship is adjusted.

Then, in the third step, as shown in FIG. 1C, the MMIC chip is then moved in the direction of the mounting substrate 1, and the electrodes 4 and the solder bumps 2 are connected so as to be in contact with each other and fixed. I do. The connection here is performed, for example, after the solder bump 2 is melted or solid-phase diffused according to a predetermined temperature profile after the contact between the electrode 4 and the solder bump 2, the connection between the solder bump 2 and the electrode 4 is made. The bonding is performed.

[0007]

When mounting by such a method, an oxide film may be formed on the surface, for example, when the solder bumps 2 come into contact with air. Then, due to the effect of the oxide film of the solder bump 2,
This may cause a so-called non-wetting phenomenon of the solder, and may cause a trouble that the solder bump 2 and the electrode 4 cannot be normally joined. Further, if the MMIC chip is mounted on the mounting substrate 1 in a state where the oxide film is formed, conduction between the solder bumps 2 and the electrodes 4 is hindered, and
May not be able to operate.

This will be described with reference to FIG. 6, the same parts as those shown in FIG. 6 are denoted by the same reference numerals, and duplicate description is avoided. In this mounting method, in the first step, as shown in FIG. 7A, the solder bumps 2 formed on the mounting substrate 1 are connected to a circuit pattern on the mounting substrate 1, but usually, for example, The oxide film 5 described above is formed on the surface of the solder bump 2 due to the presence of ambient temperature, humidity, various reactants, and the like.

For this reason, after positioning the electrodes 4 and the solder bumps 2 in the second step, the electrodes 4 of the bare chip (MMIC chip) 3 and the solder bumps 2 of the mounting board 1 are connected in the next third step. At this time, there is a possibility that the solder may not wet due to the oxide film 5 formed on the solder bump 2. As a result, the bonding between the solder bumps 2 and the electrodes 4 may become uncertain or may not be possible in the worst case.

[0010] For example, if the joining of both is uncertain, if this is left unchecked, the MM will be in the early stage after mounting.
Even if the IC operates normally, the solder bump 2
The connection between the electrode and the electrode 4 becomes poor, and the
May not be able to operate. Even if the two can be physically joined successfully, the presence of the oxide film 5 hinders the electrical conduction between the two and causes the MM to normally operate.
There is a possibility that the IC cannot be operated.

Therefore, in order to avoid such inconvenience, the oxide film may be removed by a method such as a low-pressure plasma method or a sandblast method. For example, FIG. 8 shows a method of mounting an electronic component having an oxide film removing step using the low-pressure plasma method, the sand blast method, or the like. In this figure, the same functional portions as those in FIGS. 6 and 7 are denoted by the same reference numerals, and redundant description will be avoided. Here, the reactor 6 is used to remove an oxide film by using such a low-pressure plasma method, a sand blast method or the like.

In the method of mounting an electronic component having an oxide film removing step using the reaction furnace 6, first, as before, the solder bump is formed on the mounting substrate 1 in the first step shown in FIG. 2 are formed and connected to a circuit pattern (not shown) on the mounting board 1. Here, it is assumed that the oxide film 5 is formed on the surface of the solder bump 2 due to environmental temperature, humidity, the presence of a reactant, and the like.

Next, in the second step, the above-described oxide film 5 is removed. As shown in FIG. 1B, the mounting board 1
It is housed in the reactor 6 described above, and the reactor 6 performs an oxide film removing operation 61 such as low-pressure plasma or sandblast. By this oxide film removing action 61,
The oxide film 5 is gradually removed, and the non-oxidized solder surface is exposed on the solder bump 2. In the third step, FIG.
This shows a state in which the non-oxidized solder surface after the oxide film 5 has been removed from the solder bumps 2 of the mounting board 1 is exposed. In the fourth step,
As shown in FIG. 3D, the MMIC is used as the bare chip 3.
The chip is mounted on the mounting board 1, and in the fifth step, as shown in FIG.
These steps are the same as those of the conventional method described above.

However, in the above-described method for removing an oxide film using the low-pressure plasma method, the following steps are required. 1. It is necessary to introduce an expensive reactor and to use a reactive gas that requires careful handling. 2. It is necessary to introduce a device for obtaining a low pressure, and a process time corresponding to this is required. There were problems such as the necessity of determining appropriate reaction conditions. On the other hand, in a method of removing an oxide film using a sand blast method or the like, the method is described as follows. 4. the need to introduce expensive reactors; 5. adding extra process time; 6. Appropriate sandblasting conditions need to be determined; There was a problem that a washing step after sandblasting was required.

In view of the above circumstances, an object of the present invention is to provide a highly reliable mounting method of electronic parts at a low cost by removing an oxide film by an easy procedure without using an expensive device. And

[0016]

According to the present invention, in an electronic component mounting method for mounting an electronic component on a substrate via a solder bump, an oxide film formed on the solder bump is rubbed by a cleaner before mounting. It is characterized by having a removing step of removing by action.

[0017] Further, an electronic component in which the electronic component is connected to and mounted on the substrate by bonding the substrate having the solder bumps formed thereon and the electronic component having the electrodes formed thereon to the solder bump and the electrode. In the component mounting method, the method further includes a removing step of removing an oxide film formed on the solder bump by a rubbing action of a cleaner.

Further, the board on which the solder bumps are formed and the electronic component on which the gold bumps are formed are joined by bonding the solder bumps and the gold bumps, so that the electronic component is connected to the board and mounted. The method of mounting an electronic component according to claim 1, further comprising a removing step of removing an oxide film formed on the solder bump by a rubbing action of a cleaner.

Further, in the electronic component mounting method for mounting an electronic component on a substrate via solder bumps, an oxide film formed on the solder bumps by forming a hemispherical solder material on the substrate is provided. The method is characterized by including a removing step of removing by a rubbing action of a cleaner and a fluxless step of performing fluxless solder fusion bonding after the removing step.

Further, in a method of mounting an electronic component on a substrate via a solder bump, a method for mounting an electronic component on a substrate, comprising: forming an oxide film formed on the solder bump by coating a metal core on the substrate with a solder material. It is characterized by having a removing step of removing by a rubbing action of a cleaner, and a fluxless step of performing fluxless solder fusion bonding after the removing step.

[0021]

Embodiments of the present invention will be described with reference to the accompanying drawings. In this embodiment, the same portions as those of the above-described conventional technology are denoted by the same reference numerals, and the description will not be repeated. FIG. 1 is a process chart showing a method for mounting a bare chip according to the first embodiment of the present invention, and a semiconductor device E (see FIG. 1E) is formed through each process. As in the conventional case, first, solder bumps 2 are formed on a mounting substrate 1 such as an LSI, and the solder bumps 2 and the electrodes 4 of the bare chips 3 are joined to each other to bring the bare chips 3 face-down. It is mounted on the mounting board 1 in the state. In the mounting method according to the present invention, prior to this bonding, the oxide film 5 of the solder bump 2 is removed by a rubbing type cleaner 7 (see FIG. 1B) described later.

The mounting substrate 1 can be made of various ceramics, but is preferably formed of a material such as alumina, aluminum nitride, or glass ceramic. Solder bumps 2 formed on the mounting substrate 1 include
It is preferable to use any one of a tin-lead alloy material, a tin-silver alloy material, a tin-silver-copper alloy material, a tin-bismuth alloy material, and a tin-gold alloy material. The solder bump 2 has a configuration in which a solder material is formed in a hemispherical shape on the mounting substrate 1.

On the other hand, the bare chip (semiconductor chip) 3 of this embodiment, which is a bare electronic component, includes a microwave monolithic integrated circuit such as a preamplifier, a gain control amplifier, a demodulator, etc., which handles signals in a high frequency range. (Hereinafter M
MIC chip), but various other types are also applicable. For example, as the bare chip 3, an avalanche photodiode, pi
It is also preferable to use a photoelectric conversion element such as an n-photodiode, a laser diode, or a photodiode. The rubbing type cleaner 7 mechanically and physically scrapes off the surface of the solder bump 2 on which the oxide film 5 is formed, and is preferably formed of, for example, a plastic-rubber mixed material.

Here, the operation of the semiconductor device E formed by the mounting method according to the first embodiment will be described. In the semiconductor device E, when a drive bias is supplied via a circuit pattern (not shown) on the mounting substrate 1, the drive bias is applied to the MMIC chip 3 via the solder bumps 2 and the electrodes 4. Similarly, an input signal is input to the MMIC chip 3 via the solder bumps and the electrodes. On the other hand, the output signal is output to a circuit pattern on the mounting board 1 via the electrodes 4 and the solder bumps 2.

Next, a specific mounting method for mounting a bare chip on the mounting substrate 1 will be described with reference to FIG. In the first step, as shown in FIG. 1A, solder bumps 2 are formed on a mounting board 1 and connected to a circuit pattern (not shown) on the mounting board 1. Usually, an unnecessary oxide film 5 is formed on the surface of the solder bump 2 due to environmental temperature, humidity, presence of a reactant, and the like. In the second step, the oxide film 5 is removed as shown in FIG. That is, by rubbing the surface of the mounting substrate 1 with a rubbing cleaner 7, the solder oxide film 5 is removed and the non-oxidized solder surface of the solder bump 2 is exposed. In addition, as a mode when rubbing with the rubbing type cleaner 7, various appropriate methods can be applied, and it is essential that the oxide film 5 can be mechanically and physically removed.

In the third step, as shown in FIG.
The mounting substrate 1 after the oxide film 5 has been removed from the surface of the solder bump 2 in this manner is shown. Thereby, since the non-oxidized solder surface is exposed on the solder bump 2, the occurrence of solder non-wetting can be prevented. In the fourth step, the MMIC chip 3 is mounted on the mounting substrate 1 as a bare chip (semiconductor chip) as shown in FIG. The MMIC chip 3 is aligned with the electrodes 4 provided thereon and the solder bumps 2 connecting the electrodes 4 by an appropriate method such as image processing, and is arranged with high accuracy. Then, MMIC
The chip 3 is moved in the direction of the mounting board 1 and is fixed in a state where the electrodes 4 and the solder bumps 2 are in contact with each other.

In the fifth step, as shown in FIG.
This shows a state where the electrode 4 and the solder bump 2 are joined. 4th
In the process, the electrode 4 fixed in a state of contacting
And the solder bump 2 according to a predetermined temperature profile.
The electrodes 4 and the solder bumps 2 are joined and integrated by melting or solid-phase diffusion of the solder bumps 2. Thereafter, an underfill is injected into a gap between the mounting substrate 1 and the MMIC chip 3 so as to stabilize the junction between the two and to achieve insulation.

Therefore, according to the embodiment having the above-described procedure, the oxide film 5 can be mechanically and physically removed in a relatively short time and with a simple operation without introducing an expensive device. Can be removed. As a result, a bare chip mounting method for manufacturing a highly reliable semiconductor device can be provided at low cost. In particular, it is possible to solve the conventional troubles such as the occurrence of solder leakage, which hinders the joining between the electrode 4 and the solder bump 2 and the occurrence of uncertain joining.

Next, a second embodiment according to the present invention will be described. The method for mounting a bare chip according to this embodiment is substantially the same as that of the first embodiment, except that the step of removing the oxide film 5 in the second step is performed by a procedure as shown in FIG. Done in That is, in the removing step according to the second embodiment, the top surface of the mounting substrate 1 provided with the solder bumps 2 is viewed from directly above, that is, as shown in FIG. Allocate work in multiple directions. Here, the rubbing type cleaner 7 is provided with “plastic eraser, PE-01.
A "(product of Dragonfly Pencil Co., Ltd.).

This rubbing operation is performed by assigning four rubbing directions in the order of direction A, direction B, direction C and direction D arranged and set at an angle of 90 ° to each other. The pressure at which the solder bumps 2 are mechanically and physically rubbed by the rubbing cleaner 7 is 1.2 kgf (11.8 N). This rubbing operation is repeated 10 times from the rubbing direction A, 10 times from the rubbing direction B, 10 times from the rubbing direction C, 10 times from the rubbing direction D, and is repeated 40 times for convenience.

Therefore, according to this embodiment, mechanical and physical rubbing can be performed manually, so that it can be performed in a relatively short time without using an expensive dedicated device. The oxide film 5 can be removed by a simple method.
This makes it possible to realize a mounting method with high reliability and good reproducibility. Further, according to this embodiment, it is possible to avoid occurrence of troubles such as defective bonding or inhibition of bonding between the electrode 4 and the solder bump 2 due to occurrence of the solder non-wetting phenomenon.

In this embodiment, the rubbing pressure is set to 1.
2 kgf (11.8 N), for example, 0.5 kgf
(4.9 N) to 4 kgf (39 N) may be selected. The total number of times of rubbing does not need to be 40 as in this embodiment, and may be selected, for example, in the range of 20 to 100 times. Further, the rubbing directions are not limited to the four directions set at a 90 ° intersection angle as in this embodiment, but may be arranged at equal angles in a plurality of directions.

Next, a third embodiment according to the present invention will be described. The method of mounting a bare chip according to this embodiment is substantially the same as that of the first embodiment, except that the removal step in the second step is as shown in FIGS. 3A and 3B. Batch processing is performed on a plurality of mounting boards 1 using a simple fixing jig 8. In this embodiment, only the removal step in the second step is collectively performed on the plurality of mounting boards 1, and the mounting board 1
However, for each step including the first step, the work may be simultaneously performed on a plurality of mounting boards 1 at the same time.

In the present embodiment, a plurality of (six in this embodiment) mounting substrates 1 are used to collectively remove the oxide film 5 with one rubbing-type cleaner 7. A jig main body 81 on which the jigs 1 are collectively mounted, and a fixing plate 82 which presses down the plurality of mounting substrates 1 mounted on the jig main body 81 from above and collectively fixes them together.

The jig body 81 has a long side (longitudinal) direction which is the same as or slightly longer than the short side length of the entire mounting board 1 on which the mounting substrate 1 is mounted collectively, and has one short side (horizontal) direction. Has a substantially rectangular shape that is somewhat longer than the length of the long side of the mounting substrate 1. And this jig body 8
1, a direction perpendicular to the longitudinal direction (vertical direction) of the upper surface portion is substantially the same as the width dimension of the long side of the mounting substrate 1, and the longitudinal direction is approximately the same as the length of the entire short side of the mounting substrate 1. , And a recessed portion 81A that is spotted in a substantially rectangular shape is provided.
Six mounting boards 1 are housed in the recess 81A in a lump, with their long sides abutting each other and aligned in the front-rear direction.

On the other hand, as shown in FIG. 4B, the fixing plate 82 is provided on the right and left sides of the upper surface of the jig body 81.
1 are mounted so as to be slidable in a direction parallel to the short side (horizontal) direction of the mounting substrate 1. After the mounting substrates 1 are collectively stored, the upper surfaces of the side edges of the mounting substrates 1 are pressed together from above. It has become. In this embodiment,
Although the number of the mounting substrates 1 from which the oxide film 5 is collectively removed is set to six, it is preferable that a large number of the mounting substrates 1 are collectively fixed and processed collectively.

As another fixing jig 9 for collectively fixing the mounting substrate 1, for example, as shown in FIG. 3C, a depression 91A for setting the mounting substrate 1 collectively on the upper surface side.
And a step surface 9 at the center of the upper surface of the jig body 91 on which the mounting board 1 is collectively set.
A configuration may also be provided that includes a regulating plate 92 that urges the elastic force or the like toward 1B to press and fix the mounting substrate 1 against the step surface 91B. In this case, it is preferable that the restricting plate 92 is provided with a taper at the contact surface 92A with the mounting substrate 1 so as to prevent the mounting substrate 1 from being lifted up and coming off. In addition to the method in which the mounting substrates 1 are arranged one-dimensionally in one line in the front-rear direction and fixed as in this embodiment, the mounting substrates 1 may be two-dimensionally arranged in the front-rear and left-right directions and fixed.

Next, an oxide film is removed from the fixing jig 8 having such a configuration in the second step. The method of removing the oxide film is, for example, the same as that of the first embodiment. Using a rubbing type cleaner 7, the oxide film 5 is formed in the same manner.
May be rubbed. In this case, as a mode of the rubbing operation when rubbing with the rubbing cleaner 7, various methods can be applied.

In this embodiment, for example, as in the second embodiment, the rubbing operation may be performed in a plurality of directions by the rubbing cleaner 7. In this case, it is preferable to use “plastic eraser, PE-01A” (manufactured by Tombow Pencil) for the abrasion-type cleaner 7. Then, the rubbing operation in this case includes the directions A, B, C, which are arranged at an angle of 90 ° to each other.
This is performed by assigning a plurality of rubbing directions in the order of the direction D. The pressure at which the solder bumps 2 are rubbed by the rubbing cleaner 7 may be the same as in the case of the second embodiment. Also,
Similarly, this rubbing operation is performed by, for example,
The rubbing operation may be performed 40 times in total, including 10 times from the rubbing direction B, 10 times from the rubbing direction C, and 10 times from the rubbing direction D.

Therefore, according to this embodiment, since the fixing jig 8 has a relatively simple structure, it can be reduced at a low cost. The oxide film 5 can be removed from the mounting substrate at once. As a result, the working efficiency at the time of mounting can be greatly improved, and moreover, a large number of semiconductor devices E on which bare chips having high operation reliability are mounted can be obtained at the same time.

Next, a fourth embodiment according to the present invention will be described. In the method for mounting a bare chip according to this embodiment, the configuration of the MMIC chip 3 used as a bare chip is substantially the same as that of the first embodiment, but as shown in FIG. The gold bumps 10 are formed on the surface of the substrate 4. On the other hand, this solder bump 2
The oxide film 5 is also formed on the surface of the substrate as in the case of the first embodiment. In this embodiment, the semiconductor device F (see FIG. 4E) is formed by a bare chip mounting method.

Accordingly, in the fourth embodiment, the removal of the oxide film 5 in the second step is performed in the same manner as in any one of the first to third embodiments. In the fourth step of FIG. 4D, when the MMIC chip 3 is mounted on the mounting substrate 1 as a bare chip, similarly to the above first to third embodiments, for example, a method such as image processing is used. ,
The positions of both the MMIC chip 3 and the mounting board 1 are adjusted and arranged with high accuracy. After that, the MMIC chip 3 is moved and lowered in the direction of the mounting substrate 1, and the gold bumps 10 and the solder bumps 2 are fixed in a contact state.

In the fifth step, as shown in FIG.
In the same manner as in the first to third embodiments, that is, while the gold bump 10 and the solder bump 2 are fixed in contact with each other, the solder bump 2 is melted or solid-phased according to a predetermined temperature profile. By diffusing, the bonding between the gold bump 10 and the solder bump 2 is achieved. Then, the mounting substrate 1 and M
An underfill is injected into a gap between the MIC chip 3 and the MIC chip 3 to stabilize both junctions and achieve insulation.

Here, the operation of the semiconductor device F according to the fourth embodiment will be described. In this semiconductor device F, similarly to the first to third embodiments, when a driving bias is supplied from a circuit pattern (not shown) on a mounting substrate 1 (not shown), the solder bumps 2, the gold bumps 10, and the electrodes 4 is applied to the MMIC chip 3. Similarly, an input signal is applied to the solder bump 2, the gold bump 10
And input to the MMIC chip 3 via the electrode 4. On the other hand, the output signal is output to a circuit pattern on the mounting board 1 via the electrode 4, the gold bump 10, and the solder bump 2.

Therefore, in the fourth embodiment, similarly to the first to third embodiments, the rubbing-type cleaner 7 can be used in a relatively short time without separately introducing an expensive device.
Moreover, the oxide film 5 can be mechanically and physically removed by a simple operation. As a result, a highly reliable bare chip mounting method can be realized. In particular, in this embodiment, even if the electrode 4 is formed of a material having poor solder wettability, the connection with the solder bump 2 can be stably performed by relaying the gold bump 10. .

In this embodiment, the solder bumps 2
Unlike the bonding using only the metal bumps, the gold bumps 10 are interposed between the electrodes 4 and the solder bumps 2. During the bonding, the solder bumps 2 that have melted and have lost the holding force are strongly reinforced. 10 can do. Thereby, even when the MMIC chip 3 is pressed against the mounting substrate 1 during mounting,
It is possible to secure a gap between the mounting substrate 1 and the MMIC chip 3 that is sufficient to perform underfill injection. As a result, a reliable underfill can be performed between the two, so that incomplete sealing such as air void does not occur, and a stable bonding state can be obtained.

Next, a fifth embodiment according to the present invention will be described. In the method for mounting a bare chip according to this embodiment, a mounting board 1 that is substantially the same as that of the first embodiment is used, but as shown in FIG. And a metal core 21 and a solder material 22 coated on the surface thereof. In this embodiment, the semiconductor device G (see FIG. 5E) is formed by a bare chip mounting method.

The metal nucleus 21 according to this embodiment is for preventing the shape of the solder bump 2 from being destroyed at the time of joining or removing, and is easy to form by a plating process and has good solder joints. Therefore, copper (Cu) is used. On the other hand, the same solder material as that used for forming the solder bumps 2 in the first embodiment is used as the solder material 22.

Also in the fifth embodiment, the oxide film 5 is formed on the surface of the solder material 22 due to the environmental temperature, humidity, the presence of a reactant, and the like. Therefore, in the step of removing the oxide film 5 in the second step, the rubbing operation is performed by the rubbing cleaner 7 as in the first to third embodiments.
As a result, in the third step, as shown in FIG. 5C, the oxide film 5 is effectively formed from the solder material 22 in the same manner as when the solder bumps 2 in the first to third embodiments are used. And the solder wettability is improved.

In the fourth step shown in FIG. 5D, when the MMIC chip 3 is mounted on the mounting substrate 1, for example, an appropriate image processing is performed in the same manner as in the first to third embodiments. For example, the positions of both the MMIC chip 3 and the mounting board 1 are adjusted with high accuracy and arranged. Thereafter, the MMIC chip 3 is moved and lowered in the direction of the mounting substrate 1 to fix the electrodes 4 and the solder material 22 of the solder bumps 2 in a contact state. Next, in a fifth step, the first
To the electrode material 4 and the solder material 2 in the same manner as in the third to third embodiments.
The electrode 4 and the solder material 22 are further melted or solid-phase-diffused according to a predetermined temperature profile while the electrode 4 and the electrode material 4 are kept in contact with each other.
And the metal nucleus 21 are joined. Then, the mounting substrate 1 and M
An underfill is injected into a gap between the MIC chip 3 and the MIC chip 3 to stabilize both junctions and achieve insulation.

Next, the operation of the semiconductor device G according to the fifth embodiment will be described. In this semiconductor device G,
In the same manner as in the first to third embodiments, the mounting substrate 1
When a drive bias is supplied from a circuit pattern (not shown), the drive bias is applied to the MMIC chip 3 via the metal core 21, the solder material 22, and the electrode 4. Similarly, an input signal is input to the MMIC chip 3 via the metal core 21 of the solder bump 2, the solder material 22, and the electrode 4. On the other hand, the output signal is output to the circuit pattern on the mounting substrate 1 via the electrode 4, the solder material 22 of the solder bump 2, and the metal core 21.

Therefore, in the fifth embodiment, similarly to the first to fourth embodiments, a simple rubbing type cleaner 7 can be used without using an expensive dedicated device separately. The solder oxide film 5 can be mechanically and physically removed in a short time and with a simple operation. As a result, the bonding between the electrode 4 and the solder bump 2 is hindered due to the occurrence of solder leakage as in the related art, or uncertain bonding occurs.
Such troubles can be eliminated, and a highly reliable bare chip mounting method can be realized.

In this embodiment, the mechanical strength of the solder bump 2 can be improved by the metal nucleus 21 formed in the solder bump 2. 2 can reduce the occurrence of shape destruction. As a result, even when the MMIC chip 3 is pressed against the mounting substrate 1 at the time of mounting, the metal nucleus 21 causes a sufficient amount of underfill injection between the mounting substrate 1 and the MMIC chip 3. A gap can be secured. As a result, a reliable underfill can be performed between the two, so that incomplete sealing such as air voids does not occur, and the bonding state is stabilized. Furthermore, even if the solder material 22 is strongly pressed and crushed in the removing step by the rubbing operation with the cleaner 7, the metal core 2
1, the shape can be prevented from being destroyed.
A sufficient gap can be secured between the two, and a reliable underfill can be performed.

[0054]

As described above, according to the present invention, there is provided a method of mounting an electronic component on a substrate via a solder bump, the method comprising: It has a removal process that removes using a rubbing type cleaner, eliminating the need to separately introduce expensive equipment and removing the oxide film on the solder bumps in a relatively short time and with an easy procedure. be able to. Therefore, the removal operation of the oxide film, in other words, the reliable bonding by improving the solder wettability can be realized at low cost, and a highly reliable mounting method of the electronic component can be provided at low cost.

[Brief description of the drawings]

FIG. 1 is a process chart showing a method for mounting a bare chip according to a first embodiment of the present invention.

FIG. 2 is an explanatory view specifically showing a removing step according to a second embodiment of the present invention.

3A and 3B show a fixing jig used in a method for mounting a bare chip according to a third embodiment of the present invention, wherein FIG. 3A is a schematic perspective view, FIG. 3B is a cross-sectional view, and FIG. It is a schematic sectional drawing which shows an example.

FIG. 4 is a process chart showing a method for mounting a bare chip according to a fourth embodiment of the present invention.

FIG. 5 is a process chart showing a method for mounting a bare chip according to a fifth embodiment of the present invention.

FIG. 6 is a process chart showing a conventional method for mounting a bare chip.

FIG. 7 is a process diagram showing a defect in a conventional method for mounting a bare chip.

FIG. 8 is a process chart showing another conventional method for mounting a bare chip.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mounting board 2 Solder bump 21 Metal core 22 Solder material 3 MMIC chip (Bare chip) 4 Electrode 5 Oxide film 7 Scratch-type cleaner 8 Fixing jig 81 Jig body 81A Depression 82 Fixing plate 9 Fixing jig 91 Jig body 91A recess 91B step surface 92 regulating plate 92A contact surface 10 gold bump

Claims (21)

[Claims] An electronic component mounting method for mounting an electronic component on a substrate via a solder bump, comprising a removing step of removing an oxide film formed on the solder bump by a rubbing action of a cleaner before mounting. A method for mounting an electronic component, comprising: 2. The electronic component mounting method according to claim 1, wherein a pressure at which the cleaner bumps the solder bumps is 0.5 kgf to 4 kgf. 3. The method according to claim 1, wherein the number of times the solder bump is rubbed by the cleaner is 20 to 100 times.
Or the mounting method of the electronic component of 2. 4. The method according to claim 1, wherein the number of times of the rubbing operation for rubbing the solder bumps with the cleaner is divided into a plurality of groups, and the rubbing operation is performed in the plurality of different directions on the substrate plane. The method for mounting an electronic component according to claim 1, further comprising a divided rubbing step. 5. The electronic component mounting method according to claim 4, wherein the directions of the rubbing operation are four directions forming an intersection angle of 90 degrees with each other on the substrate. 6. The method according to claim 1, further comprising a fluxless step of performing a fluxless solder fusion bonding or a fluxless solder solid-phase diffusion bonding when mounting the electronic component on the substrate after the removing step. Any one of 5
Item mounting method. 7. An electronic device in which a substrate on which solder bumps are formed and an electronic component on which electrodes are formed are connected to the electronic component on the substrate by bonding the solder bumps and the electrodes. A method of mounting an electronic component, comprising: a removing step of removing an oxide film formed on the solder bump by a rubbing action of a cleaner. 8. The method according to claim 7, further comprising a fluxless step of performing fluxless solder fusion bonding or fluxless solder solid-phase diffusion bonding after the removing step.
The electronic component mounting method described in the above. 9. A board on which solder bumps are formed and an electronic component on which gold bumps are formed, and the electronic component is connected to the board by bonding the solder bumps and the gold bumps. A method for mounting an electronic component, comprising: a removing step of removing an oxide film formed on the solder bump by a rubbing action of a cleaner. 10. The method according to claim 1, further comprising: a fluxless step of performing a fluxless solder fusion bonding or a fluxless solder solid-phase diffusion bonding after the removing step.
9. The mounting method of the electronic component according to 9. 11. An electronic component mounting method for mounting an electronic component on a substrate via solder bumps, comprising: forming an oxide film formed on the solder bumps by forming a hemispherical solder material on the substrate. A removal step of removing by a rubbing action of a cleaner, and a fluxless step of performing fluxless solder fusion bonding after the removal step,
A method of mounting an electronic component, comprising: 12. A method for mounting an electronic component on a substrate via solder bumps, the method comprising: mounting an oxide film formed on the solder bumps by coating a metal material on the substrate with a solder material. A removal step of removing by a rubbing action of a cleaner, and a fluxless step of performing fluxless solder fusion bonding after the removal step,
A method of mounting an electronic component, comprising: 13. A removing step of fixing a plurality of substrates integrally and removing an oxide film formed on the solder bumps of the substrates from the plurality of substrates collectively using a rubbing cleaner. The method of mounting an electronic component according to claim 1. 14. The electronic component mounting method according to claim 13, wherein after the removing step, the electronic component is individually mounted on each substrate. 15. The electronic component mounting method according to claim 13, wherein, after the removing step, the electronic component is mounted collectively on a plurality of substrates processed simultaneously in the removing step. 16. The solder bump is made of any one of a tin-lead alloy material, a tin-silver alloy material, a tin-silver-copper alloy material, a tin-bismuth alloy material, and a tin-gold alloy material. The method for mounting an electronic component according to claim 1, wherein the mounting method is performed. 17. The electronic component mounting method according to claim 1, wherein the cleaner performing the rubbing action is formed of a plastic-rubber mixed material. 18. The electronic device according to claim 1, wherein the electronic component is a photoelectric conversion element such as an avalanche photodiode, a pin photodiode, a laser diode, or a photodiode. How to mount electronic components. 19. The electronic component according to claim 1, wherein the electronic component is a microwave monolithic integrated circuit such as a preamplifier, a gain control amplifier, and a demodulator that handles signals in a high frequency range. Item mounting method. 20. The substrate according to claim 1, wherein the substrate is formed of a ceramic material such as alumina, aluminum nitride, glass ceramic, or the like.
Item mounting method. 21. The electronic component mounting method according to claim 1, wherein the solder bumps are formed of a metal core and a solder material covering the surface of the metal core.