JP7128994B2 - Electronic member removal method and device - Google Patents

Description

The present invention relates to technology for removing electronic components mounted on a substrate by electromagnetic induction heating.

In electronic equipment, solder joints are used to mount electronic parts such as semiconductors on circuit boards. Solder joints are performed by placing solder between objects to be joined and then heating and melting the solder.

A plurality of electronic components are mounted on the board. To remove only the relevant electronic parts while avoiding the influence on normal electronic parts when there is an abnormality or a failure.

For example, hot air is supplied to the electronic component to melt the solder, and the electronic component is removed from the substrate (for example, Patent Document 1).

By the way, in recent years, miniaturization of electronic components has progressed. For example, micro LEDs with a size of 100 μm or less are used as the number of pixels of monitors increases. It is difficult to apply sufficient hot air only to the small electronic components to be removed while avoiding the influence on the adjacent small electronic components.

In addition, the removal technology using hot air supply can be applied to substrates made of heat-resistant resins such as polyamide-imide and polyimide, but it is difficult to apply to substrates made of non-heat-resistant materials such as thermoplastic resins, paper, and cloth. is. Examples of heat-resistant thermoplastic resins include ABS resin, acryl, polycarbonate, polyester, polybutylene, polyurethane, and PET (polyethylene terephthalate).

On the other hand, electromagnetic induction heating is available as a spot heating technique. An electronic component mounted on a substrate can also be removed by electromagnetic induction heating (for example, Patent Document 2).

FIG. 7 is a conceptual diagram relating to the basic principle of electromagnetic induction heating. An electromagnetic induction heating device is composed of an induction coil, a power source, and a control device.

When an alternating current is passed through an induction coil, magnetic field lines of varying strength are generated. When a substance that conducts electricity (specifically, the object to be joined and is usually made of metal) is placed near it, eddy currents flow in the metal under the influence of the changing magnetic lines of force. Metal generally has electrical resistance, so when an electric current flows through the metal, Joule heat is generated and the metal self-heats. This phenomenon is called induction heating.

The amount of heat generated by electromagnetic induction Q is expressed by the following equation. Q = (V2/R) x t [V = applied voltage: R = resistance: t = time]

With electromagnetic induction heating, only the metal generates heat, so there is little risk of thermal damage to the surrounding resin portion. In addition, there is almost no thermal effect on the electronic parts, and there is little possibility that the electronic parts will be thermally damaged.

With electromagnetic induction heating, only metals generate heat, so they can be joined in a short time with less energy. The time required for one bonding is several seconds to ten and several seconds.

With electromagnetic induction heating, a predetermined Joule heat can be obtained within a uniform magnetic field, so the joining accuracy is high. Also, within a uniform magnetic field, a plurality of bonds can be formed at once.

In electromagnetic induction heating, it is easy to control the amount of power output and the output time by means of a control device. As a result, it is easy to control the heating temperature and heating time. A desired temperature profile can be set.

The metal terminals on the circuit board generate heat, the heat is transferred to the solder, and the solder melts. Solder is melted at the time of detachment as well as at the time of joining.

In electromagnetic induction heating, it is easy to control the magnetic force by adjusting the power output. As a result, it is possible to heat only the metal terminal on the circuit board side corresponding to the electronic component to be removed while avoiding the influence on the adjacent electronic component.

As described above, the method of removing an electronic component mounted on a circuit board by electromagnetic induction heating can cope with miniaturization of the electronic component. Also, it can be applied to substrates made of non-heat-resistant materials.

JP 2004-186491 A JP-A-2001-044616

As described above, according to the method of removing an electronic component mounted on a substrate by electromagnetic induction heating, it is possible to cope with miniaturization of the electronic component.

However, as electronic components are further miniaturized, the area of metal terminals that generate heat is also reduced. In particular, when a large number of electronic components are arranged in a given area, or when electronic components have a large number of terminals (for example, ball grid array (BGA) or chip size package (CSP)), the metal terminal area is It becomes even narrower. As a result, the resistance R increases, and a sufficient amount of heat cannot be secured (the denominator of the above theoretical formula increases).

Based on the above theoretical formula, the calorific value Q can be ensured by increasing the applied voltage V or increasing the application time t.

On the other hand, when the actual prototype model was verified, when the metal terminal area was about 1 mm x 1 mm or less, depending on the type of solder, defects such as poor heat generation were occasionally observed, and the metal terminal area was about 500 μm x 500 μm. The problem is noticeable below. In electromagnetic induction heating, although the applied voltage and the applied time can be adjusted with high accuracy, there is a limit to the problem resolution even if the applied voltage and the applied time are adjusted.

By the way, there are several types of solder, and generally, high-temperature solder (for example, SnAgCu solder, melting point of about 220° C.) to low-temperature solder (for example, SnBi solder, melting point of about 140° C.) are used. . Even if solder joints using low-temperature solder were to be targeted, the above problems would occur.

The size of the circuit-side terminal corresponding to the micro LED is about 25 μm×25 μm to 50 μm×50 μm, and no method has been established to remove only the defective micro LED. The inventors of the present application are considering application to removal of electronic components of this size in the future, and there is a high possibility that the above problems will become apparent.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide a technology for removing an electronic member that can be used even when the metal terminal area is small.

The present invention, which solves the above problems, is an apparatus for removing an electronic member mounted on a circuit board by soldering from the circuit board. The device includes a suction nozzle having a hollow, suction means for sucking the electronic member at the tip of the suction nozzle, and a heating element provided below the suction nozzle, and the heating element is heated by electromagnetic induction heating. A heating means and a conducting means for conducting heat generated by the heating element to the tip of the suction nozzle are provided.

The heat generated by the heating means is transmitted to the electronic component and the solder through the conducting means, melting the solder. During this time, the suction means maintains the state of suction between the nozzle and the electronic component. Even if the metal terminal area is small and the amount of heat generated is insufficient, the heating element generates heat. As a result, the electronic member mounted on the circuit board by soldering can be removed from the circuit board.

In the above invention, preferably, the heating element is larger than the terminals of the circuit board.

As a result, even when the area of the metal terminal is small and the amount of heat generated is insufficient, the heating element reliably generates heat.

In the above invention, preferably, the terminal size of the circuit board is 500×500 μm or less. It is more preferably 250 μm×250 μm or less, and still more preferably 100 μm×100 μm or less.

When the terminal size is 1 mm×1 mm or less, problems such as an insufficient amount of heat generated in electromagnetic induction heating are often seen, and when the terminal size is 500×500 μm or less, the problem becomes significant. As the space becomes narrower, the amount of heat generated becomes insufficient. According to the present invention, the metal terminal can be removed even when the area of the metal terminal is small.

Preferably, the above invention further comprises a ferrite core that is wrapped around the heating element.

As a result, the amount of heat generated by the heating element increases, and the amount of heat generated by the metal terminals also increases. The synergistic effect reliably melts the solder.

The present invention for solving the above problems is a method for removing an electronic member mounted on a circuit board by soldering from the circuit board. Using the above apparatus, the heating means heats the heating element, the conduction means conducts the heat generated by the heating element to the tip of the suction nozzle, melts the solder, and the suction means heats the tip of the suction nozzle. By sucking the electronic member, the electronic member mounted on the circuit board by soldering is removed from the circuit board.

Even if the metal terminal area is small and the amount of heat generated is insufficient, the heating element generates heat. As a result, the electronic member mounted on the circuit board by soldering can be removed from the circuit board.

The present invention, which solves the above problems, is an apparatus for removing an electronic member mounted on a circuit board by soldering from the circuit board. The apparatus includes a hollow suction nozzle made of metal, suction means for sucking the electronic member at the tip of the suction nozzle, heating means for heating the tip of the suction nozzle by electromagnetic induction heating, Prepare.

Even if the metal terminal area is small and the amount of heat generated is insufficient, the metal nozzle generates heat. As a result, the electronic member mounted on the circuit board by soldering can be removed from the circuit board.

The present invention, which solves the above problems, is an apparatus for removing an electronic member mounted on a circuit board by soldering from the circuit board. The apparatus includes a hollow suction nozzle made of ferrite, suction means for sucking the electronic member at the tip of the suction nozzle, and a heating element attached to the tip of the suction nozzle, wherein the heat is generated. and heating means for heating the body by electromagnetic induction heating.

Even if the metal terminal area is small and the amount of heat generated is insufficient, the heating element generates heat. As a result, the electronic member mounted on the circuit board by soldering can be removed from the circuit board.

The present invention for solving the above problems is a method for removing an electronic member mounted on a circuit board by soldering from the circuit board. Using the above apparatus, the tip of the suction nozzle is heated by the heating means to melt the solder, the electronic member is sucked at the tip of the suction nozzle by the suction means, and the electronic component mounted on the circuit board is soldered. Remove the member from the circuit board.

Even if the metal terminal area is small and the amount of heat generated is insufficient, the tip of the nozzle generates heat. As a result, the electronic member mounted on the circuit board by soldering can be removed from the circuit board.

The present invention, which solves the above problems, is an apparatus for removing an electronic member mounted on a circuit board from the circuit board by a heat fusible means. The device includes a suction nozzle having a hollow, suction means for sucking the electronic member at the tip of the suction nozzle, and a heating element provided below the suction nozzle, and the heating element is heated by electromagnetic induction heating. A heating means and a conducting means for conducting heat generated by the heating element to the tip of the suction nozzle are provided.

The present application is applicable to releasing bonds by means of heat fusible means other than solder joints. For example, the electronic member can be removed from the circuit board by releasing AFC (anisotropic conductive film) bonding or bonding with a conductive adhesive.

According to the present invention, the electronic member can be removed from the circuit board even if the metal terminal area is small.

Apparatus overview (perspective view) according to the first embodiment Apparatus overview (cross-sectional view) according to the first embodiment Operation explanatory diagram according to the first embodiment Operation explanatory diagram according to the second embodiment Apparatus overview (cross-sectional view) according to the third embodiment Apparatus overview (cross-sectional view) according to the fourth embodiment Basic principle of electromagnetic induction

<First Embodiment Configuration>
FIG. 1 is a perspective view of an apparatus outline according to the first embodiment, and FIG. 2 is a cross-sectional view.

The device comprises a nozzle 50, a suction device 60, a heating device 70, and a control device 80 (see FIG. 3).

A main part (or all) of the nozzle 50 is made of a material with high heat resistance and high thermal conductivity. Examples include ceramics, ruby, sapphire, and diamond. In addition, as of 2019, ceramics has a minimum pore diameter of 10 μm in ceramics processing accuracy, and the present invention can be sufficiently realized.

Nozzle 50 has a hollow 51 . One end of the hollow 51 sucks electronic components, and the other end of the hollow 51 is connected to a suction device 60 . Thereby, the nozzle 50 can be sucked through the hollow 51 . The tip of the nozzle 50 is preferably tapered like a cone so as to correspond to micro electronic components.

A heating element 71 is provided below the nozzle 50 so as to wind around the nozzle 50 . The heating element 71 is generally made of metal material. Metal materials include gold, silver, copper, aluminum, nickel, and chromium. Examples of the method of arranging the heating element 71 below the nozzle 50 include deposition, plating, and fitting the nozzle 50 to the cylindrical heating element 71 .

A coil 72 is arranged around the nozzle 50 . Conversely, the nozzle 50 is arranged in the coil internal space. The heating element 71, the coil 72, and the power source (see FIG. 7) constitute a heating device (heating means) 70. FIG. When a current is supplied from the power supply to the coil 72, a magnetic field is generated, and the heating element 71 within the magnetic field area heats up.

<First Embodiment Operation>
FIG. 3 is an operation explanatory diagram according to the first embodiment. 1 and 2, the heating element 71 is provided on the nozzle trunk, whereas FIG. 3 is slightly different in that the heating element 71 is provided on the nozzle weight. It is preferable that the heating element 71 is provided on the nozzle weight so as to be closer to the solder, but if it is difficult to provide the heating element 71 on the nozzle weight, the heating element 71 may be provided on the nozzle stem. The principle of operation is common.

A plurality of electronic components (for example, LEDs) 20 are mounted on the circuit board 10 . Specifically, wiring circuits 11 (not shown) and circuit-side terminals 12 are formed on the circuit board 10 . The electronic component 20 has electronic component side terminals 22 . The circuit-side terminals 12 and the electronic-component-side terminals 22 are joined via solder 30 .

When one electronic component among a plurality of electronic components has an abnormality or fails, the operation of removing only that electronic component while avoiding the influence on adjacent normal electronic components will be described.

In this apparatus, the suction device 60 and the heating device 70 are interlocked by the control device 80 .

When the suction device 60 operates, a negative pressure is generated inside the nozzle cavity 51 . When the nozzle 50 is brought close to the electronic component 20 in this state, the tip of the nozzle 50 adheres to the surface of the electronic component 20 . Here, the suction device 60, the hollow nozzle 51, and the tip of the nozzle 50 constitute suction means.

On the other hand, when an alternating current is passed through the coil 72, magnetic lines of force with varying strength are generated. When a substance that conducts electricity (a metal heating element 71 in this application) is placed near it, an eddy current flows in the metal under the influence of the changing magnetic lines of force. Since metal generally has electrical resistance, when a current flows through the metal, Joule heat is generated and the metal (heating element 71) self-heats. This phenomenon is called electromagnetic induction heating.

Heat generated by heating device 70 is conducted from heating element 71 to electronic component 20 and solder 30 via nozzle 50 having excellent thermal conductivity. The nozzle 50 itself constitutes the conducting means.

As a result, the solder 30 is melted, and the connection between the circuit-side terminal 12 and the electronic component-side terminal 21 is released. On the other hand, the suction state between the electronic component 20 and the nozzle 50 is maintained, and the electronic member 20 can be removed from the circuit board 10 by moving the nozzle 50 away from the circuit board 10 . Furthermore, when the suction device 60 stops operating, the suction state between the electronic component 20 and the nozzle 50 is released, and the electronic component 20 can be recovered.

<Remarks>
By the way, the problem of the present application is that the area of the terminals 12 is small, and a sufficient amount of heat generated by the terminals 12 cannot be ensured. However, the terminal 12 does not generate heat by itself due to electromagnetic induction heating. Heat generated at terminal 12 is also conducted to solder 30 . Therefore, it is preferable that the terminal 12 is also made of metal.

On the other hand, if the terminal 12 itself is not expected to generate heat at all, a conductive polymer, conductive carbon, or the like may be used. Also, since the wiring is thinner than the size of the terminal 12 and does not contribute to the electromagnetic induction heating, it is not considered.

Note that the wiring and the terminal 12 are made of a conductive material. Generally, it is a metallic material including gold, silver, copper, aluminum, nickel, chromium, and the like. Wiring and terminals 12 are formed by common conventional techniques (printing, etching, metal deposition, plating, silver salts, etc.).

<Examination of the size of the first embodiment>
A problem of the present application is that a sufficient amount of heat generated by the terminals 12 cannot be ensured when the area of the terminals 12 is small. Therefore, the interrelationship of each size is very important. Each size in the first embodiment will be outlined below.

When we actually tested it with a prototype model, we found that if the metal terminal area was less than 1mm x 1mm, problems such as poor heat generation were observed depending on the type of solder. became prominent. In addition, the inventor of the present application is considering removal of electronic components (for example, micro LEDs) having a metal terminal area of about 25 μm×25 μm to 50 μm×50 μm in the future.

Therefore, the metal terminal area is 1 mm×1 mm or less, preferably 500 μm×500 μm or less, more preferably 250 μm×250 μm or less, and even more preferably 100 μm×100 μm or less.

As an example, an electronic component of about 1 mm×1 mm having a metal terminal area of 250 μm×250 μm and four terminals will be described with respect to the interrelationship between sizes.

A plurality of electronic components 20 are mounted on the circuit board 10 . The electronic component interval corresponds to the electronic component size. In the above example, the intervals are 1 mm.

Here, if the nozzle diameter is 3 mm or more (≈electronic component size + distance between both sides), there is a possibility that adjacent electronic components will be affected. Therefore, it is preferable that the nozzle diameter is less than 3 mm (≈the electronic component size + the distance between both sides). On the other hand, since heat conduction occurs through contact between the tip of the nozzle 50 and the electronic component 20, the diameter of the nozzle is preferably about 1 mm (equivalent to the size of the electronic component) or more. The diameter of the suction hole (hollow 51) is preferably about 100-200 μm.

Assuming that the nozzle diameter is 1 mm, the circumferential length of the heating element 71 is about 3 mm. If the axial length of the heating element 71 is 2.5 mm (about 10 times the size of the metal terminal), the area of the heating element is 120 times the area of the metal terminal, and a sufficient area can be secured. That is, the heating element 71 is sufficiently larger than the metal terminal 12 .

As another example, an electronic component of about 200 μm×200 μm having a metal terminal area of 50 μm×50 μm and four terminals will be described with respect to the interrelationship between sizes.

A plurality of electronic components 20 are mounted on the circuit board 10 . The electronic component interval corresponds to the electronic component size. In the above example, the interval is 200 μm.

Here, if the nozzle diameter is 600 μm or more (≈electronic component size+adjacent spacing), there is a possibility that adjacent electronic components will be affected. Therefore, it is preferable that the nozzle diameter is less than 600 μm (≈the electronic component size + the distance between both sides). On the other hand, since heat conduction occurs through contact between the tip of the nozzle 50 and the electronic component 20, the nozzle diameter is preferably about 200 μm (corresponding to the size of the electronic component) or more. The diameter of the suction hole (hollow 51) is preferably about 20-40 μm. In addition, as of 2019, ceramics has a minimum pore diameter of 10 μm in ceramics processing accuracy, and the present invention can be sufficiently realized.

If the nozzle diameter is 300 μm, the circumferential length of the heating element 71 is about 0.9 mm. If the axial length of the heating element 71 is 1.2 mm (about 24 times the size of the metal terminal), the area of the heating element is 432 times the area of the metal terminal, and a sufficient area can be secured. That is, the heating element 71 is sufficiently larger than the metal terminal 12 .

<Effect of the first embodiment>
Heating by the heating element 71 also provided in the suction nozzle 50 allows the electronic member 20 to be removed from the circuit board 10 even if the area of the metal terminal 12 on the circuit side is small. At that time, it does not affect the adjacent electronic members.

<Second embodiment>
FIG. 4 is an operation explanatory diagram according to the second embodiment. At the same time, a schematic configuration will also be described. The second embodiment is a modification of the first embodiment.

That is, the ferrite core 73 is wrapped around the nozzle 50 and the heat generating element 71 . Here, the heating element 71, the coil 72, the ferrite core 73, and the power source (see FIG. 7) constitute a heating device (heating means) .

When a current is supplied to the coil 72 from a power source, a magnetic field is generated and converged along the ferrite core 73 . As a result, the amount of heat generated by the heating element 71 increases. Moreover, the amount of heat generated by the metal terminal 12 also increases. This synergistic effect ensures that the solder 30 melts.

The operation of removing the electronic member 20 from the circuit board 10 by interlocking the suction device 60 and the heating device 70 is the same as in the first embodiment.

<Third Embodiment>
FIG. 5 is a cross-sectional view of an apparatus outline according to the third embodiment. In the first and second embodiments, in order to secure the hollow space 51 of the fine holes, ceramics or the like with high processing accuracy is used for the main part of the nozzle. In contrast, in the third embodiment, the main part (or the whole) of the nozzle 55 is made of metal.

The third embodiment can be applied when the same level of metal processing accuracy as that of ceramics can be obtained, or when micropores as small as those of the first and second embodiments are not required.

Here, the metal nozzle 55, the coil 72 and the power source (see FIG. 7) constitute a heating device (heating means) 70. As shown in FIG. When a current is supplied to the coil 72 from the power supply, a magnetic field is generated, and the metal nozzle 55 within the magnetic field area heats up. The heat generated by nozzle 55 is conducted to electronic component 20 and solder 30 via the tip of nozzle 55 . The solder 30 is thereby melted.

The operation of removing the electronic member 20 from the circuit board 10 by interlocking the suction device 60 and the heating device 70 is the same as in the first embodiment.

<Fourth Embodiment>
FIG. 6 is a cross-sectional view of an apparatus outline according to the fourth embodiment. It is a combination of the technical idea according to the second embodiment and the technical idea according to the third embodiment.

That is, the main part of nozzle 56 is composed of a ferrite core. A metal heating attachment 74 is fitted to the tip of the nozzle 56 .

The heating attachment 74 has an insertion portion and a contact portion. The heat generating attachment 74 insertion portion is inserted into the hollow 51 . The contact portion of the heat-generating attachment 74 can contact the electronic component at the nozzle tip position.

Here, the ferrite core nozzle 56 , the coil 72 , the heat generating attachment 74 and the power source (see FIG. 7) constitute a heating device (heating means) 70 . When a current is supplied to coil 72 from a power supply, a magnetic field is generated and focused along ferrite core 56 . The heat-generating attachment 74 within the magnetic field generates heat. Heat generated by heat-generating attachment 74 is conducted to electronic component 20 and solder 30 . The solder 30 is thereby melted.

The operation of removing the electronic member 20 from the circuit board 10 by interlocking the suction device 60 and the heating device 70 is the same as in the first embodiment.

<Others>
The present application is applicable to releasing bonds by means of heat fusible means other than solder joints. For example, the electronic member can be removed from the circuit board by releasing AFC (anisotropic conductive film) bonding or bonding with a conductive adhesive.

REFERENCE SIGNS LIST 10 circuit board 11 wiring circuit 12 circuit side terminal 20 electronic component 22 electronic component side terminal 30 solder 50 nozzle (made of ceramics)
51 hollow 55 nozzle (made of metal)
56 nozzle (made of ferrite core)
60 suction device 70 heating device 71 heating element 72 coil 73 ferrite core 74 heating attachment 80 control device

Claims (8)

A plurality of electronic members are mounted on a circuit board at intervals of 1 mm or less, and an apparatus for removing electronic members mounted on terminals of 500×500 μm or less on the circuit board by soldering from the circuit board,
a suction means including a suction nozzle having a hollow with a diameter of 200 μm or less, and for sucking the electronic member at the tip of the suction nozzle;
a heating means including a heating element provided below the suction nozzle for heating the heating element and heating the terminals of the circuit board by electromagnetic induction heating;
and a conducting means for conducting heat generated by the heating element to the tip of the suction nozzle. 2. The device of claim 1, wherein the heating element is larger than the terminals of the circuit board. 3. The device according to claim 1, further comprising a ferrite core that is wrapped around the heating element. Using the device according to any one of claims 1, 2, and 4,
Heating the heating element with the heating means and heating the terminals of the circuit board,
Conducting the heat generated by the heating element to the tip of the suction nozzle by the conduction means to melt the solder,
A method for removing an electronic member, wherein the electronic member mounted on the circuit board by soldering is removed from the circuit board by sucking the electronic member at the tip of the suction nozzle by the suction means. A plurality of electronic members are mounted on a circuit board at intervals of 1 mm or less, and an apparatus for removing electronic members mounted on terminals of 500×500 μm or less on the circuit board by soldering from the circuit board,
a suction unit that has a hollow with a diameter of 200 μm or less and includes a suction nozzle made of metal and that sucks the electronic member at the tip of the suction nozzle;
heating means for heating the tip of the suction nozzle and the terminal of the circuit board by electromagnetic induction heating;
An apparatus comprising: A plurality of electronic members are mounted on a circuit board at intervals of 1 mm or less, and an apparatus for removing electronic members mounted on terminals of 500×500 μm or less on the circuit board by soldering from the circuit board,
a suction means having a hollow with a diameter of 200 μm or less and including a suction nozzle formed of ferrite for sucking the electronic member at the tip of the suction nozzle;
a heating means including a heating element attached to the tip of the suction nozzle, heating the heating element by electromagnetic induction heating, and heating the terminals of the circuit board;
An apparatus comprising: Using the device according to claim 6 or 7,
The heating means heats the tip of the suction nozzle and heats the terminals of the circuit board to melt the solder,
A method for removing an electronic member, wherein the electronic member mounted on the circuit board by soldering is removed from the circuit board by sucking the electronic member at the tip of the suction nozzle by the suction means. A device that removes from a circuit board a plurality of electronic members mounted on a circuit board with intervals of 1 mm or less between the electronic components, and the electronic members mounted on terminals of a size of 500×500 μm or less on the circuit board by a heat-meltable means. There is
a suction means including a suction nozzle having a hollow with a diameter of 200 μm or less, and for sucking the electronic member at the tip of the suction nozzle;
a heating means including a heating element provided below the suction nozzle for heating the heating element and heating the terminals of the circuit board by electromagnetic induction heating;
and a conducting means for conducting heat generated by the heating element to the tip of the suction nozzle.

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