JPH09225632A - Heating device for joining - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a heating device for joining with high wear resistance wherein a resistant element is small, distributions of temp. and pressure are approximately uniform and high tension is not applied to electronic parts. SOLUTION: A heat sink 12 composed of a square cylinder having a hollow part 12a is provided with. The upper end surface 12c of the heat sink 12 is made to be a flat surface connecting to a pressure device. A heat transmitting member 14 having a flat rear surface is combined to the opening end surface of the lower side of the heat sink 12 via the resistant element 13 generating heat with electric energization. The heat transmitting member 14 is formed with an insulator having high heat transmitting ratio, heat resistance and hardness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bonding heating device used for bonding an electronic component such as a semiconductor chip or a semiconductor device to a part to be bonded or thermocompression-bonding an anisotropic conductive film. is there.

[0002]

2. Description of the Related Art Conventionally, in order to solder a surface mounting type semiconductor device in which leads protrude sideways to a printed wiring board,
The lead is placed on the pad of the printed wiring board which is pre-coated with solder, and the lead is heated by the heating element placed on the upper surface of the lead. A conventional heating device of this type is disclosed in, for example, Japanese Utility Model Publication No. 2-30142. The heating device shown in this publication is shown in FIG.
It will be explained by.

FIG. 3 is a perspective view showing a main part of a conventional heating device. In the figure, reference numeral 1 indicates a heating element, and the heating element 1 is integrally formed of a resistor material made of metal such as molybdenum or stainless steel that generates heat when energized, and its lower portion is a square shape when viewed from above. In addition to being formed into a shape, the power feeding portions 2 and 2 are provided at the two upper portions. The lower portion formed in the square shape is formed so that the package portion of the semiconductor device (not shown) can be inserted into the hollow portion 1a from below, and the lower surface 1b is formed flat.

Further, the power feeding portions 2 and 2 are erected on portions of the lower portion of the square shape which are opposed to each other and have bolt holes 3 for connecting to a pressurizing device (not shown). Has been drilled. The pressurizing device is configured to support the power feeding units 2 and 2 and move the heating element 1 in the vertical direction, and to supply a pulse current to the power feeding units 2 and 2.

Using the heating element 1 thus constructed,
In order to solder a semiconductor device having a large number of leads protruding on each side to a printed wiring board, first, the leads are overlaid on the pads of the printed wiring board, and then the heating element 1 is applied to the upper surface of the lead by a pressing device. To prevent the leads from falling off the pad. At this time, the heating element 1
The package portion of the semiconductor device is exposed from below into the hollow portion 1a, and the lower surface 1b is brought into contact with all the leads on the four side portions.

After the heating element 1 is pressed against the lead in this way, a pulse current is passed through the power feeding portions 2 and 2 to heat the heating element 1. This heat is so-called Joule heat. After the solder is melted by the heat of the heating element 1, the energization is stopped and the pressed state is maintained for a predetermined time. At this time, the heat of the soldered portion is dissipated through the heating element 1 to solidify the solder. After the solder is solidified, the heating device 1 is pressed by the pressure device.
The soldering process is completed by moving the above.

[0007]

However, the heating element 1 configured as described above needs to have high rigidity so that the pressing force at the time of pressing is widely transmitted from the power feeding portion 2 to the lower square portion. Therefore, the volume cannot be reduced,
A large current must be passed to generate heat. Therefore, a power supply cable (not shown) for supplying power to the power supply unit 2
However, there is a problem in that the one having a large cross-sectional area must be used and the driving force of the pressurizing device for moving the heating element 1 in the vertical direction must be increased more than necessary.

Further, the heating element 1 has a problem that it is difficult to make the temperature distribution of the lower surface 1b contacting the leads uniform. It is considered that this is because the upper two power feeding portions 2 act as heat radiation fins when heat is generated. If the temperature distribution on the lower surface 1b varies, the leads that come into contact with the relatively low temperature portion may fail in soldering.

Further, if the power feeding parts 2 at two places are attached to the pressurizing device and the heating element 1 is pressed against the leads, the pressure distribution on the lower surface 1b also varies between the part where the power feeding part 2 is present and the other part. Also from this point, defective soldering may occur.

Moreover, since the heating element 1 is made of a conductive material, a voltage is applied to the lead when the heating element 1 generates heat. By repeatedly using the heating element 1, the lower surface 1 serves as the lead. There was also the problem of wear due to friction.

The present invention has been made in order to solve such a problem. The heating element has a small volume, the temperature distribution and the pressure distribution are substantially uniform, and a voltage is applied to the electronic parts. It is an object of the present invention to obtain a heating device for bonding which has no wear and high wear resistance.

[0012]

A bonding heating device according to a first aspect of the present invention includes a heat sink for connecting a flat upper end surface to a pressurizing device, and a lower end surface of the heat sink includes:
A heat transfer member having a flat lower surface is coupled through a resistor that generates heat when energized, and the heat transfer member is formed of an insulator having high thermal conductivity, heat resistance, and hardness.

According to this bonding heating device, when the resistor is energized, it generates heat, and this heat is conducted to the objects to be bonded via the heat transfer member. At this time, the heat of the resistor is transferred to the entire area of the heat transfer member substantially uniformly. Further, when the power supply is cut off, the heat of the article to be joined is dissipated to the heat sink via the heat transfer member and the resistor. The pressing force at the time of pressing is transmitted from the upper surface of the heat sink to the heat transfer member via the resistor along the axial direction of the heat sink, and is transmitted from the heat transfer member to the article to be joined.

The heating device for bonding according to the second invention is the first heating device.
In the heating device for bonding according to the invention described above, the heat sink is formed by a cylindrical body having a hollow portion where the package part of the electronic component faces from below, and the upper open end surface of the heat sink is a flat surface for connecting to the pressure device. With
A heat transfer member is coupled to the lower opening end surface. According to this heating device, a nozzle or a positioning mechanism for vacuum-adsorbing the objects to be joined can be exposed to the hollow portion of the heat sink.

The heating device for bonding according to the third invention is the second heating device.
In the heating device for joining according to the invention, the heat transfer member and the resistor are formed in substantially the same shape as the opening end face of the heat sink in a plan view. Therefore, the positioning of the resistor and the heat transfer member on the heat sink can be performed by using the side surface of the heat sink.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a heating apparatus for bonding according to the present invention will be described in detail below with reference to FIGS. 1 and 2. Note that, here, a case will be described in which a heating device for soldering a semiconductor device is used. FIG. 1 is a perspective view of a bonding heating device according to the present invention, and FIG. 2 is a sectional view showing a state in which a semiconductor heating device is soldered by the bonding heating device according to the present invention.

In these figures, 11 indicates a heating device for bonding according to this embodiment, and the heating device 11 is
The heat sink 12 is formed in a rectangular tube shape, and the heat transfer member 14 is joined to the lower open end surface of the heat sink 12 via a resistor 13. The heat sink 12 is made of an insulating material having high thermal conductivity, heat resistance and hardness,
For example, the hollow portion 12a is integrally formed of a ceramic such as ALN (aluminum nitride), and the hollow portion 12a is formed to have a size such that a package portion of a semiconductor device (not shown) can face from below. The portion is provided with a flange 12b protruding laterally.

The heat sink 12 has a flat upper end surface (upper open end surface) 12c, and
The flange 12b is provided with a round hole 12d through which a connecting bolt (not shown) for a pressure device is inserted. A pressurizing device (not shown) connected to the heat sink 12 is configured to be in close contact with the entire area of the upper end surface 12c.

The resistor 13 is formed of a material that generates heat when energized. In this embodiment, the resistor 13 is formed by printing a paste-like material on the upper surface of a heat transfer member 14 which will be described later and then firing it. ing. Further, the resistor 13 is integrally provided so that terminals 13a and 13b for connecting a power feeding cable (not shown) project laterally.

The heat transfer member 14 is made of the same material as the heat sink 12 in this embodiment.
The resistor 13 which is formed in the same shape as the lower opening end face of the lower side and which is provided on the upper surface as described above is adhered to the lower surface of the heat sink 12 by the adhesive 15 (FIG. 2). It is coupled through the resistor 13. That is, in this embodiment, the resistor 13 and the heat transfer member 14 are formed in substantially the same shape as the lower opening end surface of the heat sink 12 when viewed from above, that is, in a square shape. Further, the lower surface of the heat transfer member 14 is formed to be flat.

In FIG. 2, reference numeral 16 is a printed wiring board,
Reference numeral 17 is a pad formed on the upper surface of the printed wiring board 16, and 18 is a lead of the semiconductor device.

In order to solder the leads 18 of the semiconductor device having a structure in which a large number of leads project from the four sides by the heating device 11 thus constructed to the pads 17 of the printed wiring board 16, first, the solder is pre-coated. The leads 18 of the semiconductor device are superposed on the pads 17 of the printed wiring board 16, and then the pressure device is driven to press the heating device 11 against the leads 18 from above as shown in FIG. At this time, a package portion (not shown) of the semiconductor device is made to face the hollow portion of the heating device 11 from below, and all the leads 18 are brought into contact with the lower surface of the heat transfer member 14. During this pressing,
The heat sink 1 is evenly distributed over the entire area of the heat transfer member 14.
Since the pressing force is transmitted from the second side, the pressure distribution on the lower surface of the heat transfer member 14 becomes substantially uniform.

After the heating device 11 is pressed against the lead 18 in this way, a pulse current is passed through the resistor 13 to heat the resistor 13. At this time, the heat of the resistor 13 is transferred to the entire area of the heat transfer member 14 substantially evenly.
4 is conducted to the lead 18 through the heat transfer member 14
The temperature distribution on the lower surface of the is also substantially uniform.

After the heat of the resistor 13 is conducted to the leads 18 and the solder on the side of the pad 17 is melted, the current to the resistor 13 is cut off in the pressed state. By doing this, the resistor 1
3, the heat of the heat transfer member 14 and the soldering portion is conducted to the heat sink 12 side and dissipated, and the solder is solidified.

After the solder is solidified, the heating device 11 is moved upward from the semiconductor device by the pressure device to complete the soldering process.

Therefore, according to this heating device 11,
The pressing force at the time of pressing is transmitted from the upper end surface 12c of the heat sink 12 to the heat transfer member 14 through the resistor 13 along the axial direction of the heat sink 12, and from the heat transfer member 14 to the lead 18. It is not necessary to form a bracket or the like for connecting the resistor 13 to the pressure device. Therefore, the resistor 13 can be formed so as to have a minimum volume capable of obtaining the required amount of heat generation, and a power feeding cable having a smaller cross-sectional area than the conventional one can be used. Moreover, since the heat transfer member 14 is interposed between the resistor 13 and the lead 18 at the time of soldering, it is not necessary to consider solder wettability when selecting the material of the resistor 13, so that the selection range of the material is expanded. , A material with a larger resistance value can be selected.

Further, according to the heating device 11, the heat generated by the energized resistor 13 is substantially evenly conducted to the entire area of the heat transfer member 14, and is conducted to the lead 18 through the heat transfer member 14. Therefore, the temperature distribution on the lower surface of the heat transfer member 14 becomes substantially uniform. Further, since the pressing force is transmitted from the heat sink 12 side substantially evenly over the entire area of the heat transfer member 14 during pressing, the pressure distribution on the lower surface of the heat transfer member 14 becomes substantially uniform. In addition, since the heat transfer member 14 that contacts the lead 18 is formed of an insulator, current does not leak from the resistor 13 to the lead 18, and the heat transfer member 14 is formed of a material having high hardness. Therefore, the wear due to the contact of the leads 18 is small.

In addition, as in this embodiment, when the resistor 13 and the heat transfer member 14 are formed to have substantially the same shape as the lower opening end face of the heat sink 12 in a plan view, the resistor 13 is interposed in the heat sink 12. Positioning when the heat transfer member 14 is adhered can be performed by using the side surface of the heat sink 12.

In this embodiment, the heat sink 1
2, the example in which the resistor 13 and the heat transfer member 14 are formed in a rectangular shape in plan view has been described, but the planar shapes of these are not limited thereto. These may be formed in a rectangular shape in plan view, that is, a plate shape, or may be formed in an asymmetric shape in plan view. When it is formed in a rectangular shape in plan view as shown in FIGS. 1 and 2, a nozzle for vacuum-sucking the semiconductor device, a positioning mechanism for positioning the semiconductor device, and the like can be exposed to the hollow portion.

The resistor 13 and the heat transfer member 14 are
It is not always necessary to form the opening end surface of the heat sink 12 in the same shape, and only the resistor 13 is formed in the same shape.
The heat transfer member 14 may be formed to be narrower or wider than the resistor 13. Further, in order to increase the area of the heat transfer portion, a structure in which a part of the resistor 13 is buried in the heat transfer member 14 can be adopted.

Further, the material forming the heat sink 12 and the heat transfer member 14 is not limited to aluminum nitride, and any material having similar characteristics may be used. The heat sink 12 and the heat transfer member 1
It goes without saying that 4 and 4 need not be formed of the same material. The resistor 13 may be formed by baking a paste-like material, or may be formed in a foil shape and bonded to the heat sink 12 and the heat transfer member 14 with an adhesive.

Furthermore, the heating device for bonding according to the present invention is used for soldering a semiconductor device as described above, and in addition to the anisotropic conductive film, ACF (Anisotronic Conducer).
When bonding adhesives such as tiveFilm) by thermocompression bonding, COB
(Chip On Board), COG (Chip On Glass) or the like may be used to directly mount the chip.

[0033]

EXAMPLE In the above embodiment, the material of the heat sink 12 and the heat transfer member 14 is ALN (aluminum nitride),
The material of the resistor 13 was platinum as a main material and a binder and the like mixed therein. The resistor 13
When forming a foil, it is conceivable to use a nichrome foil.

The power supply cable connected to the resistor 13 is a wire for soldering a 4-direction flat package type semiconductor device having a package size of 30 to 40 mm and a lead pitch of 0.3 to 0.5 mm. A diameter of 1φ was used. In the case of soldering the same semiconductor device as described above with a conventional heating device, a power supply cable having a wire diameter of about 60φ was used.

[0035]

As described above, the heating device for bonding according to the first aspect of the present invention is provided with the heat sink for connecting the flat upper end face to the pressurizing device, and the lower end face of the heat sink is energized. This heating device is formed by connecting a heat transfer member having a flat lower surface through a resistor that generates heat by means of an insulator having high thermal conductivity, heat resistance, and hardness. At the time of pressing, the pressing force is transmitted from the upper surface of the heat sink to the heat transfer member along the axial direction of the heat sink via the resistor, and then from the heat transfer member to the article to be joined. For this reason, since it is not necessary to form a bracket or the like for connecting the resistor to the pressurizing device, the resistor can be formed to have a minimum volume capable of obtaining a necessary amount of heat generation.

Therefore, the resistor can be made to generate heat with a small current, and a cable having a smaller cross-sectional area than the conventional one can be used as the power supply cable connected to the resistor, so that the power required for the pressurizing device can be small. In addition, when this device is used for soldering, the heat transfer member is interposed between the resistor and the article to be joined, so solder wettability does not have to be taken into consideration when selecting the material of the resistor. The selection range is expanded and materials with higher resistance can be selected.

That is, not only the volume of the resistor may be small, but also the resistor may be formed of a material having a large resistance value, so that the power feeding cable should be an extremely thin cable that does not interfere with the driving of the pressure device. Good.

Further, according to this heating device, the heat generated by the energized resistor is almost evenly conducted to the entire area of the heat transfer member, and is conducted to the object to be joined through the heat transfer member. The temperature distribution on the lower surface of the heat transfer member becomes substantially uniform. For this reason, it is possible to reliably prevent the objects to be joined from becoming partially low in temperature and causing defective joining.

Further, since the pressing force is transmitted from the heat sink side substantially evenly over the entire area of the heat transfer member during pressing, the pressure distribution on the lower surface of the heat transfer member becomes substantially uniform, which is caused by variations in the pressure distribution. No joint failure will occur. In addition, since the heat transfer member that comes into contact with the article to be joined is formed of an insulator, no voltage is applied to the article to be joined even if it is an electronic component. Since it is formed of a material having high hardness, wear due to contact of the objects to be joined can be reduced.

The heating device for bonding according to the second invention is the first heating device.
In the heating device for bonding according to the invention described above, the heat sink is formed by a cylindrical body having a hollow portion where the package part of the electronic component faces from below, and the upper open end surface of the heat sink is a flat surface for connecting to the pressure device. With
Since the heat transfer member is coupled to the lower opening end face, according to this heating device, the nozzle or the positioning mechanism for vacuum-sucking the object to be bonded can be exposed to the hollow portion of the heat sink. Therefore, the space necessary for joining the objects to be joined can be effectively utilized.

The heating device for bonding according to the third invention is the second heating device.
Since the heat transfer member and the resistor are formed to have substantially the same shape in plan view as the opening end face of the heat sink in the heating device for bonding according to the invention, the side surface of the heat sink is used for positioning when attaching the resistor and the heat transfer member to the heat sink. Therefore, the work can be easily performed when the three members are integrally combined.

[Brief description of drawings]

FIG. 1 is a perspective view of a bonding heating device according to the present invention.

FIG. 2 is a cross-sectional view showing a state in which a semiconductor heating device is being soldered by the heating device for bonding according to the present invention.

FIG. 3 is a perspective view showing a main part of a conventional heating device.

[Explanation of symbols]

11 ... Heating device, 12 ... Heat sink, 12c ... Upper end surface, 13 ... Resistor, 14 ... Heat transfer member.

Claims (3)

[Claims] 1. A heat sink having a flat upper end surface connected to a pressurizing device, and a heat transfer member having a flat lower surface coupled to the lower end surface of the heat sink via a resistor that generates heat when energized. A heating device for joining characterized in that the heat transfer member is formed of an insulator having high thermal conductivity, heat resistance and hardness. 2. The joining heating device according to claim 1, wherein the heat sink is formed by a tubular body having a hollow portion where a package portion of the electronic component faces from below, and an opening end surface on an upper side of the heat sink serves as a pressing device. A heating device for joining, which has a flat surface to be connected, and a heat transfer member joined to the lower opening end surface. 3. The bonding heating device according to claim 2, wherein the heat transfer member and the resistor are formed to have substantially the same shape as the opening end surface of the heat sink in a plan view.