JP2002346736A - Solder reflow device and assembling equipment using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solder reflow device that can realize an accurate temperature profile for each type of workpiece without adding large-scale equipment to a heating furnace, and also to provide an assembling equipment using the same. SOLUTION: A workpiece A and a workpiece B which have different optimum temperature profiles are placed on the carbon fixtures 22a, 22b of the reflow devices 18a, 18b corresponding to respective workpieces. A tray 24a of the solder reflow device 18a and a tray 24b of the solder reflow device 18b respectively have different shapes and have different heat capacities; therefore, when they are simultaneously passed through the same heating furnace 26 that is controlled at a specific temperature, the optimum temperature profile can be realized for each workpiece A, B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solder reflow apparatus used for reflow soldering and an improvement of an assembling apparatus using the same.

[0002]

2. Description of the Related Art Conventionally, when an element is soldered on a substrate, the solder is supplied on the substrate in advance,
Reflow soldering is performed in which this solder is melted in a heating furnace to perform soldering.

In such reflow soldering, a predetermined work such as a printed circuit board is conveyed by a conveyor or the like into a heating furnace provided with heating means such as a heater, and the solder previously supplied to the work is heated and melted. Then, soldering is performed. An example of such reflow soldering is disclosed in, for example, JP-A-5-161961.

[0004]

However, in the above-mentioned conventional reflow soldering, a temperature sensor, a blower, a heater, a blower, and a blower are provided in the heating furnace in order to realize a predetermined temperature profile for a workpiece passing through the heating furnace. It is necessary to provide various functions such as fins, and there is a problem that the heating furnace equipment becomes large and complicated, and the equipment cost increases.

[0005] Further, there are various types of workpieces passing through the heating furnace, and their heat capacities are also different. Therefore, there is a problem that a plurality of types of workpieces cannot be processed at one time.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a solder which can realize an accurate temperature profile for each type of work without adding a large-scale facility to a heating furnace. An object of the present invention is to provide a reflow device and an assembling device using the same.

[0007]

In order to achieve the above object, the present invention provides a solder reflow for realizing a predetermined temperature profile on a work when the work is placed on the work and passed through a heating furnace. An apparatus, comprising: holding means for placing a work thereon, wherein the holding means has a heat capacity determined such that a predetermined temperature profile is realized for the work to be placed thereon.

In the above solder reflow apparatus,
The holding means includes a carbon jig on which the work is placed, and a tray for supporting the carbon jig.

In the above solder reflow apparatus,
The heat capacity of the holding means is controlled by the shape and material of the tray.

In the above solder reflow apparatus,
The holding means is characterized in that the size and shape of the tray are determined according to the size and heat capacity distribution of the work.

[0011] Further, there is provided an assembling apparatus for soldering a work using the above-mentioned solder reflow apparatus, comprising: a mounter for mounting a plurality of types of works on an appropriate holding means; and a holding means on which the works are mounted. It is characterized by comprising a heating furnace for heating, and an inspection device for inspecting a state of solder of a work on which a solder reflow process has been performed by the heating furnace in accordance with a type of the work.

[0012]

Embodiments of the present invention (hereinafter referred to as embodiments) will be described below with reference to the drawings.

FIGS. 1A to 1C are views showing a solder reflow apparatus according to the present invention and a state in which the apparatus is passed through a heating furnace. 1A, the element 14 is placed on the insulating substrate 10 via a conductor 12a such as copper.
A solder reflow apparatus 18a for use in reflow soldering of a work A for bonding a work A with a high-temperature solder 16a is shown. Further, FIG.
A solder reflow device 18b for reflow soldering a work B for bonding the work A shown in (a) on the heat radiating plate 20 with a medium-temperature solder 16b via a conductor 12b such as copper is shown.

In FIG. 1A, a solder reflow device 18a includes a carbon jig 22a for placing a work A thereon.
And a tray 24a for supporting the carbon jig 22a, and these constitute a holding means according to the present invention.

In FIG. 1B, a carbon jig 22b on which the work B is placed and a carbon jig 22
b, and a tray 24b for supporting the supporting means b.

FIG. 2 shows a power module which is a product assembled by the above-described works A and B. As described above, high-temperature solder is used as the solder 16a for bonding the element 14 to the insulating substrate 10, and the solder 16b for bonding the insulating substrate 10 to the heat sink 20.
Medium temperature solder is used. This is to reduce the thermal stress caused by the difference in linear expansion coefficient between the members of the power module by using the elastic modulus characteristics of the solder. In particular,
A high-temperature solder having a small yield stress is used under the element 14 which is likely to be damaged by thermal stress, and is different from a medium-temperature solder under the insulating substrate 10.

As shown in FIG. 2, the melting point of the high-temperature solder is 268 ° C. to 301 ° C., and the melting point of the medium-temperature solder is 183 ° C. to 215 ° C. Therefore, in order to perform each soldering by reflow soldering, the optimum temperature profile differs between the case of the work A using the high-temperature solder and the case of the work B using the medium-temperature solder. In assembling the power module, as described above, after the work A using the high-temperature solder is processed, the work A is changed to the work B, and is passed through the heating furnace again. For this reason, the temperature profile required for the work A is such that the high-temperature solder can be melted, and the temperature profile required for the work B is such that the medium-temperature solder can be melted and the high-temperature solder does not re-melt.

FIG. 3 shows the optimum temperature profiles of the work A and the work B. Thus, in order to realize a different temperature profile for each work by passing each work through the same heating furnace operated at a constant temperature, the work A and the work B are required.
It is necessary to control the temperature profile realized for each work by devising the shape and material of the solder reflow device on which the work is mounted.

For the above reasons, FIG.
Each of the solder reflow devices 18a and 18b shown in FIG.
Are different in the size and shape of the carbon jigs 22a and 22b and in the size, shape and material of the trays 24a and 24b. For example, the tray 24a shown in FIG. 1A has a hollow structure while supporting the carbon jig 22a at a peripheral portion thereof. Since the weight is small and the heat capacity is small due to the hollow, the temperature of the work A is increased more quickly. Therefore, the temperature profile of the work A using the high-temperature solder can be optimized.

FIG. 1B shows a carbon jig 22.
1b, the tray 24b supporting the b is received on the entire surface of the bottom surface of the carbon jig 22b by the upper surface of the tray 24b.
It does not have a hollow structure as in the example. For this reason, the heat capacity of the tray 24b is larger than that of the example of FIG.
The temperature rise will be further reduced. For this reason, it is possible to give an optimal temperature profile to the work B using the medium-temperature solder.

FIGS. 4A and 4B are perspective views of such trays 24a and 24b. 4A, the tray 24a has a hollow structure, and FIG.
, The tray 24b has a solid structure. As described above, by changing the shape, first, the heat capacities of the trays are different from each other, and second, the heat transfer method (radiation or conduction, etc.) is also different. Have been.

The above two types of solder reflow devices 18
The work A and the work B are put on a and b, and are passed through the heating furnace 26 shown in FIG. In addition,
The heating furnace 26 includes a heater 28, a hydrogen supply nozzle 30,
The solder reflow devices 18a and 18b, each of which is a hydrogen reduction furnace equipped with a nitrogen supply nozzle 32, and on which each work is placed, are simultaneously placed on the belt conveyor 33 and pass through the heating furnace 26. As described above, even when different works are simultaneously passed through the heating furnace 26, as described above, the carbon jigs 22a and 22b and the tray 2 of the solder reflow apparatus on which the works are placed are placed.
Since the shapes, materials, and the like of the 4a and 24b are optimally adjusted, it is possible to realize an optimal temperature profile for each work due to differences in heat capacity and thermal conductivity. In the example described above, a hydrogen reduction furnace is shown as the heating furnace 26, but the heating furnace 26 is not necessarily limited to this, and for example, a heating furnace of an atmospheric type, a nitrogen type, or the like can be used.

The heat capacity of each tray used in the solder reflow apparatus may be controlled by changing the shape of the tray or using a different material. Table 1 shown below
Shows examples of materials that can be used for the tray, and their thermal conductivity and heat capacity.

[0024]

[Table 1]

As described above, since the heat conductivity and the heat capacity are different for each material, the shape of the tray is changed and the optimum heat conductivity or heat capacity is obtained so as to realize an optimum temperature profile for a predetermined work. By selecting the material, it is possible to control the temperature profile of the work in detail.

FIGS. 5A, 5B, and 5C show examples in which the solder reflow apparatus according to the present invention is applied to a printed circuit board. Printed circuit boards have different sizes and heat capacities depending on the type, but when mixing them in the same heating furnace and performing reflow soldering, the size, shape and material of the solder reflow device are appropriately selected, and the heat capacity is selected. Alternatively, by adjusting the thermal conductivity, the temperature profile realized on each printed circuit board can be optimized.

FIG. 5 (a) shows a solder reflow device 18 for a relatively small printed circuit board 34, and FIG. 5 (b) shows a solder reflow device 18 for a relatively large printed circuit board 34. The solder reflow device 18 on which these printed boards 34 are placed flows on a conveyor rail 36 in a heating furnace, and realizes an optimum temperature profile for each printed board 34 to perform reflow soldering.

FIG. 5C shows the printed circuit board 34.
An example is shown in which the size and type of each element arranged above are uneven, so that a difference occurs in the heat capacity on the printed circuit board. In this case, for the right half of the figure where the shape is large and there are relatively many elements with large heat capacity,
The solder reflow device has a hollow structure, and the temperature of a portion of the printed circuit board 34 having a large heat capacity is easily increased. In addition, the area of the hollow portion of the solder reflow device is reduced in the left portion of the drawing where elements having relatively small shapes are gathered, and the temperature rise of the printed circuit board 34 is suppressed. Thereby, the printed circuit board 34
Even if the heat capacity is distributed above, control can be performed so that the temperature profile of the entire printed circuit board becomes the same.

FIG. 6 shows a configuration example of an assembling apparatus for performing reflow soldering on a plurality of types of works using the above-described solder reflow apparatus. 6, the assembling apparatus is provided with a mounter 38 for setting a work, and the mounter 38 includes a robot 40. This robot 40 is shown in FIG.
Multiple types of work A and work B as shown in (b)
Are respectively put on holding means of an appropriate solder reflow device. For example, in the case of work A, the assembly table 48
Above, the insulating substrate 10, the high-temperature solder 16a, the element 1
4 are set on the carbon jig 22a in this order. The work A set in this way is placed on the solder reflow device 18a and the work transport conveyor 4
2 and pass through the heating furnace 26. While passing through the heating furnace 26 in this manner, as described above,
The temperature profile shown in FIG. 3 is realized, whereby reflow soldering is performed on the work A.

The work A for which soldering has been completed is carried to the X-ray inspection device 46 by the return conveyor 44.
The X-ray inspection device 46 inspects the solder for bubble defects, and checks whether or not soldering is performed at a predetermined level. When there are many bubbles in the solder, the electric resistance increases and the heat generated from the element cannot be efficiently radiated. Therefore, it is necessary to suppress the amount of bubbles to a certain level or less.

As described above, when the quality of the solder is determined to be poor as a result of the inspection of the solder by the X-ray inspection apparatus 46, it is removed from the process by the robot 40 as a defective product. If the solder is determined to be good,
The work B is set by the robot 40 of the mounter 38. That is, on the assembly table 48, the completed product of the work A in which the element 14 is soldered to the insulating substrate 10 is put on the heat sink 20 via the medium-temperature solder 16b, and the solder reflow device 18b for the work B is placed. On the carbon jig 22b. The work B set in this way is, like the work A, the work transport conveyor 4
At 2, it passes through the heating furnace 26. At this time, the temperature profile shown in FIG. 3 is given as described above, and the work B is subjected to reflow soldering. As described above, since the temperature profile of the work B is lower than the profile of the work A, the already soldered high-temperature solder 16a does not melt again.

The work B on which the reflow soldering has been performed as described above is conveyed to the X-ray inspection apparatus 46 by the return conveyor 44, and the solder bubble defect is inspected similarly to the work A. Each work is provided with a marking for identification, the X-ray inspection apparatus 46 identifies which work is to be performed, and the inspection is executed with an optimum inspection program according to the type of the work. Have been.

When the X-ray inspection device 46 determines that the quality of the solder is poor, the solder is removed from the process by the robot 40. If the X-ray inspection device 46 determines that the quality of the solder is good, the solder is delivered as a finished product by the finished product delivery conveyor 50.

As described above, even when a plurality of types of workpieces pass through the heating furnace 26, an optimum temperature profile can be realized by the solder reflow device on which each is placed. If you keep it,
Optimal reflow soldering can be performed for each work.

[0035]

As described above, according to the present invention,
While maintaining the temperature of the heating furnace constant, the optimal temperature profile for each work can be realized by the holding means corresponding to each work, so it is possible to perform reflow soldering of multiple types of works with one heating furnace. it can.

In this case, since the temperature of the heating furnace may be constant, the apparatus configuration of the heating furnace does not become large and complicated, so that the apparatus cost can be reduced.

The heat capacity of the holding means is controlled by the shape and material of the tray constituting the holding means.
Fine control of the temperature profile according to each work can be performed.

The holding means can determine the size and shape according to the size of the work and the distribution of the heat capacity.
It is possible to respond to a work finely.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration example of an embodiment of a solder reflow device according to the present invention.

FIG. 2 is a view showing an example of a work on which reflow soldering is performed by the solder reflow apparatus shown in FIG. 1;

FIG. 3 is a diagram showing an example of a temperature profile realized on each work by the solder reflow device shown in FIG. 1;

4 is a diagram showing a configuration example of a tray used in the solder reflow device shown in FIG.

FIG. 5 is a diagram showing a configuration example of another embodiment of the solder reflow device according to the present invention.

FIG. 6 is a view showing an example of an assembling apparatus for soldering a work using the solder reflow apparatus according to the present invention.

[Explanation of symbols]

10 insulating substrate, 12a, 12b conductor, 14 elements,
16a high temperature solder, 16b medium temperature solder, 18a, 1
8b solder reflow device, 20 heat sink, 22a, 2
2b carbon jig, 24a, 24b tray, 26
Heating furnace, 28 heater, 30 hydrogen supply nozzle, 32 nitrogen supply nozzle, 33 belt conveyor, 34 printed circuit board, 36 conveyor rail, 38 mounter, 40
Robot, 42 Work conveyor, 44 Return conveyor, 46 X-ray inspection device, 48 Assembly stage, 50 Finished product delivery conveyor.

Claims (5)

[Claims] 1. A solder reflow apparatus for realizing a predetermined temperature profile for a work when the work is placed and passed through a heating furnace, comprising: holding means for mounting the work; Holding means,
A heat reflow apparatus having a heat capacity determined so that a predetermined temperature profile is realized for the workpiece placed thereon. 2. The solder reflow apparatus according to claim 1, wherein said holding means includes a carbon jig on which a work is placed, and a tray for supporting said carbon jig. 3. The solder reflow apparatus according to claim 2, wherein a heat capacity of said holding means is controlled by a shape and a material of said tray. 4. The solder reflow apparatus according to claim 3, wherein said holding means determines the size and shape of said tray in accordance with the size and heat capacity distribution of said work. . 5. An assembling apparatus for soldering a work using the solder reflow apparatus according to claim 1, wherein said holding means holds a plurality of types of works properly. A heating furnace for heating the holding means on which the work is mounted, and an inspection for inspecting the state of solder of the work on which the solder reflow process has been performed by the heating furnace according to the type of the work. And an assembly device.