JPH079556U - Hot air reflow soldering equipment - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a hot air type reflow soldering device capable of improving product quality and downsizing the device. In a warm air type reflow soldering device for blowing hot air into a reflow furnace to perform soldering, a reflow furnace 23 for circulating hot air in an up and down direction and an electric heater 2
4 has a built-in heat storage device 26, a circulation air passage 27 that connects the reflow furnace 23 and the heat storage device 26 endlessly, and ventilators 28, 29 that circulate warm air through the circulation air passage 27.
And adjusting the flow rate of circulating warm air and circulating air passage 27
It is characterized in that it is provided with control valves 30 and 31 for communicating the inside and outside of the device and a control device 33 for controlling the opening degree of the control valves 30 and 31 so as to execute a predetermined temperature profile.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a compact hot-air reflow soldering device capable of improving the quality of soldering work.

[0002]

[Prior art]

 In order to enable high-density surface mounting, hot air is blown onto the surface of the printed wiring board, etc. to melt the cream solder applied to the board surface and solder the mounting parts such as semiconductor chips to the wiring pattern. Wind-type reflow soldering equipment is widely used.

FIG. 7 is called a static type or a batch type, and this apparatus is a board on which mounting components are temporarily attached, that is, an operation console 2 that controls the loading and unloading operations of a work 1, and is loaded from this operation platform 2. The reflow furnace 3 for soldering the work 1 and the hot air generator 5 for blowing hot air 4 into the reflow furnace 3 and the like, and the electric heater 6 arranged inside the hot air generator 5 When the amount of heat generated is increased, the temperature of the hot air rises and the solder on the surface of the work is melted for soldering.

However, according to this apparatus, the temperature of the hot air cannot be changed rapidly, so it is difficult to faithfully execute the temperature profile (described later), which is the working standard of the reflow soldering work. However, there was a problem that quality concerns remained.

Here, the significance of the temperature profile will be explained. As shown by phantom lines in FIG. 6, this temperature profile uniformly heats mounting components of various sizes distributed on the substrate, and therefore the temperature of the substrate is controlled by the cream. Process 7 of preheating at a temperature (140 to 160 ° c) slightly lower than the melting point of the solder (183 ° c) for about 60 seconds, and to prevent a thermal failure by suppressing a rapid temperature rise of the mounting component and to slow it down. Process 8 to prevent the cream solder from drying and deteriorating due to excessive temperature rise, the temperature of the substrate is raised at a temperature gradient of 2 to 3 degrees c per second. It includes a process 9 for holding for about 10 seconds at a temperature of c), and if the temperature of the board is raised according to this temperature profile, good quality soldering work can be performed. .

As another device, there is a device called a conveyor type shown in FIG. This apparatus comprises a conveyor 10 that continuously conveys a large number of workpieces 1, 1, ..., And four heating furnaces 12 that heat the workpiece 1 moving on the conveyor 10 by exposing it to atmospheres of different temperatures. It is composed of 13, 14, 15, etc., and if the atmospheric temperature in each heating furnace 12, 13, 14, 15 and the transfer speed of the conveyor 10 are properly selected, a predetermined temperature profile can be executed almost faithfully. It will be possible and a high quality soldering operation can be performed.

However, the conveyor type device has the following problems. (1) Since this equipment performs continuous production, it is advantageous for large-scale production, but is disadvantageous for various types of small-volume production. That is, because the external dimensions of the device are large (the total length of the device is 4 to 5 meters), the preparation time for cold start is long (30 to 50 minutes are required), and the manufacturing cost is also high. Is.

(2) Since the work 1 moves in the heating furnaces 12, 13, 14, and 15, it is difficult to directly detect the temperature of the work 1, and instead, the temperature of the warm air is detected. Inaccurate grasp of temperature when executing temperature profile.

[0009]

[Problems to be solved by the device]

 In view of the above-mentioned problems, the present invention improves the product quality by faithfully executing a predetermined temperature profile, and at the same time, can reduce the manufacturing cost significantly by making the device small in size. It is an object to provide an attachment device.

[0010]

[Means for Solving the Problems]

 In order to solve the above problems, the present invention has the following means. (Claim 1) A warm air type reflow soldering device for blowing hot air into a reflow furnace for soldering, a reflow furnace for circulating hot air in a vertical direction, a heat storage device having a built-in electric heater, A circulation air passage that connects the reflow furnace and the heat storage device endlessly, a ventilation device that circulates warm air through the circulation air passage, and a control valve that adjusts the flow rate of the circulating warm air and connects the inside and outside of the circulation air passage. And a controller for controlling the opening of the control valve so as to execute a predetermined temperature profile, the hot-air reflow soldering device. (Claim 2) A recirculation furnace, a heat storage device, and a circulation system including a circulation air passage are arranged inside a casing having a semi-enclosed structure, and a temperature adjusting device for adjusting an atmospheric temperature in the casing is provided. The hot air reflow soldering device described in.

[0011]

[Action]

 (1) Since the hot air is filled inside the heat storage device and the circulation air passage, the heat storage amount of the heat source that heats the work is large, and the control valve controls the flow rate of the hot air and the inside of the circulation air passage. Since the hot air in the circulation air passage is discharged to the outside by communicating with the outside or the cold outside air is taken into the circulation air passage, the amount of heat supplied to the work can be changed significantly and quickly.

(2) As a result of the above item (1), it becomes possible to perform a soldering operation according to a predetermined temperature profile, and it is possible to improve product quality.

(3) Since the substrate is heated / cooled in a single reflow furnace, the external dimensions of the device can be made small, and the manufacturing cost can be greatly reduced.

(4) According to the second aspect, since the periphery of the reflow furnace, the heat storage device, and the like is surrounded by a barrier of inert gas such as nitrogen or air, it is possible to minimize heat dissipation loss. And can save heat energy.

[0015]

【Example】

 Embodiments of the present invention will be described below with reference to the drawings. 1 to 6 show an embodiment of the present invention. The main part of this embodiment is a hollow reflow furnace 23 having a hot air supply port 21 and a hot air discharge port 22 at its upper and lower portions. A heat storage device 26 in which an electric heater 24 and a forced draft fan 25 are arranged inside a large container 60, a recirculation furnace 23 and a circulation air passage 27 that connects the heat storage device 26 endlessly, and a warm air passage through this circulation air passage 27. Of the control valves 30, 31 for changing the flow rate and temperature of the hot air circulating in the circulation air passage 27, and the control valves 30, 31 for executing a predetermined temperature profile. A control device 33 for controlling the opening degree, and a circulation system excluding the control device 33, that is, a casing 34 having a semi-enclosed structure for accommodating a circulation system including the reflow furnace 23, the heat storage device 26, the circulation air passage 27, and the like. It And, before Symbol control valve 30, 31 is disposed in the reflow furnace inlet and part of the outlet side of the air circulation duct.

As shown in FIG. 2, a temperature adjusting device 35 for maintaining the temperature inside the casing 34 at room temperature (about 30 degrees c) is provided on the upper portion of the casing 34, and a lid 41 is provided on a side portion of the casing 34. A preparation chamber 37 having a closed structure is disposed, and the pallet 36 is accommodated inside the preparation chamber 37. The pallet 36 is for loading and unloading the work 32 into the furnace, and is movably arranged on the upper part of a known transporting mechanism (not shown).

The reflow furnace 23 has the largest horizontal cross-sectional area in the central portion and has a shape in which truncated quadrangular pyramids are stacked above and below a rectangular parallelepiped so as to taper in the vertical direction. A viewport 38 is provided on the front side of the. A viewport 39 is also provided on the front side of the casing 34, and an operator can observe the progress of the soldering work through the two viewports 38 and 39.

Further, at a substantially central portion of the reflow furnace 23 on the preparation chamber side, as shown in FIG. 2, a door 42 for driving a motor is provided which opens and closes in a direction of an arrow g via a hinge 40. The door 42 is opened only when the work 32 is carried in and out and is closed at other times, and prevents hot air from leaking out of the furnace during the soldering work.

The internal volume of the large container 60 that constitutes the heat storage device 26 is set to 5 to 6 times that of the reflow furnace 23, and the high temperature (about 600 degrees c) created by the electric heater 24 during operation is set. The inert gas (nitrogen gas) or air is filled in the heat storage device 26.

As shown in FIG. 4, the control valves 30 and 31 have a main body 51 having three ports 43, 44 and 45, three openings 46, 47 and 48 and a shaft 49. It is a rotary type valve that is combined with a valve body 50 that rotates in the direction of the arrow. When the valve body 50 rotates 45 degrees, the flow rate becomes zero.

Then, when the valve body 50 further rotates, the ports 43 and 45 of the main body 51 communicate with each other, and the warm air in the circulation air passage 27 is discharged to the outside as shown by an arrow c in FIG. This amount of discharge increases as the rotation angle of the valve body 50 increases, as shown by the arrow f in FIG. 5, and reaches the maximum value when the valve body rotates 90 degrees.

Further, when the valve body 50 rotates in the direction of the arrow b from the position of FIG. 4, the flow rate of the warm air flowing through the circulation air passage 27 decreases as shown by the arrow e in FIG. When it is rotated, the flow rate becomes zero. Then, when the valve body 50 further rotates, the ports 44 and 45 of the main body 51 communicate with each other, and the outside air is sucked into the circulation air passage 27 as shown by an arrow d in FIG. This suction amount increases as the rotation angle of the valve body 50 increases, as shown by the arrow f in FIG. 5, and reaches the maximum value when the valve body 50 rotates 90 degrees.

The control valve 30 in this embodiment uses a valve body 50 that rotates in the direction of arrow a when the flow rate is reduced, and uses a control valve 31 that rotates in the direction of arrow b. .

The control device 33 includes a setting unit 52 (see FIG. 1) that outputs a temperature that changes momentarily according to a predetermined temperature profile and a temperature gradient at that time as a set value, and a temperature sensor that detects the temperature of the substrate surface. 53 and the temperature signal detected by the temperature sensor 53 are compared with the temperature signal input from the setting unit 52, and the temperature gradient setting signal input from the setting unit 52 is also used as the actual value of the temperature gradient of the substrate at that time. The control unit 54 generates control signals h and i to the control valves 30 and 31 so that the difference becomes zero, and the operation panel 55 and the like.

The setting unit 52 and the control unit 54 are arranged below the preparation chamber 37 as shown in FIG. 2, and the operation panel 55 is provided on the front side of the casing 34 as shown in FIG. It is arranged so as to be located below the viewport 39. In the figure, 56 is an electric motor for driving the ventilators 28, 29, and 57 is an electric motor for opening and closing the door 42.

Next, the handling procedure and operation of this soldering apparatus will be described. First, using a vacuum pump (not shown), the heat storage device 26, the air inside the circulation air passage 27 and the air inside the casing 34 are sucked in, and nitrogen gas is sealed instead.

Next, the electric heater 24 and the ventilators 28, 29, 25 in the heat storage device are activated to circulate the hot air, and the heating device operation is performed for about 10 minutes, and the heat storage device 26 is heated to about 600 degrees. Fill with nitrogen gas in c. Further, the temperature control device 35 is activated to set the temperature of the nitrogen gas inside the casing 34 to about 30 degrees c.

Since the preparation for the soldering work is completed as described above, the work 32 is placed on the pallet 36 of the preparation chamber 37, the work 32 is carried into the furnace together with the pallet 36, and the start button (not shown) on the operation panel 55 is shown. Press).

By this operation, the control device 33 operates. That is, the setting unit 52 outputs the set values of the temperature and the temperature gradient, which change from moment to moment, to the controller 54. On the other hand, the control unit 54, which has received this set value, compares the set value with the actual values of the temperature of the substrate and the temperature gradient at that time so that the difference becomes zero. To control.

The flow rate of the control valves 30 and 31 changes as shown in FIG. 5 due to the change of the opening degree. That is, the flow rate increases as the valve opening increases to the positive side. At this time, the high-temperature nitrogen gas is filled in the heat storage container 26, the circulation air passage 27, and the like, and the heat storage amount of the heat source is large, so that the heat supply amount to the work can be rapidly increased.

When the valve opening degree increases to the minus side, the one control valve 30 communicates with the ports 43 and 45 to discharge the high temperature nitrogen gas into the casing 34, and the discharged nitrogen gas is temperature-controlled. It is cooled by the device 35 to a value close to room temperature (about 30 degrees c). At this time, the other control valve 31 communicates with the ports 44 and 45 to take the cooled nitrogen gas in the casing 34 into the circulation air passage 27. Therefore, the taken-in low-temperature nitrogen gas mixes with the high-temperature nitrogen gas in the circulation air passage to rapidly reduce the temperature of the nitrogen gas.

If this operation is applied when the work is cooled after the soldering is completed, the cooling speed can be optimally set, and the cycle time of one batch can be shortened to the minimum. it can.

The temperature rise curve 58 of the substrate is shown by the solid line in FIG. Since this curve 58 is close to the predetermined temperature profile (see the phantom line), a high quality soldering work can be performed.

It should be noted that the present invention is not limited to the above-mentioned embodiment, and for example, air may be used instead of nitrogen gas, and in this case, the casing having a semi-hermetic structure and the temperature control device are omitted. Needless to say, various modifications can be made without departing from the gist of the present invention.

[0035]

[Effect of device]

 As described above, the present invention exhibits the following excellent effects. (1) Since the hot air is filled inside the heat storage device and the circulation air passage, the heat storage amount of the heat source that heats the work is large, and the control valve controls the flow rate of the hot air and the inside of the circulation air passage. Since the hot air in the circulation air passage is discharged to the outside through the outside or the cold outside air is taken into the circulation air passage, the heat supply amount to the work can be changed significantly and rapidly.

(2) As a result of the above item (1), it becomes possible to perform a soldering operation according to a predetermined temperature profile, and it is possible to improve product quality. (3) Since the substrate is heated and cooled in a single reflow furnace, the outer dimensions of the device can be made small, and the manufacturing cost can be greatly reduced.

(4) According to the second aspect, since the reflow furnace, the heat storage device, and the like are surrounded by a barrier of inert gas such as nitrogen or air, it is possible to minimize heat loss. And can save heat energy.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a cut front view of the embodiment shown in FIG.

FIG. 3 is a view from the direction of the arrow III-III in FIG.

FIG. 4 is a cutaway plan view showing the structural principle of the control valve.

FIG. 5 is a diagram illustrating the operation of the control valve shown in FIG.

FIG. 6 is a diagram illustrating a standard temperature profile and operation of the apparatus according to the embodiment.

FIG. 7 is a cut side view showing an outline of a conventional warm air type reflow soldering device.

FIG. 8 is a cut side view showing an outline of another conventional hot air type reflow soldering device.

[Explanation of symbols]

 23 Reflow Furnace 26 Heat Storage Device 27 Circulation Air Path 28, 29 Ventilator 30, 31 Control Valve 32 Work 33 Control Device 34 Casing 35 Temperature Control Device

Claims (2)

[Scope of utility model registration request] 1. A hot-air type reflow soldering apparatus for blowing hot air into a reflow furnace to perform soldering, a reflow furnace for circulating hot air in a vertical direction, a heat storage device containing an electric heater, A circulation air passage that connects the reflow furnace and the heat storage device in an endless manner, a ventilation device that circulates warm air through the circulation air passage, and a control valve that adjusts the flow rate of the circulating warm air and communicates the inside and outside of the circulation air passage. And a controller for controlling the opening of the control valve so as to execute a predetermined temperature profile. 2. A recirculation furnace, a heat storage device, and a circulation system including a circulation air passage are arranged inside a casing having a semi-hermetic structure, and a temperature control device for controlling an atmospheric temperature in the casing is provided. The hot-air reflow soldering device described.