JP4149768B2 - Reflow device, reflow method and reflow furnace - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reflow apparatus , a reflow method, and a reflow furnace for soldering electronic components mounted on a substrate.
[0002]
[Prior art]
The configuration of a conventional reflow soldering apparatus will be described with reference to FIG. That is, in the reflow soldering apparatus, the interior of the furnace is divided into a plurality of rooms, and hot air circulation heating is mainly performed for each room. Specifically, the atmosphere in the heating chamber 102 in the furnace body 101 is sucked by the fan 100 including a large cylindrical multi-blade fan or an axial fan arranged in the furnace, and the heater passes through the flow path 103. The atmosphere heated by the heating means 104 such as the air passes through the fan 100, passes through the flow path 105, and hot air is blown from the nozzle 106 to the printed wiring board 107 disposed in the heating chamber 102. Soldering of the printed wiring board 107 on which components are mounted and solder material is applied is executed. Reference numeral 108 denotes a temperature detection means including a thermocouple disposed near the hot air outlet of the nozzle 106, 109 denotes a temperature control means for controlling the temperature of the heating means 104 by comparing the difference between the detected temperature and the set temperature, and 110 It is a motor that drives the fan 100.
[0003]
In such a configuration, in order to uniformly heat the atmosphere in the furnace body and to blow hot air on the printed wiring board at a uniform wind speed, it is necessary to make the flow path considerably complicated, and each heating chamber becomes large. The equipment is generally large. On the one hand, the heat capacity of the furnace body is large, difficult to heat, and difficult to cool, and even if the printed wiring board is continuously fed, there is an advantage that the furnace temperature is hardly affected and a stable ambient temperature can be obtained. .
[0004]
[Problems to be solved by the invention]
However, in the above-described conventional reflow apparatus, when the furnace temperature becomes higher than the set value for some reason, the heat capacity of the furnace body itself is large even when the heater continues to be turned off. Decrease time will increase. The reason why the furnace temperature becomes larger than the set value is that when the temperature of the adjacent furnace body is set to a relatively high temperature, the furnace temperature is high due to entrainment of a high-temperature atmosphere or heat transmitted from the wall surface. As a result, even if the heater is always turned off, the temperature is stabilized or continuously raised at a temperature higher than the set value. Also, when the temperature setting is reset to the low temperature side by changing the specifications of the printed wiring board that is the heating target, it takes a very long time for the above reasons until the temperature stabilizes to the low temperature side. There was a problem that led to loss of time.
[0005]
In order to solve this problem, there is a method of lowering the furnace atmosphere temperature by opening the furnace body or forcibly introducing the atmosphere outside the furnace, that is, the outside air into the furnace by a pipe or the like. When reflow in a low oxygen concentration atmosphere is required due to introduction, a considerable amount of nitrogen is required to lower the oxygen concentration to a predetermined concentration. However, the oxygen concentration increases when the furnace body is opened or when the outside atmosphere is forcibly introduced. Therefore, there is a problem that it takes time to adjust and stabilize this.
[0006]
The present invention solves the above problems, and in a reflow apparatus for performing reflow soldering, the furnace temperature can be quickly and stably stabilized even when the atmospheric temperature inside the furnace body has shifted to a higher temperature side than the set temperature. Control and ensure stable reflow soldering quality.
[0007]
[Means for Solving the Problems]
This onset Ming, solder material is applied, the electronic components are heated to carry a printed wiring board mounted to the furnace body, the reflow apparatus for melting the above solder material bonded to the electronic component on the printed circuit board in the heating chamber to heat the printed wiring board, comprising a heating means for heating the air blowing means, as well as the circulating air flow provide a circulating air flow in the heating chamber, and the inner furnace body sealable, surrounds the upper Symbol inner furnace body A cooling space is formed between the internal furnace body and an external furnace body provided with an outside air introduction port and an exhaust port of the cooling space, and the cooling port communicates with the exhaust port of the external furnace body from the exhaust port. An exhaust means for exhausting the atmosphere in the space, and the exhaust means is operated to exhaust the high-temperature atmosphere in the cooling space, and the atmosphere inside the internal furnace body is introduced by introducing a low-temperature outside atmosphere into the cooling space. Temperature control A Brighter flow device, to absorb heat from the atmosphere of the first and the heat transfer protrusions, the exposed to the inner space of the inner furnace body space to dissipate exposed to the cooling space into the atmosphere of the same cooling space A heat sink having a second heat transfer protrusion, the first heat transfer protrusion is positioned close to the outside air inlet of the external furnace body, and the second heat transfer protrusion sucks in the heated air blown to the substrate. It arrange | positions so that it may be located in the opening part returned to a ventilation means .
[0008]
[0009]
[0010]
[0011]
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the reflow apparatus in one Embodiment of this invention is demonstrated using FIGS. In FIG. 1, a furnace body 1 is composed of an internal furnace body 1a that can be sealed and an external furnace body 1b that surrounds the internal furnace body 1a and forms a cooling space 2 between the internal furnace body 1a. Yes. In the internal furnace body 1a, a heating chamber 4 that holds the printed wiring board 3 in a fixed position and heats the printed wiring board 3 in a heating atmosphere, and a blower means 5 that circulates the atmosphere in the heating chamber 4; The heating means 6 such as a heater for heating the circulating flow, which is located on the lower side of the blowing means 5, and the heated circulating flow are blown onto the printed wiring board 3 on which electronic components are mounted and solder material is applied. A nozzle 7 is provided. The heating means 6 is on / off controlled by a temperature detection means 8a disposed in the vicinity of the printed wiring board 3 and a temperature control means 8b for controlling the detected ambient temperature to a set temperature. 1 c is a suction opening for forming a circulating flow from the heating chamber 4 into the internal furnace body 1 a by the blowing means 5.
[0013]
The external furnace body 1b includes an outside air introduction port 9 into the cooling space 2 between the external furnace body 1b and the internal furnace body 1a, an exhaust port 10 for the atmosphere in the cooling space 2, and an internal furnace body 1a. A motor 11 for driving the provided air blowing means 5 is provided. A heat sink 12 is attached to the wall surface of the internal furnace body 1a, located close to the outside air introduction port 9, and is exposed to the cooling space 2 to dissipate heat to the atmosphere in the cooling space 2. It has projections 12a and a number of heat transfer projections 12b that are exposed in the internal space of the internal furnace body 1a and absorb heat from the atmosphere in the space. The exhaust port 10 is connected to a duct 13, and the duct 13 exhausts the atmosphere in the cooling space 2 by an exhaust blower 14. The exhaust blower 14 is controlled by the temperature control means 8b and operates when the atmosphere in the internal furnace body 1a needs to be cooled. Reference numeral 15 denotes a switching damper. During normal operation of the facility, the duct 16 and the exhaust blower 14 connected to the exhaust ducts 16a and 16b at both ends of the facility are used for exhausting the entire facility. When 15 is switched and the exhaust blower 14 communicates with the duct 13, exhaust of the cooling space 2 of the furnace body 1 and introduction of outside air into the cooling space 2 can be performed.
[0014]
The switching damper may be configured to automatically switch depending on the temperature of the furnace atmosphere. It is also possible not to provide a switching damper, but to exhaust the entire equipment and exhaust for adjusting the temperature of the furnace atmosphere independently.
[0015]
Although the furnace body 1 is limited to the configuration in which the upper surface of the printed wiring board 3 is heated, an independent furnace body 1 for heating the lower surface of the printed wiring board 3 is provided as shown in FIG. It is common.
[0016]
In the above configuration, the operation of the reflow apparatus will be described below. The airflow heated in the internal furnace body 1a is sprayed from the nozzle 7 to the printed wiring board 3 by the air blowing means 5, and the heated airflow is sucked in and returned to the air blowing means 5 from the opening 1c. Thereby, the atmosphere of the internal furnace body 1a circulates, the furnace atmosphere is heated by the heating means 6, and the temperature is raised to a desired atmosphere temperature.
[0017]
During normal production, the temperature of the furnace atmosphere is adjusted only by turning the heating means 6 on and off. In this method, the furnace temperature is stabilized or raised at a temperature higher than the set value as described above. May continue.
[0018]
As an example, the graph of FIG. 2 will be described. This is an example of temperature measurement when the reflow apparatus according to the embodiment of the present invention performs only the heating control without performing the cooling control.
[0019]
The temperature of the furnace body on both sides adjacent to each other is set to 250 ° C., and the temperature setting of the furnace body to be measured is set to 200 ° C. Looking at the temperature measurement results, the heating means 6 is on, and after heating up to near the set temperature at time S1, the heating means is turned off by the temperature control means 8b and once stabilizes at the set temperature. Under the influence of the temperature of the adjacent furnace body, the temperature continues to rise. During this time, the heating means 6 of the furnace body remains off. That is, the set temperature cannot be maintained unless the furnace atmosphere or the furnace wall surface is forcibly cooled.
[0020]
Next, FIG. 3 shows an example of a temperature measurement result when cooling control is performed in the above-described embodiment (FIG. 1). As for the set temperature of the furnace body, as in the case of FIG. 2, the furnace body temperature on both sides adjacent to each other is set to 250 ° C., and the temperature setting of the furnace body for temperature measurement is set to 200 ° C. In the temperature raising process up to time S1 in FIG. 3, the heating means 6 remains on and is the same as the case without the cooling function (FIG. 2). After reaching the set temperature in time S1, the heating means 6 is turned off by the temperature control means 8b, and the duct 13 and the exhaust blower 14 are operated to forcibly cool the furnace atmosphere. That is, the duct 13 causes the atmosphere in the cooling space 2 between the internal furnace body 1a and the external furnace body 1b to flow out and exhaust from the exhaust port 10 (B). At this time, the pressure in the cooling space 2 is lower than the outside air, that is, the outside atmosphere A, and the outside atmosphere A is introduced into the cooling space 2 from the outside air inlet 9 of the external furnace body 1b. As a result, the low-temperature outside atmosphere A cools the wall surface of the internal furnace body 1 a and the atmosphere inside the internal furnace body 1 a through the wall surface, and the low-temperature outside atmosphere A passes through one side 12 a of the heat sink 12. At this time, the heat of the heat sink 12 is deprived, and the temperature of the heat sink 12 itself decreases. On the other hand, the heat sink 12 cooled in the atmosphere A outside the furnace absorbs heat from the hot air circulation atmosphere in the internal furnace body 1a described above, and takes away excess heat from the adjacent furnace body. As a result, the set temperature can be stably maintained as shown in FIG. 3 without overheating the furnace atmosphere.
[0021]
【The invention's effect】
As is apparent from the above description, according to the present invention, in the reflow apparatus for performing reflow soldering, the temperature of the furnace atmosphere can be stably controlled against thermal disturbance, and the hot air temperature can be controlled. Variations can be minimized. This improves the reproducibility of the temperature profile when electronic component mounting boards are continuously carried in, improves the production quality, and reduces the time required when changing the temperature setting when switching production models. It can be planned.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory diagram of a reflow apparatus according to an embodiment of the present invention.
FIG. 2 is a view showing a profile measurement result of a furnace temperature when a cooling function is not used in the reflow apparatus according to the embodiment of the present invention.
FIG. 3 is a diagram showing a profile measurement result of the in-furnace temperature when the cooling function is used in the reflow apparatus in one embodiment of the present invention.
FIG. 4 is an explanatory diagram showing a cooling function of the reflow device in one embodiment of the present invention.
FIG. 5 is a side view of the entire reflow apparatus in one embodiment of the present invention.
FIG. 6 is a schematic view of a conventional reflow apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Furnace 1a Internal furnace 1b External furnace 2 Cooling space 3 Printed wiring board 4 Heating chamber 5 Blowing means 6 Heating means 8a Temperature detection means 8b Temperature control means 9 Outside air introduction port 10 Exhaust port 12 Heat sink 12a, 12b Heat transfer protrusion 13, 14 Exhaust means

Claims (4)

In a reflow apparatus in which a printed wiring board on which a solder material is applied and an electronic component is mounted is carried into a furnace and heated to melt the solder material and join the electronic component to the printed wiring board. heating chamber for heating, the heating chamber gives the circulating air flow with a heating means for heating the air blowing means, as well as the circulating air flow, and the internal furnace body sealable, surrounds the upper Symbol inner furnace body the inner furnace body A cooling space is formed between the external furnace body provided with an outside air inlet and an exhaust port of the cooling space, and the atmosphere of the cooling space is exhausted from the exhaust port communicating with the exhaust port of the external furnace body. and an exhaust means for, while exhausting the high temperature atmosphere of the cooling space by operating the evacuating means, by introducing a low-temperature furnace outside atmosphere to the cooling space, that controls the ambient temperature of the inner furnace body Li flow An apparatus, the cooling is exposed to the space and the first heat transfer protrusions that dissipates heat to the atmosphere in the cooling space, a second absorbing heat exposed to the inner space of the inner furnace body from the atmosphere of the space a heat sink and a heat transfer protrusion, the first heat transfer protrusions is positioned in proximity to the external air inlet port of the outer furnace body, the blowing means sucks heated air second heat transfer protrusions is blown to the substrate A reflow apparatus, wherein the reflow apparatus is disposed so as to be positioned at an opening to be returned .   Using the reflow device according to claim 1, heating is performed during temperature rise, heating is stopped after the set temperature, and cooling is performed so that the furnace temperature is raised to the set temperature and then maintained at a constant temperature. A reflow method characterized by that. In a reflow furnace in which a solder material is applied and a printed wiring board on which an electronic component is mounted is carried into a furnace and heated, and the solder material is melted to join the electronic component to the printed wiring board.
A heating chamber for heating the upper surface of the printed circuit board, a blower means for supplying a circulating airflow to the heating chamber, and a heatable means for heating the circulating airflow, and a sealable internal furnace body, and surrounding the internal furnace body A cooling space is formed between the internal furnace body, an external furnace body provided with an outside air introduction port and an exhaust port of the cooling space, and the cooling space communicating with the exhaust port of the external furnace body from the exhaust port. And exhausting the high temperature atmosphere of the cooling space by operating the exhaust means, and introducing the low temperature furnace atmosphere into the cooling space, A reflow device for controlling the heat, which is exposed to the cooling space and dissipates heat to the atmosphere in the cooling space. 1 A heat sink having a heat transfer protrusion and a second heat transfer protrusion that is exposed to the internal space of the internal furnace body and absorbs heat from the atmosphere in the space. 1 The heat transfer protrusion is positioned close to the outside air inlet of the external furnace body, and the second heat transfer protrusion is positioned at the opening that sucks the heated air blown to the substrate and returns it to the blowing means. An upper reflow device installed;
A heat chamber that heats the lower surface of the printed wiring board, a blower that gives a circulating airflow to the heating chamber, and a heatable means that heats the circulating airflow, and an internal furnace body that can be sealed and surrounds the internal furnace body A cooling space is formed between the internal furnace body, an external furnace body provided with an outside air introduction port and an exhaust port of the cooling space, and the cooling space communicating with the exhaust port of the external furnace body from the exhaust port. And exhausting the high temperature atmosphere of the cooling space by operating the exhaust means, and introducing the low temperature furnace atmosphere into the cooling space, A reflow device for controlling the heat, which is exposed to the cooling space and dissipates heat to the atmosphere in the cooling space. 1 A heat sink having a heat transfer protrusion and a second heat transfer protrusion that is exposed to the internal space of the internal furnace body and absorbs heat from the atmosphere in the space. 1 The heat transfer protrusion is positioned close to the outside air inlet of the external furnace body, and the second heat transfer protrusion is positioned at the opening that sucks the heated air blown to the substrate and returns it to the blowing means. The lower reflow device
A reflow furnace characterized by comprising.   It is a reflow furnace provided with the reflow apparatus of Claim 1, Comprising: The nozzle was provided in the ventilation means, It comprised so that heated air might be sprayed on a printed wiring board by this nozzle, The reflow furnace characterized by the above-mentioned.

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