JPH0377772A - Method and device for infrared heating type reflow soldering - Google Patents

Abstract

PURPOSE:To prevent defective soldering by preheating material to be joined on a conveyor up to the specified temperature, regulating the temperature difference generated by size of a packaging component, etc., and heating quickly the material to be joined whose temperature difference is regulated above the melting point of solder to carry out soldering. CONSTITUTION:The packaging component 9 is mounted on cream solder 11 on a substrate 8 to form the material 10 to be joined. When the material 10 to be joined is mounted on the conveyor 7 and put in a preheating part 3 of a furnace main body 1, it is heated by stages in order from the ordinary temperature to 160 deg.C and sent to a temperature difference regulation part 4 where the temperature difference among the packaging components 9 generated on the preheating part 3 is regulated by an air blasting means. When the material 10 to be joined is then proceeded in a reflow part 5, the material 10 to be joined is irradiated with a halogen lamp and heated to the specified temperature and the solder 11 is molten and the packaging component 9 is joined to the substrate 8 which is then put in a cooling part 6 and cooled rapidly by fans 18. By this method, even the substrate on which an Al electrolytic capacitor, etc., which are components having low heat resistance are packaged mixedly can be prevented from defective soldering.

Description

Detailed Description of the Invention "Field of Industrial Application" The present invention relates to an infrared heating reflow soldering method and an infrared heating reflow soldering apparatus, and in particular,
Infrared heating reflow soldering method and infrared heating reflow soldering method that performs reflow soldering by adjusting the temperature rise caused by the size of the mounted components and the sparseness and density of their placement at room temperature or above during preheating to prevent thermal shock of the mounted components. Connect to soldering equipment.

"Prior Art" In recent years, with technological development in the electronics industry, the miniaturization of electronic devices has been promoted, and chip components have come to be used in place of conventional components with lead wires.

In order to efficiently mount these chip components, the surface mounting method was introduced, and the reflow method came to be widely used as a soldering method for efficiently bonding to minute locations.

One widely used reflow method is an infrared heating type reflow apparatus as shown in FIG.

In FIG. 8, a preheating section 3 is connected to a partition wall 2;
It is divided into a reflow part 5 and a cooling part 6.

In the above-mentioned furnace body 1, a conveyor 7 running in the direction of the arrow is disposed in the middle stage.

The preheating section 3 is provided to prevent weak heat-resistant components such as aluminum electrolytic capacitors from being damaged or their characteristics deteriorate due to sudden heating, and to activate the FLA SOCS. 2~
It is divided into 4 sections.

In this preheating section 3, the materials to be joined 1O placed on the traveling conveyor 7 are sequentially heated.
Panel heater 12 for far infrared irradiation across conveyor 7
is placed as a heat source, and the material to be joined 10 is heated from room temperature to 160°C.
It is heated for about 2 to 3 minutes at a heating temperature of ℃.

As shown in FIG. 5, for example, the bonded material 10 placed on the conveyor 7 is one in which cream solder 11 is supplied to a board 8 and a mounting component 9 is mounted thereon in the previous process.

The reflow part 5 melts the applied solder in a short time and joins the mounted component 9 to the board 8. In the example shown in FIG. 8, the wavelength range 0. Halogen lamps 16 of 7 to 3 μm are placed opposite to each other across the conveyor 7, and heat the solder at about 220° C. for 10 to 30 seconds when the solder melting temperature is 183° C.

The cooling unit 6 also includes a fan 17.1 with the conveyor 7 in between.
7 are arranged opposite to each other, and the substrate 8 after the process in the reflow part 5 is completed,
The mounted component 9 is rapidly cooled.

"Problems to be Solved by the Invention" In the conventional glue flow furnace described above, for example, as shown in FIG.
On the other hand, aluminum electrolytic capacitors 19, slide switches, jacks, which are weak heat-resistant parts,
In a mounting configuration in which mounted components 9 such as connectors are arranged in isolation, a temperature difference of 50° C. to 70° C. occurs between the preheating section 3 and the reflow section 5, as shown in FIG.

Due to this temperature difference, on the one hand, the isolated and high-temperature mounted component 9 may be damaged, deformed, or have characteristics deteriorated due to heat, and on the other hand, the solder may not melt sufficiently, causing solder failure. was there.

Furthermore, in the future, considering the diversification and variety of mounted components, the occurrence of the above-mentioned situations is likely to increase.

This invention was developed in view of the above points, and even if large and small components are mixed densely and sparsely, they can be mounted continuously without causing soldering defects, thermal damage, or thermal deterioration. The object of the present invention is to provide a reflow soldering method and a reflow soldering device that can perform soldering.

"Means for Solving the Problems" In order to solve the above-mentioned problems, in the present invention, a material to be joined, on which a mounted component is mounted on a board with solder interposed therebetween, is placed on a running conveyor, and The temperature difference between the preheating process in which the materials to be joined are heated stepwise from room temperature to 160°C and the temperature difference in the heating preparatory process that occurs due to the size of the mounted components and the density and density of their arrangement is adjusted to above room temperature. 4!
1 process and temperature difference! A method characterized by sequentially performing a reflow soldering process in which the material to be joined which has been subjected to llu is rapidly heated above the melting point of the solder and the mounted component is joined to the board, and a method in which the mounted component is bonded to the board by sandwiching the solder. A preheating section includes means for placing the loaded materials to be joined on a running conveyor and heating the materials to be joined on the conveyor stepwise from room temperature to 160 degrees Celsius; Use air blowing means to eliminate the temperature difference that occurs in the preheating section due to density! g! a temperature difference adjustment section that adjusts the temperature difference, and a reflow section that rapidly heats the materials to be joined after adjusting the temperature difference above the melting point of the solder to join the mounted components to the board.
It is characterized by consisting of.

"Function" As shown in FIG. 5, in the pre-process, after the cream solder 11 is supplied onto the board 8, the mounting component 9 is mounted on the cream solder 11 to form the bonded material 10.

As shown in the process diagram of FIG. 1, the above-mentioned materials to be welded 10 are placed on the continuously running conveyor 7, and the conveyor 7 runs in the direction of the arrow and enters the preheating section 3 of the furnace body 1. As the conveyor 7 moves in the direction of the arrow, the materials 1o to be joined are successively heated in stages from room temperature to 160''C, and then sent to the temperature difference adjusting section 4.

At this time, as shown in FIG. 4, for example, the material to be bonded 10 is mounted with a relatively large QFP type LSI, a capacitor C1 resistor R, etc. packed together on one side, and an aluminum electrolytic capacitor 19 as a heat-resistant component on the other side. In an extreme case where the unit is mounted in isolation, 30 to 5
A difference of 0°C or more occurs.

In the temperature difference adjustment section 4 where the conveyor 7 runs, the temperature difference between the mounted components 9 and 9 generated in the preheating section 3 is adjusted.
By means of air blowing! l! J will be adjusted. That is, the isolated aluminum electrolytic capacitor 19 is
is rapidly cooled, and a relatively large QFP type LSI and capacitor C
5. A block packed with resistors R, etc. is slowly cooled, and both are at approximately the same temperature or an isolated aluminum electrolytic capacitor 1.
9 becomes 10°C to 20°C lower.

Next, the conveyor 7 carrying the temperature-adjusted materials 10 to be joined advances into the reflow part 5. In this reflow part 5, 10 to 30
irradiated for seconds. The material to be joined 10 irradiated with the halogen lamp 16 , 16 is heated to approximately 220° C., the applied solder 11 is melted, and the mounted component 9 is joined to the substrate 8 .

Next, as the conveyor 7 moves, the substrate enters the cooling section 6, is rapidly cooled by fans 17 and 17 arranged vertically, and is sent to the next process as a board with components mounted thereon.

"Embodiments" Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a schematic sectional view showing a first example of implementation of the reflow soldering apparatus according to the present invention.

In this FIG. 2, the furnace body 1 is divided into three
It is divided into a preheating section 3 divided into sections, a temperature difference adjustment section 4, a reflow section 5, and a cooling section 6.

Furthermore, a conveyor 7 that runs in the direction of the arrow is disposed in the middle of the furnace body 1, as shown in FIG.

Each preheating section 3 prevents thermal damage and thermal deterioration caused by rapid heating by slowly heating the material IO to be joined, which is made up of a substrate 8 and a mounted component 9 shown in FIG. 4, for example, and activates the flux. It was set up to make it easier to understand.

The material to be bonded 10 consisting of a substrate 8 and a mounted component 9 is obtained by, for example, as shown in FIG. 5, cream solder 11 is supplied to the substrate 8 and the mounted component 9 is mounted in the previous step. In this preheating section 3, panels or bar heaters using far infrared rays are arranged as a heat source across the conveyor 7 to sequentially heat and raise the temperature of the materials 10 to be joined, and a fan 13 that causes the heated air to circulate .13 is placed, and the materials to be joined 10 placed on the conveyor 7 are heated to about 160°C.

Material to be heated 1 to be preheated in the above preheating section 3
0 on the other hand, as shown in FIG.
Type LSI, capacitor C2 resistor R, etc. are crowded together, and on the other hand, there is an aluminum electrolytic capacitor 19 which is a heat-resistant component.
In the implementation form in which there are isolated cases, large variations occur as shown in FIG.

The temperature difference adjusting section 4 is a section newly provided in the present invention, and adjusts the variation in the temperature rise of the mounted component 9 that has been preheated as described above.

This temperature adjustment section 4 is arranged as close as possible to the preheating section 3.
The reflow part 5 is insulated with an air curtain (not shown), etc., and an intake fan 14 is installed across the conveyor 7 in order to eliminate variations in temperature rise without impairing the preheating effect.
*4&, 4b, to which the exhaust fan 15 is disposed, are an intake port and an exhaust port, respectively, which are open at the top and bottom of the temperature difference adjustment section 4.

In addition, high l! This temperature difference is due to the fact that the small, isolated mounted components 9 that are heated to a temperature of 100 mm cool down more easily than the large, closely packed components 9 that are less likely to be heated. l! !
In the adjustment section 4, the upper part of the mounted component 9, which is small and isolated, is
#It is desirable to set the humidity temperature lower than that of the large and densely mounted components 9 in consideration of the next process.

The Noflo part 6 melts the cream solder 1itt of the mounted component 9 whose temperature has been adjusted by the temperature difference adjustment part 4, and the solder is melted for a short time.
1 (10 seconds to 30 seconds) to bond the mounted component 9 to the board 8.

In this reflow part 5, as shown in FIGS. 1 and 2, halogen lamps 16.
A 15 μm far-infrared rod heater is carved, and a fan 17.17 for convection of heated air is provided.

If the melting temperature of the cream solder 11 printed on the substrate 8 is 183°C, the heating temperature is about 220°C.

As a result, the cream solder 11 melts and the mounted component 9
is bonded to the substrate 8.

As shown in FIG. 2, the cooling unit 6 includes an air supply fan 18.
18 are arranged opposite to each other with the conveyor 7 interposed therebetween.

And reflow ll3 by this fan 18.18
The material to be joined lO sent out from 5 is rapidly cooled.

Next, an example of the infrared heating type reflow soldering method according to the present invention will be explained in order of steps.

(a-1) Pre-process (mounted component mounting process) As shown in FIG. 5, after the cream solder 11 is supplied onto the board 8,
The mounting component 9 is mounted on the cream solder 11 and sent to the next process as a bonded material 10.

(a> Preheating step The materials 10 to be joined on the conveyor 7 are heated stepwise from room temperature to 160°C.

In order to prevent the QFP type LSI, capacitor C1 resistor R, aluminum electrolytic capacitor 19, and other mounted components 9 mounted on the board 8 in the previous process from being damaged or their characteristics deteriorating due to sudden thermal shock, they are heated from room temperature. The material to be joined 10 is heated to about 160°C by heating stepwise at 160°C.

The heating time in this preheating step is approximately 2 to 3 minutes, and the heating is performed slowly in stages.

The heated material to be joined lO is sent to the next process.

(b) Temperature Difference 11 Adjustment Process Temperature differences in the ship preliminary process caused by the size of the mounted components 9 and the spacing and density of their arrangement are adjusted to above room temperature.

The material to be heated 10 that is preheated in the preheating step is
For example, as an extreme example, as shown in Figure 4, on the one hand, a relatively large QFP type LSI, capacitor C, and resistor
etc. are crowded together, and on the other hand, the aluminum electrolytic capacitor 19, which is a weak heat-resistant component, is isolated.
The results were as shown in the graph of FIG. That is,
When preheating is completed, the heating temperature of the part where the QFP type LSI, capacitor C1 resistor R, etc. are densely mounted is 120°C, while the heating temperature of the isolated aluminum electrolytic capacitor 19 is 150°C. There was a 30 degree gap.

If the aluminum electrolytic capacitor 19 is supplied to the reflow H5 in this state, there is a risk that the isolated aluminum electrolytic capacitor 19 will be rapidly heated and its function will be destroyed.
If the heating time and heating temperature are adjusted to 9, bonding failures will occur in dense areas due to insufficient heat.

Therefore, in this invention, for example, FIGS.
As shown in the figure, a suction a opening is provided below the temperature difference adjusting section 4.
The intake fan 14 sucks in cold outside air from the opening 4a, and the hot air 2 is sucked in by the exhaust fan 15 from the upwardly opened exhaust slot 4b.
discharge.

As a result, the isolated aluminum electrolytic capacitor 19 is rapidly cooled, and the block in which the relatively large QFP type LSI, capacitor C1 resistor R, etc. are densely cooled is slowly cooled, and both are at approximately the same temperature or the isolated aluminum electrolytic capacitor 19 is cooled down slowly. becomes -10°C to -20°C lower.

(c) Reflow process The material 10 to be joined, which has been subjected to temperature difference adjustment, is rapidly heated to a temperature higher than the melting point of the solder, and the mounted components are joined to the board.

Temperature l! The conhair 7 carrying the I-aligned workpiece 10 advances into the reflow part 5. In this reflow part 5, the material to be bonded 10 is irradiated with a halogen lamp 16.16 for 10 to 30 seconds and is heated to about 220° C., the applied solder 11 is melted, and the mounted component 9 is bonded to the board 8. Ru.

(c+1) Quenching process Next, as the conveyor 7 runs, the substrate enters the cooling section 6, is rapidly cooled by fans 18 and 18 arranged vertically, and is sent to the next process as a board with components mounted thereon.

6 and 7 show a second embodiment of the present invention, in which the furnace body 1 in the first embodiment is divided into two parts, and the temperature difference adjusting section 4 is shaped like an oven. It is.

Therefore, the preheating section 3 is formed in an independent furnace body 21 and is divided into three sections by partition walls 2.2. In addition, the reflow part 5 and the cooling part 6 are connected to an independent furnace main body 3.
It is formed within 1.

In the temperature difference adjusting section 4 in this second embodiment, as shown in FIG.
．． 24 are provided oppositely. Furthermore, since the temperature difference adjustment section 4 is of oven type, the adjustment effect is exhibited as shown in the graph of FIG.

"Effects of the Invention" As described above, the present invention eliminates uneven heating of preheated boards and mounted components in reflow soldering, and lowers the temperature of mounted components that are easily heated before reflowing. Even on boards on which QFP type LSIs, aluminum electrolytic capacitors, slide switches, connectors, etc., which are weak aging-resistant components, are mounted together, it can be mounted without causing damage, deformation, or characteristic deterioration due to poor soldering or overheating. I can do it.

Therefore, it is extremely effective for the diversification and variety of mounted components in the future.

FIG. 8 is a schematic sectional view of the conventional example at position i, and FIG. 9 is a graph showing the temperature change of the heated material in the conventional example.

Furnace body Preheating section Temperature difference! 11 Orthopedic Department Reflow part

[Brief explanation of drawings]

Claims (2)

[Claims] (1) A preheating step in which the materials to be joined, on which the components are mounted with solder sandwiched between them, are placed on a running conveyor, and the materials to be joined on the conveyor are heated in stages from room temperature to 160°C. , a temperature difference adjustment step in which the temperature difference in the preliminary heating step that occurs due to the size of the mounted components and the sparseness and density of the arrangement is adjusted to above room temperature, and the materials to be joined after the temperature difference adjustment are rapidly heated above the melting point of the solder. An infrared heating reflow soldering method characterized by sequentially performing a reflow soldering process for bonding mounted components to a board. (2) A means for placing a material to be joined on which a mounted component is mounted on a board with solder sandwiched therebetween on a running conveyor, and heating the material to be joined on the conveyor in stages from room temperature to 160°C. a temperature difference adjustment part that uses an air blower to adjust the temperature difference that occurs in the preheating part due to the size of the mounted components and the sparseness of their arrangement; A reflow part that rapidly heats up and joins the mounted components to the board,
An infrared heating reflow soldering device comprising: