JPH0831689B2 - Soldering equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a soldering device for soldering components onto a printed circuit board.

BACKGROUND ART Conventionally, a soldering device that heats components to solder them to a printed circuit board, such as a reflow furnace shown in FIG. 10, comprises a printed circuit board 2 on which solder paste has been printed and attached in a previous process (not shown) and on which electronic components 3 such as LSIs are mounted, a belt conveyor 1 that transports the printed circuit board 2, a chamber 6 into which the printed circuit board 2 is carried by the belt conveyor 1, a heating device 5a that is provided inside the chamber 6 and that heats the printed circuit board 2 carried into the chamber 6 to melt the attached solder paste, and a cooling device (not shown) that cools the printed circuit board 2 carried out of the chamber 6 by the belt conveyor 1.

The solder paste is a mixture of low-melting-point solder alloy powder containing Sn, Pb, Bi, etc., organic solvent, inorganic solvent, plastic, etc. Here, it is not limited to electronic components 3, but may be other components or elements. However, in the above-mentioned conventional device, electronic components 3 are simply placed on the solder paste-printed surface of printed circuit board 2, and the solder paste is melted by heating from above to perform soldering. This requires a large amount of solder paste, leaves solder flux residue, and has poor adhesive strength. Furthermore, the heating is convective and overall, heating areas that do not require heating are also heated, resulting in a large amount of heat, which can reheat already-bonded mounted components or cause thermal damage to the entire printed circuit board.

In particular, flux residue after soldering poses an environmental problem as it requires a cleaning process.

Therefore, the present invention reduces the amount of solder paste used,
To provide a soldering device which reduces solder flux residue, heats only necessary portions, reduces the amount of heat to be heated, and thereby reduces thermal damage to the entire printed circuit board and has a simple configuration.

DISCLOSURE OF THE INVENTION The present invention relates to a printed circuit board having solder paste applied to both sides thereof and components mounted on both sides thereof;
A soldering apparatus comprising a belt conveyor for transporting the printed circuit board, a chamber into which the printed circuit board is carried by the belt conveyor, a cooling device for cooling the printed circuit board carried out of the chamber by the belt conveyor, a pressing section for pressing the components mounted on both sides of the printed circuit board so as to sandwich them, and a heating device for heating the pressing section to a temperature above the melting point of the solder paste, wherein the printed circuit board is placed upright on the belt conveyor.

Furthermore, the present invention improves on conventional soldering devices that consist of a heating device that heats a printed circuit board to which solder paste has been applied and which has components mounted thereon, thereby melting the applied solder paste.The soldering device comprises a single heat-resistant sheet that is not glued or sewn together, a sealed container with the heat-resistant sheet attached to at least the bottom opening, the heat-resistant sheet and a heat-resistant fluid filled in the container, and the heating device that is inserted to heat the heat-resistant sheet and the heat-resistant fluid within the container, and is characterized by having a pressing and heating section that is lowered from above to press and heat the components with the heat-resistant sheet.

Furthermore, the present invention improves on conventional soldering devices that consist of a heating device that heats a printed circuit board to which solder paste has been applied and which has components mounted thereon to melt the applied solder paste, and is a soldering device characterized by comprising: a pressing and heating section that consists of a single heat-resistant sheet that is not glued or sewn together, a sealed container with the heat-resistant sheet stretched over at least the lower opening, the heat-resistant sheet and a heat-resistant fluid filled in the container, and the heating device that is inserted to heat the heat-resistant sheet and the heat-resistant fluid within the container; and an up-and-down movement means that places the printed circuit board on a heating plate and raises it to press the components against the heat-resistant sheet.

According to the present invention, a pressing section that presses the components mounted on both sides of the printed circuit board so as to sandwich them, and a heating device that heats the pressing section to a temperature higher than the melting point of the solder paste are provided, and the printed circuit board is placed upright on the belt conveyor, so that the soldering strength is strengthened, and since only the pressing section and the components are heated, thermal damage to the components and the entire board is prevented.
It will be reduced.

Furthermore, a pressure heating section is provided which comprises a heat-resistant sheet that is not glued or sewn together, a sealed container with the heat-resistant sheet stretched over at least the lower opening, the heat-resistant sheet and the container filled with heat-resistant fluid, and the heating device inserted to heat the heat-resistant sheet and the heat-resistant fluid within the container, and which is lowered from above to apply pressure and conduction heating to only the unjoined components mounted on the printed circuit board with the heat-resistant sheet.

Alternatively, a pressing and heating section may be provided, which comprises a single heat-resistant sheet that is not glued or sewn together, a sealed container with the heat-resistant sheet stretched over at least the bottom opening, the heat-resistant sheet and the container filled with a heat-resistant fluid, and the heating device inserted to heat the heat-resistant sheet and the heat-resistant fluid within the container; and a vertical movement means for placing the printed circuit board on a heating plate and lifting it to press the components against the heat-resistant sheet.

This reduces the amount of solder paste used because of direct conduction heating, thereby reducing solder flux residue, and also strengthens the soldering strength through pressure, reducing the amount of heat required, and since heating is only required in the necessary areas rather than the entire printed circuit board, there is less thermal damage to the mounted components. Also, even if some of the leads of components such as LSIs are deformed so that they float slightly, the pressure ensures that the leads are firmly soldered to the copper foil pattern.

The heat capacity of heat-resistant fluids is greater than that of metals, so there is less temperature change, making it easier to control the temperature during work.
Furthermore, since a single heat-resistant sheet that is not glued or sewn is used, the pressure heating section can be simply configured and can be easily adapted to the shape of the components on the printed circuit board.

As described above, in the present invention, the components are press-heated by the pressing part heated by the heating device to a temperature equal to or higher than the melting point of the solder paste, thereby enhancing the soldering strength.
Since only the pressing part and part of the component are heated, thermal damage to the component and the entire board is reduced, and since components are mounted on both sides of the board, the soldering process can be reduced.

Furthermore, since the soldering device heats only the leads and not the main body of the electronic component, damage to the electronic component and deterioration of its performance due to heat can be prevented.Furthermore, in some cases, a reflow oven can be omitted.

Furthermore, while the heating device in a reflow furnace uses radiation heating, the present invention uses conduction heating, resulting in high heating efficiency.

Furthermore, since the leads are mounted on a patterned surface coated with solder paste, the pressure effect of the heat storage body's own weight allows soldering to be completed reliably and in a short time, further reducing the thermal impact on electronic components.

Furthermore, in the pre-process, using the conventional reflow oven method,
After only the solderable electronic components are mounted, the components that are particularly susceptible to heat can be individually mounted according to the present invention, thus enabling two-step surface mounting.

Furthermore, without using a reflow furnace, the space formed by the bottom and protruding lower end of the heat storage body and the printed circuit board can be made almost airtight, and soldering can be easily performed in an inert gas produced by decomposition of ethanol by dripping liquid ethanol onto the solder joint through a pipe attached to the heat storage body, or in a reducing gas by dripping nitrogen gas. In these atmospheres, the solder paste is less likely to become acidic, so the amount of solder paste used can be reduced.

Furthermore, direct conduction heating reduces the amount of solder paste used, thereby reducing solder flux residue, and the pressure strengthens the soldering strength, reducing the amount of heat required. Since only the necessary parts need to be heated, rather than the entire PCB, thermal damage to the mounted components is minimal. Even if some of the component leads are slightly deformed and lifted, the pressure ensures that the leads are firmly soldered to the copper foil pattern.

The heat capacity of heat-resistant fluids is greater than that of metals, so there is less temperature change, making it easier to control the temperature during work.
Furthermore, since a single heat-resistant sheet that is not glued or sewn is used, the pressure heating unit has a simple structure and is easily adaptable to the shape of the components on the printed circuit board.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram of an embodiment of the present invention, FIG. 2 is a diagram of another embodiment of the present invention, FIG. 3 is a plan view, FIG. 4 is a partially enlarged plan view, FIG. 5 is a partially enlarged sectional view, FIG. 6 is a partially enlarged sectional view, FIG. 7 is a diagram of another embodiment of the present invention, FIG. 8 is a diagram of another embodiment of the present invention, FIG. 9 is a diagram of another embodiment of the present invention,
FIG. 10 is an explanatory diagram of a conventional example.

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described based on its embodiments with reference to the drawings. Figure 1 is a diagram showing the configuration of one embodiment of the present invention. A belt conveyor 1 conveys a printed circuit board 2 in an upright position, with solder paste applied to both sides and components 3 mounted on both sides.

Furthermore, the components 3 mounted on both sides of the printed circuit board 2
a pressing unit 4 that presses the solder paste in the direction of the arrow 7 while sandwiching the solder paste; and a heating device 5 that heats the pressing unit 4 to a temperature higher than the melting point of the solder paste.
Furthermore, a printed circuit board 2 having components 3 mounted on both sides thereof is provided.

In the above embodiment, the heating device 5 is provided in contact with the pressing portions 4, 4a, but it may be provided separately so as to preheat the pressing portions 4, 4a.

Fig. 2 is a diagram showing the configuration of another embodiment of the present invention, Fig. 3 is a plan view, and Figs. 4 and 5 show the detailed configuration of the pressure heating unit 34. The conveyor 1 transports the printed circuit board 2 to which solder paste is attached and on which components 3 are mounted. However,
This conveyor 1 may not be provided.

The pressure heating unit 34 comprises a heat-resistant sheet 39 that is not glued or sewn together, a sealed container 37 with the heat-resistant sheet 39 attached to at least the bottom opening, and a heat-resistant sheet 39.
and a heat-resistant fluid 38 filled in a container 37, and a heat-resistant sheet
39 and a heating device 37e made of a nichrome wire or the like inserted in the container 37 to heat the heat-resistant fluid 38.
The chisels are individually pressed by a heat-resistant sheet 39 and heated by conduction.

The heat-resistant fluid 38 may be, for example, a molten alloy such as Sn-
Examples of suitable materials include Pb-based binary alloys, Sn-Pb-Bi-based ternary alloys with lower melting points, and heat-resistant Teflon oil. The single heat-resistant sheet 39, which is not glued or sewn, is made of a synthetic resin such as polyphenylene fluoride or polyimide film, or a plastic film, on one or both sides of which is coated, for example, with a composite sheet of copper foil or other metal foil sprayed with methanol. The heat-resistant sheet 39 may consist of a single sheet or multiple sheets.

The container 37 of the pressure heating unit 34 is equipped with a temperature control sensor 37f for measuring and controlling the temperature of the heat-resistant fluid 38, and is sealed by a lid 37a having an inlet 37g for the heat-resistant fluid 38.
2, the printed circuit board 2 on which the components 3 are mounted is pressed by the heat-resistant sheet 39. The mechanism for lowering the pressure heating unit 34 from above using a piston or the like is not shown, but the pressure heating unit 34 is lowered downward from the state shown in FIG. 2, and the printed circuit board 2 on which the components 3 are mounted is pressed by the heat-resistant sheet 39 as shown in FIG. 6.

As a result, the solder joint of the lead 3a, to which the solder paste is attached, is heated and pressed at the same time. The heat-resistant sheet 39 of the pressing and heating section 34 is flexible, so it presses while conforming to the shape of the component 3. The required pressing force at this time is controlled by the heat-resistant fluid 38 used.
In addition to adjusting the amount of pressure, a mechanism for lowering a piston or the like from above may be adjusted as necessary. In this case, in order to prevent components mounted on the printed circuit board from moving, it is possible to fix them in advance with adhesive, for example.

Although not shown, a hot air heating device that blows hot air from below may be provided on the printed circuit board 2 located below the pressure heating section 34. In this case, the conveyor 1 is configured to have a mesh structure, holes, or the like so that the hot air can pass through from below.

7 shows another embodiment of the present invention. The end of a heat-resistant sheet 39 is held inside a container 37 by an inner tube 30.
Although not shown, the container 37 may be constructed by fastening the heat-resistant sheet 39 to the inner cylinder 30 by using a rubber band to fasten the heat-resistant sheet 39 to the outer side.

8 shows another embodiment of the present invention. A belt conveyor is not used, and the printed circuit board 2 is placed on a heating plate 31 on a cylinder 32 which is a vertical movement means. By moving this heating plate 31 up and down, the printed circuit board 2 is heated.
The heat is conducted by pressure from the heat-resistant sheet 39. The vertical movement means is not limited to the cylinder 31, as a matter of course.

9 shows another embodiment of the present invention. The structure is the same as that of the embodiment of FIG. 8, but the end of the heat-resistant sheet 39 is connected to the inner cylinder 30.
The container 37 is held in place by the
The container 37 may be constructed by fastening the heat-resistant sheet 39 to the inner cylinder 30 by using a rubber band to fasten the heat-resistant sheet 39 to the outer surface thereof.

In the above embodiment, the belt conveyor 1 and a cooling device (not shown) for cooling the printed circuit boards 2 and 23 after heating are used for mass production, but these may not be used in some cases.

Industrial Applicability Used in the process of soldering components to printed circuit boards,
Used in the electrical equipment industry, etc.

Claims (5)

[Claims] [Claim 1] A soldering apparatus comprising: a printed circuit board with solder paste applied to both sides thereof and components mounted on both sides thereof; a belt conveyor for transporting the printed circuit board; a chamber into which the printed circuit board is carried by the belt conveyor; a cooling device for cooling the printed circuit board after it is carried out of the chamber by the belt conveyor; a pressing section for pressing the components mounted on both sides of the printed circuit board so as to sandwich them; and a heating device for heating the pressing section to a temperature above the melting point of the solder paste, wherein the printed circuit board is placed upright on the belt conveyor. [Claim 2] A soldering device comprising a heating device that heats a printed circuit board to which solder paste has been applied and which has components mounted thereon, thereby melting the applied solder paste, the soldering device comprising: a heat-resistant sheet that is not glued or sewn together; a sealed container with the heat-resistant sheet stretched over at least the bottom opening; a heat-resistant fluid filled in the heat-resistant sheet and the container; and the heating device inserted to heat the heat-resistant sheet and the heat-resistant fluid within the container, the soldering device being provided with a pressing heating section that is lowered from above to press and heat the components with the heat-resistant sheet. 3. The soldering apparatus according to claim 2, further comprising a hot air heating device for blowing hot air from below onto the printed circuit board located below the pressure heating section. 4. The soldering apparatus according to claim 2, wherein a conveyor for transporting the printed circuit board is provided below the pressure heating section. [Claim 5] A soldering apparatus comprising a heating device that heats a printed circuit board to which solder paste has been applied and which has components mounted thereon to melt the applied solder paste, characterized in that the soldering apparatus comprises: a heat-resistant sheet that is not glued or sewn together; a sealed container with the heat-resistant sheet stretched over at least the lower opening; a heat-resistant sheet and a heat-resistant fluid filled in the container; and the heating device inserted to heat the heat-resistant sheet and the heat-resistant fluid within the container; and an up-and-down movement means that places the printed circuit board on a heating plate and raises it to press the components against the heat-resistant sheet.