JP3926430B2 - Flux application method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is a method of applying a flux so that when soldering an electronic component to a circuit board to produce an electronic circuit board, a stable solder bonding is achieved by applying a flux to the leads of the electronic component. The present invention relates to a method and apparatus.
[0002]
[Prior art]
When soldering an electronic component to a circuit board, since the lead for soldering the electronic component is covered with an oxide film, good solder bonding cannot be expected as it is. Therefore, it has been conventionally performed to include solder in the solder and to remove the oxide film of the lead by the flux at the time of soldering and to perform soldering.
[0003]
Also, when soldering electronic components with solder formed in advance on the circuit board, the solder formed in this way contains almost no flux. It is necessary to apply a flux to the lead side of the wire.
[0004]
If the main part of the electronic component cannot be soiled by the flux or the like when the flux is applied to the lead, the flux should be applied only to the lead part without attaching the flux to the main body of the electronic component. For this reason, it is desirable to apply a very small amount of flux to the necessary local area.
[0005]
Conventionally, in order to satisfy this, an apparatus as shown in FIG. This apparatus includes a tank b for storing the flux a, and a flux supply container c and a flux diluent supply container by a pump f so that the amount and concentration of the flux a in the tank b detected by the detection unit e are constant. From d, flux a and a flux diluent are replenished.
[0006]
A coating block g is immersed in the tank b, and is moved up and down by a cylinder h. The application block g has application parts g1 and g2 opposed to the lead j of the electronic component i schematically shown in FIG. 5B. When the application block g is moved up by the cylinder h and lifted from the pool of flux a, Flux a remains on the upper surfaces of the application parts g1 and g2 as shown in FIG. 5B, and a small amount is applied to the lead j by bringing it into contact with the opposing part of the lead j of the electronic component i.
[0007]
[Problems to be solved by the invention]
However, since the application portions g1 and g2 of the application block g are close to the lateral lead j from below, the flux a can be applied to the lead j only on the lower surface of the lead j, not only on the upper surface of the lead j, Cannot be applied to the tip or side. As a result, when the solder is joined, the solder and the lead j can be joined only on the lower surface of the lead j, and the joint strength between the lead j and the solder is compared with the case where the side surface and the front end surface of the lead j are soldered. It will be as low as about 1/2 to 1/5.
[0008]
The flux a in the tank b is controlled so that the amount and concentration are constant as described above, but the flux a held in the coating block g is a part of the entire flux a in the tank b. Since the amount is very small, strict concentration control cannot be performed, and the shape of the flux a held in the coating block g is not constant because of the surface tension corresponding to the concentration. For this reason, even if the same amount of flux a is always held in the application block g, the application amount of the flux a to the lead j changes, and the application amount is excessive, and the main body of the electronic component i is contaminated. Occurs.
[0009]
The main object of the present invention is to provide a flux application method and apparatus capable of maintaining a constant flux concentration and applying a small amount with high precision to the entire periphery of the tip of the lead without fouling the main body of the electronic component for stable solder bonding. Is to provide.
[0010]
[Means for Solving the Problems]
The flux coating apparatus according to the first aspect of the present invention is a flux for supplying flux by a coating system having a flux pouring hole on the coating surface and a supply system having a closed path including a sealed reservoir in the coating block. Supply means, dispensing control means for pouring out the flux supplied to the application block in a timely manner by collecting the surface tension, and the application surface from the axial direction to the tip of the lead of the electronic component where the application block is positioned The advancing / retreating means for advancing and retreating the coating block and a stopper for regulating the advancement position of the coating block, and the coating block has a tapered surface that tapers toward the coating surface. is there.
[0011]
In such a configuration, it is sufficient flux dispensed through Note Deana provided to the coated surface of the coating block, Okeru the supply system flux Until then the closed path, the flux is an open system handling as the concentration due like diluent volatilized avoid to flux the like varies dispensing amount in the coated surface is controlled by a dispensing control means a minute amount required for the coating in It is possible to prevent the main part of the electronic component from becoming dirty due to excessive application so that only the flux exists, and the application surface where the flux is poured out is located at the tip of the tapered shape, so that the flux a protruding protection to adjacent surfaces due to the surface tension, on the basis of the advancing by moving means of the coating block and the restriction by the stopper of the advanced position, the electronic component Li From the axial direction at the tip of the de is fit faces and against the high accuracy, lead tip pierces the small amount dispensed is the stagnant flux variation reservoir shape due to surface tension without a constant concentration required for coating surface enters without change as, then both due to the distance with high accuracy in the axial direction by moving means, are applied commensurate with the change without entering the small amount remaining so that the entire circumference of the lead tip, When soldering the tip of the lead to the circuit board, the flux acts on the entire periphery of the tip of the lead so that the solder can be satisfactorily performed.
[0012]
As in the second aspect of the invention, the dispensing control means can apply more accurately if the shape or amount of the flux to be supplied to the application block is made constant.
[0017]
When the coating block is formed on the coating surface having a shape and a size corresponding to the arrangement area when a plurality of the leading ends of the leads are arranged adjacent to each other as in the invention of claim 3 , The spread flux spreads on the coated surface due to its surface tension, but the spread area is restricted to the range corresponding to the arrangement area of the tip of the lead, and the dispensed flux spreads too much and contaminates the main part of the electronic component. While preventing this, the flux can be applied at once to the adjacent tip portions of a plurality of leads facing in the same direction.
[0019]
When the release block is applied to the taper surface as in the invention of claim 4 , the flux dispensed by reducing the wettability of the flux poured onto the coating surface to the taper surface is tapered. It is possible to reliably suppress the spread to the surface, and to easily cause the flux that has overflowed to easily fall off, and to prevent the flux from spreading too much and contaminating the main part of the electronic component.
[0020]
According to a fifth aspect of the present invention, there is provided a flux application method comprising: applying a flux to a lead of an electronic component and soldering the electronic component to a circuit board; Flux is supplied by a supply system that is a closed path including a sealed reservoir, and the flux is controlled to be poured out from the inside of the coating block to the coating surface of the coating block in a timely manner by collecting the surface tension. It is characterized in that the flux poured out on the coating surface of the coating block is applied to the tip of the lead by making contact with the tip of the lead facing the coating surface from the axial direction and then separating in the axial direction. Yes, and realized by the flux coating apparatus of the invention of claim 1.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a typical embodiment of the present invention will be described with reference to FIGS. 1 to 4 together with some examples.
[0022]
In the present embodiment, the flux 1 is stored and handled in a cylinder 2 as shown in FIG. The cylinder 2 has a sealed structure so that the change in the state of the flux 1 such as volatilization of the diluent and deterioration of the flux can be prevented. Pressure is applied to the cylinder 2 from above by a gas such as pressure-controlled air or inert gas so that the flux 1 can be constantly pushed out from the lower outlet of the cylinder 2.
[0023]
The extruded flux 1 is supplied to the coating block 5 through the tube 3 via the valve 4 and is poured out from the dispensing hole 5a in the coating surface 51 to the coating surface 51 every time the valve 4 is opened. . The valve 4 opens and closes the valve in the valve 4 by a signal from the valve control unit 6.
[0024]
The electronic component 7 shown in FIGS. 1, 2 and 3 (a) and (b) to which the flux 1 is to be applied is gripped by gripping means (not shown) for handling components such as a suction nozzle and a chuck. The coating block 5 is positioned at the tip 8a of the lead 8 of the electronic component 7 being gripped at a position and orientation facing the coating surface 51 from the direction of the axis X, and the dispensed flux 1 is as shown by the solid line in FIG. The surface tension corresponding to the concentration spreads on the coating surface 51, and is indicated by phantom lines in FIG. 2, and as shown in FIGS. 4A and 4B, the tip 8a of the lead 8 and the coating surface 51 are in the X direction. 2 is again shown by a solid line in FIG. 2 and separated as shown in FIGS. 3A and 3B, the flux 1 poured out onto the coating surface 51 leads. 8 is applied to the tip 8a portion.
[0025]
When the tips 8a of the leads 8 are arranged adjacent to each other as shown in a side view (a), a plan view (b), a side view (a) and a plan view (b) in FIG. It is formed on the application surface 51 having a shape and size corresponding to the arrangement area. This is not essential, but by doing so, the spreading area when the dispensed flux 1 spreads on the coating surface 51 due to its surface tension is restricted to a range corresponding to the arrangement area of the tips 8a of the leads 8. Thus, the flux 1 is applied at once to the adjacent tips 8a of the plurality of leads 8 facing in the same direction while preventing the poured flux 1 from spreading too much and contaminating the main part of the electronic component 7. be able to.
[0026]
As shown in FIGS. 1 to 4, the leads 8 from the electronic component 7 are oriented in two directions, or in four directions, or when there are a plurality of orientations, the number corresponding to the number of orientations The application block 5 is provided as shown in FIG. Although this is not essential, the flux 1 can be simultaneously applied to the tips 8a of the plurality of leads 8 provided in a plurality of directions. In this case, if the supply system of the flux 1 for the plurality of application blocks 5 is individually provided as shown in FIG. 1, the work and various control can be freely performed to perform the individual application work at the same time. High degree is preferable.
[0027]
As shown in FIG. 2, the coating block 5 is advanced and retracted on the axis X of the tip 8 a of the lead 8 by an actuator 11 such as a cylinder or the like, and the coating surface 51 part is connected to the tip 8 a of the lead 8 by a solid line in FIG. Further, the coating is performed while being separated from each other as indicated by a virtual line. When the application surface 51 approaches or comes into contact with the tip 8a of the lead 8 as indicated by the phantom line in FIG. 2, the tip 8a of the lead 8 is pierced into the pool of flux 1 poured out and spreading on the application surface 51. Since it enters, the flux 1 remains substantially uniformly around the tip 8a portion of the lead 8 by the separation in the direction of the axis X to the state shown by the solid line in FIG. 2, and the flux 1 is evenly distributed all around the tip 8a portion. It will be in the state applied to. As a result, in order to solder-join the tip 8a portion of the lead 8 to a circuit board (not shown), the flux 1 can work around the entire periphery of the tip 8a portion of the lead 8 so that the solder joint can be performed satisfactorily.
[0028]
Further, since the flux 1 is poured into the coating surface 51 of the coating block 5 through the dispensing hole 5a, the supply system of the flux 1 can be used as a closed path as in the above-described embodiment, so that the flux 1 is an open system. It is possible to avoid the concentration from changing due to volatilization of the diluent, etc., which is handled in the process, and the amount of flux 1 dispensed is said to be the adjustment of the valve opening time by the valve control unit 6 With this control, it is possible to prevent the main body portion of the electronic component 7 from becoming dirty due to excessive application so that only a small amount of flux 1 necessary for application exists on the application surface 51.
[0029]
In addition, since the concentration of the flux 1 poured onto the application surface 51 does not vary as described above, the shape of the pool on the application surface 51 due to the surface tension of the flux 1 can be made constant, and the lead as described above. In combination with the constant movement of the tip 8a of the lead 8 from the direction of the axis X and the restriction of the advancement position of the coating surface 51 by the stopper 21, etc., in the pool of flux 1 at the tip 8a of the lead 8 When the amount of penetration of the flux 1 and the shape and amount of the flux 1 around it are made constant, the tip 8a of the lead 8 enters the flux 1 pool and spreads to the surface due to surface tension. Since the stable minimum action form between the surface 51 and the tip 8a of the lead 8 is constant, the amount of the flux 1 applied to the tip 8a portion of the lead 8 is a predetermined minute amount with high accuracy. It can be stabilized.
[0030]
If the coating surface 151 of the coating block 105 is larger than the arrangement area of the tip 8a portion of the lead 8, the spreading area of the flux 1 becomes large, and the body part of the electronic component 7 due to overcoating is soiled. When the application surface 51 is shaped like the application block 5 is simply cut into a rod-shaped body, the flux 1 poured out on the application surface 51 is likely to protrude into the surrounding surfaces following the application surface 51 and the spread of the flux 1 is increased. The area will increase. In this state, the coating surface 51 is brought close to the tip 8a of the lead 8 from the direction of the axis X, and at the moment when the tip 8a contacts the pool of flux 1, the flux 1 flows excessively toward the lead 8 side. 3C and the comparative example shown in FIG. 4C, the main part of the electronic component 7 is reached and contaminated. In particular, such a problem is likely to occur when the flux 1 is excessively poured out.
[0031]
Therefore, in the present embodiment, as shown in FIGS. 1 to 4, the application surface 51 having a shape and size corresponding to the arrangement position of the tip 8 a portion of the lead 8 is tapered toward the application surface 51. A tapered surface 52 is formed. As a result, the wettability of the flux 1 poured out on the coating surface 51 to the tapered surface 52 is reduced, and the poured flux 1 is reliably prevented from spreading out to the taper surface 52, and the flux is unlikely. Even if it is excessively poured out, the flux 1 that protrudes excessively onto the tapered surface 52 can naturally drop, and the flux 1 spreads too much, including the case where the amount of dispensing is excessive, so that the body part of the electronic component 7 Can be prevented.
[0032]
Therefore, by excessively dispensing the flux 1 each time, the concentration is not stable because it is in contact with the atmosphere at the portion of the dispensing hole 5a although it is a very small amount that is dispensed at the very beginning. It is preferable that a certain amount of flux 1 can be naturally dropped by the action of the tapered surface 52 and the remaining proper amount of flux 1 having a constant concentration can be applied.
[0033]
Also, prior to the dispensing of the flux 1 for application, if the flux 1 that is not subjected to application is dispensed empty, the flux 1 that has been dispensed can be applied immediately, so that the flux at a concentration as set. 1 is used for coating, and fluctuations in the coating amount due to changes in concentration over time in a state where the flux 1 is dispensed can be prevented, and stable soldering can be assured.
[0034]
Thus, although the density | concentration of the flux 1 used for application | coating becomes stable when the flux 1 is supplied before every application | coating operation | movement, it is not before application | coating operation | movement depending on the application quantity and the kind of the flux 1, or does not supply the flux | However, the same effect can be obtained. The amount of the flux 1 dispensed can be adjusted by adjusting the opening time of the valve 4 by the valve control unit 6, changing the opening diameter, or changing the pressure in the cylinder 2. It is possible to control the amount of the flux 1 dispensed into the.
[0035]
In the present embodiment, the valve 4 is controlled by a signal from the valve control unit 6, but it is a matter of course that the same effect can be obtained even if the valve control unit 6 controls the valve by air with a dispenser. .
[0036]
Further, when the application is continuously performed, a new flux 1 is always supplied. However, even if the operation of the processes before and after production stops for some reason and the application of the flux 1 is interrupted, the application surface 51 is applied. In order to keep the concentration of the flux 1 constant, when a predetermined time elapses, the flux 1 is poured out at a constant interval until the application of the flux 1 is resumed. It can be ensured that the concentration of the flux 1 is a predetermined concentration.
[0037]
Further, the wettability of the flux 1 poured out on the coating surface 51 to the taper surface 52 is reduced by coating the coating block 5 with a mold release layer 22 such as Teflon. Therefore, it is possible to reliably suppress the flux 1 that has been poured out to reach the tapered surface 52, and to allow the flux 1 that has excessively protruded from the tapered surface 52 to fall naturally, and the flux spreads too much and soils the main body of the electronic component 7. This can be prevented.
[0038]
Even if the application position is determined by controlling the position data of the actuator as the advance / retreat means of the application block 5 using a motor or the like, the same effect can be obtained.
[0039]
【The invention's effect】
According to the first aspect of the present invention, when soldering the electronic component to the circuit board, the flux is applied to the tip portion of the lead for soldering the electronic component with high accuracy by the application block from the axial direction of the tip portion. Supply to the opposite and butting bases, and handle the flux in the closed supply system to keep the concentration constant , and the minute amount required on the coated surface forms a pool shape due to surface tension. Since the supply is controlled by dispensing , a predetermined amount is applied with high accuracy to the entire circumference of the tip of the lead, and stable solder bonding can be performed without contaminating the main body of the electronic component.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a flux coating apparatus according to a typical embodiment of the present invention.
FIG. 2 is a side view showing an advancing / retreating drive unit of a coating block of the apparatus of FIG.
3 shows details of the coating block of the apparatus of FIG. 1 and a comparative example thereof, (a) is a side view of the coating block of the apparatus of FIG. 1, (b) is a plan view, and (c) is a comparison. It is a side view of an example.
4 shows the state of flux application by the application block of FIG. 3, wherein (a) is a side view of the application block of the apparatus of FIG. 3, (b) is a plan view, and (c) is a side view of a comparative example. It is.
FIG. 5 is a schematic configuration diagram of a conventional flux coating apparatus.
[Explanation of symbols]
1 Flux 2 Cylinder 3 Tube 4 Valve 5 Application Block 51 Application Surface 52 Tapered Surface 6 Valve Control Unit 7 Electronic Component 8 Lead 8a Tip 11 Actuator 21 Stopper 22 Releaseable Layer X Axis

Claims (5)

An application block having a flux dispensing hole on the application surface, a flux supply means for supplying flux in a supply system having a closed path including a sealed reservoir in the application block, and a flux supplied to the application block Dispensing control means for dispensing in a reservoir shape due to surface tension, advancing / retreating means for advancing / retreating the coating block from the axial direction to the tip of the lead of the electronic component where the coating block is positioned, and advancement of the coating block comprising a stopper for regulating the position, the coating block, flux coating apparatus characterized by having a tapered surface tapering toward the coated surface. The flux application apparatus according to claim 1, wherein the dispensing control means makes the accumulation shape or amount of the flux supplied to the application block constant. Coating blocks, when the distal end portion of the leads are more adjacently arranged, according to any one of claims 1 and 2 are formed on the coated surface of the shape and size corresponding to the sequence region Flux application device. The flux application apparatus according to claim 3 , wherein the application block has a taper surface subjected to a release treatment. When soldering an electronic component to a circuit board, a flux is applied to the lead of the electronic component and applied to the solder, in the flux application method,
Flux is supplied to the application block of the flux through a supply system that is a closed path including a sealed reservoir, and the flux is poured out from the inside of the application block to the application surface of the application block in a pool shape due to surface tension. It is characterized in that the flux poured out on the application surface of the application block is applied to the tip of the lead by controlling and making contact with the tip of the lead from the axial direction so as to face the application surface and then separating in the axial direction. How to apply flux .

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