JPH08307047A - Solder precoated circuit board, method and apparatus for solder precoating - Google Patents

Abstract

PURPOSE: To improve the precoating of cream solder. CONSTITUTION: Cream solder H in the container 21a of an application unit 21 is filled in the cream solder-holding grooves in a transfer plate 13 by means of a rubber roller 21b. Then the transfer plate 13 is pressed against a circuit board W on an X-Y stage 30, and is heated to alloy the part-foot land and the like on the circuit board W and the cream solder. The cream solder holding grooves in the transfer plate 13 are arranged in almost the same pattern as the part-foot land and the like. The amount of solder to be precoated is controlled by the depth of the cream solder-holding grooves.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solder precoat circuit board, a solder precoat method, and a solder precoat apparatus, in which a solder precoat for joining a lead electrode of a circuit component to a component foot land of a printed circuit pattern is joined. Is.

[0002]

2. Description of the Related Art When mounting circuit components on a circuit board,
Generally, solder is used to join the lead electrodes of the circuit component to the component foot lands of the circuit board, and the conventional mounting method using solder is to melt the thread solder with a soldering iron. While introducing it between the component foot land and the lead electrode of the circuit component, dipping the circuit board temporarily holding the circuit component in the solder melting bath, or mixing powdered solder with flux or binder. The so-called reflow soldering that supplies a cream-shaped paste to the component foot lands of the circuit board by screen printing, etc., mounts the circuit components on it, and heats it with infrared rays or laser light to melt the cream solder Laws are being developed.

[0003]

However, according to the above-mentioned prior art, the method using the soldering iron is inefficient because it requires a lot of manual work as described above.
In the dipping method, particularly when mounting a circuit component having a narrow lead pitch, solder bridging frequently occurs and the product yield is remarkably reduced. The reflow soldering method, which allows relatively stable soldering even for small circuit components and has excellent mass productivity, is now widely used. In the process of supplying to the foot lands, if the space between the component foot lands is narrow, it is difficult to apply an appropriate amount of cream solder, and problems such as insufficient solder or solder bleeding occur.

More specifically, there are a dispenser method using an application nozzle and a printing method using a printing plate (screen) for applying the cream solder to the component foot land of the circuit board. In the dispenser method, the solder is used. Due to the relatively large particle size of the powder and the viscosity of the cream solder, the diameter of the coating nozzle cannot be made too small. For this reason, it is difficult to accurately supply the cream solder to a narrow space.

Further, the printing method using a printing plate determines the plate thickness of the printing plate and the size of the opening through which the cream solder passes according to the required amount of the cream solder, and a large amount of solder material is required. In some cases, increase the plate thickness of the printing plate to deal with it, or if the spacing between component foot lands is large, open the printing plate opening larger than the size of the component foot lands on the circuit board. On the contrary, when the amount of solder material is small, that is, when mounting IC components with a narrow lead pitch, even if an attempt is made to reduce the plate thickness of the printing plate, as described above, Since the particle size of the solder powder contained in the cream solder is relatively large, the plate thickness of the printing plate cannot be made very thin, and its limit value is significantly influenced by the particle size of the solder powder. Further, there is a limit to reducing the opening size of the printing plate, and in this case as well, it depends on the particle size of the solder powder.

Further, when the opening size of the printing plate becomes small and the pitch of the opening becomes narrow, the cream solder does not easily enter the opening of the printing plate.
There is a possibility that the cream solder may remain on the printing plate and the amount of solder may be insufficient when the cream solder that has entered is transferred to the component foot land on the circuit board.

As described above, it is difficult to precisely control the amount of solder to be supplied, and it is impossible to avoid variations in the amount of solder to be supplied and bleeding of cream solder, so that solder bridges are placed between the component foot lands of the circuit board. Occurs, and the reliability of the electrical connection of the mounted components is significantly impaired.

The present invention has been made in view of the problems of the above-mentioned conventional technique, and it is supplied even if the component foot lands for supplying solder have a small area or their intervals are narrow. It is an object of the present invention to provide a solder precoat circuit board, a solder precoat method, and a solder precoat device, which have an appropriate amount of solder and do not cause a solder shortage or a solder bridge.

[0009]

In order to achieve the above object, a solder precoat circuit board of the present invention is a solder precoat circuit board having a solder precoat on a mounting surface for mounting a circuit component. However, it is formed by a process of transferring the cream solder to the mounting surface by filling the recess of the transfer member with the recess with cream solder and then pressing the transfer member with the recess against the mounting surface and heating. It is characterized by being.

In the solder precoating method of the present invention, after the cream solder is filled in the recesses of the transfer member with recesses,
The method further comprises the step of pressing the transfer member with recesses onto a circuit board and heating the transfer member to transfer the cream solder to the circuit board.

It is preferable to have a step of aligning the recessed transfer member filled with cream solder with the circuit board.

Further, it is preferable to have a step of cooling the transfer member with the recess, to which the cream solder is transferred, to a predetermined temperature and then retracting it from the circuit board.

Further, it is preferable to monitor the temperature of the recessed transfer member.

The solder precoating device of the present invention comprises a transfer member with a recess having a recess for filling with cream solder,
The present invention is characterized in that the transfer member with a recess is aligned with the circuit board and a transport pressing mechanism for pressing the transfer member with the circuit board and a heating means for heating the transfer member with the recess are provided.

It is preferable that the transfer member with a recess is detachably attached to the heating means.

Temperature detecting means for monitoring the temperature of the transfer member having a recess may be provided.

Further, it is preferable to provide a cooling means for cooling the transfer member with recess.

The transfer member with recesses may be made of a solder non-adhesive material having a low affinity for solder.

[0019]

[Function] By filling means, cream solder is filled in the recesses of the transfer member having recesses, and the transfer member having recesses is pressed against the mounting surface of the circuit board to heat the cream solder to melt the solder paste, thereby making the component foot land on the mounting surface. Etc., and then the transfer member with recess is cooled and retracted to form a solder precoat.

The recesses of the transfer member with recesses are arranged in the same pattern as the component foot lands on the mounting surface of the circuit board to which the solder precoat is applied, and by changing the depth of the recesses, the amount of solder to be precoated Can be controlled in an extremely wide range.
Even if the surface area of the component foot land etc. is small or the interval between the component foot land etc. is narrow, it is possible to control the amount of solder in an appropriate amount with extremely high accuracy, so especially when mounting a small electronic component etc. It is possible to perform highly reliable electrical connection without causing solder variations or solder bridges.

If the heating of the transfer member with recesses is stopped after alloying the cream solder with the component foot land or the like, the cream solder will cool and solidify from the inner surface side of the recesses of the transfer member with recesses. When the recessed transfer member is retracted, the entire amount of cream solder is transferred to the component foot land or the like. Therefore, there is no possibility that a part of the solder is left in the recess of the transfer member with the recess and the amount of solder in the solder precoat is insufficient.

If there is a step of forcibly cooling the transfer member with a recess and then retracting it from the circuit board, the next work of filling the cream solder can be performed immediately, so that the work tact is shortened and the productivity is improved. be able to.

In addition, when the temperature of the transfer member with recess is monitored by the temperature detecting means in the heating process or the cooling process of the transfer member with recess, if the temperature of the transfer member with recess is accurately controlled, the cream solder will be removed. Not only the step of melting and alloying with the component foot land etc. and then forcibly cooling, but also the preparation step of cooling the transfer member with recess to a proper temperature for the next cycle, etc. can be performed smoothly and quickly. Productivity can be further improved.

The recesses of the transfer member with recesses can be easily formed into a predetermined pattern by a known method such as etching.

If the transfer member with recess is detachably attached to the heating means, only the transfer member with recess may be replaced according to the pattern shape of the component foot land.

If the recessed transfer member is made of a solder non-adhesive material having a low affinity for solder, cream solder is alloyed with the component foot land and the recessed transfer member is retracted. Since the cream solder is easily peeled off from the recess of the transfer member with recess when doing so, it is possible to reliably avoid troubles such as the cream solder remaining on the transfer member with recess and the amount of solder in the solder precoat is insufficient.

[0027]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a solder precoating apparatus for obtaining a solder precoat circuit board according to one embodiment. This is a heating / cooling head having a heater (not shown) as heating means and a cooling pipe as cooling means. 11
And a heat transfer member 12 integrally connected thereto, and a solder transfer unit 10 including a transfer plate 13 which is a transfer member with a recess detachably attached to the heat transfer member 12 The heater of the head 11 is heated by the wiring 11a, the cooling medium is supplied to the cooling pipe of the heating / cooling head 11 by the supply pipe 11b, and the temperature of the heat transfer member 12 is a temperature sensor including a thermocouple or the like serving as temperature detecting means. Monitored by 12a.

The solder transfer unit 10 conveys the cream solder applied to the transfer plate 13 by the cream solder applying device 20 as a filling means to above the XY stage 30 and transfers it to the circuit board W on the XY stage 30. The heating / cooling head 11 of the solder transfer unit 10 is suspended from the lower end of a Z-axis member 14b supported by a support 14a so as to be vertically movable, and the Z-axis member 14b is vertically moved by a Z motor 14c. Support 14a extends horizontally X
It can be reciprocally moved on the shaft member 15a by its rotation, and the X shaft member 15a is rotated by the X motor 15b.

That is, the support 14a and the Z-axis member 14
b, Z motor 14c, X axis member 15a, X motor 15b
And the like constitute a transport pressing mechanism that transports the solder transfer unit 10 from the cream solder application position shown by the solid line to a position above the XY stage 30 shown by the broken line, and then presses the solder transfer unit 10 onto the circuit board W.

The cream solder coating device 20 is provided with a container 21a containing the cream solder H and a coating unit 21 composed of a rotatable rubber roller 21b whose lower half is immersed in the cream solder H. ,
The transfer roller 13 is reciprocally moved in the horizontal direction by the X motor 22, and the rubber roller 21b is brought into contact with the transfer plate 13 of the solder transfer unit 10 and rotated, so that the cream solder H in the container 21a is filled in the transfer plate 13.

XY stage 30 holding circuit board W
Has a suction plate 31 that sucks the circuit board W, an X stage 32 that supports the circuit board W, and a Y stage 33 that supports the X stage 32 so as to be capable of reciprocating in a predetermined horizontal direction. The X stage 3 is supported so as to be capable of reciprocating in a horizontal direction orthogonal to the moving direction of the stage 32.
2 and the Y stage 33 respectively include an X motor 32a and a Y motor 32a.
It is driven by the motor 33a.

A monitor camera 40 for aligning the transfer plate 13 of the solder transfer unit 10 and the circuit board W is arranged above the XY stage 30. The monitor camera 40 is arranged along the XY stage 30 by the robot 41. It can be moved horizontally to any position within a specified range,
The XY stage 30 can be retracted to an inoperative position beside it.

The monitor camera 40 is mounted on the transfer plate 13 of the solder transfer unit 10 carried over the XY stage 30.
Of the alignment mark 13b (see FIG. 2 (c)), and the XY stage 3
0 has a downward detection unit 40b for detecting the alignment mark of the circuit board W on the 0. First, the robot 41 is driven to detect the alignment mark 13b of the transfer plate 13 by the upward detection unit 40a of the monitor camera 40. Then
Then, until the alignment mark of the circuit board W is detected by the downward detection unit 40b, the XY stage 30
Drive. Upward detecting section 40a and downward detecting section 4
0b simultaneously detects the alignment mark 13b of the transfer plate 13 and the alignment mark of the circuit board W, respectively, the alignment of the transfer plate 13 and the circuit board W is completed, and the monitor camera 40 retracts to the inoperative position.

Next, the transfer plate 1 of the solder transfer unit 10
3 will be described in detail. As shown in FIG. 2A, the transfer plate 13 is heated or cooled by the heating / cooling head 11 via the heat transfer member 12, and is attached to the heat transfer member 12 downward in the drawing. As shown in (b), a cream solder holding groove 13a, which is a recess, is formed on the surface of the transfer plate 13 by known etching, and the cream solder holding groove 13a is formed as shown in (c). The pattern is formed in substantially the same pattern as a component foot land (not shown) provided on the mounting surface of the circuit board W, and an alignment mark 13b for alignment with the circuit board W is provided at a corner of the transfer plate 13. A screw hole 13c is provided for detachably attaching the transfer plate 13 to the heat transfer member 12, and the transfer plate 13 can be exchanged according to the pattern of the component foot land of the circuit board W.

The material of the transfer plate 13 is preferably a solder non-adhesive material having a low affinity for the melted cream solder. This is because when the transfer plate 13 having the cream solder holding groove 13a filled with the cream solder is transferred to the circuit board W on the XY stage 30, all the cream solder in the cream solder holding groove 13a is the component foot land of the circuit board W. It is extremely important to prevent the transfer to the cream solder holding groove 13a and to prevent it from remaining in the cream solder holding groove 13a.

Next, the process of pre-coating the component solder of the circuit board W with cream solder by using this solder pre-coating device will be described.

First, the cream solder applicator 20 fills the cream solder groove 13a of the transfer plate 13 of the solder transfer unit 10 with the cream solder. This is done by moving the rubber roller 21b immersed in the container 21a in the horizontal direction together with the container 21a while contacting the downward surface of the transfer plate 13 of the solder transfer unit 10 as described above. Then, the X motor 15b of the solder transfer unit 10 is driven to move the solder transfer unit 10 to the X position.
The monitor camera 40 is moved to a position above the Y stage 30, the alignment mark 13b of the transfer plate 13 and the alignment mark of the circuit board W are confirmed by the monitor camera 40, and then the monitor camera 40 is retracted to the inoperative position.

By driving the Z motor 14c, the solder transfer unit 10 is lowered onto the circuit board W, and the transfer plate 13 is pressed against this to energize the heater of the heating / cooling head 11 so that the cream solder holding groove 13a of the transfer plate 13 is formed. Heat and melt the cream solder. At this time, the heating / cooling head 11
Is monitored by the temperature sensor 12a and is fed back to the heater of the heating / cooling head 11. In this way, the heating time and temperature of the heating / cooling head 11 are controlled,
The cream solder of the transfer plate 13 is alloyed with the component foot land of the circuit board W.

Next, the energization of the heater of the heating / cooling head 11 is stopped, the cooling medium is supplied from the supply pipe 11b to the heating / cooling head 11 to cool it to a predetermined temperature, and then Z
The motor 14c is reversely driven to raise the solder transfer unit 10. At this time, the cream solder in the cream solder holding groove 13a is alloyed with the component foot land of the circuit board W, and further, the cream solder is cooled and solidified from the inner surface side of the cream solder holding groove 13a.
As described above, since the transfer plate 13 is made of a solder non-adhesive material, the solder transfer unit 10 rises while leaving all the cream solder on the component foot land. The elevated solder transfer unit 10 returns to its position on the cream solder applicator 20 for the next solder precoat cycle. During this time, the heating / cooling head 11 is continuously cooled, and when returning to the cream solder coating apparatus 20, the temperature is controlled to be the most suitable temperature state for the next solder precoat cycle.

The in-process temperature sensor 12a constantly monitors the temperature of the heating / cooling head 11.

When the pattern of the component foot land of the circuit board to be pre-coated with the cream solder in the next solder pre-coating cycle is different from that in the previous soldering pre-coating cycle, the transfer plate 13 is replaced with a predetermined one.

Instead of the cream solder applicator which fills the cream solder holding groove of the transfer plate facing downward of the solder transfer unit with a rubber roller, as shown in FIG.
As shown in, the solder transfer unit 50 for supporting the transfer plate 53 similar to the transfer plate 13 upward is provided, and
You may use what was comprised so that the cream solder on the cream solder receiving plate 60 arrange | positioned by the side of the upward transfer plate 53 may be spread on the transfer plate 53 by the rubber squeegee 61. In this case, it is necessary to fill the cream solder holding groove of the transfer plate 53 with the cream solder and then lower the solder transfer unit 50 and rotate it by 180 degrees so that the transfer plate 53 faces downward.

According to the present embodiment, the cream solder holding groove of the transfer plate is filled with the cream solder and then the transfer plate is pressed against the circuit board to transfer the cream solder. By forming it in almost the same pattern as the component foot land etc. of, it is possible to prevent the cream solder pre-coated on the component foot land etc. from bleeding or solder bridging.
By changing only the depth of the cream solder holding groove, the solder amount of the solder precoat can be appropriately controlled in a wide range.

Even if the surface area of the component foot land or the like is small or the interval of the component foot land or the like is small, the solder amount can be controlled with an extremely high accuracy and an appropriate amount, so that particularly small electronic components (for example, a lead pitch of 300 μm, The reliability of electrical connection when mounting (IC parts) etc. can be greatly improved.

Further, as described above, since the cream solder is heated and melted to be transferred to the circuit board and then the transfer plate is retracted, the entire amount of the cream solder is left on the component foot lands of the circuit board. There is no fear that the amount of solder will run short as in the case of cream solder printing.

Furthermore, the solder transfer unit quickly cools the transfer plate in the process of returning to the cream solder applicator for the next solder precoat cycle, and the transfer plate becomes too hot in the next cycle, which hinders the cream solder filling work. It is possible to avoid problems such as being caught. As a result, the work cycle of the solder precoating process can be significantly reduced.

[0048]

Since the present invention is configured as described above, it has the following effects.

Even if the component foot land or the like to be soldered has a small area or its interval is narrow, the amount of solder in the solder precoat is appropriate, and troubles such as insufficient solder and solder bridge can be avoided. As a result, the mounting process of particularly small electronic components can be greatly improved.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a solder precoating device according to an embodiment.

2A and 2B are explanatory views of a solder transfer unit of the apparatus of FIG. 1, in which FIG. 2A is a partial elevational view showing a main part of the solder transfer unit, FIG. 2B is a partial sectional view showing only a transfer plate, and FIG. )
FIG. 6 is a perspective view showing the transfer plate in an upside-down state.

FIG. 3 is a diagram illustrating a solder precoating device according to a modification.

[Explanation of symbols]

 10,50 Solder transfer unit 11 Heating / cooling head 12 Heat transfer member 13,53 Transfer plate 13a Cream solder holding groove 13b Alignment mark 20 Cream solder applying device 21 Applying unit 21a Container 21b Rubber roller 30 XY stage 40 Monitor camera 61 Rubber squeegee

Claims (11)

[Claims] 1. A solder precoat circuit board having a solder precoat on a mounting surface for mounting a circuit component, wherein the solder precoat fills a recess of a transfer member with a recess with cream solder and then forms the recess. A solder pre-coated circuit board, which is formed by a step of pressing a transfer member having a transfer onto the mounting surface and heating the transfer member to transfer the cream solder to the mounting surface. 2. A solder having a step of filling cream solder into a recess of a transfer member with recess and then pressing the transfer member with recess to heat the circuit substrate to transfer the cream solder to the circuit substrate. Precoat method. 3. A step of aligning a transfer member with a recess filled with cream solder with a circuit board.
The solder precoating method described. 4. The solder precoating method according to claim 2 or 3, further comprising the step of cooling the transfer member with the recess onto which the cream solder is transferred to a predetermined temperature and then retracting the recessed transfer member from the circuit board. 5. The solder precoating method according to claim 2, wherein the temperature of the recessed transfer member is monitored. 6. A transfer member with a recess having a recess for filling with cream solder, a transfer pressing mechanism for aligning the transfer member with the recess with a circuit board and pressing the transfer member, and the transfer with the recess. A solder precoat device having a heating means for heating a member. 7. The transfer member with a recess is detachably attached to the heating means.
The described solder precoat device. 8. The solder precoating apparatus according to claim 6, further comprising temperature detecting means for monitoring the temperature of the transfer member having the recess. 9. The solder precoating apparatus according to claim 6, further comprising cooling means for cooling the recessed transfer member. 10. The solder precoating apparatus according to claim 6, wherein the transfer member with recesses is made of a solder non-adhesive material having a low affinity for solder. 11. The solder precoating apparatus according to claim 6, wherein a filling means for filling the cream solder is provided in the recess of the transfer member with the recess.