JP2003017846A - Lead-free soldering method and device thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve solder-wicking property and to reduce appearance deficiencies of solder of a board with high through holes by using lead-free solder. SOLUTION: The soldering device performs soldering of a MID board 10 in one solder bath 5 in the atmospheric. When a board housing 30 held by a robot is transferred to above a nozzle 51 of the solder bath 5, the bath 5 makes a turbulent flow region and jets solder liquid from the underside of the MID board 10. The board housing 30 is consecutively conveyed forward in the turbulent flow region for 3.5-4 sec. by the robot. In this way, the solder jet onto the MID board 10 rises in a through-hole 14 in the MID board 10. After the completion of the forward conveyance, the solder bath 5 turns to a laminar flow region and the board housing 30 is conveyed backward in the laminar flow region. Consequently, the solder is cut back without waste, and the occurrence of solder bridges, icicle-like solder or the like is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead-free soldering method and apparatus for soldering a patterned wiring board. The wiring board includes a three-dimensional molded board, a printed board, a flexible board, and the like, and mainly relates to a lead-free soldering method and apparatus suitable for a board to which a wire harness is connected.

[0002]

2. Description of the Related Art Conventionally, a patterned wiring board such as a printed circuit board is generally soldered by a flow soldering method or a reflow soldering method. For example, the one disclosed in Japanese Patent Laid-Open No. 2000-144424 is one in which flow soldering is performed on the back surface side after reflow soldering the mounted product on the front surface, and in the flow soldering, it is stored in a solder bath. Soldering is performed by jetting molten solder and jetting the jetted solder onto the back surface side of a printed circuit board conveyed by a conveyor. Then, when jet solder is sprayed onto the printed circuit board for soldering, cool air is supplied from above the conveyed printed circuit board to cool the front surface side of the printed circuit board.

Further, the solder which has been conventionally used in the reflow soldering method is, as shown in FIG. 8, a eutectic solder of lead and tin (mainly Pb-63S) in a nitrogen atmosphere.
n) was used. Since the eutectic solder containing lead has a low melting point (about 183 ° C.) and excellent wettability, it has good solderability after soldering. However, because lead-containing materials have an environmental problem that lead elutes by rainwater and pollutes groundwater, lead-free soldering methods that do not contain lead components have been obliged to be adopted. ing.

[0004]

On the other hand, when the work to be soldered is not a printed circuit board but, for example, a three-dimensional molded board of a rotation detection device (rotation sensor) used in a vehicle is lead-free soldered, the lead is not used. Free solder has a higher melting point (about 232 ° C) than eutectic solder because it does not contain lead, and has poor wettability. Therefore, failure in rising through holes, solder bridges and solder icicles after soldering It is easy to cause poor appearance. In other words, the three-dimensional molded board has magnetic detection elements such as Hall ICs, circuit components such as bias magnets, capacitors, and resistors mounted on a resin base, and the terminals of each circuit component are soldered to a wiring pattern formed on the resin base. However, unlike the printed circuit board, the through hole height is extremely high, and the unevenness shape of the soldered portion is formed to be large. Moreover, a wire harness is attached to the three-dimensional molded substrate. Therefore, the raised height of the through hole is high in the three-dimensional molded substrate, and the temperature of the dangling is taken away by the wire harness,
It was difficult for the solder to go up through the high through holes.

Moreover, tin 100 having a high melting point and poor wettability is used.
% (Or lead-free tin-based alloy) solder is used, the plated portion of the solder rising part of the wiring of the three-dimensional molded substrate can be exposed to the solder bath for a short time because the peel strength is reduced. Is in a state. For this reason, especially in the through holes, the solderability is deteriorated, and a defective appearance such as a solder bridge or a solder icicle is likely to occur.

The present invention solves the above-mentioned problems, and provides a lead-free soldering method and apparatus which can prevent the appearance failure by ensuring the rising by using a solder having a high wettability and a high melting point. The purpose is to

[0007]

In order to solve the above-mentioned problems, the lead-free soldering method and apparatus according to the present invention are as follows. That is, claim 1
The lead-free soldering method described, when the substrate to be patterned is transported to the solder bath, in the solder bath, the jet solder solution is in a turbulent region, and the substrate is subjected to the flow of the jet solder solution for a predetermined time. Since the jet solder solution is sequentially fed and dipped in the substrate, the jet solder solution is infiltrated into the through hole, and soldering is performed on the patterned soldering portion. Therefore, the jet solder liquid can rise up even in a high through hole.

Next, after the turbulent flow region of the solder bath is stopped to form a laminar flow region, the attached solder is cut back by reversing the substrate with respect to the flow of the jet solder liquid. At this time, a mechanical relationship occurs between the moving speed of the substrate, the flow velocity of the solder, the surface tension of the solder, and the peelback speed in the portion where the solder is separated from the substrate. Then, by setting the respective speeds so that this mechanical relationship is suspended, the solder can be cut back without waste, so that the appearance can be improved by eliminating the generation of solder bridges and icicles.

By sequentially controlling this, the productivity can be improved.

According to the second aspect of the present invention, as described above, this lead-free soldering can inject the jet solder liquid onto the substrate in the turbulent flow region / laminar flow region, and further sequentially and reversely feed the substrate. Since the solder bath can be carried, the solder bath can be made into one bath, and the apparatus can be made compact by making it into one bath.

According to the third aspect of the invention, the soldering work can be performed in an extremely short time by performing the soldering in the air atmosphere, and the workability can be improved.

Further, in the invention according to claim 4, the substrate has a high through-hole height like a three-dimensional molded substrate, and
Even if the concavo-convex shape is formed large, it is possible to improve the rising due to the jet flow in the turbulent region, and it is possible to prevent defective appearance by switching between forward and reverse feeding
Alternatively, even if the wire harness is attached to the three-dimensional molded substrate or the printed circuit board, the soldering can be performed in the solder bath without enclosing the wire harness and heating the wire harness. .

Further, in the lead-free soldering device according to the fifth aspect, since the substrate is stored in the pallet, for example,
Whether the board is a three-dimensional molded board, a printed board, or a flexible board, it is possible to store all the boards by making a pallet suitable for each board, especially with a wire harness. By enclosing the wiring board in the wiring harness, soldering can be performed in the solder bath without heating the wiring harness. Then, the stored pallets are transferred to the solder bath by the robot, and the finished soldering board can be collected from the collection device together with the pallet. Can be done.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. The lead-free soldering method of the embodiment describes soldering a three-dimensional molded substrate (hereinafter referred to as a MID substrate) used for a rotation detection device (rotation sensor) of a vehicle, and FIGS. The soldering apparatus M shown in FIG. Soldering device M
Is arranged on the machine base 1 and accommodates the MID substrate 10 in the pallet 20 and holds the pallet 20 containing the MID substrate 10 with the hand 201, and the MID substrate 10 accommodated in the pallet 20. Flux device 3 for flux processing and M stored in pallet 20
A heating device 4 for preheating the ID board 10, a solder bath 5 for soldering the MID board 10, and a MID board 10
Are placed in a pallet 20 and placed in a soldering device M, and the soldered MID substrate 10 is placed in the pallet 2
It is configured to have a charging / collecting device 6 for collecting 0.

The MID board 10 has an M
An ID board body 11 and a wire harness 15 are provided, and M
The ID substrate body 11 is a Hall IC on the resin base 12.
A circuit pattern such as a magnetic detection element such as a magnetic field detector, a bias magnet, a capacitor, and a resistor is mounted (not shown because it is mounted on the back surface side in FIG. 3) and terminals of each circuit component are formed on the resin base 12. It is made by soldering and resin molding. The terminals of each circuit component are inserted into the through holes 14 formed in the resin base 12 and soldered to form the wiring pattern 1.
3 will be formed.

In the MID board 10 of this embodiment, the through hole 14 for inserting the terminal of each electronic component is formed to have a height of about 2.5 mm, and the unevenness of the soldered portion has a step difference of about 40 μm. Have this is,
The height of the through hole 13 is about 2.5 times and the unevenness difference is about 8 times that of an ordinary printed circuit board. Also, MID
Wire harness 15 extending from one end side of the substrate body 11
Is formed with a connector portion 16 (see FIG. 4) at the tip.

A pallet 20 for accommodating the MID board 10
As shown in FIGS. 4 to 6, covers the base plate 21 on which a printed circuit board or the like can be mounted in addition to the MID board 10, the front cover 25 that presses the MID board 10 from above, and the wire harness 15. It has a rear lid portion 27. The base plate 21 in the embodiment has a board mounting portion 22 that houses the MID board body portion 11 and a wire harness housing portion 23 that houses the wire harness, and is formed in a substantially rectangular shape. The gripped portion 24 that is gripped by the hand 201 of the robot 2 on the side with respect to the axial direction of 10
Are provided in two places each.

The substrate mounting portion 22 includes the MID substrate body 1
A support portion 221 (see FIG. 6) for supporting both ends of the MID board 1 is formed, and an opening 222 for injecting a solder jet from below the MID board body 11 is formed in substantially the same width as the MID board body 11. Has been done. Furthermore, the board placement unit 2
2 shows the MI in which the front lid portion 25 is supported by the support portion 221.
In order to press the D substrate body 11 from above, one end thereof is axially supported by the substrate mounting portion 22 and is arranged to be openable and closable. A pressing portion 252 (see FIG. 5 or 6) that gently presses both ends of the MID board body portion 11 is protruded downward from the body 251 (see FIG. 5 or 6) of the front lid portion 25 on the front lid portion 25. The magnet 223 on the substrate placing portion 22 side and the magnet 253 on the front lid portion 25 side can be fixed to the substrate placing portion 22 when the front lid portion 25 is closed.

The wire harness accommodating portion 23 is used for accommodating the wire harness 15 of the MID board 10, and in the embodiment, is used for accommodating the connector portion 16 by bending the wire harness within about half the space thereof. ing. Then, one end of the rear lid portion 27 is pivotally supported by a part of the wire harness accommodating portion 23, and the wire is arranged to be openable and closable so as to cover the harness 15. Similarly to the front lid portion 25, the rear lid portion 27 has the other end fixed to the wire harness accommodating portion 23 by a magnet or the like when closed.

The pallet 20 includes a substrate storage section 22,
Wire harness storage 23, hand 201 of robot 2
To be grasped 24, a front lid portion 25 for pressing each substrate, a rear lid portion 27 for covering the wire harness 15, M
The shape is not particularly limited as long as the opening 222 for injecting the jet solder liquid is formed or arranged on the lower surface of the ID substrate body 11, and the MID is not limited thereto.
The entire shape may be formed according to the shape of the substrate, the printed board, or another substrate.

The robot 2 is arranged so as to be located at a substantially central portion on the machine base 1 and is loaded into the loading / recovering device 6 to move to the M
The pallet 20 accommodating the ID substrate 10 is gripped by the hand 201, and the MID substrate 10 is conveyed to the flux device 3, the heating device 4, and the solder bath 5 in this order and recovered by the loading / collecting device 6. .

The flux device 3 is constructed so that the flux liquid can be applied to the back surface side of the MID substrate 10 carried by the hand 201 of the robot 2 to perform soldering. It In the embodiment, in the flux device 3, the solder liquid ULF-3000 is used as the flux liquid, and the flux liquid is applied by the intermittent spray method in about 2 seconds.

The heating device 4 is constituted by a carrying section 41 and a heating section 42, and the pallet 20 which holds the MID substrate 10 and is gripped by the hand 201 of the robot 2 is heated by releasing the grip of the hand 201. When placed on one end of the device 4,
The pallet 20 accommodating the MID substrate 10 is transported by the transport unit 41 toward one side within a predetermined time, and during that time, the heating device 42 preheats the MID substrate 10. In embodiments, this preheat temperature is about 80-10.
The temperature is set to 0 ° C and the preheating time is set to about 10 seconds.

The solder bath 5 adopts a flow soldering system, and is constructed so that the jet solder liquid that has become a jet is sprayed from the back side through the opening 222 of the pallet 20 to perform soldering. As shown in FIG. 7, it has a nozzle 51 and a solder flow guide 52, and is constituted by one tank. In the solder bath 5, a nozzle 51 for spraying the jet solder liquid, a solder flow guide 52 for forming a flow of the jet solder liquid jetted from the nozzle 51,
It has a motor (not shown) for generating a turbulent flow in the jet solder liquid. Then, in the solder bath 5, the jet solder liquid is stirred by operating the motor to form a turbulent flow region by the high-speed solder flow.

Then, in the solder bath 5, the MID substrate 10
With the hand 201 of the robot 2 holding the pallet 20 storing the pallets 20, the robot 2 controls the pallet 20 to be fed forward or backward above the nozzle 51 in the turbulent flow region or the laminar flow region. This operation will be described in detail in the operation described later.

The soldering work in the solder bath 5 is carried out in the atmosphere, and the vacuum device 8 (see FIG. 2) for sucking the temperature raised above the solder bath 5 by the soldering work It is arranged above the tank 5.

Next, the operation of the soldering apparatus M configured as described above will be described with reference to FIGS.

When the MID substrate 10 (hereinafter referred to as a substrate container 30) set on the pallet 20 outside the soldering device M is loaded into the soldering device M from the loading / collecting device 6, the robot 2 The hand 3 grasps the grasped portion 24 of the pallet 20 from both sides and holds the substrate container 30.

The substrate storage body 30 held by the robot 2
Applies the flux liquid to the back surface side of the MID substrate 10 while being transported to the flux device 3 and held by the robot 2.

Next, the substrate container 30 coated with the flux liquid is conveyed to the heating device 4 by the robot 2.
In the heating device 4, when the robot 2 releases the substrate storage body 30 with the hand 201, the substrate storage body 30 moves to the transport unit 41.
Preheated while being transported in. At this time, the substrate storage body 30
The robot 2 that has released the grip is preheated by the heating device 4 and immediately before standing by at the tip of the preheating unit 42.
Is transferred to the solder bath 5 for soldering. Then, after the soldered board housing 30 is collected by the loading / collecting device 6, the new board housing 30 is gripped, subjected to flux treatment, and conveyed again to the heating device 4. As a result, the takt time can be shortened.

Substrate container 30 transferred to solder bath 5
Is conveyed above the nozzle 51 of the solder bath 5 while being held by the robot 2. As shown in FIG. 8, the solder of the embodiment is made of 100% tin having a high melting point and poor wettability, and has MID solderability (solder rising).
In order to reduce the appearance of the solder while ensuring the solderability, when the substrate housing 30 is arranged above the nozzle 51 of the solder bath 5, the solder bath 5 performs sequence control as shown in the soldering conditions in Table 1 below. Alternatively, a turbulent flow region is formed by a computer-programmed motor, and the MID substrate 1
The immersion depth of 0 is set to 2 to 2.5 mm. The jet solder liquid jetted from the nozzle 51 of the solder bath 5 jets into the MID substrate 10 from the lower opening 222 of the pallet 20 of the substrate container 30 and flows along the solder flow guide 52 (forward direction). When the board housing 10 is moved above the solder bath 5 by the robot 2, the board housing 30 is within a range of an MID board angle of 0 to 8 ° (about 8 ° in the embodiment) with respect to the horizontal direction. Move along the forward direction of the solder flow. This movement takes about 3.5-4 seconds, during which time the solder will be immersed in the MID substrate 10.

[0032]

[Table 1]

After the substrate container 30 is conveyed for a predetermined time, the solder bath 5 then stops the turbulent flow region and forms a laminar flow region. Then, the substrate container 30 is sent back by the robot 2 to the flow of the jet solder liquid. The soldering condition of the solder bath 5 at this time is, as shown in the second soldering condition of Table 2 below, the amount of the jet solder liquid is 2.5 to 3 mm, and the depth of the MID substrate is 2 to 2 in the laminar flow region. Set to 2.5 mm. Then, the substrate container 30 is moved by the robot 2
The MID substrate is moved at an angle of 3 to 8 ° in the backward direction with respect to the jet solder solution for 3.5 to 4 seconds.

[0034]

[Table 2]

As a result, the solder attached to the soldered portion of the MID board 10 is cut back cleanly without waste because the solder is adhered to the soldering portion of the MID board 10 in the laminar flow region of the board housing 30 and balanced by a mechanical relationship. It will be.

Under the soldering conditions as described above, the robot 2
By soldering the MID substrate 10 of the substrate housing body 30 gripped at 1 in the solder bath 5 of one bath, it can be performed in the atmosphere, and as a result, as shown in FIG. MID with wire harness 15
The substrate 10 can be soldered.

The graph of FIG. 8 is performed by a soldering apparatus M according to the present invention and a soldering apparatus M according to the present invention in which a printed circuit board is generally flow soldered in a nitrogen atmosphere (shown by a two-dot chain line). 5 shows a comparison of temperature profiles of the MID substrate 10 flow-soldered in an air atmosphere (shown by a solid line).

As described above, even if 100% tin having a high melting point (about 232 ° C.) is used, the robot 2 conveys the material in the turbulent flow region and in the laminar flow region in the air atmosphere. The soldering can be performed in an extremely short time as compared with the generally used soldering method.

It should be noted that the operation of the robot 2 for performing the forward feeding in the turbulent flow region and the backward feeding in the laminar flow region on the solder bath 5 can be performed only once because the position and the movement amount are stored. If it is taught, it will be repeated.

Therefore, as described above, the soldering method of the embodiment can achieve the following effects.

First, in the solder bath 5, the MID substrate 1 is used in a state where the solder bath 5 is in a turbulent region by a motor.
The substrate storage body 30 in which 0 is stored is sequentially fed to the flow of the jet solder liquid for 3.5 to 4 seconds by the operation of the robot 2 to immerse the jet liquid in the MID substrate. The solder solution is infiltrated and soldering is performed on the patterned soldering part. Therefore, the solder can rise even in the through hole having a high height.

Next, after the turbulent flow region of the solder bath is stopped to make it into a laminar flow region, the flow of the jet solder liquid is sent back by the operation of the robot 2 to cut back the solder. At this time, the moving speed of the MID board 10 and the flow rate of the solder are provided in a portion where the solder is separated from the MID board 10.
A mechanical relationship occurs between the surface tension of the solder and the peelback speed. Then, by setting the respective speeds so that this mechanical relationship is suspended, the solder can be cut back without waste, so that the appearance can be improved by eliminating the generation of solder bridges and icicles.

By sequentially controlling this, the patterned soldering portion can be soldered to improve the productivity.

Secondly, as described above, this lead-free soldering can jet the jet solder liquid onto the MID substrate 10 in the turbulent flow region, and further, the MID substrate 10 can be sequentially fed by the forward / backward feeding.
Since it is possible to transfer the substrate storage body 30 containing therein the robot 2 by the robot 2, the solder bath 5 can be made into one bath, and the solder bath M
It becomes possible to configure itself compactly.

Thirdly, since the substrate storage body 30 is fed forward or backward by the robot 2 and soldering is performed in the solder bath 5 in the turbulent flow region and the laminar flow region, it can be performed in the atmosphere. By performing the soldering in the air atmosphere, as shown in FIG. 8, for example, the soldering work can be performed in an extremely short time as compared with the soldering performed on the printed circuit board by the normal flow soldering. Can be improved.

Fourthly, in the soldering apparatus M of the embodiment,
Even if the substrate has a high through-hole height like the MID substrate 10 and the uneven shape is formed large, the jet flow in the turbulent region makes it possible to improve the rising, and the appearance can be changed by switching between forward and reverse feeding. It is possible to prevent defects.

Since the MID board 10 is stored in the pallet 20, even if the board is a three-dimensional molded board, a printed board, or a flexible board, a pallet suitable for each board can be used. All the boards can be housed by manufacturing, and in particular, by confining the wire harness 15 of the MID board 10 to which the wire harness 15 is attached in the wire harness housing part 23, the solder bath can be heated without heating the wire harness 15. The soldering can be carried out at step 5.

Fifthly, in the soldering apparatus M of the embodiment, after the substrate housing 30 is fluxed and preheated, it is transferred to the solder bath 5 by the robot 2 and the soldering is completed.
Since the D substrate 10 can be collected together with the pallet 20 from the loading / collecting device 6, an MI of good quality can be obtained.
It is possible to increase the productivity of the D substrate 10 and perform the work.

The substrate accommodated in the substrate accommodating body 30 is not limited to the MID substrate 10, but may be a printed circuit board with a wire harness or an M without a wire harness.
It may be an ID board, a printed board, a flexible board, or the like.

Further, in the above-mentioned embodiment, the solder bath 5 is constituted by one bath, but of course, it may be formed by two or more baths.

Further, the solder in the solder bath 5 may be lead-free solder such as Sn-, even if it is not 100% tin.
It may be Sn-based solder such as Ag, Sn-Ag-Cu, Sn-Ag-Bi.

[Brief description of drawings]

FIG. 1 is a plan view showing a soldering device according to an embodiment of the present invention.

FIG. 2 is a side view showing the soldering device in FIG.

FIG. 3 is a MID soldered by the soldering apparatus of FIG.
It is a top view which shows a board | substrate.

FIG. 4 is a plan view showing a pallet for storing a MID board.

FIG. 5 is a front sectional view of the same.

FIG. 6 is a side sectional view of the same.

7 is a simplified cross-sectional view showing a state where soldering is performed in the solder bath in FIG.

FIG. 8 is a grab comparing temperature profiles of soldering according to the present invention and conventional soldering.

[Explanation of symbols]

M ... Soldering equipment 1 ... Machine stand 2 ... robot 3 ... Flux device 4 ... Heating device 5 ... Solder bath 6 ... Input / collection device 10 ... MID substrate (three-dimensional molded substrate) 11 ... MID substrate body 14 ... Through hole 15 ... Wire harness 20 ... Palette 21 ... Base plate 22 ... Substrate mounting section 222 ... Aperture 23 ... Wire harness storage section 24 ... Gripping part 25 ... Front lid 27 ... Rear lid 51 ... Nozzle 52 ... Solder flow guide

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B23K 1/08 320 B23K 1/08 320B // B23K 101: 42 101: 42 (72) Inventor Haruki Mizutani Aichi 1-chome, Showa-cho, Kariya city, Japan F-term in DENSO CORPORATION (reference) 4E080 AA01 AB03 BA04 CA14 5E319 AA03 AC01 BB01 CC24 CD35 GG05 GG20

Claims (5)

[Claims] 1. A lead-free soldering method for carrying a substrate to be patterned into a solder bath and heating the solder with a jet solder solution jetted from the solder bath for soldering. While making the jet solder liquid into a turbulent flow region, while dipping the substrate in the jet solder liquid for a predetermined time, the substrate is sequentially fed along the flow of the jet solder liquid, and then the jet flow in the solder bath. With the solder liquid in the laminar flow region, the substrate is sent back to the flow of the jet solder liquid, the turbulent flow region is generated, the substrate is sequentially fed, the laminar flow region is generated, and the substrate is fed back, A lead-free soldering method characterized in that the steps are sequentially controlled. 2. The lead-free soldering method according to claim 1, wherein the jetting of the solder is performed in one solder bath. 3. The lead-free soldering method according to claim 1, wherein the jet of the jet solder liquid is performed in an air atmosphere. 4. The lead-free soldering method according to claim 1, wherein the board is a three-dimensional molded board with a wire harness or a printed board. 5. A lead-free soldering device for transporting a substrate to be patterned to a solder bath and heating it with a jet liquid jetted from the solder bath for soldering, comprising a machine base and the machine. A pallet that is placed in a table and stores the board, a robot that conveys the pallet that stores the board, a solder tank that conveys the pallet that stores the board and solders the board with lead-free solder, and soldering And a recovery device for recovering the substrate together with the pallet, wherein the jet solder solution in the solder bath is made into a turbulent region, and the substrate is kept in the jet solder liquid for a predetermined time. While dipping in, the substrate is sequentially fed along the flow of the jet solder liquid, and then with the jet solder liquid in the solder bath in a laminar flow region, The substrate is reversely fed to the flow of the jet solder solution, and the turbulent flow region is generated, the substrate is sequentially fed, the laminar flow region is generated, and the substrate is fed backward. Lead-free soldering equipment.