JPH09206931A - Constant heat type heating device and solder joining method using this - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a constant heat type heating device capable of solder joining by the same system as the system using a pulse heat type heater. SOLUTION: A heater head 20 attached to a heater member 10 provided with a constant heat source 12 is butted to the lead 61 of an electronic parts 60 to melt a solder, thereby performing solder joining. The heater head 20 is formed from high heat conductive materials (e.g. Al, Al alloy, etc.). Furthermore, the heater head 20 is composed of an attaching part 21 butted to the heater member 10, a butting part 23 butted to the lead 61, and a heat transmitting part 22 which is formed in a part connecting the attaching part 21 to the butting part 23 and transmits heat fed to the attaching part 21 to the butting part. Also, a cooling passage 25 and an air nozzle 30, which cools at least the vicinity of the butting part 23 in the heater head 20, are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for soldering and joining leads of an electronic component (IC module, connector, etc.) mounted on a conductive pad (wiring pattern) of a printed circuit board. The present invention relates to a heater device and a method of soldering and joining with the heater device. In particular, the present invention relates to a heater device and a solder joining method using a constant heat type heater as a heat source.

[0002]

2. Description of the Related Art As shown in FIG.
21 of the electronic components 210 and 220 on the conductive pad of the
As a method of soldering 1 and 221, a reflow method of heating and melting cream solder in a furnace, a method of using a pulse heater, and the like are well known in the art. When using the reflow method, apply solder paste on the conductive pad and place the electronic components on the printed circuit board so that the corresponding leads are positioned on the conductive pad, and heat the printed circuit board in this state. It is heated in a furnace to melt the cream solder and solder the leads onto the conductive pad.

The use of the reflow method has an advantage that a large number of electronic components can be simultaneously soldered on a printed circuit board and work efficiency is good. However, since the printed circuit board and the entire electronic components placed on it are heated, the problem that the printed circuit board is easily distorted by heating,
There is a problem that it cannot be applied unless it is an electronic component that has heat resistance enough to withstand heating up to the solder melting temperature. Further, when a part of the lead of the electronic component is deformed and the lead is separated from the conductive pad with the electronic component placed on the substrate (in the case of the lead 211a shown in FIG. 9), There is also a problem that this lead cannot be solder-joined, resulting in poor joining.

On the other hand, when a pulse heater is used, the heater head is pressed against the lead and only this portion is heated for soldering, so that the above problem does not occur. A method using this pulse heater is shown in FIG. The pulse heater head 250 has the smallest cross-sectional area of the lower end contact portion 251 as shown in the drawing, and the electric wire 25
A low-voltage high current (for example, a current of about 3 V and 1000 A) is passed from the current control device 260 to the head 250 via 5. As a result, the contact portion 251 having the smallest cross-sectional area and the largest electric resistance is locally heated, and the contact portion 2
51 is pressed against the lead 211 to perform solder joining.

Specifically, the conductive pad 20 of the substrate 200
1 is preliminarily coated with cream solder 202 (preliminary solder or pre-melting solder), and leads 21 of electronic component 210
1 is solder plated (gold plated) and conductive pad 2
The lead 211 is placed on 01 and then the lead 2
The contact portion 251 is pressed onto 11 to melt the solder and perform soldering. When the solder joining using such a pulse heater is performed, only the periphery of the lead portion, that is, the solder joining portion is heated, so that the substrate 200 is not likely to be thermally deformed, and the deformed lead 211a exists. Also, there is an advantage that soldering can be performed in a state where the contact portion 251 is pressed and the deformation is restored.

[0006]

However, when a pulse heater is used, it is necessary to pass a high current through the heater head, so that the electric wire 255 having a large capacity (thick) is used.
It is necessary to use an expensive current control device 260 in addition to the above, and there is a problem that a large and complicated device is required and the device cost becomes very expensive. Further, since the contact portion 251 through which such a high current flows is brought into contact with the lead 211 of the electronic component 210, there is a problem that the electronic component 210 may be damaged by the high current.

Further, it is difficult to complicate the head shape of the pulse heater head 250 because it is necessary to provide the contact portion 251 having a small cross-sectional area at the lower end and to connect an electric wire having a large capacity. . Therefore, only one row of leads can be heated at one time by the pulse heater head having only one device power supply. In the case where the electronic component 210 shown in FIG. 8 has the leads 211 arranged in a row at each of four locations around the periphery, it is necessary to perform the work four times only by attaching one electronic component 210, which leads to the work efficiency. There is also the problem of not being good.

Even if some of the leads 211a are deformed as shown in FIG. 9, the solder can be heated and melted while the contact portion 251 is pressed to recover the deformation. However, if the contact portion 251 is not lifted after the solder hardens, the lead 211a returns to the deformed state due to the elastic force and separates from the conductive pad 201 if the solder is lifted in a molten state, and a connection failure may occur. There is. Therefore, after the contact portion 251 is pressed onto the lead 211 to be electrically heated, the current is cut to lower the temperature of the contact portion 251 and after the molten solder is solidified, the head 250 is lifted to complete the solder joining. I am trying to do it. Therefore, it is necessary to detect the temperature of the head 250, and the thermocouple 253 is attached near the tip of the head by welding or the like.

In this case, the pulse heater head 250
In the above, since only the abutment portion 251 located at the lower end generates heat when energized, the time when this portion rises to a predetermined temperature after the start of energization and the time when the temperature of this portion decreases after the energization cut are compared. Short (about 5 to 6 seconds). Therefore, the above-described solder joining can be performed in a relatively short time by using the pulse heater. This is the main reason for using pulse heaters.

Conversely, as long as it is sufficient to heat the lead portion to melt the solder in that portion, a constant heat type heater (so-called nichrome wire heater) may be used. Type heaters have the advantages of much lower equipment cost and easier control. However, since the constant-heat type heater heats the entire heater head, it takes a long time for the temperature of the heater head to drop even if the energization is cut off. Therefore, after the heater head is pressed against the lead to melt the solder, it is necessary to cut off the energization and wait for a long time until the temperature of the heater head is lowered and the solder is solidified. As described above, the constant heat type heater has an extremely long working time, and it is almost impossible to use it.

In view of the above problems, the present invention provides a constant heat type heater device and a solder joining method using this device, which enables soldering and joining by the same method as that using a pulse heat type heater. The purpose is to provide.

[0012]

In order to achieve such an object, in the constant heat type heater device of the present invention, a heater head attached to a heater member having a constant heat source is brought into contact with a solder joint portion. The solder head is made of a material having high thermal conductivity (for example, aluminum, aluminum alloy, etc.) so that the solder is melted and the solder joint of the solder joint portion is performed. Further, the heater head is formed in a mounting portion joined to the heater member, an abutting portion abutting against the solder joint portion, and a portion connecting the mounting portion and the abutting portion, and is supplied from the heater member to the mounting portion. And a heat transfer part for transmitting the generated heat to the contact part, and a cooling means for cooling at least the vicinity of the contact part in the heater head is provided.

As the cooling means, cooling air blowing means for blowing cooling air to the outer surface near the contact portion,
It is possible to use a cooling fluid supply means or the like that causes a cooling fluid to flow through the cooling holes formed in the vicinity of the contact portion in the heater head.

In the solder joining method according to the present invention, in the constant heat type heater device as described above, the solder is fused by bringing the abutting portion into contact with the solder joining portion to melt the solder. This is a joining method. First, the heater member is heated by a constant heat source, and after the temperature of the contact portion rises to a first set temperature higher than the melting point of the solder, the heater head is moved to bring the contact portion into contact with the solder joint. After the solder of the solder joint portion is melted, at least the vicinity of the contact portion in the heater head is cooled by the cooling means, and the heater head is moved after the temperature of the contact portion drops to the second set temperature lower than the melting point of the solder. The contact portion is separated from the solder joint portion.

At this time, when the heater member is heated by the constant heat source with the contact portion in the air, the heat supply amount Q1 transmitted from the heater member to the mounting portion.
It is desirable that the temperature of the abutting portion when the amount of heat radiated from the heater head and the amount of heat radiated by the heater head Q2 are balanced be substantially the first set temperature.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the heater device 1 according to the present invention is composed of a heater member 10 and a heater head 20.
The leads 61 of the electronic component 60 placed on the printed circuit board 50 are soldered and joined to the conductive pads 51.

The heater member 10 is constructed by having two constant heat sources 12 in a rectangular body 11 made of aluminum. The heat source 12 is a heater made of a general nichrome wire, and generates heat when energized at 100 V and 3 A. A thermocouple 15 that detects the temperature of the heater member 10 is attached to the side surface of the body 11. The heater head 20 is made of a material having a high thermal conductivity such as aluminum or an aluminum alloy and has a T-shaped cross section. The heater head 20 has a mounting portion 21 joined to the lower surface of the heater member 10 on the upper portion thereof, and a heat transfer portion 22 having a flat and wide heat radiating surface 22a on the left and right in the middle portion.
And has a contact surface 23 that contacts the solder joint at the lower end.

A cooling hole 25 penetrating in the lateral direction is formed in a portion of the heat radiating portion 22 close to the contact surface 23, and a cooling pipe 35 connected to both ends of the cooling hole 25, respectively.
A cooling fluid (cooling air or cooling water) can flow from the cooling hole 25 to the cooling hole 25. Further, an air nozzle 30 for blowing cooling air toward the lower portion of the heat dissipation portion 22 is also provided.

Here, as shown in FIG. 2A, the heater head 20 is bonded to the lower surface of the heater member 10, and the contact surface 23 of the heater head 20 is in the air (contact with the solder bonding portion). Consider the heat balance in the state (when not). At this time, the cooling fluid has not flowed through the cooling holes 25. In this state, the heat quantity Q1 is transmitted from the heater member 10 heated by the heat source 12 through the mounting portion 21 to the heater head 20, and the heater head 20 is heated. On the other hand, the heat quantity Q2 is radiated from the heater head 20 (mainly from the heat radiation surface 22a). As the temperature of the heater head 20 increases, the heat quantity Q1 supplied from the heater member 10 decreases and the heat quantity Q2 radiated from the heater head 20 increases, so that the heater head 2
When 0 rises to a predetermined temperature, both heat amounts balance. The temperature T of the contact surface 23 when balanced in this way
The capacity of the heat source 12 and the shape of the heater head 20 are set so that 1 is higher than the melting point of the solder (for example, about 180 to 200 degrees Celsius).

As shown in FIG. 3A, the printed circuit board 5
The cream solder 55 (preliminary solder or pre-melting solder) is applied to the upper surface of the conductive pad 51 formed on the surface of 0,
The leads 61 are placed on the solder layer 55. In this state, the heater head 20 in the state where the supplied heat amount Q1 and the radiated heat amount Q2 are balanced as described above is moved downward so that the contact surface 23 thereof is on the lead 61 as shown in FIG. 2B. It can be pressed. As a result, the amount of heat Q3 from the contact surface 23
Is supplied to the solder 55 through the leads 61, and the solder 55 is melted.

After the solder 55 is melted in this way,
A cooling fluid (cooling air or cooling water) is caused to flow from the cooling pipe 35 to the cooling hole 25, and cooling air is blown from the air nozzle 30 to the periphery of the contact surface 23. This allows
The lower part of the heater head 20 and the periphery of the conductive pad 51 are cooled, the temperature of this part is lowered, and the temperature of the contact surface 23 is also lowered. Here, since the lead 61 and the conductive pad 51 are made of metal and have a much higher heat transfer coefficient than air, the contact surface 23 has a larger heat transfer coefficient than that in the air.
The amount of heat radiated from the heater head 20 is increased by the amount Q3 of heat transferred through the leads 61, and the contact surface 2 is accordingly increased.
The temperature decrease of 3 is accelerated.

As a result, the once-melted solder is solidified again, and if the heater head 20 is lifted in this state, the soldering can be completed. This soldering completed state is shown in FIG. 3B, where the molten solder 55 is the lead 6
A fillet is formed so as to surround 1 and the lead 61 is securely bonded to the conductive pad 51.

[0023]

EXAMPLE The soldering work will be described with reference to the flowchart of FIG. The temperature change of the contact surface 23 at this time is shown in FIG. In FIG. 5, the abscissa indicates the passage of time t, and the ordinate indicates the change in the temperature T of the contact surface 23.

When performing the soldering work, first, the heater heat source 12 is energized, and the heater head 20 is heated by the heat generated by the heat source 12 (step S1).
The temperature of the contact surface 23 also rises (time t1 to t2). At this time, the contact surface 23 is in the air, and the supply heat amount Q1 and the heat radiation amount Q2 are balanced at time t2 so that the temperature of the contact surface 23 is higher than the solder melting point temperature Tm (TH
Set temperature).

Here, the temperature of the contact surface 23 is calculated or estimated from the detected value of the thermocouple 15, and when it is detected that the contact surface temperature is equal to or higher than the first set temperature (steps S2 to S3). ), The lamp indicating that the soldering operation may be performed is turned on (step S4). In response to this, when the operation switch is turned on at time t3 (step S5), the heater head 20 is moved downward to move the contact surface 23.
Contacts the lead 61 of the electronic component 60 mounted on the substrate 50 (step S6).

By the contact with the lead 61, the contact surface 23
The amount of heat is transmitted from the lead 61 to the lead 61 and the solder 55 is melted. After the melting of the solder is completed (step S7), a cooling fluid is caused to flow from the cooling pipe 35 to the cooling hole 25, and cooling air is blown from the air nozzle 30 to the periphery of the contact surface 23 to lower the heater head 20 and the conductive pad 51. The area around is cooled (step S8). Since the heater head 20 is provided with the heat dissipation surface 22a, even if the heat generation from the heat source 12 of the heater member 10 is continued,
By such forced cooling, only the peripheral portion of the contact surface 23 can be rapidly cooled. The contact surface temperature is also detected at this time, and when the temperature of the contact surface 23 becomes the temperature TL lower than the solder melting point temperature Tm (this is the second set temperature) (time t4) After a predetermined time (time t
The heater head 20 is raised to 5) (step S1).
0).

At this time, the supply of the cooling fluid and the blowing of the cooling air are stopped at the same time, and the temperature of the contact surface 23 gradually rises to the first set temperature TH at time t6. This completes one soldering joint operation, as shown in FIG.
Soldering joining as shown in is completed. At this point, the next operation can be performed, and thereafter the same operation as described above (operations of steps S5 to S10) can be performed to repeat the soldering and joining work.

In the above work, the heater head 20 is made of a material having a high thermal conductivity such as aluminum, the heat dissipation surface 22a is provided, and the contact surface 23 is provided.
Is forcibly cooled, the heater head 20 leads 6
It is a short time that the temperature of the contact surface 23 drops to the second set temperature TL after the solder is melted by bringing the contact surface 1 into contact with 1.
Therefore, in the apparatus of this example, the constant heat type heater is used as the heat source, but the soldering work can be performed efficiently.

In this soldering operation, since the contact surface 23 of the heater head 20 is pressed against the lead 61, there is no problem even if some of the leads 61a are deformed as shown in FIG. 2 (a). It can be performed. That is, the deformed lead 61a is also pressed against the conductive pad 51 by the contact surface 23 as shown in FIG.
The solder 55 is melted while the deformed lead 61a is also in contact with the conductive pad 51. After that, since the solder 55 is solidified while being pressed by the contact surface 23, the deformed lead 61a remains in contact with the conductive pad 51 even if the heater head 20 is lifted and the contact surface 23 is separated in this state. Held in the state of.

The heater head 20 has a heat radiating surface 22a.
Therefore, when the contact surface 23 comes into contact with the lead 61, the contact surface temperature is rapidly reduced, and the mounting portion 21 moves from the contact surface 2 to the contact surface 2.
It is conceivable that the amount of heat transferred to No. 3 is insufficient and the solder 55 cannot be melted sufficiently. For this reason,
As shown in FIG. 6, the contact surface 23 may be provided with a heat storage portion 22b that bulges outward so that the solder 55 can be reliably melted by the amount of heat stored in the heat storage portion 22b. Moreover, you may form the adjustment hole 22c which adjusts the heat radiation amount Q2 from the heat radiation surface 22a.

In the above example, the heater head 23 is designed to solder-bond the leads 61 arranged in a line, but it is also possible to solder-bond a plurality of lines of the leads simultaneously. For example, as shown in FIG. 7, four heater heads 31, which are rectangular in shape, are formed on the lower surface of the heater member 30,
32, 33, 34 are attached to the contact surfaces 31a, 32
The leads of four rows around the electronic component may be simultaneously solder-joined by a, 33a, and 34a. In addition, instead of using four heater heads
Individual heater heads may be used. At this time, a cooling pipe 35 'for connecting the cooling holes of each heater head in series
Is provided. The shape of the heater head is not limited to such a rectangular array, and can be freely set according to the shape of the object to be joined.

In the case of the pulse heater system used conventionally, the heater head is energized to generate heat. Since the heater head is composed of electrodes, the replacement of the heater head is not easy. However, in the case of the heater device of the present invention, since the heater head is simply attached to the lower surface of the heater member, replacement of the heater head is extremely easy. Therefore, the heater head can be replaced and soldering of electronic components of various shapes can be easily performed. Further, since the heater head is not energized, no electric current will flow through the electronic components.
In addition, the temperature of the heater head can be detected even if a thermocouple is attached to the heater member. This makes it unnecessary to replace the thermocouple even when replacing the heater head, and it is very easy to replace the heater head. is there.

In the above example, as the cooling means, the cooling holes for flowing the cooling fluid and the air nozzles for blowing the cooling air are used, but the cooling means may be constructed by using only one of them. . Further, in the example of FIG. 4, the heater head is vertically moved and forced cooling is automatically performed, but it is needless to say that this may be manually performed.

[0034]

As described above, according to the present invention,
The heater head is made of a material having high thermal conductivity (eg, aluminum, aluminum alloy, etc.), and the heater head is provided with a mounting portion joined to the heater member and an abutting portion abutting on the solder joint portion. And a heat transfer part that is formed in a portion connecting the attachment part and the contact part and that transfers the heat supplied from the heater member to the attachment part to the contact part, and cools at least the vicinity of the contact part in the heater head. Since the cooling means is provided, the mounting portion is heated to a temperature equal to or higher than the melting point temperature of the solder by the heat from the constant heat source of the heater member to which the heater head is mounted, and then this is brought into contact with the solder joint portion so that the solder joint The solder can be melted, and then the cooling means cools the periphery of the solder joint to re-solidify the molten solder, and then the heater head is released to facilitate soldering joint. It can be carried out and reliably.

The solder joining method according to the present invention is a method of performing solder joining using the above constant heat type heater device. First, the heater member is heated by a constant heat source, and the temperature of the contact portion is higher than the melting point of the solder. After the temperature rises to the first set temperature, the heater head is moved to bring the contact portion into contact with the solder joint portion, and after the solder in the solder joint portion is melted, at least the vicinity of the contact portion in the heater head is cooled by the cooling means. Then, after the temperature of the abutting portion has dropped to the second set temperature lower than the melting point of the solder, the heater head is moved to separate the abutting portion from the solder joint portion, which enables quick and reliable soldering. Bonding can be done.

[Brief description of drawings]

FIG. 1 is a cross-sectional perspective view showing a heater device according to the present invention and a printed circuit board or the like solder-bonded by the heater device.

FIG. 2 is a front view showing a state before and during solder joining by the heater device.

FIG. 3 is a cross-sectional view showing an electronic component lead placed on a conductive pad of a printed circuit board before and after solder joining.

FIG. 4 is a flowchart showing a solder joining method for performing solder joining using the heater device.

FIG. 5 is a graph showing a temperature change of a contact surface when soldering is performed by the heater device.

FIG. 6 is a front view and a side view showing a different example of the heater device according to the present invention.

FIG. 7 is a perspective view showing another example of the heater device according to the present invention.

FIG. 8 is a perspective view showing a printed circuit board on which electronic components are mounted.

FIG. 9 is a front conceptual view showing a pulse heat type heater device used conventionally.

[Explanation of symbols]

 10 Heater Member 12 Constant Heat Source 20 Heater Head 21 Mounting Part 22 Heat Dissipation Part 23 Contact Surface 25 Cooling Hole 30 Air Nozzle 35 Cooling Pipe 50 Printed Circuit Board 51 Conductive Pad 55 Solder 60 Electronic Component 61 Lead

Claims (6)

[Claims] 1. A heater member having a constant heat source, a heater head attached to the heater member, and cooling means for cooling the heater head. The heater head is brought into contact with a solder joint portion to solder. A constant heat type heater device for melting and soldering the solder joint portion, wherein the heater head is made of a material having high thermal conductivity, and the mounting portion is attached to the heater member, and the solder joint. An abutting portion that abuts on the mounting portion, and a heat transfer portion that is formed in a portion that connects the mounting portion and the abutting portion and that transfers heat supplied from the heater member to the mounting portion to the abutting portion. The constant heat type heater is characterized in that the cooling means cools at least the vicinity of the contact portion in the heater head. Coater apparatus. 2. The constant heat type heater device according to claim 1, wherein the heater head is made of aluminum or an aluminum alloy. 3. The constant heat type heater device according to claim 1, wherein the cooling means is cooling air blowing means for blowing cooling air to the outer surface in the vicinity of the contact portion. 4. The cooling means comprises a cooling hole formed in the heater head in the vicinity of the abutting portion, and a cooling fluid supply means for supplying a cooling fluid to the cooling hole. The constant heat type heater device according to 1 or 2. 5. A heater member having a constant heat source, a heater head attached to the heater member, and cooling means for cooling the heater head,
The heater head is made of a material having high thermal conductivity, and a mounting portion mounted on the heater member, an abutting portion abutting on the solder joint portion, and a portion connecting the mounting portion and the abutting portion And a heat transfer section that transfers heat supplied from the heater member to the mounting section to the contact section, and the cooling means can cool at least the vicinity of the contact section in the heater head. In a constant-heat-type heater device, the contact portion is brought into contact with the solder joint portion to melt the solder,
A solder joining method for performing solder joining of the solder joining portion, wherein the heater member is heated by the constant heat source, and the temperature of the abutting portion rises to a first set temperature higher than a solder melting point, and then the heater The head is moved to bring the contact portion into contact with the solder joint portion, and after the solder in the solder joint portion is melted, at least the vicinity of the contact portion in the heater head is cooled by the cooling means, Solder using a constant heat type heater device characterized in that the heater head is moved to separate the contact part from the solder joint part after the temperature of the contact part has dropped to a second set temperature lower than the melting point of the solder. Joining method. 6. When the heater member is heated by the constant heat source while the contact portion is in the air,
When the supply heat quantity Q1 transmitted from the heater member to the mounting portion and the heat radiation quantity Q2 from the heater head are balanced, the temperature of the contact portion is substantially the first.
The solder joining method using a constant heat type heater device according to claim 5, wherein the solder joining method is configured so as to reach a set temperature.