JP2001177233A - Method and device for soldering surface-mounted component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and device for soldering surface-mounted parts by which the soldering quality of the components can be improved. SOLUTION: At forcible cooling of molten solder by blowing a cooling wind from a cooling nozzle 11 upon the solder, the solder is solidified with the cooling wind by adjusting the flow rate of the wind to such a degree that parts 9 are not moved by the wind as a first stage, and a heater chip 10 is cooled by increasing the flow rate of the cooling wind as a second stage. Accordingly, the soldering quality of the parts 9 can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for soldering surface-mounted components, which are suitable for surface mounting of, for example, QFP type semiconductor package components.

[0002]

2. Description of the Related Art In recent years, due to demands for high-density mounting and multifunctional mounting, multi-pin surface-mounted electronic components represented by QFP (Quad Flatpack Package) have been frequently used. These surface mount components are automatically positioned and arranged in advance on the solder material applied on the lands of the printed wiring board, and then the external leads and lands of the components are collectively soldered in a reflow furnace. After the components are mounted, the printed wiring board is shipped to the next process through visual inspection and electrical testing.If any defects are found in this inspection stage, the defective component is removed from the wiring board. , Good quality parts will be retrofitted.

[0003] A retrofitting device for parts is disclosed in, for example, Japanese Patent Application Laid-Open No. 9-8 / 1997
As disclosed in Japanese Patent No. 3126, a board supporting portion for horizontally supporting a wiring board with its mounting surface facing upward,
A heater chip mounted on a plurality of external leads of the surface mount component positioned and arranged on the wiring board and heated to a soldering temperature; and heating the heater chip, and applying a heater chip to the plurality of external leads. 2. Description of the Related Art A device for soldering a surface mount component is known which includes a heating / pressing unit for applying pressure and a cooling unit for blowing cooling air toward a plurality of external leads.

That is, the above-mentioned apparatus transmits heat of a heater block to a plurality of external leads via a heater chip, melts solder under these external leads, and then blows cooling air from cooling means to forcibly cool the solder. It is something to do. The cooling air also cools the heater chip.

[0005]

However, the cooling means in the above-mentioned conventional apparatus has a large flow rate required to cool the solder and the heater chip within a predetermined time because the flow rate of the blowing cooling air is always constant. When the cooling air blows out,
Since the heater chip itself is lightweight,
There is a problem that components to be soldered move at the time of jetting of the cooling air, causing a displacement and a deterioration in soldering quality.

On the other hand, for example, as described in JP-A-5-261527 and JP-A-11-163512,
There is a configuration in which components are pressed to the board side when the solder is forcibly cooled.However, the components are pressurized with a force large enough to prevent the components from moving due to the blowing of cooling air, so that warpage of the board and component leads Deformation, etc., which may impair soldering quality.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a method and an apparatus for soldering a surface mount component, which can improve the soldering quality of the component.

[0008]

In order to solve the above-mentioned problems, in the method of soldering a surface mount component according to the first aspect of the present invention, the intensity of the cooling air blown from the cooling means is switched in multiple stages. It is characterized in that the solder is forcibly cooled.

That is, the strength of the cooling air is changed stepwise to prevent the parts from moving. In particular,
At first, the solder is solidified by cooling air having a flow rate that is small enough to prevent the components from moving. Thereafter, the strength of the cooling air is increased to cool the heater chip. Thereby, the movement of components during forced cooling can be prevented, and the quality of soldering can be improved.

After the solidification of the solder is completed, the component does not easily move. Therefore, after cooling to the vicinity of the solidification point of the solder, the intensity of the cooling air is increased stepwise or the intensity of the cooling air is reduced. It is also possible to apply.

[0011] In order to solve the above problems, a soldering apparatus for a surface mount component according to claim 3 of the present invention comprises:
The cooling means includes: a first state in which a cooling air at a first flow rate necessary for cooling the molten solder at a predetermined cooling rate is jetted; And a second state in which a cooling air of a second flow rate necessary for cooling at a cooling rate of 2 is jetted.

Therefore, by switching between the first state and the second state, it is possible to eject cooling air at an optimum flow rate to each of the solder and the heater chip, and to simplify the device configuration while easily simplifying the components. Soldering quality can be improved.

[0013]

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

FIG. 1 shows an entire soldering apparatus for retrofitting a surface mount component according to an embodiment of the present invention. The soldering apparatus 1 mainly includes an extending direction (X) of a horizontal girder 4 installed above a base member 2 via a pair of support columns 3.
Direction), a heater block 6 suspended from a lower part of the head portion 5, and a print head which is disposed between the base member 2 and the heater block 6 and is movable in a direction perpendicular to the paper of FIG. A substrate supporting portion for supporting the wiring substrate so that its mounting surface faces upward; and a plurality of external leads of the component which cover the surface mounting components disposed on the wiring substrate and apply heat from the heater block to the external leads. The apparatus includes a heater chip 10 for transmitting the cooling air, and a pair of cooling nozzles 11 for blowing out cooling air from a flat nozzle opening.

The head portion 5 mainly has a guide member 12 attached to the horizontal beam 4 and three shaft members 13A penetrating therethrough. A support member 14 provided at the lower end of the shaft member 13A The heater block 6 is suspended via the engaging heater block support sleeve 15. The shaft member 13A is configured to be vertically movable in the Z direction in the drawing by the driving action of a pair of shaft members 13B, 13B, one end of which is fitted into the guide member 12, by a driving means (not shown). The heater chip descends and can contact the heater chip located below.

Referring to FIG. 2, the heater block 6 is formed by covering a block body composed of an upper lid 19, a heater 16, a heat storage body 17, a thermocouple 18, and a lower lid 20 with a cover 21, and in the vicinity thereof, The cooling nozzle 11 and a pressure arm 22 that can press the heater chip 10 when descending are arranged. The cooling nozzle 11 and the pressure arm 22 are fixed to a support plate 23 provided integrally with the support member 14. One of the cooling nozzles 11 is further fixed via a fixture 24, and the pressure arm 22 is It is installed via a pressure spring 25 (see FIG. 1).

Next, a method for soldering a surface mount component according to the present invention using the soldering apparatus will be described.

FIG. 3 is a flowchart illustrating a soldering method according to the present embodiment. First, the printed wiring board 7 is placed on the board supporting portion 8 such that the mounting surface faces upward (step S1). Many electronic components are mounted on the wiring board 7, and defective components are removed in a previous process. In the present embodiment, a case will be described in which a non-defective component, for example, a QFP type surface mount semiconductor package component 9 is soldered in place of the removed defective component.

Next, a solder material is supplied to a predetermined land on the wiring board 7 on which the component 9 is mounted, and the component is temporarily attached to the land (steps S2 and S3). In the work of temporarily attaching the components, several external leads 9a located at the four corners of the component 9 are soldered using a soldering iron.

Next, the heater chip 10 is mounted on the external lead 9a so as to cover the temporarily attached component 9, and the heater block 6 maintained at the soldering temperature is lowered (steps S4 and S5). Here, immediately before the heater block 6 comes into contact with the heater chip 10, the pressing arm 22 reaches the inside of the recess 10 a formed on the upper surface of the heater chip 10, and presses the heater chip 10 toward the component 9 with a predetermined pressure. . Thus, the swing of the heater chip 10 due to the contact with the heater block 6 is prevented, and the heat can be efficiently transmitted from the heater block 6 to the external leads 9a. The depth of the recess 10a is formed to be larger than the thickness of the pressing arm 22, so that the pressing arm 22 does not directly contact the heater block 6.

When the heater block 6 comes into contact with the heater chip 10, the heater chip 10 is heated to the soldering temperature. This heat is transmitted to the external lead 9a of the component, and the solder on the lower surface of the external lead 9 is melted.

Next, the heater block 10 moves upward by a predetermined distance to interrupt heat transfer to the external leads 9a, and in the state shown in FIG. 2, cooling air is blown from the cooling nozzle 11 at a first flow rate (air Blow 1), forcibly cooling the molten solder (steps S6, S7). The first flow rate is relatively weak, specifically, a flow rate required to cool the solder 10 at the first predetermined cooling rate, and a size that does not move the component 9 due to ejection of the cooling air. Is done. In the present embodiment, the solder used is a eutectic solder of lead-tin,
Is about 350 ° C., and the blowing time of the cooling air in the first stage is less than 10 seconds.

After the solidification of the solder, the flow rate of the cooling air blown from the cooling nozzle 11 is switched from the first flow rate to the second flow rate (air blow 2), and the heater chip 10 is forcibly cooled (FIG. 2). Step S8). This second flow rate is
The flow rate is larger than the first flow rate, specifically, a flow rate required to cool the heater chip 6 at a second predetermined cooling rate. In the present embodiment, the blowing time of the cooling air in the second stage is set to 15 seconds to 20 seconds.

The cooling of the heater chip 10 is performed because it is necessary to keep the temperature rise of the heater chip 10 constant when the work of retrofitting parts is performed continuously. In addition, as a heater chip, aluminum having small heat capacity and large heat conduction, durable titanium, etc.
It is preferable to use a metal material having high non-soldering properties.

By soldering the component 9 by the above-described method, the component does not move when the cooling air is blown and does not shift, so that the solderability of the component can be improved as compared with the related art. it can. Note that, as shown in FIG.
In addition, according to the present embodiment, since the pressing and holding force can be weakened according to the present embodiment, the warpage of the wiring board 7 and the deformation of the external leads 9a are greatly reduced. Is suppressed.

Next, the configuration of an apparatus for switching the flow rate of the cooling air will be described.

FIG. 4 shows a piping configuration of a cooling means including a cooling nozzle 11 in the soldering apparatus 1 of the present embodiment. The cooling means includes a pneumatic source 26 and a cooling nozzle 11.
And first and second flow control valves 27 and 28 and a 5-port 3-position electromagnetic switching valve 29 provided in parallel in a pipe route between the air pressure source 26 and the cooling nozzle 11. Have.

In the present embodiment, the first flow control valve 27
Is constituted by a variable throttle that adjusts the compressed air from the air pressure source 26 to the first flow rate, and the second flow rate adjustment valve 28 adjusts the compressed air from the air pressure source 26 to the second flow rate. It is composed of a variable aperture.

The electromagnetic switching valve 29 is provided at a position A for interrupting the communication between the air pressure source 26 and the cooling nozzle 11, and cools the compressed air from the air pressure source via the first flow control valve 27. The B position for causing the first state (the first stage) to be ejected from the nozzle 11 and the second state (the above-described state) where the compressed air is ejected from the cooling nozzle 11 via the second flow control valve 28. And the C position for performing the second step). The switching to the B position and the C position is performed by exciting the solenoids 29a and 29b, respectively.

In this embodiment, switching from the position B to the position C is automatically performed using a timer (not shown).

With the above configuration, the forced cooling of the molten solder and the forced cooling of the heater chip 10 can be automatically performed at the optimum flow rates.

Although the embodiment of the present invention has been described above, the present invention is, of course, not limited to this, and various modifications can be made based on the technical idea of the present invention.

For example, in the above embodiment, the cooling air flow rate is switched between two levels. However, it is needless to say that the cooling flow can be controlled in three or more steps to perform more detailed cooling control. It is.

In the above-described embodiment, the control for increasing the strength of the cooling air in a stepwise manner is performed. However, the intensity of the flow rate is appropriately changed, for example, by intermittently blowing the cooling air. It is also possible.

In the above embodiment, the first and second flow control valves are each constituted by a variable restrictor as a cooling means of the soldering apparatus. It is also possible to construct a fixed aperture with a quantity. Further, instead of providing a plurality of these flow control valves in parallel, one variable throttle is provided,
Switching between the stage and the second stage can be performed only by adjusting the aperture amount. In this case, it is desirable that the adjustment of the aperture amount be performed electrically.

Further, the component retrofitting device is not limited to the above-described configuration, and a device having another configuration may be used. The present invention is also applicable to a case where soldering is performed manually. In this case, an air ejection tool such as an air gun may be used as a cooling nozzle, and the ejection amount may be switched stepwise. Also, the component 9 is not limited to a QFP type electronic component,
The present invention is also applicable to other surface mount components having external leads such as SOP.

[0037]

As described above, according to the method and apparatus for soldering a surface mount component of the present invention, the following effects can be obtained.

That is, according to the method for soldering a surface mounted component according to the first aspect, the forced cooling of the solder can be performed with an optimum air volume, and the displacement according to the movement of the component can be prevented by the invention according to the second aspect. Thus, the quality of soldering can be improved.

According to the apparatus for soldering surface mounted components according to the third aspect, it is possible to adjust the flow rate of the cooling air optimally for the forced cooling of the molten solder and the cooling of the heater chip. According to the invention of item 4, the soldering quality can be stabilized when components are continuously mounted with a simple device configuration.

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view showing the entire surface mounting component soldering apparatus according to an embodiment of the present invention.

FIG. 2 is an enlarged view of the main part.

FIG. 3 is a flowchart illustrating a method for soldering a surface mount component according to an embodiment of the present invention.

FIG. 4 is a piping system diagram showing a configuration of a cooling unit of the soldering device according to the present invention.

[Description of Signs] 1 ... Soldering device, 6 ... Heater block, 7 ... Wiring board, 8 ... Board support, 9 ... Parts, 9a ... External lead, 1
0: heater chip, 11: cooling nozzle, 22: pressurizing arm, 26: pneumatic source, 27: first flow control valve, 28: second flow control valve, 29: electromagnetic switching valve.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B23K 31/02 310 B23K 31/02 310H // B23K 101: 42 101: 42

Claims (4)

[Claims] 1. A plurality of external leads of a surface mount component are positioned and arranged on a wiring board to which solder has been supplied in advance, and the solder is heated and melted to solder the external leads. In a method for soldering a surface-mounted component in which cooling air is blown onto the molten solder to forcibly cool the solder, the strength of a cooling air blown out from the cooling means is switched in multiple stages to forcibly cool the solder. A method for soldering a surface mount component, the method comprising: 2. The method according to claim 1, wherein the intensity of the cooling air blown from the cooling means is increased stepwise. 3. A board supporting portion for horizontally supporting a wiring board with its mounting surface facing upward, and a plurality of external leads of a surface mount component positioned and arranged on the wiring board, and having a soldering temperature. A heater chip to be heated; a heating / pressurizing unit for heating the heater chip and pressing the heater chip against the plurality of external leads; and a cooling unit for blowing cooling air toward the plurality of external leads A soldering apparatus for a surface mount component, comprising: a first state in which a cooling air is blown at a first flow rate necessary to cool the molten solder at a predetermined cooling rate; A second state in which a cooling air of a second flow rate larger than the first flow rate and required to cool the heater chip at a predetermined cooling rate is jetted. Surface mount components Removal equipment. 4. The cooling means is provided in parallel in a pipe path between the air pressure source, a nozzle for jetting cooling air, and the air pressure source and the nozzle, and First and second flow control valves for adjusting the compressed air to the first and second flow rates, respectively, and the first and second flow control valves, wherein the compressed air is supplied to the nozzle via the first flow control valve. And a switching valve for selectively switching the second state supplied to the nozzle via the second flow control valve. 5. The surface mount component according to claim 3, wherein Soldering equipment.