JPH0745944A - Method of soldering surface-mount component - Google Patents

Abstract

PURPOSE:To eliminate a fear that an unsoldered defect or the both is caused when surface-mount components are soldered to like the surface and the back of a circuit board. CONSTITUTION:A soldering land 4 on the back 2 of a circuit board 1 to which a mounting operation is first performed is coated with solder paste 6, a surface- mount component 9 is placed temporarily, the solder paste is then hardened to a half-dried state, and the surface-mount component 9 is fixed temporarily without using an adhesive which is used in conventional cases. Then, a soldering land 5 on the surface 3 of the circuit board 1 is coated with solder paste 7, a surface-mount component 10 is placed temporarily, this assembly passes through a heating furnace, the solder paste 6, 7 on both faces are made to reflow, and the surface mount components 9, 10 are soldered simultaneously. A soldering operation which avoids an unsoldered part or the like can be performed surely, and a circuit correction operation or the like after the soldering operation can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for soldering surface mount components, and more particularly, it is most suitable for simultaneously soldering surface mount components to be soldered on both the front and back surfaces of a circuit board. Regarding the soldering method.

[0002]

2. Description of the Related Art It is known to solder a connecting electrode of a surface mount component to a predetermined soldering land corresponding to a surface of a circuit board to form a required mount circuit device. In particular,
In the circuit board having the circuit board surface on both the front surface and the back surface, the mounting of the surface mounting component on the corresponding predetermined soldering land by reflow soldering is performed as follows.

That is, as schematically shown in FIGS. 3 and 4, the paste-like solder 6 is applied onto the surface of the soldering land 4 formed on the back surface 2 of the circuit board 1, and then the adhesive 8 is applied. It is applied between the two soldering lands 4, the surface mounting component 9 is mounted so that the connection electrodes 11 thereof contact the paste-like solder 6, and the adhesive 8 is irradiated with ultraviolet rays to cure the adhesive 8. As a result, the surface mount component 9 is temporarily fixed to the back surface 2 of the circuit board 1.

After that, the circuit board 1 is turned over, the paste-like solder 7 is applied on the surface of the soldering land 5 formed on the surface 3 of the circuit board 1, and then the surface-mounted component 10 is connected to the connecting electrode 12 thereof. Is mounted so as to be in contact with the paste-like solder 7, and thereafter, the paste-like solders 6 and 7 are simultaneously melted by passing through a heating furnace or the like, so-called reflow soldering is performed.

As described above, according to the conventional method, the surface mount component 9 is temporarily fixed with the adhesive 8 interposed between the surface mount component 9 and the rear face 2 on the rear surface 2 of the circuit board 1 to be mounted first. After that, the surface mount component 10 was mounted on the surface 3 of the circuit board 1, and thereafter, the paste solders 6 and 7 were simultaneously melted by reflow.

[0006]

However, in the above-described soldering method, as schematically shown in FIG. 5, when the adhesive 8 is cured, the surface mount component is as thick as the thickness of the adhesive 8. 9 is fixed in a raised state.

Therefore, when reflowing, the so-called self-alignment effect in which the surface mount component 10 is fixed in the correct position by the surface tension of the solder 14 melted on the front surface 3 cannot be expected on the back surface 2 and the melted solder 13 is not expected. There is a problem that the soldering land 4 is incompletely connected, electrical continuity cannot be obtained, and so-called unsoldering is likely to occur.

The present invention has been made in order to solve such a problem, and an object thereof is to provide a method for soldering a surface-mounted component, which completely eliminates the possibility of causing problems such as unsoldered solder.

[0009]

SUMMARY OF THE INVENTION The present invention is a method for soldering a surface mount component, wherein a surface mount component is soldered to a predetermined position surface of a conductor pattern formed on a circuit board. After applying the paste-like solder on the soldering land, the surface-mounting component is temporarily placed and the surface-mounting component is temporarily fixed by curing the paste-like solder to a semi-dry state, and then the paste-like component is passed through a heating device. This is to reflow the solder.

Further, the present invention provides a method for soldering surface-mounted components, wherein surface-mounted components are soldered to predetermined positions of conductor patterns formed on both surfaces of a circuit board, respectively. After applying the paste-like solder on the soldering land to be soldered and temporarily placing the surface-mounted component, the surface-mounted component is temporarily fixed by curing the paste-like solder to a semi-dry state,
Next, paste-like solder is applied on the soldering land for soldering the conductor pattern on the other surface, and after temporarily mounting the surface mount component, the paste-like solder on both surfaces is reflowed through a heating device.

[0011]

In the method for soldering a surface-mounted component according to the present invention, the surface-mounted component itself is temporarily placed and then the paste-shaped solder is cured to a semi-dry state, so that the surface-mounted component itself is replaced by the paste-shaped solder itself instead of the adhesive. Is temporarily fixed, the surface mount component does not float due to the adhesive, and
Since self-alignment effect due to molten solder occurs during reflow soldering, unsoldered solder can be easily prevented, and
There is no need to modify the circuit after reflow soldering.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the method for soldering surface mount components according to the present invention will be described below with reference to FIGS. 1 and 2 schematically show an embodiment of the present invention.

First, as shown in FIG. 1, a required circuit board 1 is prepared, and on each soldering land 4 formed on the back surface 2 (or the surface to be mounted first) of this circuit board 1. Then, the required paste solder 6 is applied.

Next, the surface mounting component 9 prepared in advance for mounting is applied onto the soldering land 4 on the lower surface of the soldering portion of the connecting electrode 11 included in the surface mounting component 9. The surface mount component 9 is positioned and temporarily placed on the back surface 2 of the circuit board 1 so as to come into contact with the paste-like solder 6 that is formed.

Next, the circuit board 1 is placed in an oven or the like as it is, and the paste-like solder 6 is cured in a semi-dried state at a temperature at which the paste-like solder 6 is not melted. 9 is temporarily fixed.

Next, the circuit board 1 is turned over, and the required paste-like solder 7 is applied to each soldering land 5 formed on the remaining surface of the circuit board 1, that is, the surface 3. Then, the surface mount component 10 is replaced with the surface mount component 1
0 is provided on the surface 3 of the circuit board 1 so that the lower surface of the soldered portion of the connecting electrode 12 contacts the paste-like solder 7 applied on the soldering land 5. Positioning and temporary placement.

Next, for example, by passing through a tunnel type heating furnace or the like and reflowing the paste-like solders 6 and 7 applied on the soldering lands 4 and 5, as shown in FIG. Soldering is achieved.

In the means constructed as described above,
Unlike the conventional method, since no adhesive is used below the surface mount component 9, the surface mount component 9 does not float, and due to the self-alignment effect of the solders 13 and 14 melted in the reflow process, unsoldered or the like. And the electrical connection is ensured at the correct position. Therefore, there is no need to modify the circuit after reflow soldering, and the time and labor required for the conventional modification can be greatly reduced, and the device for applying the adhesive and the device required It does not require time or manpower.

[0019]

As described above, according to the present invention,
It is not necessary to use an adhesive, and the risk of unsoldered connection electrodes can be easily avoided. Therefore, the surface-mounted components can be efficiently reflow-soldered on the circuit board, and a highly reliable mounted circuit board or mounted circuit device can be easily obtained. Moreover, since it is not necessary to modify the circuit after soldering, the time and manpower required for the modification can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing a state before reflow in an embodiment of a method for soldering a surface mount component according to the present invention.

FIG. 2 is a cross-sectional view schematically showing a state after reflow in the embodiment example.

FIG. 3 is a cross-sectional view schematically showing a state before reflow in an example of a conventional method for soldering a surface mount component.

FIG. 4 is a plan view schematically showing a state before reflow in the above conventional example.

FIG. 5 is a cross-sectional view schematically showing a state after reflow for explaining the problem in the conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Circuit board 2 Back surface of circuit board 3 Front surface of circuit board 4 Back surface soldering land 5 Surface soldering land 6 Back surface paste solder 7 Surface paste solder 9 Back surface mounting component 10 Surface surface mounting component 11 Backside surface mounting component connection electrode 12 Front surface mounting component connection electrode 13 Backside molten solder 14 Frontside molten solder

Claims (2)

[Claims] 1. A method of soldering a surface mount component for soldering a surface mount component to a predetermined position surface of a conductor pattern formed on a circuit board, comprising: a paste-like solder on a soldering land for soldering the conductor pattern. After applying, place the surface mount parts temporarily,
A method of soldering a surface mount component, comprising: temporarily fixing the surface mount component by curing the paste solder in a semi-dried state, and then reflowing the paste solder through a heating device. 2. A soldering method for surface-mounting components, comprising soldering surface-mounting components to predetermined positions of conductor patterns formed on both surfaces of a circuit board, wherein the conductor pattern is soldered on one surface. After applying the paste-like solder on the attachment land and temporarily placing the surface-mounting component, the paste-like solder is cured to a semi-dry state to temporarily fix the surface-mounting component, and then the conductor pattern on the other surface. The paste-like solder is applied onto the soldering land to be soldered, and the surface-mounted component is temporarily placed, and then the paste-like solder on both sides is reflowed through a heating device.