JP2004319249A - Method of manufacturing surface-mounted electronic part - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for an electronic part which is mounted on a surface of a circuit substrate by which a heat melting conductive body can be easily mounted to a conductive terminal. <P>SOLUTION: A connector 1 of the electronic part is mounted on the surface of the circuit substrate, and is provided with an insulating inner case 4 and the conductive terminal 6. The terminal 6 is processed by bending metal wire to constitute a connecting part 6a stored to a storing recessed part 4a of the case 4 and connected to a pin 2a of CPU2, a retaining part 6b pressed into a retaining opening 4c of the case 4 and a solder melting part 6c to which solder 8 is stuck. The solder melting part 6c is formed in an approximate V shape so that it spread in the widthwise direction of the circuit substrate as shown in diagram 3c. In the process of solder melting the solder 8 to the solder melting part 6c, the solder melting part 6c is pulled out after being dipped in melted solder 8 and is soldered so that the solder 8 projects more than a projection 4b projecting from the back surface of the case 4. After that, in a flat surface processing procedure, the tip of the solder 8 is brought into a pressurized contact with a straightening table 13 and coplanarity of the solder 8 is established. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing an electronic component surface-mounted on a circuit board.
[0002]
[Prior art]
As an electronic component mounted on the surface of a circuit board, an IC, a connector for detachably mounting an IC or another circuit board on a circuit board, and the like are known. Among such surface-mounted electronic components, a conductive terminal electrically connected to a land of a circuit board via a heat-fusible conductor is provided, and the heat-fusible conductor is previously attached to this terminal. What is worn is known.
[0003]
Among such electronic components, a connector such as a CPU socket will be described as an example. For example, a connector disclosed in Patent Document 1 below is known. The surface mount connector disclosed in Patent Literature 1 is called a ball grid array system (hereinafter, referred to as a BGA system), and includes a case formed of an insulator and placed on a circuit board, and a case arranged in a vertical direction. It has a through hole that penetrates, and a terminal that is mounted in the through hole and electrically connects a pin and an electric circuit of the circuit board via a solder ball that is a heat-fusible conductor. In such a surface mount type connector, the connector is placed on a circuit board in a state where the solder ball is mounted, and the solder ball is melted by heating these members, thereby connecting the electric circuit of the circuit board to the terminal. are doing.
[0004]
A conventional BGA type connector forms a solder ball by melting solder once to form a ball, and when attaching the solder ball to the terminal, a part of the solder ball is melted and fixed at the lower end of the terminal. I have.
[0005]
However, it is difficult to make the solder into a ball without distortion. In addition, a part of the solder is melted and fixed to the terminal. However, if the solder ball is melted too much, the shape of the solder ball is broken and the solder ball cannot be used for a product. Conversely, if the melting is insufficient, the bonding strength with the terminal is weak, and the solder ball may be detached from the terminal when attaching the terminal with solder balls to the case or transporting the completed connector. is there.
[0006]
As described above, in order to mount a heat-fusible conductor on a surface-mounted electronic component in advance, strict management of the shape of the heat-fusible conductor and management of the connection state between the heat-fusible conductor and the terminal are required. It had to be done and it was not technically easy.
[0007]
[Patent Document 1]
JP-A-10-162909 (front page)
[0008]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION The present invention aims to improve a method of manufacturing a surface-mounted electronic component, and more particularly, to provide a method capable of easily attaching a heat-fusible conductor to a conductive terminal in order to solve the above-mentioned disadvantages. The purpose is to do.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, a method of manufacturing a surface-mounted electronic component according to the present invention is a method of manufacturing an electronic component mounted on a surface of a circuit board having lands, wherein the electronic components are thermally connected to the lands. A conductive terminal electrically connected through a fusible conductor, and an insulating case for fixing the terminal toward the circuit board side, wherein the terminal faces the circuit board side. A heat-fusible conductor that extends from the back surface of the case and extends along at least the circuit board has a fusion-bonded portion to which the heat-fusible conductor is adhered by being heated and fused. When the land is connected, a projection that keeps a predetermined distance between the back surface of the case and the surface of the circuit board is provided, and the fused portion of the terminal is at or above the melting temperature and near the melting temperature. Heat-fusible conductor melted at temperature After dipping, draw out, solidify the heat-fusible conductor and attach it to the fusion portion so as to protrude beyond the protrusion, and a flat straightened front end of the heat-fusible conductor. Deforming by pressing against a correction table having a height of the heat-fusible conductor higher than or equal to the height of the protrusions, and a uniformity of the protrusion amount of the heat-fusible conductor protruding from the back surface of the case. It is characterized by having.
[0010]
In the manufacturing method of the present invention, the terminal is provided with a fusion bonding portion extending at least along the circuit board of the circuit board, and the heat-fusible conductor is at a temperature equal to or higher than its melting temperature and near the melting temperature. When the terminal is immersed in the melted heat-fusible conductor and pulled up because the viscosity of the heat-fusible conductor that has been melted is high, the heat-fusible conductor that is fused to the fused portion is formed in the case. Can be made to exceed the height of the projection. Further, in the manufacturing method of the present invention, the flattening amount (coplanarity) of the tip of the heat-fusible conductor is ensured because the amount of protrusion of the heat-fusible conductor projecting from the case is made uniform by the straightening step. be able to.
[0011]
In the method of manufacturing a surface-mounted electronic component according to the present invention, the correcting step includes pressing the correcting table heated to a temperature lower than the melting temperature of the heat-fusible conductor and in the vicinity of the melting temperature. It is preferable to soften and deform the conductive material and to cool the heat-fusible conductive material having a uniform amount of protrusion.
[0012]
When the correction table is heated to a temperature lower than the melting temperature of the heat-fusible conductor and in the vicinity of the melting temperature, the heat-fusible conductor is softened when pressed, so that the distal end portion is easily deformed. Further, since the temperature of the correction table is lower than the melting temperature of the heat-fusible conductor, the heat-fusible conductor does not melt again and its shape is not deformed more than necessary. In addition, since the heat-fusible conductor is cooled afterward and does not fuse to the correction table, the heat-fusible conductor can be easily removed from the correction table. In addition, the shape of the heat-fusible conductor is stable while coplanarity of each heat-fusible conductor is ensured, since the heat-fusible conductor is cooled while the protrusion amount of the heat-fusible conductor is uniform. I do.
[0013]
In addition, the method for manufacturing a surface-mounted electronic component of the present invention preferably includes a cooling step of cooling the terminals prior to the fusing step. By cooling the terminal and then immersing it in the molten heat-fusible conductor, the heat of the heat-fusible conductor in contact with the fused portion of the terminal is absorbed by the terminal, and It becomes easy to adhere.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, a method of manufacturing a surface-mounted electronic component according to the present invention will be described with reference to FIGS. 1 is an explanatory view showing a connector manufactured by the manufacturing method of the present embodiment, FIG. 2 is a partially enlarged view of a portion II-II in FIG. 1, and FIG. 3 is a side view of the connector showing a state where solder is fused. FIG. 4 is an explanatory view showing the relationship between the inner case, the terminal and the solder, FIG. 5 is an explanatory view showing a terminal processing step, FIG. 6 is an explanatory view showing a fusion step, and FIG. 7 is an explanatory view showing a straightening step. FIG. 8 is an explanatory view showing another embodiment of the terminal.
[0015]
The connector 1 manufactured by the manufacturing method of the present embodiment is a CPU socket for detachably mounting a CPU 2 on a circuit board 3 as shown in FIG. The connector 1 includes an inner case 4 and an outer case 5 each formed of an insulator, and is fixed to the inner case 4 and connected to the pins 2a of the CPU 2 and reflow soldered to lands (not shown) of the circuit board 3. And an operation lever 7 for sliding the outer case 5 in the front-rear direction with respect to the inner case 4.
[0016]
The inner case 4 is made of a synthetic resin, and has a plurality of terminals 6 arranged in a lattice as shown in FIG. Further, as shown in FIG. 4, a storage recess 4a is provided in which a connection portion 6a of the terminal 6 described later is stored and the pin 2a of the CPU 2 is inserted. On the back surface, as shown in FIG. 3, there is provided a projection 4b protruding toward the circuit board 3, so that a stand-off is formed when the connector 1 is surface-mounted on the circuit board 3. It has become.
[0017]
The outer case 5 is made of a synthetic resin, is slidably attached to the inner case 4 in the front-rear direction (vertical direction in FIG. 2), and has an insertion hole 5a through which the pin 2a of the CPU 2 is inserted. . The outer case 5 is slid in the front-rear direction with respect to the inner case 4 by the rotation of the operation lever 7. When the operation lever 7 is raised as shown in FIG. 1, the outer case 5 is moved rearward (upward in FIG. 2). When the operation lever 7 is rotated forward as shown in FIG. 3, the outer case 5 is moved forward (downward in FIG. 2).
[0018]
Next, the terminal 6 of the connector 1 will be described with reference to FIG. 4A is a partially enlarged plan view of the inner case 4 and the terminal 6, FIG. 4B is a sectional view taken along line bb of FIG. 4A, and FIG. 4C is a sectional view taken along line cc of FIG. 4A. The terminal 6 is formed by bending a beryllium copper wire having a diameter of 0.15 mm, the surface of which is plated with gold. As shown in FIG. 4, the terminal 6 includes a connecting portion 6a connected to the pin 2a of the CPU 2, a holding portion 6b held in the holding hole 4c of the inner case 4, and a solder 8 which is a heat-fusible conductor. And a fused portion 6c to be fused. The holding portion 6b is pressed and held in a holding hole 4c provided in the inner case 4 as described later. Further, the surface of the holding portion 6b is a rough surface portion 6d provided with irregularities on the surface, and the connection between the holding portion 6b and the holding hole 4c is strengthened.
[0019]
The fusion portion 6c protrudes downward from the back surface of the inner case 4, extends along the circuit board 3 as shown in FIG. 4, and is bent in a substantially V shape in FIG. 4c. As shown in FIGS. 4B and 4C, a substantially conical solder 8 is fused to the fusion portion 6c. 4B and 4C, the tip of the solder 8 is processed into a flat shape, and the amount of each solder 8 projecting from the back surface of the inner case 4 is uniform.
[0020]
The solder 8 is formed so as to protrude below the protrusion 4b of the inner case 4, as shown in FIG. On the other hand, the lower end of the fused portion 6c of the terminal 6 is formed so as to be located above the projection 4b of the inner case 4. Therefore, when the connector 1 is placed on the circuit board 3 during reflow soldering, the solder 8 comes into contact with the surface of the circuit board 3, and when the solder 8 is heated and melted, the lower ends of the circuit board 3 and the terminals 6 are formed. A predetermined interval is formed between the first and second portions.
[0021]
Next, a method for manufacturing the connector 1 of the present embodiment will be described with reference to FIGS. The method of manufacturing the connector 1 according to the present embodiment includes a terminal mounting step of mounting the terminal 6 on the inner case 4 and a terminal processing step of processing a portion of the terminal 6 protruding from the inner case 4 to form a fused portion 6c. A fusion step of fusing the solder 8 melted to the fusion section 6c, and a correction step of aligning the tips of the solder 8 fused to the fusion section 6c. The straightening step includes a heating step of heating and deforming the tip of the solder 8 and a cooling step of cooling the deformed solder 8.
[0022]
First, in the terminal mounting step, as shown in FIGS. 5A and 5B, a terminal 6 having a connecting portion 6a formed by bending a linear wire is pressed into a holding hole 4c of the inner case 4. At this time, the terminal 6 is firmly held in the holding hole 4c of the inner case 4 by the rough surface portion 6d provided on the holding portion 6b of the terminal 6.
[0023]
Next, in a terminal processing step, as shown in FIGS. 5C to 5E, a fused portion 6c is formed below the terminal 6 by a terminal processing jig 10. Specifically, the tip of the terminal 6 is inserted into the groove 10a of the terminal processing jig 10, and the terminal processing jig 10 is rotated. Thereby, the tip of the terminal 6 is bent along the side surface shape of the terminal processing jig 10 and is formed in a substantially V shape.
[0024]
Next, in the fusion step, as shown in FIG. 6A, the connector 1 is transported by the transport arm 11 to above the molten solder tank 12 filled with the molten solder 8. Next, as shown in FIG. 6B, the fused portion 6c of the terminal 6 is immersed in the molten solder 8. Next, as shown in FIG. 6C, the fusion part 6 c is pulled up from the solder 8 by the transfer arm 11. As a result, the solder 8 has a substantially conical shape downward as shown in FIG. 7A, and is cooled by being exposed to the outside air and fused to the fusion portion 6c.
[0025]
In the present embodiment, the temperature of the solder 8 melted in the molten solder tank 12 is a temperature close to the melting temperature, for example, lower than when solder plating is performed, and the viscosity of the solder 8 is reduced. It is getting higher. For example, when solder plating is applied to the tip of an IC terminal or the like, the solder is heated to a temperature higher than its melting temperature by about 70 ° C. or more so that the viscosity is kept low and the surface of the terminal is coated with solder thinly. . On the other hand, in the present embodiment, by increasing the viscosity of the molten solder 8 at a temperature within 50 ° C., preferably within 25 ° C. from the melting temperature, the fused portion 6 c is removed from the molten solder 8. When it is pulled up, it has a roughly conical shape like an icicle. As a result, as shown in FIG. 3, the tip of the solder 8 protrudes below the projection 4b of the inner case 4.
[0026]
Next, in the correction step, first, in the heating step, the inner case 4 including the terminal 6 to which the solder 8 is fused is placed on the surface of the correction table 13 as shown in FIG. The correction table 13 has a flat surface and is heated to a temperature slightly lower than the melting temperature of the solder 8. Although the tip of the solder 8 fused to the fusion portion 6c in the fusion step is sharp as shown in FIG. 7A, the correction table 13 is heated to a temperature slightly lower than the melting temperature of the solder 8. Therefore, the solder 8 is softened and easily deformed. Accordingly, when the inner case 4 is placed on the surface of the correction table 13, the tip of the solder 8 is deformed into a flat shape by the weight of the inner case 4 and the terminal 6 (see the solder 8 on the left side in FIG. 7B). ).
[0027]
In this embodiment, as shown in FIG. 7C, the connector 1 is further pressed against the surface of the correction table 13 by a press (not shown). Next, in the cooling step, the correction table 13 is cooled, and the shape of the solder 8 is stabilized. Thereby, the coplanarity of each solder 8 is ensured. Thereafter, the connector 1 is assembled by assembling the outer case 5 and the operation lever 7 to the inner case 4.
[0028]
In the connector 1 manufactured by the above process, as a method of attaching the solder 8 to the terminal 6, a simple method of dipping the fused portion 6c of the terminal 6 into the molten solder 8 and pulling it up is used. It is easy to mount the solder 8 on the terminal 6. In addition, since the amount of solder 8 projecting from the back surface of the inner case 4 is made uniform by the correction process, coplanarity of each solder 8 is ensured.
[0029]
The fused portion 6c is not limited to the shape of the above-described embodiment, and may be bent horizontally in a round shape as shown in FIGS. 8A to 8C, or may be bent in a square or a triangle. Further, in the above embodiment, the terminal 6 of the connector 1 is described as an example in which a beryllium copper wire is bent, but the present invention is not limited to this, and as shown in FIG. The solder 8 may be fused to the terminal 6 'formed by bending. A terminal 6 ′ shown in FIG. 8D includes a connecting portion 6 a connected to the pin 2 a of the CPU 2, a holding portion 6 b held by the inner case 4, and a fusion portion 6 c extending substantially parallel to the circuit board 3. It has. The terminal 6 ′ shown in FIG. 8D is provided with a communication hole 6 d communicating vertically between the fusion portion 6 c and the solder 8 is firmly fused to the fusion portion 6 c by the communication hole 6 d. Has become.
[0030]
In the correction process, the solder 8 is pressed against the heated correction table 13. However, the present invention is not limited to this, and the solder 8 may be pressed against the correction table 13 at room temperature. Further, in the above-described embodiment, the inner case 4, the outer case 5, and the operation lever 7 are assembled after the straightening process. However, the present invention is not limited to this. And then a straightening step may be performed.
[0031]
Further, in the above-described embodiment, the connector 1 which is a CPU socket has been described as an example of a surface-mounted electronic component. However, the present invention is not limited to this, and a connector for connecting circuit boards to each other or mounted on the surface of the circuit board. It can also be applied to electronic components such as ICs and resistors.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a connector manufactured by a manufacturing method according to an embodiment.
FIG. 2 is a partially enlarged view of a portion II-II in FIG. 1;
FIG. 3 is an explanatory side view of the connector in a state where solder is fused.
FIG. 4 is an explanatory diagram showing a relationship between an inner case, terminals, and solder.
FIG. 5 is an explanatory view showing a terminal processing step.
FIG. 6 is an explanatory view showing a fusing step.
FIG. 7 is an explanatory view showing a correction step.
FIG. 8 is an explanatory view showing another embodiment of the terminal.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Connector (electronic component), 3 ... Circuit board, 4 ... Inner case, 6 ... Terminal, 6c ... Fused part, 8 ... Solder (heat-fusible conductor), 13 ... Correcting table.

Claims (3)

A method for manufacturing an electronic component mounted on a surface of a circuit board having lands,
The electronic component includes a conductive terminal electrically connected to the land via a heat-fusible conductor, and an insulating case for fixing the terminal toward the circuit board,
The terminal has a fusion portion that protrudes from the rear surface of the case toward the circuit board side and extends at least along the circuit board and to which a heat-fusible conductor is adhered by being heated and melted, and the case has the heat-fusibility. When the conductor is heated and melted and the terminal and the land are connected, the terminal has a projection that maintains a predetermined distance between the back surface of the case and the surface of the circuit board,
After immersing the fused portion of the terminal at a melting temperature or higher and at a temperature close to the melting temperature in a hot-melt conductor that has been melted and pulled out, the hot-melt conductor is solidified so as to protrude beyond the protrusion. A fusion step of attaching to the fusion portion,
The tip of the heat-fusible conductor is pressed against a correction table having a flat correction surface and deformed, and the height of the heat-fusible conductor is set to be equal to or more than the protrusion, and protrudes from the back surface of the case. And a correcting step for making the amount of protrusion of the heat-fusible conductor uniform. The straightening step, while being pressed against the straightening table heated to a temperature lower than the melting temperature of the hot-melt conductor and near the melting temperature to soften and deform the hot-melt conductor, the amount of protrusion is uniform. The method for manufacturing a surface-mounted electronic component according to claim 1, wherein the heat-fusible conductor is cooled. 3. The method of manufacturing a surface-mounted electronic component according to claim 1, further comprising a cooling step of cooling the terminal before the fusing step.

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