JPH0337851B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is used in a lead terminal attachment step included in the manufacturing process of an electronic component in which the lead terminal is soldered to an electrode of an electronic component element. This relates to a method for attaching lead terminals.

2. Description of the Related Art For example, manufacturing electronic components such as ceramic capacitors with lead terminals attached involves a process of attaching lead wires to electrodes provided on the electronic component body. This process is often performed by soldering, but when processing large quantities of electronic components efficiently, soldering is accomplished by immersion in a solder bath.

However, when the above-mentioned dipping method is adopted, the solder adheres to the entire electrode of the electronic component, and a relatively large amount of solder is taken away from the parts that do not directly contribute to the connection of the lead terminals, resulting in wasted solder. It was becoming a problem.

Therefore, the following method was proposed. In other words, soldering is achieved by applying solder only to the tip of the lead terminal in advance, heating it while keeping it in contact with the electrode of the electronic component body, and melting the solder on the spot. It is. FIGS. 5 and 6 show a ceramic capacitor being subjected to such a soldering process.

Referring to FIGS. 5 and 6, for example, electrodes 2 and 2 are provided on the front and back surfaces of the disk-shaped element body 1, respectively.
is provided. The lead terminal 3 is prepared by bending a single metal wire, and solder is applied to each end in advance, and flux is also applied if necessary. The element body 1 is elastically held between each end of the lead terminal 3. The preliminary assembly 4 of the lead terminal 3 and the element body 1 temporarily held in this manner is sent in the direction of the arrow 5 in FIG. 5 with the respective electrodes 2 being arranged on one plane.

Hot air is applied to the plurality of pre-assemblies 4, which are being sent in an array, in the direction and position indicated by the arrow 6 in FIG. This hot air is blown out from a fixed outlet (not shown) having a size of, for example, 1×45 mm. The longitudinal direction of this outlet is
It is arranged to match the direction of advance of the pre-assembly (arrow 5). The blowing direction of the hot air is perpendicular to the traveling direction of the preliminary assembly 4 and is oblique to the lead terminals 3. The hot air is not directly applied to the soldered portion of the lead terminal 3, but as shown in FIG.
It is chosen to avoid direct hot air hitting the element body 1. The reason for this is to avoid cracks in the element body 1 that may occur if hot air is applied directly.

In this way, in the conventional method described above, the lead terminal 3 is first heated at the part where the hot air is applied, and the heat is transmitted through the lead terminal 3, melting the solder that has been applied in advance, and melting the solder applied to the electrode 2. Soldering between the lead terminal 3 and the lead terminal 3 will be performed.

Problems to be Solved by the Invention According to the above-mentioned prior art, most of the amount of heat required to raise the temperature of the preliminary solder applied to the lead terminals 3 to the melting point is due to heat conduction through the lead terminals 3. Therefore, it takes a relatively long time to transfer such heat, making it impossible to increase productivity. Also, since the hot air outlet is only on one side (for example, the upper side in Fig. 6), the lead terminal 3
The manner in which heat is transferred to each end of the element body 1 is fundamentally different, and even if a cover (not shown) is installed to appropriately generate hot air circulation, the soldering of each of the upper and lower electrode surfaces 2 of the element body 1 will be different. Another drawback was that the conditions could not be equalized.

Further, in the conventional method described above, although consideration is given to preventing the occurrence of cracks in the element body 1 due to hot air, the occurrence of cracks is still not completely avoided. This will be explained with reference to FIGS. 7 to 11.

7 and 8 show the distribution of heat transmitted from the lead terminal 3 in the heated state to the element body 1 using isothermal lines, and FIG. 7 is shown in the cross-sectional direction of the element body 1,
FIG. 8 shows the element body 1 in the plane direction. As shown in these drawings, when the heating method shown in FIGS. 5 and 6 is adopted, the lead terminal 3 is heated gradually toward its end, and the element body 1 is connected to the lead terminal 3. Temperature increases starting from the parts that are in contact.

9 and 10 show by arrows the thermal strain force applied to the element body 1 as a result of the above-mentioned temperature rise, and FIG. 9 shows the force in the cross-sectional direction of the element body 1,
FIG. 10 shows the force in the plane direction of the element body 1. Note that the arrows indicated by dotted lines in FIG. 10 represent the distribution of force on the back side of the element body 1 as shown in the figure. The element body 1 becomes hotter at the part where it is in contact with the lead terminal 3 and has a large expansion force, but as it gets further away from the lead terminal 3, the temperature becomes lower and the expansion force decreases, so the force applied to the element body 1 is 9th
It becomes as shown by the arrow in the figure and FIG. 10, respectively.

As a result, as shown by arrows 7a and 7b in FIG. 11, cracks 8a and 8b occur in portions where the force applied to the element body 1 is large.

SUMMARY OF THE INVENTION Therefore, the present invention solves the above-mentioned productivity problems and problems in a lead terminal mounting method in which solder is melted while blowing hot air onto lead terminals to which solder has been applied in advance, thereby performing soldering. Problems with uneven soldering on the upper and lower surfaces of the body,
This is an attempt to solve the problem of occurrence of cracks in the element body.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention is characterized by the way in which hot air is applied to melt the solder. That is, a pipe is prepared in which a slit that extends continuously in the axial direction is formed and a hot air outlet for supplying hot air so as to flow in the axial direction. On the other hand, a lead terminal to which solder has been applied in advance is prepared, and the electronic component element is temporarily held on the lead terminal with the soldered portion of the lead terminal in contact with the electrode of the electronic component element. The electronic component element temporarily held by this lead terminal (hereinafter referred to as a preliminary assembly)
is passed into the pipe with the lead terminal passed through the slit and pulled out of the pipe. At this time, the traveling direction of the preliminary assembly is opposite to the direction of the hot air. In this way, the solder applied to the lead terminals is melted and soldering is achieved.

Effects of the Invention According to this invention, the hot air that enables solder melting is supplied into the pipe, resulting in high energy efficiency, which has been confirmed to be more than 50% higher than conventional energy efficiency. There is. Further, the preassembly to be passed through the pipe is preheated from the stage of being introduced into the pipe, and can be sufficiently preheated while passing through the pipe. Therefore, it is possible to avoid cracking of the element body due to thermal shock, and it is possible to realize a highly reliable lead terminal attachment method. Furthermore, since the heating state can be made uniform at different locations on the element body, uniform soldering can be achieved at each location. Furthermore, since the lead terminal and the element body can be preheated at the same time, high-speed processing becomes possible and productivity is improved.

Embodiment FIG. 1 shows soldering being carried out according to an embodiment of the invention. In FIG. 1, the preliminary assembly 4 is similar to that shown in FIGS. 5 and 6, and each end of the lead terminal 3 is pre-applied with solder, and after applying flux if necessary, the preparatory assembly 4 is The body 1 is held by being held between each end of the lead terminal 3. Each pre-assembly 4 has a respective element body 1
are arranged so that the surfaces on which the electrodes 2 are formed are lined up on one plane, and are moved in the direction shown by arrow 9. This movement is performed while the bent portions of the lead terminals 3 of each preparatory assembly 4 and/or the vicinity thereof are held by appropriate means (not shown).

The preassembly 4 described above is threaded into the pipe 10. The pipe 10 is made of iron or any other material and is provided with a slit 11 extending continuously in the direction of its axis. The lead terminals 3 of the preliminary assembly 4 described above are drawn out to the outside of the pipe 10 through this slit. The preassembly 4 can therefore be held outside the pipe 10. The width of the slit 11 is preferably as small as possible so long as it allows the lead terminal 3 to pass therethrough. For example, the width of the slit 11 is about 5 mm.

A hot air outlet 12 is provided at a predetermined length from the inlet end of the pipe 10. In this embodiment, there are two hot air outlets 12 facing each other at the top and bottom of the pipe 10.
is provided. Conduit 1 forming hot air outlet 12
3 extends through the pipe 10. The distance between the tip of the conduit 13 and the central axis 14 of the pipe 10 is about 20 to 30 mm. two conduits 13,
The respective central axes 15, 15 of the pipes 13 intersect at one point on the central axis 14 of the pipe 10. and,
The angle at which the central axis 15 of the conduit 13 and the central axis 14 of the pipe 10 intersect is, for example, 15 degrees.
In this manner, when the conduit 13 is provided at an angle, the hot air blown out from the hot air outlet 12 flows in the direction of the arrow 16 within the pipe 10. This arrow 16 is opposite to the direction of movement of the preassembly 4 (arrow 9). The preliminary assembly 4 passing through the pipe 10 is positioned such that its element body 1 passes over the central axis 14 of the pipe 10.

As described above, the preliminary assembly 4 is attached to the pipe 1.
0, the soldering is preheated while passing through the air, and finally the soldering is completed before the hot air is directly received from the heat outlet 12.

FIG. 2 is a view in the direction of arrow A in FIG.
The association between preassembly 4 and hot air 17 in 0 is shown. As can be seen from FIG. 2, the hot air 17 acts equally on the upper and lower surfaces of the element body 1 included in the preliminary assembly 4, and therefore the heat is evenly transferred. Therefore, good soldering is possible. Further, the hot air 17 acting on the preparatory assembly 4 that has been soldered will preheat the subsequent preparatory assembly 4 one after another. Therefore, the occurrence of cracks due to thermal shock in the element body 1 can be avoided, reliability can be greatly improved, and energy efficiency can also be improved by more than 50% compared to the conventional one.

3 and 4 show the temperature distribution within the pipe 10 implemented according to the invention. The data shown in these drawings is for the case where a pipe with a total length of about 1 m and an inner diameter of 16.0 mm was used, and hot air at 500°C was supplied from the hot air outlet. Third
In the figure and FIG. 4, the horizontal axis shows the radial distance from the central axis 14 of the pipe 10, and the vertical axis shows the temperature. Moreover, the temperature expressed on the vertical axis is measured on a straight line passing through the center axis 14 of the pipe 10 and the center of the slit 11 in the width direction.

In Figure 3, 300mm from the hot air outlet,
The temperature inside the pipe 10 at a position of 600 mm is shown. On the central axis 14 of the pipe 10, the temperature increases from 200°C to 300°C as the preassembly progresses. Therefore, it is confirmed that there is a preheating effect.

FIG. 4 shows the temperature distribution at the hot air outlet. On the central axis 14 of the pipe 10, the highest hot air region of 500° C. occurs. As the preliminary assembly 4 passes through such the highest hot air region,
Soldering is completed.

As can be seen from FIGS. 3 and 4, the temperature of the preliminary assembly is gradually raised while being preheated, and soldering is completed instantaneously near the hot air outlet.

Although the present invention has been described above in connection with one embodiment, the form of the electronic component, that is, the preliminary assembly applied to the present invention is not limited to that shown in the drawings. Therefore, since the positions of the electronic component body and the electrodes formed thereon differ depending on the type of electronic component, the electrode surfaces are not necessarily aligned on one plane as shown in the figure. The pre-assembly does not necessarily proceed after being arranged. Naturally, the posture in which the preliminary assembly is advanced may be changed depending on the state of formation of the electrodes of the electronic component body.

Further, in the illustrated embodiment, the pipe 10 has a circular cross section, but it may have another shape. That is, such a pipe may have any shape or structure as long as it allows hot air to flow in the axial direction. In addition, although the hot air outlet is shown as one pair, two or more pairs may be provided along the axial direction of the pipe, and the hot air outlet temperature of each pair is changed, that is, as the hot air outlet approaches the intake port of the preliminary assembly. Therefore, the temperature of the hot air at the outlet can be lowered in stages as necessary.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a state in which the step of attaching the lead terminal 3 to the element body 1 according to the present invention is being carried out. FIG. 2 is a view along arrow A in FIG. 1 showing the relationship between each preliminary assembly 4 and hot air 17 in the pipe 10 in FIG. 1. Figures 3 and 4
The figure shows the temperature distribution inside the pipe 10, Figure 3 shows the temperature distribution at positions 300 mm and 600 mm from the hot air outlet, respectively, and Figure 4 shows the temperature distribution at the hot air outlet. . Figures 5 and 6 are
FIG. 5 is a diagram illustrating a conventional method for attaching a lead terminal, and FIG. 5 shows the progress of the preliminary assembly, and FIG. 6 shows the state of hot air being applied to the preliminary assembly. 7 and 8 show the temperature distribution in the element body 1 that appears in the conventional method shown in FIGS. 5 and 6. Figures 9 and 10 are
8 shows the thermal strain applied to the element body 1 as a result of the temperature distribution shown in FIG. FIG. 11 shows a crack condition caused by the forces shown in FIGS. 9 and 10. In the figure, 1 is an electronic component body, 2 is an electrode, and 3
1 is a lead terminal, 4 is a preliminary assembly, 10 is a pipe, 11 is a slit, 12 is a hot air outlet, and 17 is a hot air.

Claims (1)

[Claims] 1. A method for attaching a lead terminal to an electrode provided on an electronic component body, which comprises: preparing a lead terminal to which solder has been applied in advance; and attaching the soldered portion of the lead terminal to an electrode provided on an electronic component body. The electronic component body is temporarily held on the lead terminal while in contact with the electrode, and a slit that extends continuously in the axial direction is formed, and a hot air outlet is provided to supply hot air so that it flows in the axial direction. The electronic component element, which is temporarily held by the lead terminal, is advanced in the opposite direction to the direction of the hot air, with the lead terminal passing through the slit and being pulled out of the pipe; A method for attaching a lead terminal to an electronic component, comprising steps of melting the solder applied to the lead terminal and performing soldering.