JP4986146B2 - Coil component soldering method and differential transformer - Google Patents

Description

  The present invention relates to a soldering method for a coil component such as a transformer in which a plurality of coils are wound around a bobbin, and a differential transformer.

  When an electronic component is mounted on a printed circuit board to form an electronic circuit, an electronic component, for example, a coil component such as a transformer, is produced by soldering a terminal of a coil wound around a bobbin to an input / output terminal. For example, in an electrophotographic developing device using a magnetic developer containing toner, in order to obtain a clear image, a differential transformer type toner sensor is installed in the developer tank, and the toner concentration and the remaining amount of toner are reduced. It is configured to detect and output a DC voltage corresponding to the toner concentration and the remaining amount of toner to a circuit that drives the toner replenishing means. In this differential transformer, the primary coil is connected to an AC power supply, the detection coil and the reference coil are differentially connected to the secondary side, and the detection circuit element is mounted to extract the differential output of the detection coil and the reference coil. It is arrange | positioned in the case with the printed circuit board (for example, refer patent document 1).

In the above differential transformer, a plurality of coils are wound around a cylindrical bobbin formed of a thermoplastic resin, and the winding start and end of each coil are wound around a terminal, and then the winding portion is used as a solder liquid. It is produced by dipping. When manufacturing a coil component such as an operating transformer, the coil component is set on a jig (holder) in order to tie the end of the coil to the input / output terminal and solder the tangled portion. Is lowered toward the solder liquid surface, and soldering work is performed so that the terminals are immersed perpendicularly to the liquid surface (see, for example, Patent Document 2).

Japanese Patent No. 3900442 (pages 4-6, FIG. 1, FIG. 2, FIG. 3) Japanese Patent No. 2728983 (2nd page, FIG. 4)

  Since the conventional soldering jig has an open shape at least on the side of the terminal where the coil is entangled, when the portion where the coil is entangled is immersed in the liquid surface, the heat of the solder liquid is the terminal. The resin at the base of the terminal is melted to form a bulging portion called a blister on the upper surface of the terminal. In particular, when a lead-free solder composition is used as the solder, the temperature of the solder solution is about 400 ° C., so that a blister is likely to occur. When a circuit board with a blistered differential transformer connected to one end is housed in a case and covered with a cover, the blistered portion hits the cover. Such a phenomenon that the case is stored in a case tilted with respect to FIG. 2 or stress is applied to the differential transformer causes a decrease in detection accuracy. In addition, since the cover is strongly pressed against the case side, the cover may be damaged (the weld portion when the cover is molded may be torn).

Accordingly, an object of the present invention is to provide a method of soldering a coil component that can prevent the occurrence of blisters and a differential transformer that suppresses blisters .

  In order to achieve the above object, a soldering method of the present invention includes a base portion having a holding groove that accommodates at least a part of a coil component having a bobbin around which a coil is wound and a terminal having a coil end wound around. And after setting the coil component in a soldering jig having a lid portion having a heat shield portion, one end side of which is supported by the base portion and the other end side is close to or in contact with the terminal, It is characterized by being immersed in a solder solution.

  In the present invention, it is preferable that the soldering jig has a structure in which the base portion has a restricting portion that restricts rotation of the bobbin.

  The differential transformer of the present invention includes a primary coil wound around a coil bobbin made of polymethylpentene and connected to an oscillation circuit, a detection coil coupled to the primary coil and having an output voltage that varies depending on toner concentration, and a primary coil And a reference coil in which the output voltage does not change according to the toner concentration, the detection coil and the reference coil are differentially connected, and each coil has a terminal with which the terminal is entangled. Are preferably soldered by a vertical dipping method and the terminal has a substantially flat surface.

  According to the present invention, the portion where the coil end is entangled is immersed in the solder solution in a state where the surface side of the terminal provided on the bobbin is covered with the heat shield portion, so that the occurrence of blistering is greatly increased. It can be suppressed or burns can be eliminated.

  Details of the present invention will be described below with reference to the accompanying drawings (FIGS. 1 to 9).

  1 is a plan view showing an example of a toner sensor, FIG. 2 is a cross-sectional view taken along line AA of FIG. 1, FIG. 3 is a front view of a differential transformer, and FIG. 4 is an arrow view of FIG. 5 is a perspective view showing a state in which a part of the soldering jig on which the differential transformer is set is cut out, FIG. 6 is a sectional view of the soldering jig shown in FIG. 5, and FIG. 8 is a cross-sectional view taken along the line CC, FIG. 8 is a cross-sectional view taken along the line DD in FIG. 7, and FIG. 9 is a cross-sectional view taken along the line EE in FIG.

[Toner sensor]
As shown in FIGS. 1 and 2, the toner sensor 1 includes a case 2 formed of a resin having a detection head portion 21 on one end side, a differential transformer 3 housed in the detection head 21, and a detection A printed circuit board 4 on which elements 5 (C: capacitor, D: diode, IC: logic IC, R: resistor, etc.) constituting the circuit are mounted is provided. A differential transformer 3 is connected to one end of the printed circuit board 4, and a connector 6 is connected to the other end of the printed circuit board 4. The case 1 is covered with the cover 7 (assembled in the direction of the arrow in FIG. 2), the through hole 22 formed on one end side of the case 2, the through hole 72 formed in the cover 7, and the case 2 Each of the through holes 23 formed on the other end side is installed in a developing device (not shown) by attaching a fastening member (not shown) such as a screw.

The differential transformer 3 has a coil 32 wound around a coil bobbin 31. The coil 32 is an oscillating circuit the primary coil L ₁ connected to the (not shown), and the sensing coil L ₂ which the output voltage varies in accordance with the toner concentration is coupled to the primary coil L _1, coupled to the primary coil L ₁ is the output voltage becomes a reference coil L ₃ does not change depending on the toner density detection coil L ₂ and the reference coil L ₃ is (are differentially connected) wound in a direction in which the output voltage cancel each other forming Is done. According to this toner sensor, applied when the two-component developer comprising a magnetic carrier and a nonmagnetic toner in the vicinity of the detection coil L ₂ is present, the high frequency voltage primary coil L ₁ output from the oscillator circuit Once, the inductance of the reference coil L ₃ does not change, the inductance of the detection coil L ₂ is changed according to the change in the apparent magnetic permeability of the developer based on a change of the toner concentration, changes in amplitude and phase of the output voltage To do. The phase of the output voltage is compared with the phase of the AC voltage on the primary side, a signal corresponding to the phase difference is output, the output signal is smoothed, and a DC voltage corresponding to the toner density is output. The coil bobbin 31 is screwed with a screw core 34 made of a high permeability material in order to adjust the sensitivity of the sensor (inductance between the primary coil and the reference coil) (see FIG. 1). After the sensor is installed in the developing device, the screw core 34 is rotated by a driver (not shown) inserted from the adjustment hole 71 of the cover 7 and fixed at a predetermined position.

[Differential transformer]
The structure of the differential transformer 3 will be described with reference to FIGS. The differential transformer 3 includes a coil bobbin 31 that is a cylindrical member having a pedestal 310 and collar portions 311, 312, and 313, and a coil 32 wound around the coil bobbin 31 (a primary coil L ₁ , a reference coil L ₂ , and a detection coil L _3. ), Terminal pins 33 to which terminals (winding start and winding end) of each coil are connected, and a screw core 34 (see FIG. 1) screwed into the coil bobbin 31. Since five terminals are used in this example, the winding start of the detection coil, the winding start of the reference coil, the winding start of the primary coil, and the winding end of the primary coil are connected to the four terminals. The coil bobbin 31 to which the winding start of the detection coil and the winding start of the reference coil are connected is preferably formed of a resin that has high electrical insulation and does not deform even when exposed to high temperatures. Specific examples of the resin include polyolefin resins such as polybutylene terephthalate (PBT) and polymethylpentene. In particular, polymethylpentene is a copolymer having 4 methylpentene-1 as a main monomer {manufactured and sold by Mitsui Chemicals, Inc. under the registered trademark of TPX. }, And is excellent in environmental characteristics (contamination resistance) in addition to high electrical insulation, and is therefore used effectively in the present invention.

[Soldering jig]
The structure of the soldering jig according to the present invention will be described with reference to FIGS. The soldering jig 10 has a base portion 11 having a holding groove 110 for accommodating the differential transformer 3 and having restriction portions 112 and 113 close to the pedestal 310 at an end portion on the terminal side, and a hinge portion on one end side, for example. (Not shown) includes a lid portion 12 having a heat shield portion 121 supported by the base portion 11 and abutting the terminal 33 on the other end side. Since this soldering jig 10 is provided with a restricting portion 113 on the base portion 11 so as to sandwich the side on which the terminal 33 of the base 310 is provided (see FIG. 7), the coil bobbin 31 is prevented from rotating. Can do. In this soldering jig 10, the height h7 (see FIG. 8) on the terminal side of the base portion 11 covers all the coils in order to prevent the coils from coming into contact with the solder solution during soldering. Set to the correct dimensions. A state in which the coil bobbin 31 can be normally soldered by reducing the gap between the outer peripheral surface of the flange portions 311, 312, 313 of the coil bobbin 31 and the inner peripheral surface of the holding groove 110 {the terminal is connected to the solder liquid (liquid level) ) To be parallel to.

If the base portion and the lid portion 12 are formed of a material having high thermal conductivity (for example, a metal material), when the heat shield portion 121 approaches the solder solution, the surface temperature of the solder solution is lowered and normal. Soldering is hindered. Therefore, the base portion 11 and the lid portion 12 are made of a thermosetting material such as a material having low thermal conductivity, such as a phenol resin, in order to suppress a decrease in the surface temperature of the solder solution when the heat shield portion 121 is brought close to the solder solution. Made of resin. Furthermore, the tied part is immersed in the solder liquid, since the end face of the heat shield section 121 is also in contact with the solder liquid, in order to prevent deterioration, than the base portion 11 and the heat shield section 12 1, such as glass tape It is desirable to fix a member (not indicated) made of a material having high heat resistance.

[Soldering method]
According to the soldering jig 10 described above, soldering by the vertical dipping method can be performed by the following procedure. First, the lid portion 12 is opened (rotates counterclockwise in FIG. 5), the differential transformer 3 is set on the base portion 11, and then the lid portion 12 is closed. 10 is attached to a conveying device (not shown), and the portion where the coil terminal is entangled is immersed in the solder solution, the heat of the solder solution is transferred from the terminal to the coil bobbin, and as shown in FIGS. The surrounding resin is melted and solidified by cooling, and the bulging portion M is formed. However, since the growth of the bulging portion M is suppressed by the heat shield portion 121 provided in the lid portion 12, the height h3 (= h2-h1) of the bulging portion M is, for example, less than 0.1 mm (0 Can be included). Therefore, the use of this soldering jig 10 makes the surface of the terminal substantially flat, and the size of the blister is large enough to attach the differential transformer to the detection surface of the case. Can be prevented.

[Solder solution]
The solder solution can be adjusted by melting a bar material made of, for example, a Pb-free solder composition. Examples of Pb-free solder compositions include Sn-Ag alloys (eutectic point: 3.5% Ag, eutectic temperature: 221 ° C), Sn-Bi alloys (eutectic point: 5.8% Bi, co-crystal). Crystal temperature: 138 ° C), Sn-Zn alloy (eutectic point: 9.0% Zn, eutectic temperature: 199 ° C), Sn-Ag alloy (eutectic point: 3.5% Ag, eutectic temperature) : 221 ° C.) or a ternary alloy such as a Sn—Ag—Cu alloy can be used. Among these, those having a eutectic temperature close to the eutectic temperature (183 ° C.) of the Pb—Sn alloy (for example, Sn—Ag alloy, Sn—Zn alloy) are preferable.

  The soldering jig of the present invention is not limited to the structure shown in FIGS. 5 to 9 and can be variously modified. For example, a plurality of holding grooves are provided in a row in the base portion, and a differential transformer is provided in each holding groove. By housing, a plurality of differential transformers can be soldered in a single operation.

[Reference example]
Next, a soldering jig of a reference example will be described with reference to the accompanying drawings (FIGS. 10 to 14).

  10 is a perspective view showing a soldering jig in which a differential transformer is set, FIG. 11 is a perspective view showing a state in which a part of the soldering jig of FIG. 10 is cut out, and FIG. 13 is a cross-sectional view of the soldering jig shown, FIG. 13 is a cross-sectional view taken along the line FF of FIG. 12, and FIG. 14 is a plan view showing a state in which the differential transformer is rotating. Parts are denoted by the same reference numerals.

  The soldering jig of the present invention can be formed in various shapes, but those having no heat shield part in the lid part as shown in FIGS. 10 to 13 are inconvenient for the following reasons. It is. The soldering jig 10 includes a cylindrical holding groove 110 that accommodates the differential transformer 3 and a base portion 11 having a cylindrical core 111 that is press-fitted into a hollow portion (a portion into which the screw core is screwed) of the coil bobbin 31. One end side has a lid portion 12 supported on the base portion 11 with, for example, a hinge (not shown). In this soldering jig 10, the height h5 of the core 111 is set lower than the height h6 of the base portion 11 (h5 <h6), and the height h4 on the terminal side of the base portion 11 is a part of the bobbin. The dimension is set so as to cover.

  According to the soldering jig 10 described above, since there is no heat shield part in the lid part 12, there is a problem that a blister occurs. Further, since the core 111 is press-fitted into the coil bobbin 31, there is a problem that a rib for biting into the screw portion of the screw core of the bobbin is crushed. Further, since the inner diameter of the holding hole 110 is larger than the outer diameter of the flange portions 311, 312, 313 of the coil bobbin 31, when the core is press-fitted into the coil bobbin, as shown in FIG. In some cases, the coil bobbin 31 is set obliquely with respect to the surface 114, and since the terminals are not parallel to the solder liquid (liquid surface), there is a problem that all terminals are not soldered.

  5 is manufactured, and the differential transformer (bobbin material: TPX (registered trademark), collar outer diameter: 7 mm, height: 6.70 mm) shown in FIG. Was immersed in a solder solution (about 400 ° C.) for about 1 to 2 seconds to perform soldering 10 times. The base part 11 and the lid part 12 were formed of bakelite, and a glass tape was fixed to the surface of the heat shield part 121 facing the solder solution. Table 1 shows the results of measuring the height of the differential transformer after soldering.

  For comparison, a soldering jig shown in FIG. 10 was manufactured and soldered under the same conditions as described above. Table 1 shows the results of measuring the height of the differential transformer after soldering.

  From Table 1, in the jig of the present invention, the maximum value of h2 is 6.74 mm (No. 8), the minimum value is 6.70 mm (No. 6), the average value is 6.72 mm, and the maximum value of h3 It can be seen that the value is 0.04 mm (No. 8), the minimum value is 0.00 mm (No. 6), and the average value is 0.02 mm. On the other hand, in the jig of the reference example, the maximum value of h2 is 7.08 mm (No. 10), the minimum value is 6.91 mm (No. 4), the average value is 6.99 mm, and h3 It can be seen that the maximum value is 0.38 mm (No. 10), the minimum value is 0.21 mm (No. 4), and the average value is 0.29 mm). Therefore, according to this invention, it turns out that the suppression effect of a blister is acquired.

FIG. 4 is a plan view illustrating an example of a toner sensor. It is the sectional view on the AA line of FIG. It is a front view of a differential transformer. It is the arrow line view which looked at FIG. 3 from the B direction. It is a perspective view which shows the jig for soldering concerning the Example of this invention. It is sectional drawing of the jig for soldering shown in FIG. It is CC sectional view taken on the line of FIG. It is the DD sectional view taken on the line of FIG. It is the EE sectional view taken on the line of FIG. It is a perspective view of the jig for soldering concerning a comparative example. It is a perspective view of the jig for soldering which notched a part of FIG. It is sectional drawing of the jig for soldering shown in FIG. It is the FF sectional view taken on the line of FIG. It is a top view which shows the state which the differential transformer set to the jig | tool for soldering is rotating.

Explanation of symbols

1: toner sensor, 2: case, 21: detection head, 22, 23: through-hole, 3: differential transformer, 31: coil bobbin, 310: pedestal, 311, 312, 313: collar, 32: coil, 33: Terminal: 34: Screw core, 4: Printed circuit board, 5: Element, 51: Capacitor, 52: Diode, 53: IC, 54: Resistor, 6: Connector, 7: Cover, 71, 72: Through hole, 10: Soldering Jig, 11: Base part, 110: Holding groove, 111: Core, 112: Side wall, 113: Restricting part, 114: Surface, 12: Cover part, 121: Heat shield part

Claims (2)

Accommodating a resin bobbin which a coil is wound, the bobbin of the coil component having a terminal provided on the organic and the bobbin a root resin portion for supporting the terminal pin terminal has been tied in the coil a base portion made of a phenol resin having a holding groove which is supported at one end side of the base portion, provided with a lid portion made of a phenol resin having a heat shield unit which is the other end close to or in contact with the base resin portion of the terminal A method of soldering a coil component, comprising setting the coil component on a soldering jig and then immersing a portion of the terminal pin in which the coil is wound in a solder solution. The method for soldering coil components according to claim 1, wherein the base portion has a restricting portion that restricts rotation of the bobbin.

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