JP5573341B2 - Manufacturing method of electronic parts - Google Patents

Description

  The present invention relates to a method for manufacturing an electronic component.

  The electronic component manufacturing method may include a step of applying solder for mounting to the surface of the terminal electrode. As such a process, for example, in the surface treatment method described in Patent Document 1, in a tank containing two layers of liquid separated into an upper layer composed of a surface treatment liquid using saturated fatty acid and a lower layer composed of a molten solder liquid. Techniques for immersing electronic components are disclosed. According to this method, the dirt due to the metal oxide adhered to the surface of the terminal electrode is removed by the surface treatment liquid of the upper layer, and then the molten solder is adhered to the surface of the terminal electrode by the molten solder liquid of the lower layer. As it passes through the processing solution, a saturated fatty acid film is coated on the surface of the molten solder.

Patent No. 4203281

  However, the above-described conventional method has a problem that it is difficult to obtain a uniform solder layer because the shape of the solder layer formed on the surface of the terminal electrode is often uneven after the electronic component is pulled out of the tank. . This problem is considered to be caused by the surface tension of the molten solder itself attached to the terminal electrode. However, the viscosity of the solder layer due to temperature changes when the electronic component is pulled up from the tank, and the partial composition due to oxidation It is considered that there is a part due to non-uniform change of conditions due to change or the like.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for manufacturing an electronic component that can form a solder layer having a uniform shape on the surface of a terminal electrode.

  In order to solve the above problems, an electronic component manufacturing method according to the present invention is a method for manufacturing an electronic component including a solder layer forming step of forming a solder layer on a surface of a terminal electrode formed on the electronic component, In the solder layer forming step, the electronic component is immersed in a tank containing two layers of liquid separated into an upper layer composed of a surface treatment liquid using saturated fatty acid and a lower layer composed of a molten solder liquid, and a terminal electrode of the electronic component Soldering process to attach the molten solder so as to cover the surface, and when pulling up the electronic component from the upper liquid surface, spray an antioxidant fluid at a temperature equal to or higher than the melting point of the molten solder toward the electronic component near the liquid surface And a solder removing step of removing an excess portion of the molten solder adhering to the electrode.

  In this method of manufacturing an electronic component, an antioxidant fluid is sprayed onto the molten solder attached to the terminal electrode of the electronic component, so that the momentum overcoming the surface tension of the molten solder is given to the solder, and the molten solder attached to the terminal electrode Excess parts are removed. Further, in this method of manufacturing an electronic component, when the electronic component is pulled up from the upper liquid level, an antioxidant fluid having a temperature equal to or higher than the melting point of the molten solder is sprayed on the electronic component near the upper liquid level. As a result, the temperature of the molten solder adhered to the terminal electrode is maintained and oxidation is prevented, so that a partial composition change of the molten solder is suppressed, and a uniform solder layer is formed on the surface of the terminal electrode. Can be formed.

  Moreover, it is preferable to use the solution which melt | dissolved the saturated fatty acid in the solvent as an antioxidant fluid. In this case, a protective film made of saturated fatty acid can be reliably formed on the surface of the solder layer after removing the excess portion.

  Further, it is preferable that the electronic component is pulled up substantially vertically from the liquid surface of the upper layer, and the antioxidant fluid is sprayed on the electronic component obliquely from above. In this case, the excess portion of the molten solder can be removed more reliably. Further, when a plurality of electronic components are continuously pulled up from the liquid level, it is possible to prevent the molten solder removed by the antioxidant fluid from adhering to the processed electronic components.

  Moreover, it is preferable to prepare a tank separately in a solder adhesion process and a solder removal process. In this case, it is possible to prevent the surface treatment liquid from being contaminated by the excess portion of the removed molten solder.

  Further, the same tank may be used in the solder attachment process and the solder removal process, and the temperature of the upper layer of the liquid put in these tanks may be maintained at a temperature equal to or higher than the melting point of the molten solder. Alternatively, the tank used in the solder removal step may contain only the surface treatment liquid maintained at a temperature equal to or higher than the melting point of the molten solder. In this case, the equipment used for carrying out the solder layer forming process is simplified, and the molten solder flow state adhered to the terminal electrode is maintained until just before the antioxidant fluid is sprayed. Can be removed.

  According to the present invention, a uniform solder layer can be formed on the surface of the terminal electrode.

It is a perspective view which shows an example of the electronic component manufactured using the manufacturing method of the electronic component which concerns on this invention. It is the II-II sectional view taken on the line in FIG. It is a figure which shows the structural example of the solder layer forming apparatus 21 used for the manufacturing method of the electronic component which concerns on this invention. It is sectional drawing of the board | substrate which fixes an electronic component. It is a figure which shows the solder adhesion process by a solder layer forming apparatus. It is a figure which shows the solder removal process by a solder layer forming apparatus. It is a figure which shows a washing | cleaning cooling process. FIG. 8 is a diagram showing a step subsequent to FIG. 7. It is a figure which shows an example of an element assembly substrate.

  Hereinafter, preferred embodiments of an electronic component manufacturing method according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a perspective view showing an example of an electronic component manufactured using the method for manufacturing an electronic component according to the present invention. 2 is a cross-sectional view taken along line II-II in FIG. The electronic component 1 shown in FIGS. 1 and 2 is a chip-type multilayer ceramic capacitor. The electronic component 1 has a substantially rectangular parallelepiped shape with a length of 2.0 mm, a width of 1.2 mm, and a depth of 1.2 mm, for example.

The electronic component 1 includes an element body 2 formed by laminating a plurality of dielectric layers 4 and a pair of terminal electrodes 3 and 3 formed so as to cover both ends of the element body 2. The element body 2 is formed by sintering a laminated body of ceramic green sheets including a dielectric ceramic such as a BaTiO ₃ system, a Ba (Ti, Zr) O ₃ system, or a (Ba, Ca) TiO ₃ system. Yes. In the element body 2, the dielectric layers 4 are integrated to such an extent that the mutual boundary cannot be visually recognized.

  As shown in FIG. 2, a first internal electrode 6 a and a second internal electrode 6 b are provided inside the element body 4. The first internal electrode 6a and the second internal electrode 6b are formed by, for example, patterning a conductive paste containing Cu on a ceramic green sheet by printing or the like, and sintering the pattern together with the ceramic green sheet. Yes.

  The first internal electrodes 6a and the second internal electrodes 6b are alternately arranged in the stacking direction so as to sandwich the dielectric layers 4 corresponding to at least one green sheet layer, and the end portions of the first internal electrodes 6a are The element body 2 extends to one end face 2 a, and the end portion of the second internal electrode 6 b extends to the other end face 2 b of the element body 2.

  The element body region sandwiched between the first internal electrode 6a and the second internal electrode 6b is a portion that substantially generates a capacitance in the electronic component 1. This element region is also a region where mechanical strain is generated by the electrostrictive effect. That is, when a voltage is applied between the first internal electrode 6a and the second internal electrode 6b, the element body region expands in the stacking direction of the element body 2 and connects the opposing side surfaces of the element body 2. Shrink in the direction.

  The terminal electrode 3 is composed of, for example, a base electrode layer 11 formed by baking with Cu as a main component and a Ni diffusion layer 12 formed so as to cover the base electrode layer 11. The base electrode layer 11 includes a first electrode layer 11a containing a metal component containing Cu and a glass component, and a second electrode layer 11b having a glass component content higher than that of the first electrode layer 11a. .

  The first electrode layer 11a and the second electrode layer 11b are formed using a conductive paste containing a metal component, a glass component, and at least one of a binder, a dispersant, and a solvent. The first electrode layer 11a contains about 2 to 15% by weight of a glass component with respect to the Cu particles. The second electrode layer 11b contains 1% by weight or less of a glass component with respect to the Cu particles. The second electrode layer 11b may not contain any glass component.

  A solder layer 13 is provided on the surface of the terminal electrode 3. This solder layer 13 is formed of, for example, Sn—Ag—Cu—Ni—Ge ternary lead-free solder. The ternary lead-free solder is composed mainly of Sn, for example, Ag of 1.0 wt% to 4.0 wt%, Cu of 0.1 wt% to 2.0 wt%, and Ni of 0.01 wt%. -1.0 wt%, Ge is contained 0.005 wt%-0.1 wt%. The Ni component in the ternary lead-free solder diffuses toward the base electrode layer 11 to form the Ni diffusion layer 12 described above. The melting point of the ternary lead-free solder in this embodiment is 217 ° C., for example.

  Then, the manufacturing method of the electronic component 1 mentioned above is demonstrated.

In manufacturing the electronic component 1, first, the element body 2 is formed (element body forming step). In this step, a ceramic green sheet to be the dielectric layer 4 is prepared. The ceramic green sheet is obtained by applying a ceramic slurry on a PET film using a doctor blade method or the like and drying it. The ceramic slurry can be obtained, for example, by adding a solvent and a plasticizer to a dielectric material mainly composed of BaTiO ₃ and mixing them.

  Next, an electrode pattern to be the internal electrodes 6a and 6b is formed on the ceramic green sheet by screen printing and dried. For screen printing of the electrode pattern, for example, an electrode paste in which a binder, a solvent, or the like is mixed with Cu powder is used. After forming the electrode pattern, the ceramic green sheets are laminated in a predetermined order to obtain a laminated body.

  Next, the obtained laminated body is cut to obtain a laminated chip. After chip formation, binder removal is performed by heat treatment. The heat treatment is preferably performed at 180 ° C. to 400 ° C. for 0.5 hours to 30 hours, for example. After the heat treatment, the laminated chip is baked at 800 ° C. to 1400 ° C. for about 0.5 hours to 8.0 hours. Further, the element body 2 is formed by chamfering by barrel polishing and forming the corners of the laminated chip into an R shape.

  After the element body 2 is formed, the base electrode layer 11 is formed (terminal electrode forming step). In forming the base electrode layer 11, for example, a conductor paste in which glass frit is added to a component containing a Cu paste for a conductor green sheet is used. Next, by immersing the end portion of the element body 2 in the conductor paste, the conductor paste to be the first electrode layer 11 a is attached so as to cover the end portion of the element body 2.

  Next, a conductive paste to be the second electrode layer 11b is applied to a predetermined thickness on the PET film and dried to form a conductive green sheet. Thereafter, the obtained conductor green sheet is cut into a desired size on the PET film, and the PET film is peeled off. Subsequently, the formed conductor green sheet is attached to the end surfaces 2 a and 2 b of the element body 2. At this time, the organic solvent contained in the conductor paste that becomes the first electrode layer 11a penetrates into the conductor green sheet that becomes the second electrode layer 11b, and dissolves the organic components remaining in the conductor green sheet. As a result, the conductor paste to be the first electrode layer 11a and the conductor green sheet to be the second electrode layer 11b are integrated. By drying and baking these, a laminated chip K (see FIG. 4) on which the base electrode layer 11 is formed is obtained.

  After the base electrode layer 11 is formed, the solder layer 13 is formed (solder layer forming step). In forming the solder layer 13, for example, a solder layer forming apparatus 21 as shown in FIG. 3 is used. The solder layer forming apparatus 21 includes a tank 22, a pump 23, and a pair of nozzles 24 and 24.

  The tank 22 is filled with two layers of liquid separated into an upper layer 26 made of a surface treatment liquid (antioxidation fluid) using saturated fatty acid and a lower layer 27 made of a molten solder liquid. Examples of saturated fatty acids used in the surface treatment liquid for the upper layer 26 include palmitic acid, stearic acid, oleic acid, myristic acid, lauric acid, and the like. The surface treatment liquid of the upper layer 26 is maintained at 240 ° C., for example, and is in a high temperature active state. Also, the molten solder solution of the lower layer 27 is a Sn-Ag-Cu-Ni-Ge ternary lead-free solder melt. The molten solder liquid of the lower layer 27 is maintained at 240 ° C., for example.

  The pump 23 is a high-temperature liquid pump. The pump 23 is controlled by a control unit (not shown) and supplies a part of the surface treatment liquid of the upper layer 26 to the nozzles 24 and 24. The nozzles 24, 24 are arranged toward the liquid level of the upper layer 26. The nozzles 24, 24 are supplied with the surface treatment liquid from the pump, and spray the surface treatment liquid obliquely from above toward substantially the same position on the liquid surface of the upper layer 26.

  The plurality of laminated chips K on which the base electrode layer 11 is formed are set in advance on the substrate 31 as shown in FIG. The substrate 31 has a main body portion 32 formed in a rectangular shape with, for example, metal, and the surface of the main body portion 32 is covered with a heat-resistant fluorine-based rubber 33. The main body 32 is provided with a plurality of holes 32a through which the element body 2 is passed, and the laminated chip K is fitted into each hole 32a.

  After setting the laminated chip K on the substrate 31, the substrate 31 is immersed in the tank 22 as shown in FIG. 5. When the substrate 31 passes through the upper layer 26 made of the surface treatment liquid, the surface of the base electrode layer 11 is cleaned and unnecessary oxides are removed by the high-temperature active action of the saturated fatty acid. When the substrate 31 that has passed through the upper layer 26 reaches the lower layer 27 further, molten solder adheres to the surface of the surface-treated base electrode layer 11 and the solder layer 13 is formed (solder attaching step).

  Next, as shown in FIG. 6, the substrate 31 is pulled up from the tank 22. When the substrate 31 reaches the upper layer 26 from the lower layer 27 again, the surface of the molten solder adhering to the base electrode layer 11 is coated with saturated fatty acid. Further, when the substrate 31 is pulled up from the liquid level 26 a of the upper layer 26, the pump 23 is operated to spray the surface treatment liquid from the tips of the nozzles 24, 24 toward the substrate 31 in the vicinity of the liquid level 26 a. In spraying, for example, the surface treatment liquid is heated to, for example, 250 ° C. by heating means (not shown) provided in the nozzles 24, 24. Then, spraying for about 10 seconds per time is performed about once to three times toward the molten solder adhering to the base electrode layer 11.

  Thereby, the momentum which overcomes the surface tension of the molten solder is given to the solder, and the excess portion of the solder adhering to the base electrode layer 11 is removed (solder removing step). The surface of the solder layer 13 after the excess portion of the solder is removed is kept coated with saturated fatty acids by the surface treatment liquid sprayed from the nozzles 24 and 24.

  After the substrate 31 is completely lifted from the tank 22, as shown in FIG. 7, the substrate 31 is immersed in a tank 28 filled with an absol cleaning liquid, and the solder layer 13 is cleaned and cooled (cleaning cooling process). When the molten solder is cooled and solidified, Ni diffuses between the base electrode layer 11 and the solder layer 13 due to the heat of the solder layer 13. As a result, the Ni diffusion layer 12 is formed between the base electrode layer 11 and the solder layer 13. After the solder layer 13 is cleaned and cooled, as shown in FIG. 8, when the element body 2 is removed from the hole 32a of the substrate 31, the electronic component 1 shown in FIGS. 1 and 2 is obtained.

  As described above, in this method of manufacturing an electronic component, the momentum that overcomes the surface tension of the molten solder is given to the solder by spraying an antioxidant fluid to the molten solder attached to the terminal electrode 3 of the electronic component 1, The excess portion of the molten solder adhering to the terminal electrode 3 is removed. In this electronic component manufacturing method, when the electronic component 1 is pulled up from the liquid level 26 a of the upper layer 26, an antioxidant fluid having a temperature equal to or higher than the melting point of the molten solder is sprayed on the electronic component 1 near the liquid level 26 a of the upper layer 26. ing. As a result, the temperature of the molten solder adhered to the terminal electrode 3 is maintained and oxidation is prevented, so that partial composition change of the molten solder is suppressed, and the surface of the terminal electrode 3 has a uniform shape. The solder layer 13 can be formed.

  In this method of manufacturing an electronic component, a solution in which a saturated fatty acid such as palmitic acid, stearic acid, oleic acid, myristic acid, lauric acid or the like is dissolved in a solvent is used as an antioxidant fluid sprayed on molten solder. Thereby, the protective film by a saturated fatty acid can be reliably formed by the surface of the solder layer 13 after removing the excess part.

  In this electronic component manufacturing method, the multilayer chip K is pulled up substantially vertically from the liquid level 26a of the upper layer 26, and an antioxidant fluid is sprayed on the multilayer chip K from obliquely above. Thereby, the excess part of molten solder is more reliably removed by its own weight. In the present embodiment, by using the substrate 31, the plurality of laminated chips K are continuously pulled up from the liquid level 26a. Therefore, it is possible to prevent the removed molten solder from adhering to the processed laminated chip K located above the liquid level 26a by spraying the antioxidant fluid on the laminated chip K obliquely from above. Further, since the unprocessed laminated chip K is located in the surface treatment liquid of the upper layer 26, it is possible to prevent the removed molten solder from adhering.

  In the present embodiment, the same tank 22 is used in the solder attaching process and the solder removing process, and the temperature of the upper layer 26 of the liquid in the tank 22 is maintained at a temperature equal to or higher than the melting point of the molten solder. . This simplifies the equipment used for carrying out the solder layer forming step and maintains the flow state of the molten solder adhering to the terminal electrode 3 until just before the antioxidant fluid is sprayed. Part can be removed.

The present invention is not limited to the above embodiment. For example, in the above-described embodiment, a chip-type multilayer ceramic capacitor is exemplified as the electronic component 1, but the manufacturing method of this electronic component can also be applied to other electronic components such as a chip varistor, a chip inductor, and a chip bead. In the above-described embodiment, the surface treatment liquid of the upper layer 26 is used as the antioxidant fluid, but an inert gas such as N ₂ may be used instead of the surface treatment liquid made of saturated fatty acid. In the above-described embodiment, the solder attachment process and the solder removal process are performed in the same tank 22, but separate tanks 22 may be prepared and the solder attachment process and the solder removal process may be performed. . In this case, it is possible to prevent the surface treatment liquid from being contaminated by the excess portion of the removed molten solder. At this time, if only the surface treatment liquid maintained at a temperature equal to or higher than the melting point of the molten solder is put in the tank 22 for performing the solder removal step, the liquid temperature can be easily managed, and the amount of the molten solder removed is suitably set. Can be controlled.

  In the above-described embodiment, the laminated chip K obtained by cutting the green sheet laminate is fixed to the substrate 31 and immersed in the tank 22. For example, an element assembly as shown in FIG. The substrate 31 may be immersed in the tank 22. The element assembly substrate 41 has a rectangular main body 42 corresponding to the element body 2, and, for example, three rows of strip-shaped grooves 43 are formed in the central portion of the main body 42. A terminal electrode 44 is formed on the inner wall of the groove portion 43 so as to extend in the thickness direction of the main body portion 42 and be folded back to the one surface side and the other surface side of the main body portion 42 along the extending direction of the groove portion 43. Several are arranged.

  Even when such an element assembly substrate 41 is used, the excess portion of the molten solder attached to the terminal electrode 44 is removed through the same solder attaching step and solder removing step as those in the above-described embodiment. In addition, since the temperature of the molten solder adhered to the terminal electrode 44 is maintained by the antioxidant fluid and oxidation is prevented, the partial composition change of the molten solder is suppressed, and the surface of the terminal electrode 44 is uniformly formed. A solder layer 13 having a proper shape can be formed. After forming the solder layer 13, as shown in FIG. 9, when the main body 42 is cut so as to include the terminal electrodes 44, 44 at the portion between the grooves 43, 43, the terminal electrodes 44 are formed at both ends of the element body. The obtained electronic component 1 is obtained.

  DESCRIPTION OF SYMBOLS 1 ... Electronic component, 3 ... Terminal electrode, 13 ... Solder layer, 26 ... Upper layer, 26a ... Liquid surface, 27 ... Lower layer.

Claims (6)

An electronic component manufacturing method comprising a solder layer forming step of forming a solder layer on a surface of a terminal electrode formed on an electronic component,
The solder layer forming step includes
The electronic component is immersed in a tank containing two layers of liquid separated into an upper layer made of a surface treatment solution using saturated fatty acid and a lower layer made of a molten solder solution, and melted so as to cover the terminal electrode of the electronic component. A solder attachment process for attaching solder;
When the electronic component is pulled up from the liquid level of the upper layer, an excess of the molten solder adhering to the terminal electrode is sprayed on the electronic component located on the liquid level by spraying an antioxidant fluid having a temperature equal to or higher than the melting point of the molten solder. A method of manufacturing an electronic component, comprising: a solder removal step of removing a portion.   2. The method of manufacturing an electronic component according to claim 1, wherein a solution obtained by dissolving the saturated fatty acid in a solvent is used as the antioxidant fluid.   3. The method of manufacturing an electronic component according to claim 1, wherein the electronic component is pulled up substantially vertically from the liquid surface of the upper layer, and the antioxidant fluid is sprayed obliquely from above the electronic component. The tank is prepared separately in the solder adhesion step and the solder removal step ,
The said tank for performing the said solder adhesion process puts the said 2 layer liquid, and puts only the said surface treatment liquid in the said tank for performing the said solder removal process of Claims 1-3 characterized by the above-mentioned . The manufacturing method of the electronic component as described in any one of Claims.   2. The same tank is used in the solder attaching step and the solder removing step, and the temperature of the upper layer of the liquid put in these tanks is maintained at a temperature equal to or higher than the melting point of the molten solder. The manufacturing method of the electronic component as described in any one of -3. 5. The method of manufacturing an electronic component according to claim 4, wherein only the surface treatment liquid maintained at a temperature equal to or higher than the melting point of the molten solder is placed in a tank used in the solder removal step.

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