JP5286558B2 - Electronic component, electronic device, and method of manufacturing electronic component - Google Patents

Description

  The present invention relates to an electronic component, an electronic device, and a method for manufacturing the electronic component.

  Since lead (Pb) has toxicity, it causes problems such as contamination of groundwater. For this reason, the movement which restricts the use of Pb for electrical and electronic products is intensifying worldwide.

Correspondingly, as a film provided on an external electrode of an electronic component used in an electric / electronic product, replacement of a film containing lead with a film containing no lead is progressing. Specifically, the Sn (tin) -Pb-based plating film is replaced with a Sn plating film or a plating film that does not contain Pb and has a Sn group (Sn-based alloy plating). Examples of the plating film having a Sn group and not containing Pb include a Sn-Bi (bismuth) system and a Sn-Ag (silver) system (see, for example, Patent Document 1). These films ensure the solderability of electronic components.
JP 2002-161396 A

  However, the above-described Sn plating film or Sn-based alloy plating film not containing Pb has a problem that whiskers are easily generated. This is because Pb having an effect of suppressing the generation of whiskers is not contained. In particular, whiskers are likely to occur in the Sn plating film.

  The whisker is obtained by recrystallizing Sn and growing in a needle shape. Whisker may grow to a length of a few millimeters in some cases and may cause an electrical short circuit. For this reason, when the electronic component which is easy to generate | occur | produce as mentioned above is used for an electronic device, the short circuit by a whisker might arise in the electronic device.

  The present invention has been made to solve the above-described problems, and is capable of preventing the occurrence of whiskers while ensuring solderability, and an electronic component, an electronic device, and an electronic component manufacturing method The purpose is to provide.

The electronic component of the present invention has a main body, an external electrode, a coating film, and a first film. The external electrode protrudes from the main body. The coating film covers the base of the external electrode. The first film covers at least a part of the external electrode and contains an imidazole compound. The coating film is made of resin, and the resin is either paraffin or silicone.

  The electronic device of the present invention includes an electronic component, a solder part, and a circuit part. The electronic component has a main body, an external electrode, and a first film. The external electrode protrudes from the main body. The first film covers at least a part of the external electrode and contains an imidazole compound. At least a part of the external electrode has a surface to be soldered. The solder part is provided on this surface. The circuit part is electrically connected to the electronic component via the solder part.

  The manufacturing method of the electronic component of this invention is a manufacturing method of the electronic component which has a main-body part and the external electrode which protrudes from a main-body part, Comprising: It has the following processes.

A treatment liquid containing an imidazole compound is prepared. A coating film covering the base of the external electrode is formed. The coating film is made of resin, and the resin is either paraffin or silicone. At least a part of the external electrode is immersed in the processing liquid. By removing the external electrode from the treatment liquid, a film covering at least a part of the external electrode and containing the imidazole compound is formed.

  According to the present invention, the first film containing the imidazole compound covers at least a part of the external electrode, thereby ensuring solderability. Moreover, since it is not necessary for the first film to contain Sn, it is possible to prevent the generation of whiskers due to Sn.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 is a plan view schematically showing a configuration of an electronic component according to Embodiment 1 of the present invention. FIG. 2 is a schematic cross-sectional view taken along line II-II in FIG.

  With reference to FIG. 1 and FIG. 2, the electronic component of this Embodiment has the mold part 1, the lead 2, and the antirust film | membrane 4 (1st film | membrane).

  The mold part 1 is a main body part of an electronic component, and has, for example, a semiconductor element and a resin part that seals the semiconductor element. The resin portion is made of, for example, an epoxy resin.

  The lead 2 is an external electrode protruding from the mold part 1. The electronic component of the present embodiment can be mounted by soldering the surface of the tip of the lead 2 to a substrate (not shown) or the like. The lead 2 is made of copper (Cu) or a copper alloy. The copper alloy is, for example, a Cu-based alloy such as Cu—Sn, Cu—Zn, or Cu—Fe.

  The rust preventive film 4 covers a part of the lead 2. The rust preventive film 4 is an organic rust preventive film mainly composed of an imidazole compound. An imidazole compound is a compound containing an imidazole group which is a nitrogen-containing aromatic heterocyclic ring containing a nitrogen atom at the 1- and 3-positions on a 5-membered ring.

  Preferably, as the imidazole compound, an alkyl imidazole compound, an aryl imidazole compound, an aralkyl imidazole compound, an alkyl benzimidazole compound, an aryl benzimidazole compound, or an aralkyl benzimidazole compound is used.

  Preferably, the rust prevention film 4 is provided with a space SP between the rust prevention film 4 and the mold part 1. More preferably, the interval SP is 0.1 mm or more.

  Next, an electronic component mounting method according to the present embodiment will be described. First, the lead 2 covered with the antirust coating 4 is inserted into a through hole (not shown) of the substrate. Then, post flux is applied to the portions of the lead 2 and the through holes where soldering is performed. The rust preventive film 4 that has come into contact with the post flux is removed from the lead 2. After that, mounting is performed by soldering.

  Next, a method for forming the rust preventive film 4 of the electronic component of the present embodiment will be described. 3 and 4 are diagrams schematically showing first and second steps of the electronic component manufacturing method according to Embodiment 1 of the present invention.

  With reference to FIG. 3, first, an electronic component having a mold part 1 and leads 2 and an antirust treatment liquid 3 stored in a container 30 are prepared. The antirust treatment liquid 3 contains an imidazole compound. Specifically, the rust prevention liquid 3 is composed of, for example, an imidazole compound and a carboxylic acid.

  Referring mainly to FIG. 4, a part of the lead 2 is immersed in the antirust treatment liquid 3 for a predetermined time. This immersion is performed so that the mold part 1 does not contact the antirust treatment liquid 3. For this reason, the immersion is performed so that the liquid surface of the antirust treatment liquid 3 does not wave. The immersion is performed so that the rust preventive liquid 3 does not contact the vicinity of the root of the lead 2. For this reason, preferably, the distance SP between the mold part 1 and the rust preventive liquid 3 is set to 0.1 mm or more.

  Next, the lead 2 is taken out from the antirust treatment liquid 3. As a result, the antirust treatment liquid 3 is applied onto the lead 2. Next, the applied antirust treatment liquid 3 is dried. Thereby, a part of the lead 2 is covered and a rust preventive film 4 (FIG. 2) containing an imidazole compound is formed.

  According to the present embodiment, the rust preventive film 4 containing an imidazole compound covers a part of the lead 2, thereby preventing an oxide film (rust) from being generated on the lead 2. Thereby, the wettability of the solder of the lead 2 is ensured. Therefore, the solderability of the lead 2 is ensured.

  Moreover, since it is not necessary for a rust preventive film to contain Sn, generation | occurrence | production of the whisker resulting from Sn can be prevented.

  Moreover, the antirust treatment liquid 3 contains an imidazole compound. Thereby, the antirust treatment liquid 3 has excellent film forming properties. Also, as a result, the antirust treatment liquid 3 forms a complex and selectively forms an organic film only on the copper surface, so that a film can be selectively formed on the lead 2.

  Moreover, since the mold part 1 of the electronic component is not immersed in the rust preventive liquid 3 when the rust preventive film 4 is formed, it is possible to prevent the rust preventive liquid 3 from entering between the mold part 1 and the lead 2. Accordingly, it is possible to prevent the corrosion of the circuit, the short circuit due to ion migration, and the like from occurring inside the mold part 1 due to the penetration of the rust preventive liquid 3. Therefore, the reliability of the electronic component can be improved.

  Further, when the interval SP (FIG. 4) is set to 0.1 mm or more, the intrusion of the rust prevention liquid 3 can be more reliably prevented.

  Moreover, the penetration | invasion of said rust prevention liquid 3 can be prevented more reliably by making the rust prevention liquid 3 not ripple during immersion shown in FIG.

  Referring to FIG. 2, since soldering is not performed on the portion corresponding to the interval SP of the leads 2, there is no problem in solderability even if the rust preventive film 4 is not formed on this portion.

  Moreover, in this Embodiment, the penetration | invasion of the antirust process liquid 3 to the mold part 1 was prevented by controlling so that the liquid surface of the antirust process liquid 3 may not be waved, but this invention is limited to this is not. For example, if a resin film or a water-repellent film that is difficult to dissolve in the antirust treatment liquid 3 is formed in the vicinity of the root of the lead 2 before dipping, the intrusion of the antirust treatment liquid 3 can be prevented. As a material of such a film, for example, paraffin or silicone can be used.

(Embodiment 2)
FIG. 5 is a cross-sectional view schematically showing the configuration of the electronic device according to the second embodiment of the present invention. Referring to FIG. 5, the electronic device according to the present embodiment includes the electronic component according to the first embodiment, solder part 5, and circuit part 60.

  The circuit unit 60 includes a base 61, wiring 62, and through-hole electrodes 6. The through hole electrode 6 has a through hole 7.

  The material of the base material 61 is an insulator. This insulator is, for example, a glass cloth impregnated with an epoxy resin, or a paper base material or a polyester base material impregnated with an epoxy resin or a phenol resin.

  The solder portion 5 is provided so as to connect the surface of the tip portion of the lead 2 and the inner surface of the through hole 7. As a result, the solder part 5 electrically connects the lead 2 and the through-hole electrode 6. The solder portion 5 is, for example, Sn—Cu, Sn—Ag, or Sn—Zn. Specifically, the material of the solder part 5 has, for example, a Sn-3.0Ag-0.5Cu composition.

  Next, a method for manufacturing the electronic device of this embodiment will be described. First, the electronic component of Embodiment 1 is prepared. Next, the lead 2 covered with the antirust coating 4 is inserted into the through hole 7. Next, post flux is applied. Next, for example, solder melted by being heated to 225 ° C. or higher is supplied to the through hole 7. Thereby, the electronic apparatus of this Embodiment is obtained.

  According to the present embodiment, since the color of the lead 2 covered with the rust preventive coating 4 is light red and the color of the solder portion 5 is silver white, the rising state of the solder in the through hole 7 is visually observed. Easy to confirm. Therefore, the inspection property in the manufacture of electronic equipment can be improved.

  Moreover, since the rust preventive film 4 reacts with the post flux and is removed by flow, the composition of the solder portion 5 is prevented from being changed by the rust preventive film 4. Therefore, it is possible to obtain the solder part 5 having the mechanical characteristics as designed.

(Embodiment 3)
FIG. 6 is a cross-sectional view schematically showing the configuration of the electronic component according to Embodiment 3 of the present invention.

  Referring to FIG. 6, the electronic component of the present embodiment has a mold portion 1V instead of mold portion 1 (FIG. 1). In addition to the structure which the mold part 1 has, the mold part 1V further has the metal part 8 and the antirust coating 9. FIG.

  The material of the metal part 8 is copper or a copper alloy. As the copper alloy, for example, a Cu-based alloy such as Cu—Sn, Cu—Zn, or Cu—Fe can be used.

  Moreover, the metal part 8 is a heat sink, for example. This heat radiating plate and the electronic circuit inside the mold part 1 are insulated by the resin part of the mold part 1. Further, the heat radiating plate has a function of making it easy to transfer the heat inside the mold part 1 to an external member or to radiate the heat to the outside. Specifically, this heat radiating plate is a metal plate affixed on the surface of the resin part of the mold part 1, for example.

  The rust preventive film 9 covers the metal part 8. The material of the rust preventive film 9 is the same as that of the rust preventive film 4 (FIG. 1).

  Since the configuration other than the above is substantially the same as the configuration of the first embodiment described above, the same or corresponding elements are denoted by the same reference numerals, and description thereof is not repeated.

  According to the present embodiment, the rust preventive film 9 prevents the metal part 8 from being oxidized. This prevents the metal part 8 from being oxidized while the electronic component is stored in the atmosphere or while the electronic component is heated for a short time for mounting on the substrate.

  Moreover, when the metal part 8 is a heat sink, it can prevent that a heat sink is oxidized when an electronic component is mounted in a board | substrate. Therefore, when a heat radiating body such as a heat sink is connected to the heat radiating plate after mounting the electronic component, it is possible to prevent the connection thermal resistance from increasing due to the oxidized portion.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention can be applied particularly advantageously to electronic components, electronic devices, and methods for manufacturing electronic components.

It is a top view which shows roughly the structure of the electronic component in Embodiment 1 of this invention. It is a schematic sectional drawing in alignment with line II-II of FIG. It is a figure which shows schematically the 1st process of the manufacturing method of the electronic component in Embodiment 1 of this invention. It is a figure which shows schematically the 2nd process of the manufacturing method of the electronic component in Embodiment 1 of this invention. It is sectional drawing which shows schematically the structure of the electronic device in Embodiment 2 of this invention. It is sectional drawing which shows roughly the structure of the electronic component in Embodiment 3 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Mold part, 2 lead | read | reed, 3 rust prevention liquid, 4 rust preventive film, 5 solder part, 6 through-hole electrode, 7 through hole, 8 metal part, 9 rust preventive film.

Claims (9)

The main body,
An external electrode protruding from the main body,
A coating film covering the base of the external electrode;
Covering at least a portion of the external electrode, and comprising a first film containing an imidazole compound ,
The coating film is made of a resin, and the resin is one of paraffin and silicone . The electronic component according to claim 1, wherein the at least part of the external electrode is made of one of copper and a copper alloy. Wherein the body portion includes a resin portion, the electronic component according to claim 1 or 2. Said first coating, said are spaced between the body portion, the electronic component according to any one of claims 1-3. The main body includes a metal part,
The metal portion covers, and further comprising a second coating containing an imidazole compound, an electronic component according to any one of claims 1-4. The electronic component according to claim 5 , wherein at least a part of the metal part is made of one of copper and a copper alloy. The electronic component according to any one of claims 1 to 6 , wherein the at least part of the external electrode has a surface to be soldered, and further, a solder portion provided on the surface;
An electronic apparatus comprising: a circuit unit electrically connected to the electronic component through the solder unit. A method of manufacturing an electronic component comprising a main body and an external electrode protruding from the main body,
Preparing a treatment liquid containing an imidazole compound;
And forming a coating film covering the base of the outer electrode, the coating film is made of resin, the resin is either paraffin and silicone, after the step of further forming the coating film Immersing at least a part of the external electrode in the treatment liquid;
And a step of covering the at least part of the external electrode and forming a film containing an imidazole compound by removing the external electrode from the treatment liquid. The method of manufacturing an electronic component according to claim 8 , wherein the soaking step is performed so that the main body portion does not come into contact with the processing liquid.

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