JP6561453B2 - Method for manufacturing electronic circuit module component - Google Patents

Description

  The present invention relates to an electronic circuit module component.

  Electronic circuit module components manufactured by mounting electronic components such as passive elements on a substrate are used by being mounted on a substrate of an electronic device. Pb-free solder containing no Pb (lead) is known as a solder used for joining electronic components in electronic circuit module components and mounting electronic circuit module components.

  When the electronic circuit module component is mounted on the board of the electronic device, reflow for melting the solder is performed. In this reflow, various studies have been made in order to prevent the solder joining the electronic component in the electronic circuit module component and the substrate from being melted and scattered or the solder moving (for example, Patent Document 1).

JP 2007-268568 A

  However, even when bonding is performed using the solder described in Patent Document 1, there is a problem that the scattering and movement of the solder cannot be completely suppressed. Further improvements are also required from the viewpoint of durability.

  The present invention has been made in view of the above, and an object of the present invention is to provide an electronic circuit module component in which breakage of the bonding metal when reheated in the manufacturing process is prevented.

  To achieve the above object, an electronic circuit module component according to the present invention includes an electronic component, a circuit board on which the electronic component is mounted, and a terminal electrode of the electronic component and a terminal electrode of the circuit board. And an Sn alloy phase, a Ni—Sn alloy phase that is dispersed between the Sn alloy phases and contains at least Fe, and a plurality of holes having a diameter of 5 μm or less formed inside the Ni—Sn alloy phase And a center distance between the adjacent hole portions is 10 μm or more.

  According to the above electronic circuit module component, since the joining metal is formed including the Ni—Sn alloy phase having a melting point higher than that of the Sn alloy phase, remelting of the joining metal is prevented even when reheated. The In addition, since the Ni—Sn alloy phase harder than the Sn phase is dispersed and formed between the Sn alloy phases, even if cracks or the like occur in the bonding metal, the progress is suppressed. Is prevented from being damaged. Furthermore, since a hole of 5 μm or less is provided inside the Ni—Sn alloy phase, even if cracks occur in the Ni—Sn alloy phase, the progress can be suppressed, so that durability Will improve.

  Here, the bonding metal may further include a Bi alloy phase. By further including a Bi alloy phase harder than the Ni—Sn alloy phase, durability against cracks and the like is further improved.

  The Bi alloy phase may have an equivalent diameter of 3 μm or less. When the equivalent diameter of the Bi alloy phase is 3 μm or less, it is possible to prevent a decrease in durability of the entire bonded metal due to segregation of the Bi alloy phase.

  Moreover, it can be set as the aspect which contains a Ni-Fe alloy phase in the area | region where the center distance was separated from the hole part by 10 micrometers or more. As described above, when the Ni—Fe alloy phase is included, a large number of regions having different hardnesses are formed, so that the progress of cracks can be suppressed as a whole of the bonded metal, thereby improving durability.

  ADVANTAGE OF THE INVENTION According to this invention, when the reheating is carried out in a manufacturing process, the electronic circuit module component by which damage of the joining metal was prevented is provided.

It is sectional drawing of an electronic circuit module component. It is a side view which shows the state which attached the electronic circuit module component to substrates, such as an electronic device. It is a key map of Pb free solder concerning this embodiment. It is a key map of Pb free solder concerning this embodiment. The structure of the 1st solder after hardening is shown typically. The structure of the 1st solder after hardening is shown typically. It is a figure which shows the change of the solid-phase temperature at the time of changing the addition amount of Bi with respect to the sum of Sn and Bi, and liquid phase temperature.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a cross-sectional view of an electronic circuit module component. FIG. 2 is a side view showing a state in which the electronic circuit module component is attached to a substrate such as an electronic device. As shown in FIG. 1, the electronic circuit module component 1 is a module having a group of functions in which a plurality of electronic components 2 are mounted on a substrate 3. The electronic component 2 may be mounted on the surface of the substrate 3 or may be mounted inside the substrate 3. In the present embodiment, the electronic component 2 constituting the electronic circuit module component 1 includes, for example, a passive element such as a coil, a capacitor, or a resistor, but an active element such as a diode or a transistor, an IC (Integral Circuit), or the like can also be used. The electronic component 2 may be mounted on the surface of the substrate 3 or inside the substrate 3. Moreover, the electronic component 2 is not limited to these.

  As shown in FIG. 1, an electronic circuit module component 1 includes a substrate 3 that is a circuit board on which the electronic component 2 is mounted, an insulating resin 4 that covers the electronic component 2, and a shield layer 5 that covers the surface of the insulating resin 4. And comprising. The electronic circuit module component 1 may not have the shield layer 5. The terminal electrode of the electronic component 2 and the terminal electrode of the substrate 3 are joined by Pb-free solder (hereinafter referred to as first solder) 6A according to this embodiment. As a result, the electronic component 2 is mounted on the substrate 3. As described above, the first solder 6 </ b> A serves as a bonding metal interposed between the terminal electrode of the electronic component 2 and the terminal electrode of the substrate 3.

  As shown in FIG. 1, in the electronic circuit module component 1, the electronic component 2 mounted on the substrate 3 is covered with an insulating resin 4. In the electronic circuit module component 1, the surface of the substrate 3 on which the electronic component 2 is mounted (referred to as a component mounting surface) is simultaneously covered with the insulating resin 4. As described above, the electronic circuit module component 1 covers the plurality of electronic components 2 and the component mounting surface with the insulating resin 4, thereby integrating the substrate 3 and the plurality of electronic components 2 and securing the strength.

  A shield layer 5 is formed on the surface of the insulating resin 4 covering the plurality of electronic components 2. As the insulating resin 4, a thermosetting resin such as an epoxy resin can be used, but the insulating resin 4 is not limited to this. In addition, additives such as fillers may be included.

  In the present embodiment, the shield layer 5 is made of a conductive material (a material having conductivity, which is a metal in the present embodiment). In the present embodiment, the shield layer 5 may be composed of a single conductive material or may be composed of a plurality of conductive material layers. The shield layer 5 covers the surface of the insulating resin 4 to shield the electronic component 2 enclosed in the insulating resin 4 from high-frequency noise or electromagnetic waves from the outside of the electronic circuit module component 1, High frequency noise radiated from 2 is shielded. Thus, the shield layer 5 functions as an electromagnetic shield. In the present embodiment, the shield layer 5 covers the entire surface of the insulating resin 4. The shield layer 5 may be coated with the insulating resin 4 so as to exhibit a necessary function as an electromagnetic shield, and does not necessarily need to cover the entire surface of the insulating resin 4. Therefore, the shield layer 5 only needs to cover at least a part of the surface of the insulating resin 4.

  In addition, the electronic circuit module component 1 does not need to provide the shield layer 5. In this case, the region corresponding to the shield layer 5 of the electronic circuit module component 1 is also covered with the insulating resin 4.

The electronic circuit module component 1 is manufactured by the following procedure, for example.
(1) A solder paste containing the first solder 6 </ b> A is printed on the terminal electrode of the substrate 3.
(2) The electronic component 2 is mounted on the substrate 3 using a mounting device (mounter).
(3) When the substrate 3 on which the electronic component 2 is mounted is placed in a reflow furnace and the solder paste is heated, the first solder 6A contained in the solder paste is melted and hardened, whereby the terminal electrode of the electronic component 2 The terminal electrode of the board | substrate 3 is joined (reflow process).
(4) The flux adhering to the surface of the electronic component 2 or the substrate 3 is washed.
(5) Covering the electronic component 2 and the substrate 3 with the insulating resin 4 (molding process).

  Among the above procedures, in the reflow process, generally, the first solder 6A included in the solder paste is melted and hardened so that the maximum temperature of the reflow furnace is about 240 ° C to 260 ° C. The molding process is appropriately changed depending on the material of the insulating resin 4 and the like. For example, the insulating resin 4 is cured by heating at 175 ° C. for 4 hours.

  The substrate 3 has terminal electrodes (module terminal electrodes) 7 on the side opposite to the component mounting surface. The module terminal electrode 7 is electrically connected to the electronic component 2 included in the electronic circuit module component 1 and, as shown in FIG. 2, a substrate (for example, a substrate of an electronic device) to which the electronic circuit module component 1 is attached. The terminal electrode (device substrate terminal electrode) 9 of the device substrate 8) and the solder (hereinafter referred to as second solder) 6B. As a result, the electronic circuit module component 1 exchanges electrical signals and power between the electronic component 2 and the device substrate 8.

  A device substrate 8 shown in FIG. 2 is a substrate on which the electronic circuit module component 1 is mounted. For example, the device substrate 8 is mounted on an electronic device (such as an in-vehicle electronic device or a portable electronic device). When the electronic circuit module component 1 is mounted on the device substrate 8, for example, a solder paste containing the second solder 6B is printed on the device substrate terminal electrode 9, and the electronic circuit module component 1 is mounted on the device substrate 8 using the mounting device. To do. Then, by putting the device substrate 8 on which the electronic circuit module component 1 is mounted in a reflow furnace and heating the solder paste, the second solder 6B contained in the solder paste is melted and hardened, whereby the module terminal electrode 7 and The device substrate terminal electrode 9 is joined. Thereafter, the flux adhering to the surfaces of the electronic circuit module component 1 and the device substrate 8 is washed.

  Generally, the melting temperature of Pb-free solder used for manufacturing electronic circuit module components is about 220 ° C., whereas the maximum temperature during reflow is about 240 ° C. to 260 ° C. The first solder 6A used when the electronic component 2 constituting the electronic circuit module component 1 is mounted on the substrate 3 is reflowed when the electronic circuit module component 1 is mounted on the device substrate 8 as described above. Therefore, solder that does not melt at this reflow temperature (high temperature solder) is used.

  Among the solders using Pb, there is a solder having a melting temperature of about 300 ° C., but there is no Pb-free solder having a melting temperature of 260 ° C. or more and appropriate characteristics. For this reason, when Pb-free solder is used, the solder (first solder 6A) used for joining the electronic component 2 constituting the electronic circuit module component 1 and the solder used when the electronic circuit module component 1 is mounted on the device substrate 8 For the (second solder 6B), one having a small difference in melting temperature between them must be used.

  When the solder used for joining the electronic components 2 constituting the electronic circuit module component 1 is remelted during reflow, problems such as movement of the first solder 6A and solder flash (solder scattering) occur. As a result, there is a risk of causing a short circuit or poor contact of the electronic component 2. For this reason, the solder that joins the electronic component 2 of the electronic circuit module component 1 does not remelt during reflow when the electronic circuit module component 1 is mounted, or remelting may cause movement of the first solder 6A or solder flash. It is desirable to use a material that does not invite There are conductive adhesives (Ag paste, etc.) as an alternative to solder with a high melting temperature, but there are problems such as low mechanical strength, high electrical resistance, and high cost, and it is not a substitute for solder. . The first solder 6A used for joining the electronic component 2 constituting the electronic circuit module component 1 of the present embodiment is a Pb-free solder that satisfies such a requirement.

  3 and 4 are conceptual diagrams of Pb-free solder according to the present embodiment. The Pb-free solder according to this embodiment, that is, the first solder 6A, before use (before melting), the first metal 61 containing at least Sn (tin) and Bi (bismuth), and at least Ni (nickel) -Fe And a second metal 62 including an (iron) alloy. The first solder 6A shown in FIG. 3 is obtained by dispersing a granular first metal 61 and a granular second metal 62 in a paste material PE to form a solder paste. The first solder 6A shown in FIG. 4 has a second metal 62 as a core and the outside is covered with a first metal 61 to form a wire-like solder. As described above, the first solder 6A may be in a state in which the first metal 61 containing at least Sn and Bi and the second metal 62 containing at least a Ni—Fe alloy can be mixed at the time of melting before melting. .

  The first metal 61 includes at least Sn and Bi, but the first solder 6A is Pb-free solder, and thus does not include Pb. The first metal 61 may include at least one of Ag (silver) and Cu (copper). The second metal 62 includes at least a Ni—Fe alloy. That is, the second metal 62 is essentially a Ni—Fe alloy, and may contain at least one of Co (cobalt), Mo (molybdenum), Cu (copper), and Cr (chromium).

  In the present embodiment, so-called SnBi solder (Pb-free solder) is used as the first metal 61. In the first metal 61, the sum of Sn and Bi is 90% by mass or more, and Bi is 5% by mass or more and 15% by mass or less. In such a solder, the Sn phase occupies most of the structure after reflow, and therefore the Sn phase remelts when reflowed a plurality of times. For this reason, in the present embodiment, a second metal 62 containing at least a Ni—Fe alloy is added to the first metal 61 as a metal that easily forms a compound with Sn during reflow. That is, a Ni—Fe alloy is added to the first metal 61 containing Sn and Bi. Accordingly, when the first solder 6A is first melted, Sn contained in the first metal 61 reacts with Ni—Fe of the second metal 62, and when the first solder 6A is cured, the heat resistance is high. Create an organization. For example, even when the first solder 6A is heated by reflow or the like again, remelting of the first solder 6A is suppressed.

  5 and 6 schematically show the bonding metal formed by curing the first solder 6A. FIG. 5 shows that the Bi addition amount in the first metal 61 before curing is 7.5 mass%, and FIG. 6 shows that the Bi addition amount in the first metal 61 before curing is 12.5 mass%. Is. As shown in FIGS. 5 and 6, in the joining metal formed by hardening the first solder 6 </ b> A, the Bi phase 72 (Bi alloy phase) is contained in the Sn phase 71 (Sn alloy phase) derived from the first metal 61. It is dispersed and precipitated. Further, the Ni—Sn phase 74 (Ni—) in which Sn derived from the first metal 61 and Ni derived from the second metal 62 are reacted around the Ni—Fe phase 73 (Ni—Fe alloy phase) derived from the second metal 62. Sn alloy phase) is formed. The Ni—Sn phase 74 includes Fe derived from Ni—Fe contained in the second metal 62. That is, the Ni—Sn phase 74 includes at least Fe.

  In the region where the reaction between Ni and Sn has progressed, the portion where the Ni—Fe phase 73 on the inside of the Ni—Sn phase 74 is located becomes a hole 75 formed by a void and is formed in the first solder 6A after curing. A plurality are formed. It is considered that the hole 75 was formed by scattering of the material constituting the Ni—Fe phase by heating along with the progress of the reaction between Ni and Sn. The hole 75 formed inside the Ni—Sn phase 74 is substantially spherical and has a diameter of 5 μm or less in a sectional view. Even if a crack occurs in the Ni—Sn phase 74, the Ni—Sn phase 74 is sufficiently harder than the Sn phase 71 when the hole 75 having a diameter of 5 μm or less is provided in the Ni—Sn phase 74. Therefore, the progress of the crack can be suppressed by reaching the hole 75 formed by the gap. On the other hand, when the hole 75 is larger than 5 μm, the hole 75 itself may affect the durability of the bonding metal.

  Further, the adjacent hole portions 75 have a center distance of 10 μm or more in a sectional view. The center distance refers to the distance between the centers of adjacent hole portions 75. If the center distance between the adjacent hole portions 75 is smaller than 10 μm, the adjacent hole portions may be interlocked with each other when a crack or the like is generated.

  When the hole 75 is not formed in the Ni—Sn phase 74, the Ni—Fe phase 73 remains in the Ni—Sn phase 74. The Ni—Fe phase 73 is substantially spherical and has a diameter of 5 μm or less in a sectional view. Further, the hole 75 and the Ni—Fe phase 73 have a center distance of 10 μm or more in a sectional view.

  Further, when the addition amount of Bi is increased, as shown in FIG. 6, the size of the Ni—Sn phase 74 formed around the Ni—Fe phase 73 is reduced, and the Ni phase in the Sn phase 71 is reduced. -The Sn phase 74 is dispersed. Further, the Bi phase 72 is formed around the Ni-Sn phase 74 when the amount of Bi added is small (FIG. 5), whereas when the amount of Bi added increases (FIG. 6), the Sn phase 71. The Bi phase 72 may be composed of Bi alone, or may be composed of, for example, a Bi—Sn alloy. The Bi phase 72 preferably has an equivalent diameter of 3 μm or less. The equivalent diameter is 4 × A / C when the area of the Bi phase 72 is A and the peripheral length is C in a sectional view. When the equivalent diameter of the Bi phase 72 is larger than 3 μm, cracks may easily progress due to the hard and brittle nature of the Bi phase 72 Bi itself.

  Thus, in the hardened first solder 6A (joining metal), the Ni—Sn phase 74 is dispersed in the Sn phase 71 derived from the first metal 61, and the hole is formed inside the Ni—Sn phase. 75 is formed. Since the Ni—Sn phase 74 obtained by the reaction of Ni and Sn has a melting point higher than 400 ° C., it is prevented from being remelted during reflow of the second solder 6B. The Sn-phase 71 having a low melting point also exists around the Ni-Sn phase 74, but the formation of the Ni-Sn phase 74 suppresses the scattering and movement of solder due to the melting of the Sn phase 71. The

  In addition, since the Ni—Sn phase 74 harder than the Sn phase 71 is dispersed in the Sn phase 71, the occurrence of solder cracks in the first solder 6A can be prevented. Even if the first solder 6A after being cured is subjected to some impact or the like and a crack is generated in a part thereof, the same phase spreads because the Ni—Sn phase 74 is dispersed in the Sn phase 71. Compared to the case, it is possible to prevent the crack from becoming large. The effect of preventing the occurrence of solder cracks is particularly improved when the Ni—Sn phase 74 is less biased and dispersed in the Sn phase 71 as shown in FIG. Further, in the first solder 6A after curing, the Bi phase 72 that is harder than the Sn phase 71 is also dispersed in the Sn phase 71, so that different phases dispersed in the Sn phase 71 increase, and therefore, solder cracks are generated. The effect concerning prevention is improved, and a highly durable electronic circuit module component is obtained.

  In the solder containing Bi like the first metal 61, the liquid phase temperature and the solid phase temperature change depending on the amount of Bi added. FIG. 7 shows the change in the solid phase temperature as a solidus line and the change in the liquid phase temperature as a liquidus line when the amount of Bi added is changed with respect to the sum of Sn and Bi. . As shown in FIG. 7, when Bi is added in an amount of 5% by mass or more, the solid phase temperature is lowered, so that the reaction between Ni and Sn can be promoted at a lower temperature. Therefore, for example, in the molding process in which the electronic component 2 and the substrate 3 are covered with the insulating resin 4 after the first solder 6A is cured, the reaction between Ni and Sn can be promoted, so the reaction between Ni and Sn. There is no need to separately provide a heating step or the like for promoting the above.

  As shown in FIG. 7, if the amount of Bi added exceeds 15% by mass, the solid phase temperature falls to the eutectic temperature (about 139 ° C.). One solder may be remelted. Moreover, when the addition amount of Bi exceeds 15 mass%, in the 1st solder 6A after hardening, the segregation amount of Bi may become large. Since the hardness of Bi is higher than that of the solder phase mainly composed of Sn, if the amount of Bi segregation increases in the first solder 6A after hardening, cracks are likely to proceed due to the hard and brittle nature of Bi itself. There is.

  Furthermore, in this embodiment, the 2nd metal 62 containing the Ni-Fe alloy which is easy to react with Sn is added to the 1st metal 61 containing Sn and Bi. Thereby, the reaction between Sn and the Ni—Fe alloy can be rapidly advanced in a short time required for reflow.

  In order to raise the melting point of the hardened first solder 6A after melting, it is necessary to promote the reaction between Sn and Ni—Fe during melting and promote the formation of the Ni—Sn phase. For this reason, it is preferable that the 1st metal 61 and the 2nd metal 62 which comprise the 1st solder 6A before a fusion | melting are made granular as shown in FIG. By doing so, the contact area between the first metal 61 and the second metal 62 increases, and the reaction between Sn and Ni—Fe is promoted. As a result, remelting of the first solder 6A that has been cured after melting can be prevented. In addition, as shown in FIG. 4, when making the 1st solder 6A before melting into a wire form, it is preferable to make the 2nd metal 62 into a granular form at least.

  In addition, it is known that the smaller the average particle diameter of the second metal 62 is, the less the first solder 6A tends to absorb heat energy. This tendency is the same even if the ratio of the second metal 62 changes. In addition, as the average particle diameter of the second metal 62 decreases, the contact area between the first metal 61 and the second metal 62 increases at the time of melting, so that the reaction between Sn and the Ni—Fe alloy easily proceeds. -The formation of Sn phase is promoted. On the other hand, as the average particle size of the second metal 62 becomes smaller, it becomes difficult to manufacture and handle the particles of the second metal 62.

  Therefore, the average particle diameter of the second metal 62 is preferably 3 μm or more and 50 μm or less, and more preferably 5 μm or more and 30 μm or less. When the average particle diameter of the second metal 62 is 50 μm, the structure of the first solder 6A after hardening does not sufficiently progress to form the Ni—Sn phase, and the melting point rises after the first solder 6A melts and hardens. Becomes smaller. In addition, when the average particle diameter of the second metal 62 is less than 3 μm, it may be difficult to manufacture and handle the particles of the second metal 62. In addition, if the average particle size of the second metal 62 is smaller than 5 μm, the surface area with respect to the particle size tends to be increased, so that the second metal 62 tends to oxidize. There is a risk that something will happen. When the average particle diameter of the second metal 62 is 5 μm or more, it is more preferable because the remaining of the oxidized particles can be suppressed. In the present embodiment, the average particle diameter of the first metal 61 is in the range of 10 μm to 36 μm.

  In the present embodiment, the addition ratio of the second metal 62 is preferably 5% by mass or more and 30% by mass or less with respect to the sum of the first metal 61 and the second metal 62. Within this range, it is assumed that after the electronic component 2 is mounted on the substrate 3 of the electronic circuit module component 1 using the first solder 6A, the reflow is performed again when the electronic circuit module component 1 is mounted on the device substrate 8. In addition, the generation of solder flash and the movement of the first solder 6A can be suppressed. Further, when the electronic component 2 is mounted on the substrate 3 using the first solder 6A, an appropriate self-alignment effect can be obtained, so that the electronic component 2 can be positioned. Thus, if the addition ratio of the 2nd metal 62 is the said range, it is suitable for mounting of the electronic component 2 which comprises the electronic circuit module component 1. FIG.

  The powder of the 2nd metal 62 is produced by metal powder manufacturing methods, such as a water atomizing method and a gas atomizing method, for example. When the water atomization method is used, the surface of the produced powder is oxidized. When the surface of the powder of the second metal 62 is oxidized and added to the first metal 61 to form the first solder 6A, the first metal 6 is hardened in the molten state due to the influence of the oxide film. It collects on the surface of the solder 6A. As a result, the first metal 61 and the second metal 62 are almost separated from each other. Therefore, the reaction between the first metal 61 and the second metal 62 is not promoted, and an increase in the melting point of the first solder 6A cannot be expected.

  Therefore, when the second metal 62 is oxidized in the process of producing the metal powder, it is preferable to add it to the first metal 61 after reducing it in a hydrogen atmosphere, for example. As a result, the first metal 61 promotes the reaction between the first metal 61 and the second metal 62 during the first melting, so that the first solder 6A cured after melting has a higher melting point than before melting. Can be secured.

  Reaction acceleration between the first metal 61 and the second metal 62 was evaluated using the amount of oxygen contained in the powder of the second metal 62 as a parameter. As a result, when the proportion of oxygen contained in the powder of the second metal 62 is 1.5 mass%, the reaction between the first metal 61 and the second metal 62 is not sufficiently promoted, and the melting point of the first solder 6A increases. Can't hope. On the other hand, if the proportion of oxygen contained in the powder of the second metal 62 is reduced to 0.24% by mass, the reaction between the first metal 61 and the second metal 62 is promoted, and the melting point of the first solder 6A is increased. To rise.

  The proportion of Fe in the second metal 62 is not particularly limited, but an increase in the melting point of the first solder 6A that has been hardened after melting is recognized if it is 8% by mass or more. If the proportion of Fe is 5% by mass or more, the melting point of the first solder 6A cured after melting becomes higher than the reflow temperature (240 ° C. to 260 ° C.) again. On the other hand, if it exceeds 16% by mass, the formation of the Ni—Sn phase does not proceed sufficiently, and the melting temperature of the first solder 6A may decrease. Therefore, the proportion of Fe in the second metal 62 is preferably 5% by mass to 16% by mass, and more preferably 8% by mass to 16% by mass.

  As described above, the electronic circuit module component according to the present embodiment has the Ni—Fe phase 73 inside the Ni—Sn phase 74 dispersed in the Sn phase 71 in the bonding metal (cured first solder 6A). A plurality of portions are formed as hole portions 75 formed by gaps. Since the Ni-Sn phase 74 is a region in which the hole 75 having a diameter of 5 μm or less is provided in the Ni-Sn phase 74 and the Ni-Sn phase 74 is sufficiently higher in hardness than the Sn phase 71, the Ni-Sn phase 74 is temporarily assumed. Even if a crack occurs, the progress of the crack can be suppressed by reaching the hole 75 formed by the gap, and the durability as an electronic circuit module component is improved. In particular, in the conventional electronic circuit module component, when the bonding metal (first solder 6A) is sealed not only by the insulating resin 4 but also by the shield layer 5, the problem of solder flash appears remarkably. It is considered that the durability improvement effect is increased by having the configuration of the electronic circuit module component according to the above.

  The Pb-free solder used for the first solder 6A is a Pb-free solder obtained by adding a second metal containing at least a Ni—Fe alloy to a first metal containing at least Sn and Bi (the first solder 6A described above). Configure. In the process where the Pb-free solder is first melted, the reaction between the Sn of the first metal and the Ni—Fe alloy of the second metal proceeds rapidly. By forming a Ni—Sn phase after the reaction, the cured Pb-free solder has a higher melting point and improved heat resistance than before melting first. As a result, even if the Pb-free solder once melted is reheated by the subsequent reflow, the Pb-free solder does not melt or is prevented from melting.

  Then, by using the above-mentioned Pb-free solder for joining the electronic components constituting the electronic circuit module component, in the reflow when mounting the electronic circuit module component on the device board or the like, solder flash or The risk of solder movement can be reduced. Since the electronic circuit module component according to the present embodiment using such Pb-free solder can reduce the possibility of occurrence of defective bonding of terminals of the electronic component, the yield is improved.

  In addition, since the Pb-free solder used for the electronic circuit module component according to the present embodiment once melts and hardens, the melting point rises, so that it is also effective for joining parts that require heat resistance. In this case, the temperature at which the Pb-free solder according to the present embodiment is first melted is the same as that of SnBi-based (Sn as a base material to which Bi is added) solder (about 220 ° C.). There is no loss of workability. Furthermore, since the first metal containing Sn and Bi can be used as a heat treatment for promoting the formation of the Ni-Sn phase, for example, a heat treatment step in the manufacturing process of the electronic circuit module component such as a molding step can be used. No additional heat treatment step is required. For this reason, workability is greatly improved. In addition, since the Pb-free solder according to the present embodiment uses relatively inexpensive metals such as Sn, Bi, Ni, and Fe, an increase in manufacturing cost of electronic circuit module components and the like can be suppressed.

  Furthermore, in the electronic circuit module component 1 according to the present embodiment, the hole 75 is provided inside the Ni—Sn phase 74 in the bonding metal (cured first solder 6A), so that the inside of the Ni—Sn phase 74 is provided. Even if a crack occurs, the progress of the crack can be suppressed by reaching the hole 75 formed by the gap. Therefore, durability as an electronic circuit module component is improved. When the diameter of the hole 75 is 5 μm or less and the center distance between the adjacent holes 75 is 10 μm or more, the effect of improving the durability becomes remarkable.

  Further, when the bonding metal further includes a Bi phase 72, the hardness of Bi is higher than that of the other phases. Therefore, the progress of cracks is suppressed by forming regions having different hardness in the bonding metal. When the equivalent diameter of the Bi phase 72 is 3 μm or less, the effect of suppressing the progress of cracks is particularly achieved.

  Further, even when the Ni—Fe phase 73 is formed in a region having a center distance of 10 μm or more from the hole 75 of the bonding metal, a crack is progressed by forming a region having different hardness in the bonding metal. It is suppressed.

  The Pb-free solder and electronic circuit module component according to the embodiment of the present invention have been described above. However, the Pb-free solder and electronic circuit module component according to the present invention are not limited to the above configuration.

  In the above embodiment, the case where SnBi-based solder is used as the Pb-free solder has been described. However, other materials may be used as the first solder of the electronic circuit module component including the above-described joining metal. As described above, in reflow, in order to reduce the possibility that solder flash or solder movement occurs in the electronic circuit module component, it is sufficient that Bi is added to the Pb-free solder used for the joining metal. The addition form is not limited to the above embodiment. For example, as a method of including Bi in the solder composition, a method using Sn—Bi solder (configuration described in the above embodiment) or Sn—Ag—Bi solder can be considered. On the other hand, as a method of adding Bi as an additive as in the case of the second metal, a method of adding it as particles having a Ni-Bi composition or a Ni-3Bi composition is conceivable. In either case, the melting point of the bonding metal in the electronic circuit module component is increased, and the durability is improved.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example at all.

<Example 1>
Twenty samples (electronic circuit module parts) according to Example 1 were prepared in the following procedure.
(1) Ni—Fe alloy particles (Fe 10 mass%, average particle diameter 20 μm) with respect to the sum of SnBi solder (Sn 92.5 mass%, Bi 7.5 mass%) on the terminal electrode of the substrate A solder paste containing Pb-free solder added so as to be 15% by mass was printed.
(2) A chip-type resistance element was placed on the substrate as an electronic component using the mounting apparatus.
(3) Pb-free solder contained in the solder paste is melted by placing the board on which the electronic component is mounted in a reflow furnace and heating the solder paste in a normal reflow process (peak temperature 240 ° C., melting 1 minute). And cured. And the terminal electrode of the electronic component and the terminal electrode of the board | substrate were joined by the Pb free solder after hardening.
(4) The flux adhering to the surface of the electronic component and the substrate was washed.
(5) The electronic component and the substrate were covered with an insulating resin. As the insulating resin covering the electronic component and the substrate, an epoxy resin added with a filler (for example, silica filler in this evaluation) was used. And it apply | coated so that an electronic component and a board | substrate might be covered with insulating resin, and it heat-press-cured in the vacuum chamber. The mold post cure treatment was performed at 175 ° C. for 4 hours. As a result, the electronic component was sealed with an insulating resin. Twenty electronic circuit module components according to Example 1 were prepared.

<Example 2>
In the manufacturing method described in Example 1, 20 electronic circuit module components according to Example 2 were prepared under the same conditions as Example 1 except that the amount of Ni—Fe alloy particles added was 5 mass%.

<Example 3>
In the manufacturing method described in Example 1, 20 electronic circuit module components according to Example 3 were created under the same conditions as Example 1 except that the reflow conditions were a peak temperature of 240 ° C. and a melting time of 2 minutes.

<Example 4>
In the manufacturing method described in Example 3, 20 electronic circuit module components according to Example 4 were prepared under the same conditions as Example 3 except that the addition amount of Ni—Fe alloy particles was changed to 5% by mass.

<Example 5>
In the manufacturing method described in Example 1, 20 electronic circuit module components according to Example 4 were produced under the same conditions as Example 1 except that the particle diameter of the Ni—Fe alloy particles was changed to 10 μm.

<Example 6>
In the manufacturing method described in Example 5, 20 electronic circuit module components according to Example 6 were produced under the same conditions as Example 5 except that the addition amount of Ni—Fe alloy particles was changed to 5% by mass.

<Example 7>
In the manufacturing method described in Example 5, 20 electronic circuit module components according to Example 7 were created under the same conditions as Example 5 except that the reflow conditions were a peak temperature of 240 ° C. and a melting time of 2 minutes.

<Example 8>
In the manufacturing method described in Example 7, 20 electronic circuit module components according to Example 8 were created under the same conditions as Example 7 except that the amount of Ni—Fe alloy particles added was 5 mass%.

<Example 9>
Twenty electronic circuit module components according to Example 9 were prepared under the same conditions as Example 1 except that Sn metal solder added with Bi metal particles was used instead of SnBi solder.

<Example 10>
Twenty electronic circuit module components according to Example 10 were prepared under the same conditions as Example 3 except that Sn metal solder added with Bi metal particles was used instead of SnBi solder.

<Comparative Example 1>
In the manufacturing method described in Example 1, 20 electronic circuit module components according to Comparative Example 1 were produced under the same conditions as Example 1 except that high-temperature heat treatment (200 ° C. for 1 hour) was further added.

<Comparative example 2>
In the manufacturing method described in Example 1, 20 electronic circuit module components according to Comparative Example 2 were produced under the same conditions as Example 1 except that the amount of Ni—Fe alloy particles added was 35 mass%.

  The electronic circuit module component obtained by the above method was evaluated for the structure observation of the bonded metal, heat resistance (solder flash suppression), and impact resistance (crack suppression).

<Evaluation method: 1. Observation of bonding metal structure>
When the cross section of the electronic circuit module component is observed with a scanning electron microscope, the size of the hole (maximum hole diameter), the minimum distance between the holes, the size of the Ni-Fe phase when there is a Ni-Fe phase, Ni -The thickness of the Sn phase (the distance between the Sn phase and the hole) was measured.

<Evaluation method: 2. Heat resistance (solder flash suppression)>
The heat resistance (solder flash) was evaluated as follows. First, a sample (electronic circuit module component) used for evaluation was placed in a reflow furnace at 260 ° C., and the movement of solder at the joint between the electronic component and the substrate in the electronic circuit module component was observed. When the situation where the joining metal (solder material) of the joint part is scattered apart from the joint part is observed, ×, but the part of the joint surface with the substrate side of the joint part has changed, although not discrete △, the case where the change in the shape of the electronic component terminal side of the joint portion is recognized is ◯, and the case where the joint surface or shape of the joint portion is not changed is marked ◎.

<Evaluation method: 3. Thermal shock resistance (crack suppression)>
Thermal shock resistance (crack suppression) was evaluated as follows. First, a sample for evaluation (in which the electronic component and the substrate are not covered with insulating resin) is placed in a thermal shock tester that holds alternately for 30 minutes in an environment of −55 ° C. and 125 ° C. for 500 cycles. I left it alone. Then, the joint part formed with the solder after hardening was observed and the progress of the solder crack by surface crack and cross-sectional observation was confirmed and evaluated.

  If no crack is generated at the joint, ◎, if crack is confirmed but the length is 1/3 or less of the solder thickness of the joint, the crack length is bonded. When the solder thickness was 1/3 or more and 1/2 or less of the solder part, Δ, and when the crack length was 1/2 or more of the solder thickness of the joint part, x.

<Evaluation results>
The results of the above evaluation are shown in Table 1. When at least one of heat resistance (solder flash suppression) and thermal shock resistance (crack suppression) is ◯, the overall evaluation is ◯. In addition, when there are one or more items with an evaluation Δ, the overall evaluation is Δ. When both evaluations were ◎, the overall evaluation was ◎.

  DESCRIPTION OF SYMBOLS 1 ... Electronic circuit module component, 2 ... Electronic component, 3 ... Board | substrate, 4 ... Insulating resin, 5 ... Shield layer, 6A ... 1st solder, 6B ... 2nd solder, 61 ... 1st metal, 62 ... 2nd metal.

Claims (4)

On the terminal electrodes of the circuit board, Sn and Bi 100 wt% the sum of, or the remainder I der least 90 wt% consists of at least one of Ag or Cu, Bi is 5 mass% or more 15 a first metal particles or less by mass%, the proportion of Fe is from 5 mass% to 16 mass% der Ru N i-Fe alloy, 5 with respect to the sum of the first metal particles and second metal particles wt% is added such that 15 mass% or more, and the second metal particles having an average particle diameter of 3μm or more 50μm or less, comprising the steps of printing a solder paste including Pb-free solder consisting of,
Placing an electronic component on the solder paste;
Heating the solder paste in a reflow furnace and bonding the terminal electrode of the circuit board and the terminal electrode of the electronic component with a bonding metal solidified by the Pb-free solder;
Have
In the bonding metal, a Ni—Sn alloy phase containing at least Fe is dispersed between Sn alloy phases, and a plurality of holes having a diameter of 5 μm or less are formed inside the Ni—Sn alloy phase and adjacent to each other. A method for manufacturing an electronic circuit module component, wherein a center distance between holes is 10 μm or more.   The method for manufacturing an electronic circuit module component according to claim 1, wherein the bonding metal further includes a Bi alloy phase.   The electronic circuit module component manufacturing method according to claim 2, wherein the Bi alloy phase has an equivalent diameter of 3 μm or less.   The manufacturing method of the electronic circuit module component as described in any one of Claims 1-3 which contains a Ni-Fe alloy phase in the area | region where the center distance is 10 micrometers or more from the said hole part.

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