Transformer module

Abstract

A transformer module includes multiple lead terminals, each of which includes a bent portion bent along a substrate and a connecting portion extending along the substrate. Terminal pads arranged in parallel on the substrate include an enlarged terminal pad and standard terminal pads. Connecting portions of the lead terminals that are adjacent to each other in a parallel arrangement direction of the lead terminals and have the same electrical potential are soldered to the enlarged terminal pad via a solder layer. Each connecting portion is soldered to one of the standard terminal pads via the corresponding solder layer.The enlarged terminal area is formed by connecting the standard terminal areas to which the lead terminals adjacent to each other in the parallel arrangement direction and having the same electric potential are to be soldered, via a connecting terminal area and in the parallel arrangement direction.

Description

BACKGROUND1. Area

[0001] The present disclosure relates to a transformer module. 2. Description of the state of the art

[0002] The transformer module comprises a substrate and a transformer. The transformer comprises a winding and a plurality of lead terminals electrically connected to the winding. The lead terminals are arranged in parallel. Each of the lead terminals is bent from its root, and a portion containing its tip is soldered to a pad of the substrate via a solder layer.

[0003] In a transformer module, the transformer is a relatively large component. Consequently, the transformer is also susceptible to vibration when the transformer module is subjected to external vibrations or similar forces. The bent portions of the lead terminals are locations where stress is likely to occur when the transformer vibrates. Therefore, it is preferable to reinforce the bent portions of the lead terminals in the transformer module. One reinforcing method involves bonding a portion of the solder layer to the bent portion. To bond a portion of the solder layer to the bent portion, it is necessary to increase the amount of solder paste applied to the terminal surface. As a method for increasing the amount of solder paste applied to the terminal surface, the technique disclosed in Japanese Laid-Open Patent Publication No. H7-131139, for example, is known.In this publication, a printed circuit board includes a land for soldering terminals and an auxiliary land continuous with the land. As the solder paste applied to the auxiliary land moves toward the land, the amount of solder paste supplied to the land increases.

[0004] However, as disclosed in the above publication, adding an auxiliary pad to the substrate results in an increase in the overall size of the substrate. SUMMARY

[0005] This Summary is provided to introduce, in a simplified form, a selection of concepts that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0006] In one general aspect, a transformer module comprises a transformer and a substrate. The transformer includes a plurality of lead terminals electrically connected to corresponding windings, and a terminal support on which the plurality of lead terminals are arranged in parallel. A plurality of terminal pads, to which the lead terminals are respectively soldered, are arranged in parallel on the substrate. Each of the lead terminals includes a bent portion bent along the substrate and a connecting portion extending along the substrate. Each connecting portion is soldered to the corresponding terminal pad via a solder layer. The terminal pads include an enlarged terminal pad and a plurality of standard terminal pads. The connecting portions of some of the lead terminals are soldered to the enlarged terminal pad via the corresponding solder layer.Some of the lead terminals are adjacent to each other in a parallel arrangement direction in which the lead terminals are arranged in parallel. Some of the lead terminals have the same electrical potential. Each connection section is soldered to one of the standard connection pads via the corresponding solder layer. The enlarged connection pad is formed by connecting the standard connection pads to which the lead terminals adjacent to each other in the parallel arrangement direction and having the same electrical potential are to be soldered, via a connection pad and in the parallel arrangement direction.

[0007] Further features and aspects will become apparent from the following detailed description, drawings and claims. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a plan view showing a transformer module according to an embodiment. Fig. 2 is a side view of the Fig. 1 shown transformer module. Fig. 3 is an enlarged view showing a lead terminal and a solder layer in the Fig. 1 shows the enlarged connection area. Fig. 4 is a plan view showing the lead terminals and the solder layer in the Fig. 3 shows the enlarged connection area. Fig. 5 is a plan view showing a substrate of a reference example. Fig. 6 is a plan view showing a transformer module according to a first modification. Fig. 7 is a plan view showing a transformer module according to a second modification.

[0008] In the drawings and the detailed description, the same reference numerals refer to the same elements. The drawings may not be to scale, and the relative size, proportions, and representation of elements in the drawings may be exaggerated for clarity, illustration, and convenience. DETAILED DESCRIPTION

[0009] This description provides a comprehensive understanding of the described methods, devices, and / or systems. Modifications and equivalents of the described methods, devices, and / or systems will be apparent to one of ordinary skill in the art. Sequences of operations are exemplary and may be changed as would be apparent to one of ordinary skill in the art, except for operations that necessarily occur in a particular order. Descriptions of functions and structures well known to one of ordinary skill in the art may be omitted.

[0010] Example embodiments may take various forms and are not limited to the described examples. However, the described examples are thorough and complete, and will fully convey the scope of the disclosure to those of ordinary skill in the art.

[0011] In this description, “at least one of A and B” should be understood to mean “only A, only B, or both A and B”.

[0012] A transformer module 10 according to an embodiment will now be described with reference to the Fig. 1 to Fig. 5 described. Transformer module

[0013] As in Fig. 1 and Fig. 2, the transformer module 10 comprises a transformer 11 and a substrate 50 to which the transformer 11 is soldered.

[0014] The transformer 11 includes a bobbin 12, a magnetic core 13 combined with an outer peripheral portion of the bobbin 12, and a primary winding 14 and a secondary winding 15 wound around the bobbin 12. The bobbin 12 includes a flange portion 12a at one end in the axial direction and a flange portion 12b at the other end in the axial direction. The primary winding 14 and the secondary winding 15 are wound around the bobbin 12 such that one flange portion 12a, the primary winding 14, the secondary winding 15, and the other flange portion 12b are arranged in this order in the axial direction. The number of turns differs between the primary winding 14 and the secondary winding 15. The magnetic core 13 may be an EI-type core or an EE-type core.A primary-side terminal holder 16 and a secondary-side terminal holder 17 are formed below the coil bobbin 12. Each of the primary-side terminal holder 16 and the secondary-side terminal holder 17 has a block shape, and their longitudinal directions coincide with each other.

[0015] The primary-side terminal bracket 16 is provided with five primary-side lead terminals 20. The five primary-side lead terminals 20 include a first lead terminal 21, a second lead terminal 22, a dummy lead terminal 25, a third lead terminal 23, and a fourth lead terminal 24, which are arranged in this order from one end to the other end in the longitudinal direction of the primary-side terminal bracket 16. The first lead terminal 21 to the fourth lead terminal 24 and the dummy lead terminal 25 are arranged in parallel on the primary-side terminal bracket 16 at equal intervals in the longitudinal direction of the primary-side terminal bracket 16. Therefore, the direction in which the five primary-side lead terminals 20 are arranged in parallel coincides with the longitudinal direction of the primary-side terminal bracket 16.

[0016] Any two of the primary-side lead terminals 20 adjacent to each other in the longitudinal direction of the primary-side lead holder 16 are separated from each other by a distance greater than or equal to the insulation distance. The first lead terminal 21 to the fourth lead terminal 24 are electrically connected to the primary winding 14. The first lead terminal 21 and the second lead terminal 22 adjacent to each other in the longitudinal direction of the primary-side lead holder 16 have the same electrical potential, and the third lead terminal 23 and the fourth lead terminal 24 adjacent to each other in the longitudinal direction of the primary-side lead holder 16 have the same electrical potential.

[0017] Accordingly, the transformer 11 included in the transformer module 10 includes the first lead terminal 21 to the fourth lead terminal 24 electrically connected to the primary winding 14, and the first lead terminal 21 to the fourth lead terminal 24 are arranged in parallel on the primary-side terminal bracket 16.

[0018] The secondary-side terminal bracket 17 is provided with four secondary-side lead terminals 30. The four secondary-side lead terminals 30 include a first lead terminal 31, a second lead terminal 32, a third lead terminal 33, and a fourth lead terminal 34, which are arranged in this order from one end to the other end in the longitudinal direction of the secondary-side terminal bracket 17. The first lead terminal 31 to the fourth lead terminal 34 are arranged in parallel in the longitudinal direction of the secondary-side terminal bracket 17. The parallel arrangement direction of the four secondary-side lead terminals 30 coincides with the longitudinal direction of the secondary-side terminal bracket 17 and also coincides with the parallel arrangement direction of the five primary-side lead terminals 20.

[0019] The first lead terminal 31 to the fourth lead terminal 34 are electrically connected to the secondary winding 15. The first lead terminal 31 and the second lead terminal 32, which are adjacent to each other in the longitudinal direction of the secondary-side terminal holder 17, have different electrical potentials, and the third lead terminal 33 and the fourth lead terminal 34, which are adjacent to each other in the longitudinal direction of the secondary-side terminal holder 17, have different electrical potentials. The second lead terminal 32 and the third lead terminal 33, which are adjacent to each other in the longitudinal direction of the secondary-side terminal holder 17, have different electrical potentials.

[0020] Accordingly, the transformer 11 included in the transformer module 10 includes the first lead terminal 31 to the fourth lead terminal 34 electrically connected to the secondary winding 15, and the first lead terminal 31 to the fourth lead terminal 34 are arranged in parallel on the secondary-side terminal bracket 17.

[0021] For example, in the transformer 11, when AC input power is input to the primary winding 14 through the first line terminal 21 and the fourth line terminal 24 on the primary side, an output voltage is generated at the first line terminal 31 and the third line terminal 33 on the secondary side. In the transformer 11, when AC input power is input to the primary winding 14 through the second line terminal 22 and the third line terminal 23 on the primary side, an output voltage is generated at the second line terminal 32 and the fourth line terminal 34 on the secondary side. An input voltage is converted into an output voltage according to the ratio of the number of turns between the primary winding 14 and the secondary winding 15.

[0022] Each of the primary-side lead terminals 20 and the secondary-side lead terminals 30 is formed by bending a thin plate into an L-shape. The primary-side lead terminals 20 and the secondary-side lead terminals 30 have the same shape. Therefore, in the following description, the components included in both the primary-side lead terminals 20 and the secondary-side lead terminals 30 are assigned the same component names and reference numerals.

[0023] As in Fig. 3 and Fig. As shown in Figure 4, each of the primary-side lead terminals 20 and the secondary-side lead terminals 30 integrally includes a rectangular plate-shaped extending portion 41, a rectangular plate-shaped connecting portion 42, and a bent portion 43. The extending portion 41 extends from the primary-side terminal bracket 16 or the secondary-side terminal bracket 17 on which the terminal 20, 30 is disposed. The connecting portion 42 extends to intersect the extending portion 41. The bent portion 43 connects the extending portion 41 and the connecting portion 42 to each other. Substrat

[0024] As in Fig. 1 and Fig. 2, the substrate 50 includes a first main surface 51 and a second main surface 52 located on opposite sides in the thickness direction. The substrate 50 includes terminal pads provided on the first main surface 51. The terminal pads include a plurality of primary-side terminal pads 60 and a plurality of secondary-side terminal pads 70. In the plan view in which the transformer module 10 is viewed in the thickness direction, the primary-side terminal pads 60 are arranged at positions corresponding to the primary-side terminal bracket 16 of the transformer 11, and the secondary-side terminal pads 70 are arranged at positions corresponding to the secondary-side terminal bracket 17 of the transformer 11.In the plan view in which the transformer module 10 is viewed in the thickness direction, the primary-side terminal surfaces 60 and the secondary-side terminal surfaces 70 are arranged with the transformer 11 arranged therebetween.

[0025] The primary-side lead terminals 20 are soldered to the primary-side connection pads 60 via solder layers 18. Accordingly, the primary-side connection pads 60, to which the primary-side lead terminals 20 are respectively soldered, are arranged in parallel on the substrate 50. The secondary-side lead terminals 30 are soldered to the secondary-side connection pads 70 via the corresponding solder layers 18. Accordingly, the secondary-side connection pads 70, to which the secondary-side lead terminals 30 are respectively soldered, are arranged in parallel on the substrate 50.

[0026] Each of the primary-side pads 60 has a rectangular shape. The primary-side pads 60 are arranged such that the short sides of all primary-side pads 60 extend in the same direction. The direction in which the short sides of the primary-side pads 60 extend is defined as a first direction X of the substrate 50. The direction in which the long sides of the primary-side pads 60 extend is defined as a second direction Y of the substrate 50. The primary-side pads 60 are arranged parallel in the first direction X of the substrate 50. Accordingly, the parallel arrangement direction of the primary-side pads 60 coincides with the first direction X of the substrate 50.Any two of the primary-side pads 60 that are adjacent to each other in the first direction X of the substrate 50 are separated from each other in the first direction X by a distance that is greater than or equal to the insulation distance.

[0027] The primary-side connection areas 60 include standard connection areas 61, to each of which a connecting section 42 is soldered via the solder layer 18. The primary-side connection areas 60 include an enlarged connection area 62 to which two connecting sections 42 are soldered. On the substrate 50, three standard connection areas 61 and one enlarged connection area 62 are arranged in parallel from one end to the other end in the first direction X of the substrate 50.

[0028] Each standard pad 61 has a surface area sufficient to allow the application of a quantity of solder paste required to solder a single interconnect portion 42 to the primary-side pad 60 via a solder layer 18. This quantity of solder paste is sufficient to form the solder layer 18 to bond to the entire back and side surfaces of the interconnect portion 42 while securing the interconnect portion 42 to the primary-side pad 60.

[0029] The standard connection surfaces 61 and the enlarged connection surface 62 have the same dimension in the second direction Y. The standard connection surfaces 61 and the enlarged connection surface 62 have different dimensions in the first direction X. A dimension L1 of the enlarged connection surface 62 in the first direction X is larger than a dimension L2 of the standard connection surface 61 in the first direction X. The dimension L1 of the enlarged connection surface 62 is sufficiently larger than twice the dimension L2 of the standard connection surface 61.

[0030] A substrate 80 of a reference example shown in Fig. 5 will now be described.

[0031] The substrate 80 of the reference example includes five standard pads 61 as the primary-side pads 60 and four standard pads 71 ​​as the secondary-side pads 70. The dimensions in the first direction X of the standard pads 61, 71 in the reference example are the same as the dimension L2 of the standard pads 61, 71 in the embodiment. The dimensions in the second direction Y of the standard pads 61, 71 in the reference example are the same as the dimension in the second direction Y of the standard pads 61, 71 in the embodiment. The distance between any two of the standard pads 61, 71 adjacent to each other in the first direction X is also the same as the distance between any two of the standard pads 61, 71 adjacent to each other in the first direction X in the embodiment.On the substrate 80 of the reference example, two standard pads 61 are provided instead of the enlarged pad 62.

[0032] As in Fig. 1 and Fig. 4, the enlarged land 62 of the embodiment is formed by connecting two standard lands 61 located at one end in the first direction X and adjacent to each other in the first direction X on the substrate 80 of the reference example. In particular, as shown by the long-double-short-dashed lines in Fig. 1, the enlarged pad 62 is formed by connecting two standard pads 61, to which the third lead terminal 23 and the fourth lead terminal 24, which have the same potential and are adjacent to each other in the parallel arrangement direction, are to be soldered, respectively, with a connection pad 64 and in the parallel arrangement direction. These two standard pads 61 are connected to each other over the entire length of the standard pads 61 via the connection pad 64. That is, the connection pad 64 connects the standard pads 61, which are adjacent to each other in the parallel arrangement direction, over the entirety of the standard pads 61 in the direction orthogonal to the parallel arrangement direction.Accordingly, the dimension of the enlarged pad 62 in the second direction Y of the substrate 50 is the same as the dimension of the standard pad 61 in the second direction Y, while the dimension of the enlarged pad 62 in the first direction X of the substrate 50 is sufficiently larger than twice the dimension of the standard pad 61 in the first direction X. The surface area of ​​the enlarged pad 62 is the sum of the surface areas of the two standard pads 61 and the surface area of ​​the connecting pad 64. Therefore, the surface area of ​​the enlarged pad 62 is sufficiently larger than twice the surface area of ​​each standard pad 61.

[0033] The surface of the enlarged pad 62 and the surface of the standard pad 61 refer to the surface of the enlarged pad 62 and the surface of the standard pad 61, respectively, in the plan view of the first main surface 51 of the substrate 50 as viewed in the thickness direction.

[0034] As in Fig. 1, on the substrate 50 of the embodiment, the distance in the first direction X between the outer edges of the primary-side pads 60 located at the opposite ends in the first direction X is referred to as a standard distance K1. As shown in Fig. 5, on the substrate 80 of the reference example, the distance in the first direction X between the outer edges of the standard pads 61 located at the opposite ends in the first direction X is referred to as a reference distance K2. The standard distance K1 is equal to the reference distance K2. Accordingly, the substrate 50 of the embodiment includes the enlarged pad 62 without increasing the surface area of ​​the region where the primary-side pads 60 are arranged in the first direction X compared to the substrate 80 of the reference example. Furthermore, the substrate 50 of the embodiment does not increase the surface area of ​​the region where the primary-side pads 60 are arranged in the second direction Y compared to the substrate 80 of the reference example.

[0035] As in Fig. 1, each of the secondary-side pads 70 has a rectangular shape. The secondary-side pads 70 are arranged such that the short sides of all the secondary-side pads 70 extend in the first direction X. The secondary-side pads 70 are arranged parallel in the first direction X of the substrate 50. Any two of the secondary-side pads 70 that are adjacent to each other in the first direction X of the substrate 50 are separated from each other in the first direction X by a distance that is greater than or equal to the insulation distance.

[0036] Each of the four secondary-side terminal pads 70 is a standard terminal pad 71 to which a secondary-side lead terminal 30 is soldered. The primary-side terminal pads 60 and the secondary-side terminal pads 70 are arranged at positions opposite to each other in the second direction Y of the substrate 50. Specifically, at one end in the first direction X of the substrate 50, two standard terminal pads 61 and two standard terminal pads 71 ​​are arranged on the opposite sides in the second direction Y. At the other end in the first direction X of the substrate 50, the enlarged terminal pad 62 and two standard terminal pads 71 ​​are arranged on the opposite sides in the second direction Y.No secondary-side terminal surface 70 is arranged at a position aligned in the second direction Y with the standard terminal surface 61 in the center of the five primary-side terminal surfaces 60 arranged in parallel in the first direction X. Transformer module

[0037] The transformer module 10 comprising the transformer 11 having the above-described configuration and the substrate 50 will now be described.

[0038] As in Fig. 1, on the primary side of the transformer 11, each of the first lead terminals 21 and the second lead terminals 22 is soldered to the corresponding standard pad 61 of the primary-side pad 60 via a solder layer 18. On the primary side of the transformer 11, the connecting portions 42 of two of the primary-side lead terminals 20 are soldered to the enlarged pad 62 via a solder layer 18. These two primary-side lead terminals 20 are adjacent to each other in the parallel arrangement direction in which the plurality of primary-side lead terminals 20 are arranged in parallel and have the same electrical potential. Therefore, the transformer module 10 includes the enlarged pad 62 on the substrate 50. The enlarged pad 62 is soldered to the connecting portions 42 of the third lead terminal 23 and the fourth lead terminal 24 via a solder layer 18.The third lead terminal 23 and the fourth lead terminal 24 are adjacent to each other in the parallel arrangement direction in which the primary-side lead terminals 20 are arranged in parallel, and have the same electrical potential. The dummy lead terminal 25 is connected via a solder layer 18 to the standard pad 61 located in the center of the parallel arrangement direction of the substrate 50. On the secondary side of the transformer 11, the first lead terminal 31 to the fourth lead terminal 34 are connected via the solder layers 18 to the standard pads 71 ​​of the secondary-side pads 70.

[0039] As in Fig. 2, the extension portion 41 of each of the primary-side lead terminals 20 soldered to the primary-side terminal pads 60 extends from the lower surface of the primary-side terminal holder 16 toward the substrate 50. Although not shown, the extension portion 41 of each of the secondary-side lead terminals 30 soldered to the secondary-side terminal pads 70 extends from the lower surface of the secondary-side terminal holder 17 toward the substrate 50.

[0040] As in Fig. 3, each of the primary-side lead terminals 20 includes a bent portion 43 bent along the substrate 50 and a connecting portion 42 extending along the substrate 50 and soldered to the corresponding primary-side pad 60 via a solder layer 18. Although not shown, each of the secondary-side lead terminals 30 includes a bent portion 43 bent along the substrate 50 and a connecting portion 42 extending along the substrate 50 and soldered to the corresponding secondary-side pad 70 via a solder layer 18.

[0041] As in Fig. 3 and Fig. 4, the solder layer 18 is bonded to the connecting portions 42 over the entire length of the connecting portions 42, and is also bonded to the distal end surfaces of the connecting portions 42 and the outer surfaces of the bent portions 43. The solder layer 18 is bonded to the opposite side surfaces in the transverse direction of each connecting portion 42. Thus, the solder layer 18 is bonded to the connecting portions 42 so as to surround the connecting portions 42.

[0042] The solder layer 18, which solders the third lead terminal 23 and the fourth lead terminal 24 to the enlarged land 62, includes a solder fillet 18a that extends downward while being inclined to spread from the upper edge of the connecting portion 42 toward the outer edge of the standard land 61. That is, the connecting portions 42 are connected to the upper portion of the solder layer 18, which is formed to rise on the enlarged land 62. The solder fillet 18a extends downward while being inclined to spread from the upper ends of the bent portions 43 toward the outer edge of the enlarged land 62. Therefore, the solder layer 18 is connected to the bent portions 43 over the entire height of the bent portions 43. That is, the solder layer 18 covers the entire height of the bent portions 43. Operation of the embodiment

[0043] As a specific example of a method for soldering the transformer 11 to the substrate 50, a method for soldering the third lead terminal 23 and the fourth lead terminal 24 to the enlarged pad 62 will be described along with the operation of the transformer module 10 according to the present embodiment.

[0044] First, a solder paste is applied to each of the primary-side terminal pads 60 and the secondary-side terminal pads 70. Next, the connecting portions 42 of the primary-side lead terminals 20 are placed on the solder paste applied to the primary-side terminal pads 60, and the connecting portions 42 of the secondary-side lead terminals 30 are placed on the solder paste applied to the secondary-side terminal pads 70.

[0045] There, as in Fig. 1, the enlarged pad 62 is formed by connecting two standard pads 61 via the connecting pad 64, the surface area of ​​the enlarged pad 62 is sufficiently larger than twice the surface area of ​​each standard pad 61. Accordingly, the amount of solder paste that can be applied to the enlarged pad 62 is increased. As the amount of solder paste applied to the enlarged pad 62 increases, the solder paste is more likely to flow toward the connecting portions 42, and thus, the solder paste is more likely to flow toward the bent portions 43. As a result of the solder paste rising along the connecting portions 42 and the bent portions 43, the solder layer 18 is connected to the bent portions 43 over the entire height. Advantages of the embodiment

[0046] The embodiment described above has the following advantages.

[0047] On the substrate 50, the enlarged pad 62 is formed by connecting two standard pads 61 arranged in the parallel arrangement direction via the connecting pad 64. Therefore, the amount of solder paste that can be applied to the enlarged pad 62 is increased compared to a case where the solder paste is applied only to one standard pad 61. The third lead terminal 23 and the fourth lead terminal 24, which have the same electrical potential, are soldered to the enlarged pad 62 via a solder layer 18. The solder layer 18 is thus connected to the bent portion 43 of each of the third lead terminal 23 and the fourth lead terminal 24. Consequently, the solder layer 18 reinforces the bent portions 43 where stress due to vibration or the like is likely to occur.

[0048] The enlarged terminal area 62 is formed by connecting two standard terminal areas 61, to which the third lead terminal 23 and the fourth lead terminal 24 are to be soldered at the same electrical potential, via the connecting terminal area 64. Since the primary-side terminal areas 60, to which the primary-side lead terminals 20 are to be soldered at the same electrical potential, do not need to be insulated from each other, the adjacent primary-side terminal areas 60 can be connected to each other via the connecting terminal area 64 arranged therebetween. In other words, the enlarged terminal area 62 increases the surface area of ​​a terminal area by effectively utilizing the area between the adjacent standard terminal areas 61.Therefore, although the enlarged pad 62 is formed, the arrangement area of ​​the primary-side pads 60 on the substrate 50 is not increased in the parallel arrangement direction of the primary-side pads 60. Accordingly, the bent portions 43 are reinforced without increasing the size of the substrate 50.

[0049] (2) The solder layer 18 is connected to the third lead terminal 23 and the fourth lead terminal 24, which are soldered to the enlarged pad 62, via the solder fillet 18a over the entire height of the bent portions 43. This strengthens the bent portions 43 in a favorable manner.

[0050] (3) The transformer 11 includes the dummy lead terminal 25. The dummy lead terminal 25 is provided in the transformer 11 as a primary-side lead terminal 20. The number of primary-side lead terminals 20 including the dummy lead terminal 25 is five, and the number of secondary-side lead terminals 30 is four. Since the primary-side lead terminals 20 and the secondary-side lead terminals 30 can be clearly distinguished from each other, the primary-side lead terminals 20 can be prevented from being soldered to the secondary-side terminal pads 70.

[0051] (4) The enlarged land 62 is formed by connecting two standard lands 61 via the connecting land 64 over the entire length of the standard lands 61. The enlarged land 62 thus has a rectangular shape. Accordingly, for example, the surface area of ​​the enlarged land 62 is increased compared to a case where an H-shaped enlarged land is formed by connecting only parts of the two standard lands 61 in the longitudinal direction via the connecting land 64. Consequently, the amount of solder paste that can be applied to the enlarged land 62 is sufficiently increased. Furthermore, the flowability of the solder paste applied to the enlarged land 62 is increased compared to a case where only parts of the two standard lands 61 in the longitudinal direction are connected via the connecting land 64.The solder paste thus flows easily toward the connecting portions 42 and the bent portions 43. Accordingly, the bent portions 43 are advantageously reinforced by the solder layer 18 formed from the solder paste applied to the enlarged pad 62. Modifications

[0052] The above-described embodiment may be modified as follows. The above-described embodiment and the following modifications may be combined as long as the combined modifications remain technically consistent with each other.

[0053] As in Fig. 6, elongated pads 73 having a longer dimension in the second direction Y than the standard pads 71 ​​may be provided on the substrate 50 as part of the secondary-side pads 70. Such elongated pads may be provided on the substrate 50 as part of the primary-side pads 60. In such a configuration, the amount of solder paste that can be applied to each elongated pad 73 is increased compared to the amount of solder paste applied to each standard pad 71. Accordingly, in each elongated pad 73, the solder layer 18 is also bonded to the bent portion 43 of the primary-side lead terminal 20 or the secondary-side lead terminal 30. Consequently, the solder layer 18 reinforces the bent portions 43 where stress due to vibration or the like is likely to occur.

[0054] As in Fig. As shown in Fig. 7, among the secondary-side standard lands 71 ​​arranged in parallel in the first direction X, each of the standard lands 71 ​​arranged at opposite ends in the parallel arrangement direction may increase in size in a direction away from the adjacent standard land 71. Among the standard lands 61 of the primary-side land 60, the standard land 61 arranged at one end in the parallel arrangement direction may also increase in size in a direction away from the adjacent standard land 61.

[0055] Accordingly, even a lead terminal other than the third lead terminal 23 and the fourth lead terminal 24, which have the same electrical potential, can be soldered to the corresponding standard pad 71 with an increased amount of solder paste. Since the dimension of the standard pad 71, which is arranged at least at one end in the parallel arrangement direction, increases in a direction away from the adjacent standard pad 71, the standard pad 71, which is arranged at least at one end, does not short-circuit with the adjacent standard pad 71. Therefore, the bent portion 43 of the secondary-side lead terminal 30, which is connected to the standard pad 71, is slightly reinforced.

[0056] In the primary-side terminal surfaces 60, the first lead terminal 21 and the second lead terminal 22, which are arranged in the parallel arrangement direction and have the same electrical potential, can be soldered to the enlarged terminal surface 62.

[0057] In the embodiment described above, one of the five primary-side line terminals 20 is used as the dummy line terminal 25. However, this one line terminal can be used as a line terminal driven in the same manner as the other four line terminals of the primary-side line terminals 20.

[0058] In the transformer module 10, the number of primary-side lead terminals 20 and the number of secondary-side lead terminals 30 arranged in the parallel arrangement direction may be different from those in the embodiment. The number of primary-side lead terminals 20 or secondary-side lead terminals 30 adjacent to each other in the parallel arrangement direction and having the same electric potential may be three or more. According to the number of primary-side lead terminals 20 or secondary-side lead terminals 30 having the same electric potential, the enlarged lead pad 62 may be formed by connecting the same number of standard lead pads 61 as the number of primary-side lead terminals 20 or secondary-side lead terminals 30 having the same electric potential via a connecting lead pad 64.

[0059] Various changes in form and details may be made to the above examples without departing from the spirit and scope of the claims and their equivalents. The examples are for the purpose of description only and not of limitation. Descriptions of features in each example are to be considered applicable to similar features or aspects in other examples. Suitable results may be obtained if sequences are performed in a different order and / or if components in a described system, architecture, device, or circuit are combined differently and / or substituted for or supplemented with other components or their equivalents. The scope of the disclosure is defined by the claims and their equivalents, not the detailed description.All variations within the scope of the claims and their equivalents are included in the disclosure.

Claims

[1] Transformer module (10), comprising: a transformer (11) having a plurality of line terminals (20, 30) electrically connected to corresponding windings (14, 15), and a terminal holder (16, 17) on which the plurality of line terminals (20, 30) are arranged in parallel; and a substrate (50) on which a plurality of connection surfaces (60, 70) to which the line connections (20, 30) are respectively soldered are arranged in parallel, wherein each of the line connections (20, 30) comprises: a bent portion (43) bent along the substrate (50); and a connecting portion (42) extending along the substrate (50), each connecting section (42) is soldered to the corresponding connection surface (60, 70) via a solder layer (18), the connection surfaces (60) comprise an enlarged connection surface (62) and a plurality of standard connection surfaces (61), the connecting portions (42) of some of the lead terminals (20) are soldered to the enlarged connection surface (62) via the corresponding solder layer (18), wherein the some of the lead terminals (20) are adjacent to one another in a parallel arrangement direction in which the lead terminals (20) are arranged in parallel, and the some of the lead terminals (20) have the same electrical potential, each connecting section (42) is soldered to one of the standard connection surfaces (61) via the corresponding solder layer (18), and the enlarged terminal surface (62) is formed by connecting the standard terminal surfaces (61) to which the lead terminals (20) adjacent to each other in the parallel arrangement direction and having the same electrical potential are to be soldered, via a connecting terminal surface (64) and in the parallel arrangement direction. [2] Transformer module (10) according to claim 1, wherein the standard connection surfaces (61, 71) are arranged parallel in the parallel arrangement direction, and among the parallel arranged standard terminal surfaces (71), the standard terminal surface (71) arranged at least at one end in the parallel arrangement direction has a dimension that increases in a direction away from another standard terminal surface (71) adjacent thereto. [3] Transformer module (10) according to claim 1 or 2, wherein each solder layer (18) is connected to an entirety of the corresponding bent portion (43). [4] The transformer module (10) according to any one of claims 1 to 3, wherein the connection pad (64) connects the standard pads (61) adjacent to each other in the parallel arrangement direction over an entirety of the standard pads (61) in a direction orthogonal to the parallel arrangement direction.

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