JP2015041696A - Substrate, connection structure of substrate, optical module, optical communication device, optical communication system and connection method of substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To implement narrow-pitch packaging at low cost by lead pin connection that facilitates alignment with a small-sized package.SOLUTION: A substrate comprises: a first dielectric layer; a second dielectric layer; a plurality of inner layer conductors which are provided while being held between the first dielectric layer and the second dielectric layer; a plurality of surface conductors provided on a surface of the first dielectric layer; a plurality of lead-pin penetration holes which are provided while penetrating each of the plurality of surface conductors, the first dielectric layer and the second dielectric layer; and a plurality of through holes which are provided while penetrating each of the plurality of surface conductors, the first dielectric layer, each of the plurality of inner layer conductors and the second dielectric layer and electrically connect the plurality of surface conductors and the plurality of inner layer conductors, respectively.

Description

  The present invention relates to a board, a board connection structure, an optical module, an optical communication device, an optical communication system, and a board connection method.

  2. Description of the Related Art Conventionally, in an optical module in which an optical semiconductor element is mounted in a package, light that is electrically connected by inserting a lead pin of the package into a hole in a land of a flexible printed circuit board (hereinafter referred to as FPC) and soldering it. Modules are known (see, for example, Patent Document 1). Conventionally, an optical module in which an FPC is directly soldered and electrically connected to a package is also known (for example, see Non-Patent Document 1).

Japanese Patent Laying-Open No. 2006-295115 (FIGS. 5 to 7)

S. Kanazawa, et al. "Ultra-Compact 100GbE Transmitter Optical Sub-Assembly For 40-km SMF Transmission," Journal of Lightwave Technology, E11. (P.605, FIG.11.)

  In an optical module incorporating a large number of optical semiconductor elements such as an integrated optical module, a large number of lead pins are arranged in a small package, and a narrow pitch mounting is desired for an FPC structure. However, when circular lands are arranged at a narrow pitch, a short circuit between adjacent lands becomes a problem. In the conventional optical module disclosed in Patent Document 1, although the adjacent circular lands are closely arranged so as to avoid short-circuiting, they are densely arranged, but additional for bending the lead pins However, there is a problem that the processing cost increases. Further, in the conventional optical module disclosed in Non-Patent Document 1, since the FPC wiring pattern is soldered directly to the package wiring pattern, the positioning of the narrow pitch mounting is highly accurate. was there.

  The present invention has been made to solve the above-described problems, and realizes an FPC structure that can be mounted on a small pitch at a low cost by using a lead pin connection method that is easy to align with a small package and does not require additional processing. The purpose is to do.

  The substrate according to the present invention includes a first dielectric layer, a second dielectric layer, a plurality of inner layer conductors provided between the first dielectric layer and the second dielectric layer, and A plurality of surface conductors provided on the surface of the first dielectric layer, and each of the plurality of surface conductors provided through the first dielectric layer and the second dielectric layer. A plurality of lead pin through-holes, a plurality of the surface conductors, the first dielectric layer, a plurality of the inner layer conductors, and the second dielectric layer are provided through the plurality of the surface conductors. And a plurality of through holes that electrically connect the conductor and the plurality of inner layer conductors, respectively.

  According to the present invention, it is possible to mount a narrow pitch at a low cost by the lead pin connection that is easy to align on the substrate.

The block diagram which shows the optical module using the board | substrate by Embodiment 1 of this invention The block diagram which shows the optical module using the board | substrate by Embodiment 1 of this invention The block diagram which shows the optical module using the board | substrate by Embodiment 1 of this invention The block diagram which shows the optical module using the board | substrate by Embodiment 1 of this invention The block diagram which shows the optical module using the board | substrate by Embodiment 1 of this invention The block diagram which shows the optical module using the board | substrate by Embodiment 1 of this invention The block diagram which shows the optical module using the board | substrate by Embodiment 2 of this invention The block diagram which shows the optical module using the board | substrate by Embodiment 2 of this invention The block diagram which shows the optical communication system by Embodiment 3 of this invention

Embodiment 1 FIG.
1 to 4 are configuration diagrams showing an optical module using a substrate according to Embodiment 1 of the present invention. FIG. 1 shows an overall view of the optical module, and FIG. 2 shows an enlargement of the periphery of the lead pin of FIG. FIG. 3 shows a cross-sectional view of the AA portion of FIG. 2, and FIG. 4 shows a dimension example of the surface conductor. In each figure, the same numerals indicate the same or corresponding parts.

  1-4, 1 is a receptacle, 2 is a package, 3 is ceramic, 4 is a power supply lead pin, 5 is a signal lead pin, 6 is a flexible printed circuit (hereinafter referred to as FPC), and 7 is a lead pin. Through hole, 8 through hole, 9 through hole, 10 signal land, 11 surface conductor, 12 inner layer conductor, 12a inner layer conductor, 13 reinforcing plate, 14 as first dielectric layer A dielectric layer, 15 is a dielectric layer as a second dielectric layer, 16 is solder as a connecting material, and 17 is solder.

  In FIG. 1, a receptacle 1 is an optical interface member to which an optical fiber (not shown) is connected, a package 2 is a member for accommodating an optical semiconductor element in an airtight state, and a ceramic 3 has a two-layer structure for a power source. The lead pin 4 and the signal lead pin 5 are connected to each other, and the power lead pin 4 and the signal lead pin 5 are connected to the electric wiring inside the package 2.

  In FIG. 1, an FPC 6 is an electrical interface member that is connected to a power supply lead pin 4 and a signal lead pin 5 and is connected to a transceiver board (not shown). The material of the FPC 6 is, for example, polyimide, and FIG. 1 is a diagram assuming that the FPC 6 is bent in the Z-axis direction so that the substrate of the transmitter / receiver is sandwiched from above and below to be connected. The reinforcing plate 13 is installed between the ceramic 3 and the FPC 6 and is a member for the purpose of preventing stress application to the surface conductor 11 formed on the FPC 6 when the FPC 6 is bent. The material of the reinforcing plate 13 is, for example, polyimide, and the reinforcing plate 13 may be formed at the same time as the FPC 6 is manufactured.

  2 and 3, six lead pin through holes 7 are holes through which the six power supply lead pins 4 pass, respectively, and pass through the FPC 6. A plurality of lead pin through holes 7 are arranged in a narrow pitch in the X-axis direction. The six through holes 8 penetrate the FPC 6 and electrically connect the six surface conductors 11 and the six inner layer conductors 12 by side metallization. The four through holes 9 are holes through which the four signal lead pins 5 pass, respectively, and penetrate the FPC 6 to electrically connect the four signal lands 10 and the four inner layer conductors 12a by side metallization. It goes without saying that the number of lead pin through holes 7 and through holes 8, 9 is not limited to this. 2, 5, and 7, illustration of the solders 16 and 17 is omitted.

  In FIG. 3, the solder 16 electrically connects the power supply lead pin 4 and the surface conductor 11. The solder 17 electrically connects the signal lead pin 5 and the signal land 10. Furthermore, the solder 17 flows into the through hole 9 and is electrically connected to the inner layer conductor 12a through the side metallization of the through hole 9. The inner layer conductor 12 is formed on the dielectric layer 15, the dielectric layer 14 is formed on the upper surface, the surface conductor 11 is formed on the upper surface, and the through hole 8 is formed. The inner layer conductor 12a is formed on the dielectric layer 15, the dielectric layer 14 is formed on the upper surface, the signal land 10 is formed on the upper surface, and the through hole 9 is formed. The reinforcing plate 13 is formed on the lower surface of the dielectric layer 15.

  Next, the operation will be described. First, the operation of an optical module as an optical transmission module in which two light emitting elements as optical semiconductor elements and one Peltier element are mounted in the package 2 will be described. Two power supply lead pins 4 and two signal lead pins 5 are connected to one light emitting element via an electric wiring inside the package 2, and two power supply lead pins 4 are connected to one Peltier element inside the package 2. Connected via electrical wiring.

  1 and 2, a power supply voltage is applied to the power supply lead pin 4 through the inner layer conductor 12, the through hole 8, the surface conductor 11, and the solder 16 of the FPC 6 connected to a transceiver board (not shown). When an electrical signal is input to the signal lead pin 5 through the inner layer conductor 12a of the FPC 6 connected to the transceiver board (not shown), the through hole 9, the signal land 10 and the solder 17, the package 2 in the package 2 (not shown) Two light emitting elements emit optical signals, and the emitted optical signals are combined by an optical multiplexer (not shown) in the package 2 and output to an optical fiber (not shown) via the receptacle 1. Further, the power supply voltage is applied to the power supply lead pin 4 connected to the Peltier element, whereby the temperature of the light emitting element is maintained at a predetermined value.

  The operation of the optical module as an optical receiving module in which two light receiving elements as optical semiconductor elements are mounted in the package 2 will be described. Two power supply lead pins 4 and two signal lead pins 5 are connected to one light receiving element via electric wiring inside the package 2.

  1 and 2, a power supply voltage is applied to the power supply lead pin 4 through the inner layer conductor 12, the through hole 8, the surface conductor 11, and the solder 16 of the FPC 6 connected to a transceiver board (not shown). When an optical signal is input to two light receiving elements (not shown) in the package 2 via a receptacle 1 connected to an optical fiber (not shown) and an optical demultiplexer (not shown) in the package 2, the optical signal is converted into an electrical signal. The converted electric signal is output to a substrate of a transceiver (not shown) connected to the substrate FPC 6 through the signal lead pin 5, the solder 17, the signal land 10, the through hole 9, and the inner layer conductor 12a. The It is also possible to maintain the temperature of the light receiving element with a Peltier element as in the case of the optical transmission module.

  As described above, when the power supply lead pins 4 are arranged in a small package in parallel at a narrow pitch, if the surface conductor 11 is formed as a circular land on the entire circumference of the lead pin through hole 7, a short circuit is a problem. It becomes. To solve this, the FPC 6 according to the first embodiment of the present invention extends in the Y direction, which is perpendicular to the direction in which the power supply lead pins 4 are arranged, as shown in FIG. The surface conductor 11 having the following width is formed, thereby preventing the occurrence of a short circuit between the adjacent surface conductors 11.

  In this case, if the lead pin through hole 7 is to be a through hole, an electric field can be applied to the entire circumference of the lead pin through hole 7 because the surface conductor 11 is not formed on the entire circumference of the lead pin through hole 7. However, the problem is that it is difficult to form through holes by plating. Therefore, in the FPC 6 according to the first embodiment of the present invention, the formation of the through hole in the lead pin through hole 7 is stopped, the through hole is formed in another location, and the power supply lead pin 4 and the inner layer conductor 12 are electrically connected. Features a connectable structure. That is, the structure is such that a through hole 8 that can be electrically connected is provided on the surface conductor 11 having a width equal to or smaller than the diameter of the lead pin through hole 7.

  Here, since the solder 16 is applied only to the upper surface of the surface conductor 11 in the vicinity where the power supply lead pin 4 and the FPC 6 are connected, the bonding strength is weaker than when the solder is also applied to the through hole. Become. At this time, if the FPC 6 is bent as shown in FIG. 1B without the reinforcing plate 13, the connecting portion of the solder 16 and the surface conductor 11 becomes the starting point of the FPC bending, and the solder 16 and the surface conductor 11 The problem is that stress is applied in the vicinity of the through hole 8. Therefore, the FPC 6 which is a substrate according to the first embodiment of the present invention is characterized by a structure in which a reinforcing plate 13 is added between the power lead pins 4 and the through holes 8.

  At this time, by making the reinforcing plate 13 sufficiently thicker than the dielectric layers 14, 15, the bending start position when the FPC 6 is bent becomes a connecting portion between the dielectric layer 15 and the reinforcing plate 13, and the solder 16, the surface conductor 11 and the application of stress can be avoided by preventing deformation near the through hole 8. As an example of suitable thickness, the reinforcement board 13 is 150 micrometers, and the dielectric material layers 14 and 15 are 25-50 micrometers.

  The inner layer conductors 12 and 12a, regardless of the presence or absence of the reinforcing plate 13, does not cause stress application even if the FPC 6 is bent. This is because the dielectric layers 14 and 15 serve as a protective layer by sandwiching the inner layer conductors 12 and 12a. Generally, if the FPC bending radius is 0.3 mm or more, it is considered that there is no problem in applying stress, and it can be said that there is no problem because the FPC bending radius in actual use is 0.4 mm or more.

  In this way, the electrical connection between the power supply lead pin 4 and the surface conductor 11 is performed by the solder 16, and a through hole 8 having a diameter smaller than the width of the surface conductor 11 is formed in the vicinity of the power supply lead pin 4. Since the power supply lead pin 4 is not inserted into the through hole 8, the diameter of the through hole 8 can be made smaller than the diameter of the lead pin through hole 7 and the width of the surface conductor 11. Thereby, the surface conductor 11 can be formed in the perimeter of the through hole 8, and formation of electroplating is attained. Therefore, the through hole 8 can be a through hole in which side metallization is formed, and the surface conductor 11 and the inner layer conductor 12 can be electrically connected.

  As described above, the power supply lead pins 4 can be arranged at a narrow pitch in the X direction, and even if an FPC bend occurs, stress application to the vicinity of the solder 16, the surface conductor 11, and the through hole 8 can be avoided. It becomes possible to maintain the electrical connection of the conductor 12.

  The surface conductor 11 is not limited to those provided on both sides in the Y direction of the lead pin through-hole 7, and can be electrically connected to the surface conductor 11 by the solder 16 on one side on the through hole 8 side. Has the effect of. Further, since the surface conductor 11 is arranged so as to extend in the Y direction which is perpendicular to the direction in which the power supply lead pins 4 are arranged, it is suitable for narrow pitch mounting, but is not limited to this. An arrangement extending in the direction is also possible. Further, the solder 16 is exemplified as a commonly used bonding material, and a material such as a conductive adhesive may be used.

  5 and 6 are configuration diagrams showing an optical module using the substrate according to Embodiment 1 of the present invention. As another example, FIG. 5 shows an enlarged view around the lead pin of FIG. FIG. 6 is a cross-sectional view taken along the line BB in FIG. In each figure, the same numerals indicate the same or corresponding parts. As shown in FIGS. 5 and 6, the reinforcing plate 13 may be provided on the upper surface of the dielectric layer 14, and a similar effect is achieved in that application of stress to the surface conductor 11 during FPC bending can be avoided. In addition, the shape of the reinforcing plate 13 is not limited to the shape formed on the entire circumference, and may be, for example, a U-shape, and may be any shape as long as the deformation of the surface conductor 11 can be prevented.

  Next, a dimension example of the surface conductor 11 according to Embodiment 1 of the present invention is shown in Example 1 of FIG. In Example 1 of FIG. 4, when the dimension a × b of the power supply lead pin 4 is 0.1 mm × 0.2 mm and the lead pitch f is 0.6 mm, the positional deviation of a general power supply lead pin is 0.1 mm. The diameter c of the lead pin through hole 7 is φ0.42 mm. The width d of the surface conductor 11 is 0.42 mm which is the same as the diameter c of the lead pin through hole 7. The diameter e of the through hole 8 can be formed as small as 0.2 mm because the power supply lead pin 4 is not inserted. Since the surface conductor 11 having a width of 0.11 mm or more can be formed on the entire circumference of the through hole 8, electroplating is possible and the through hole 8 can be formed. The gap g between the adjacent surface conductors 11 is secured to 0.18 mm, and the power supply lead pins 4 can be arranged in a narrow pitch without occurrence of a short circuit between the surface conductors 11 or a short circuit due to the solder 16.

On the other hand, a dimension example of the surface conductor 11 assuming a conventional configuration is shown in Example 2 of FIG. In the example 2 of FIG. 4, when the width d of the surface conductor 11 is larger than φ0.42 mm of the diameter c of the lead pin through hole 7 and is 0.62 mm capable of electroplating, the adjacent surface conductor layers 11 The gap g is -0.02 mm, and it can be seen that the surface conductors 11 are short-circuited. As described above, the relational expression of the diameter e of the through hole 8, the diameter c of the lead pin through hole 7, and the width d of the surface conductor 11 is expressed by the following expressions (1) and (2). Example 1 is characterized in that the relationship between c and d is different from Example 2 assuming a conventional configuration.
Example 1: e <d ≦ c (1)
Example 2: e <c <d (2)

  As described above, in the optical module using the substrate according to the first embodiment of the present invention, the electrical connection between the power supply lead pin 4 inserted into the lead pin through hole 7 and the surface conductor 11 is performed by the solder 16, and the lead pin penetration is performed. The electrical connection between the surface conductor 11 having a width equal to or smaller than the diameter of the hole 7 and the inner layer conductor 12 is performed by the through hole 8 having a diameter smaller than the width of the surface conductor 11. As a result, it is possible to achieve a narrow pitch mounting at a low cost by the lead pin connection that is easy to align.

Embodiment 2. FIG.
7 and 8 are block diagrams showing an optical module using a substrate according to Embodiment 2 of the present invention. FIG. 7 shows an enlarged view around the lead pin of FIG. 1 (a), and FIG. -C shows a sectional view of part C. In each figure, the same numerals indicate the same or corresponding parts. 7 and 8, the optical module using the substrate according to the second embodiment has an FPC structure in which solder 18 is added to the through hole 8 in addition to the configuration of the first embodiment. Since the other configuration is the same as that of the first embodiment shown in FIGS. 1 to 6, the description including the operation thereof is omitted. The solder 18 is exemplified as a commonly used bonding material, and a material such as a conductive adhesive may be used.

Next, the operation will be described. 7 and 8, the basic operation of the optical module using the substrate according to the second embodiment is the same as that of the first embodiment. However, in the second embodiment with the solder 18, the connection cross-sectional area between the through hole 8 and the surface conductor 11 is about 2 from the following formulas (3) and (4), as compared with the first embodiment without the solder 18. .78 times. In this example, the radius r of the through hole 8 is 0.1 mm, and the thickness t of the conductor layer is a general 0.018 mm. As a result, the resistance value in the conductor layer is lowered, which is effective in preventing voltage drop and temperature rise in a path through which a large current flows, such as a Peltier element.
No solder 18: 2πr × t = 2π × 0.1 × 0.018 = 0.011 mm ² (3)
18 solder: πr ² = π × 0.1 ² = 0.031 mm ² (4)

  As described above, in the optical module using the substrate according to the second embodiment of the present invention, the through hole 8 is filled with the solder 18 in addition to the same configuration as the first embodiment. As a result, in addition to the same effects as those of the first embodiment, the resistance value of the path is reduced, which is effective for preventing voltage drop and temperature rise, and as a result, has the effect of excellent transmission performance and reception performance and low power consumption. Play.

  In addition, in the board | substrate by Embodiment 1, 2 of this invention, although the structural example by the flexible printed circuit board which uses a polyimide for the material was shown, material and a structure are not restricted to this, For example, other than a polyimide A material may be used, or a so-called rigid printed board may be used, and the same effect can be obtained for narrow pitch mounting. In addition, when using the rigid printed circuit board which is not bent, it cannot be overemphasized that the reinforcement board 13 is omissible.

  Further, in the substrates according to the first and second embodiments of the present invention, the configuration example suitable for the narrow pitch mounting of the optical module such as the integrated optical module has been shown. In short, if the mounting is narrow pitch by lead pin connection, the same effect is obtained.

  Further, as described above, the optical module using the substrate according to the first and second embodiments of the present invention uses a lead pin connection method that can be easily aligned with a small package, and does not require additional processing for bending the lead pin, and is inexpensive. By performing narrow pitch mounting, it can be configured as an optical module. Thereby, the throughput of the narrow pitch mounting process is good, and there is an effect that it is possible to realize an economical, highly integrated and compact optical module. Furthermore, according to the optical module using the substrate according to the second embodiment of the present invention, there is an effect that it is possible to realize a module having excellent transmission performance or reception performance and low power consumption.

Embodiment 3 FIG.
FIG. 9 is a block diagram showing an optical communication system according to Embodiment 3 of the present invention. In each figure, the same numerals indicate the same or corresponding parts. In FIG. 9, the optical communication system according to the third embodiment includes an optical transmitter 21 and an optical receiver 22, and is optically connected via an optical transmission line 23 such as an optical fiber.

  The substrates according to the first and second embodiments of the present invention include an optical module as the above-described optical transmission module using the substrate, and a transmitter that transmits an optical signal converted from an electrical signal by the optical module. It can be configured as an optical transmission device 21 which is an optical communication device. As a result, the optical module is economical, highly integrated and compact as described above, and it has excellent transmission performance and low power consumption, thus realizing an economical optical transmitter with excellent installation and transmission performance. There is an effect of being able to.

  The substrates according to the first and second embodiments of the present invention include an optical module as the above-described optical receiver module using the substrate, and a receiver that receives an electrical signal converted from an optical signal by the optical module. The optical receiver 22 can be configured as an optical communication device provided. As a result, the optical module is economical, highly integrated and compact as described above, and it has excellent reception performance and low power consumption, thus realizing an optical receiver that is economical and excellent in installation and reception performance. There is an effect of being able to.

  In FIG. 9, the optical module using the substrates according to the first and second embodiments of the present invention transmits the optical signal transmitted from the optical transmission device 21 through the optical transmission path 23 and receives it by the optical reception device 22. You may make it apply to a communication system. Thereby, since the optical transmitter 21 and the optical receiver 22 have the above-described excellent economy and performance, there is an effect that an optical communication system that is economical and excellent in optical communication performance can be realized. In addition, the structure which applies the optical module using the board | substrate by Embodiment 1, 2 of this invention to either an optical transmitter or an optical receiver is also possible.

  DESCRIPTION OF SYMBOLS 1 Receptacle, 2 Package, 3 Ceramic, 4 Power supply lead pin, 5 Signal lead pin, 6 Flexible printed circuit board (FPC), 7 Lead pin through-hole, 8, 9 Through hole, 10 Signal land, 11 Surface conductor, 12, 12a Inner layer conductor, 13 Reinforcing plate, 14, 15 Dielectric layer, 16, 17, 18 Solder, 21 Optical transmitter, 22 Optical receiver, 23 Optical transmission line.

Claims (9)

  A first dielectric layer; a second dielectric layer; a plurality of inner layer conductors sandwiched between the first dielectric layer and the second dielectric layer; and the first dielectric A plurality of surface conductors provided on the surface of the layer, and a plurality of lead pin through holes provided through the first dielectric layer and the second dielectric layer, respectively. Each of the plurality of surface conductors, the first dielectric layer, each of the plurality of inner layer conductors, and the second dielectric layer are provided through the plurality of surface conductors and the plurality of inner layer conductors. And a plurality of through-holes for electrically connecting the two to each other.   The diameter of the plurality of lead pin through holes is c, the width of the plurality of surface conductors is d, and the diameter of the plurality of through holes is e, e <d ≦ c. Item 4. The substrate according to Item 1.   The flexible printed circuit board comprising a reinforcing plate provided on the surface of the first dielectric layer or the surface of the second dielectric layer so that the plurality of surface conductors are not deformed. The substrate according to claim 1 or 2.   The substrate according to claim 1, wherein an electrical connection material is filled in the plurality of through holes.   5. A plurality of lead pins are respectively inserted into the plurality of lead pin through holes of the substrate according to claim 1, and the plurality of inserted lead pins are electrically connected to the plurality of surface conductors by connecting members, respectively. Board connection structure, characterized in that it is connected electrically.   An optical module comprising the substrate connection structure according to claim 5.   An optical communication apparatus that transmits an optical signal or receives an optical signal using the optical module according to claim 6.   8. An optical communication system, wherein an optical signal transmitted from the optical communication apparatus according to claim 7 is transmitted through an optical transmission path, and the transmitted optical signal is received by an optical reception apparatus.   A first dielectric layer; a second dielectric layer; a plurality of inner layer conductors sandwiched between the first dielectric layer and the second dielectric layer; and the first dielectric A plurality of surface conductors provided on the surface of the layer, and a plurality of lead pin through holes provided through the first dielectric layer and the second dielectric layer, respectively. Each of the plurality of surface conductors, the first dielectric layer, each of the plurality of inner layer conductors, and the second dielectric layer are provided through the plurality of surface conductors and the plurality of inner layer conductors. A plurality of through holes for electrically connecting the plurality of lead pins, the plurality of lead pins being inserted into the plurality of lead pin through holes, and the plurality of inserted lead pins being inserted into the plurality of lead pins. Depending on the connecting material on the surface conductor Connection method of a substrate, characterized by electrically connecting.

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