JP2009054929A - Junction structure of multiple boards, and junction method of multiple boards - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of jointing a plurality boards without complicating a process in jointing the plurality of boards nor getting low in joint strength between the boards by solder. <P>SOLUTION: Solder is mounted on a wiring land of a first board; then a second board is positioned and stacked on the first board while inserting the solder into an opening of the second board; and the solder in the opening of the second board is heated to joint a wiring land facing the opening of the second board to the wiring land of the first board by the solder. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a structure in which a plurality of substrates are joined and a method for manufacturing the structure.

  In recent years, it has been necessary to make electronic devices thinner. For example, in the field of optical disc devices, slim drives for notebook computers, which were generally 12.7 mm thick, have been reduced to 9.5 mm thickness and further to 7 mm thickness. In order to reduce the thickness of the optical disk device, for example, the height of the connector that connects the flexible wiring connected to each component such as a disk motor to the circuit board must be strictly limited.

  Japanese Laid-Open Patent Publication No. 2006-100522 describes a printed circuit board wiring structure in which two substrates are joined in a thickness direction without depending on a connector. In this structure, the diameter of the opening provided in the rigid printed wiring board is made smaller than the diameter of the opening provided in the flexible printed wiring board, and a land is provided only on the substrate bonding surface of the opening. An opening land provided in the flexible printed wiring board is welded from above the flexible printed wiring board with solder, and the rigid printed wiring board and the flexible printed wiring board are physically and electrically joined.

Japanese Patent Laid-Open No. 2002-94206 describes that the solder paste filled in the interlayer connection hole portion of the flexible printed wiring board is solidified to form the interlayer connection portion between the two wires.
Japanese Patent Laid-Open No. 2006-100522 JP 2002-94206 A

  In the printed circuit board wiring structure disclosed in Japanese Patent Application Laid-Open No. 2006-1000056, it is necessary to form holes in the rigid printed circuit board, and the openings formed in the rigid printed circuit board and the flexible printed circuit board There is a difficulty and hassle of having to properly align with the provided holes and filling the holes with solder, and furthermore, the amount of solder in the storage of the flexible printed circuit board is insufficient and the bonding strength between the boards There is also a risk of shortage. Japanese Patent Application Laid-Open No. 2002-94206 does not describe joining two substrates.

  It is an object of the present invention to provide a method for joining a plurality of substrates that does not complicate the steps for joining the plurality of substrates and further does not have insufficient soldering strength between the substrates. is there. Another object of the present invention is to provide a structure having excellent bonding strength between a plurality of substrates even when the openings are filled with solder.

  In order to achieve the above object, a bonding structure between a plurality of substrates according to the present invention includes a second substrate stacked on a first substrate, and the two substrates bonded together by a conductive bonding material. In the bonding structure, the first substrate includes a first wiring land that faces the opening from the second substrate and is formed flat on a surface thereof, and the second substrate includes the first substrate. An opening facing the wiring land, and a second wiring land formed around the opening, and the conductive bonding material filled in the opening is connected to the second through the opening. The first substrate and the second substrate are joined by going around the wiring land and joining to the second wiring land, and further joining to the plane of the first wiring land. It is what.

  Furthermore, the bonding method between the plurality of substrates according to the present invention includes a step of depositing solder on a wiring land of the first substrate, and the second method while inserting the solder into an opening of the second substrate. A step of aligning and overlapping the substrate with the first substrate, and a step of heating the solder in the opening of the second substrate, the wiring land facing the opening of the second substrate, The wiring land of the first substrate is joined with the solder.

  As described above, according to the present invention, there is provided a method for joining a plurality of substrates, which does not complicate the process for joining a plurality of substrates and further does not have insufficient solder joint strength between the substrates. Even if the openings are filled with solder, a structure having excellent bonding strength between a plurality of substrates can be provided.

  Next, embodiments of the present invention will be described with reference to the drawings. A method for bonding a plurality of substrates and a structure in which the plurality of substrates are bonded will be described as an example applied to a slim type optical disc drive.

  FIG. 1 is a perspective view illustrating an optical disk drive to which a joining structure according to the present invention is applied, being enlarged obliquely from the back side. In FIG. 1, reference numeral 14 denotes a flexible printed circuit board. The flexible printed board 14 connects each electronic component such as a spindle motor and a circuit board 22 on which a control circuit for controlling the electronic component is mounted. The end of the flexible printed board 14 on the circuit board side has a plurality of contacts 16, and the wiring land of each contact 16 is connected to the wiring land on the circuit board 22 side.

  FIG. 2 is a plan view of the flexible printed circuit board 14. The flexible printed circuit board has a metal pattern connected to each conductor of the wiring, and a contact 16 exists at the end of the metal pattern. In the center of the contact 16, an opening 18 that penetrates the flexible printed circuit board in the thickness direction is formed. The insulating film around the opening 18 is peeled off, and the wiring land 20 made of a doughnut-shaped planar conductor is exposed on the surface of the flexible printed board.

  FIG. 3 is a plan view of the circuit board 22. The circuit board includes a plurality of wiring lands 24 formed so as to fit the respective openings 18 of the flexible printed board, and a metal pattern 26 such as a copper foil connected to the wiring lands. An insulating material is coated on the metal pattern, and the wiring land 24 is exposed from the circuit board. Solder is piled up in advance on each wiring land. The wiring land 24 is formed with a circular shape on the surface of the circuit board 22. The solder is provided in the frame of the wiring land with a size equal to or smaller than the diameter of the wiring land.

  FIG. 4 is a cross-sectional view showing a state in which the flexible printed board 14 is superimposed on the circuit board 22. In FIG. 4, reference numeral 22 </ b> A denotes a circuit board main body, and reference numeral 24 denotes the above-described wiring land joined to the flexible printed board 14, and a metal pattern 26 is connected to the wiring land 24. The metal pattern 26 and the substrate body 22A are covered with an insulating resist 22B.

  The solder 30 is piled up on the wiring land 24 of the circuit board. When the flexible printed board 14 is overlaid on the circuit board 22, the solder 30 on the wiring land 24 enters the opening 18 of the flexible printed board so that the flexible printed board 14 and the circuit board 22 can be easily aligned. . When the flexible printed circuit board 14 is correctly aligned on the circuit board 22, the openings 18 are aligned with the wiring lands 24.

  As shown in FIG. 4, the flexible printed circuit board 14 has a flexible structure in which a conductor 21 made of metal is sandwiched between insulating layers 23 such as polyimide, and the insulating layer on the surface side around the opening 18 is circular. The wiring land 20 described above is formed by being peeled off.

  The mountain-shaped solder 30 is placed on the circuit board 22 and formed so as to have a height substantially equal to or slightly protruding from the upper end of the flexible printed board 14. The diameter of the wiring land 24 on the circuit board side 22 is substantially equal to the diameter of the opening 18 of the flexible printed board 14.

  Next, when the soldering iron 32 is applied to the solder 30 from the surface of the flexible printed circuit board 14, the solder 30 is melted and the side surface 20A of the wiring land facing the opening 18 of the flexible printed circuit board 14 as shown in FIG. It reaches the surface 20B of the land.

  Next, when the soldering iron 32 is separated from the flexible printed board 14, the solder is solidified and fixed to the wiring land 24 of the circuit board and the wiring land 20 of the flexible printed board. Thereby, the circuit board 22 and the flexible printed circuit board 14 are joined.

  Note that solder may be added to the opening 18 and the wiring land 20 when the soldering iron 32 is applied to the solder 30 having a mountain shape. By doing so, the amount of solder that wraps around the wiring land 20 of the flexible printed board 14 increases, and the adhesion of the solder to the wiring land 20 is further improved.

  6 and 7 are modifications to FIGS. 4 and 5. In this modification, the diameter (H1) of the opening 18 of the flexible printed circuit board is formed slightly larger than the diameter (H2) of the wiring land 24 of the circuit board.

  When the flexible printed circuit board 14 is overlapped on the circuit board 22 and soldered, the gap between the wiring land 24 on the opening 18 side of the circuit board 22 and the end of the back opening 18 on the flexible printed circuit board 14 The gas generated in the process of melting and solidifying the solder can be discharged from the minute gap (T) formed in the solder, and the solder wraps up to the side surface 24A of the land 24 of the circuit board 22 so that the circuit board and the flexible printed board are connected. The strength of solder to be joined is improved.

  Next, a second embodiment of the present invention will be described. This embodiment is different from the previous embodiment in that the first flexible printed board and the second flexible printed board are stacked on the circuit board 22 and these boards are joined by solder.

  There are the following three types of bonding between the circuit board, the first flexible printed board, and the second flexible printed board.

  The first is that the circuit board, the first flexible printed board, and the second flexible printed board are joined together, and the second is that the circuit board and the first flexible printed board are joined together. The circuit board and the second flexible printed board are not joined. Third, the circuit board and the second flexible printed board are joined, but the circuit board and the first flexible printed board are joined. It is not done.

  FIG. 8A is a plan view of the circuit board 22 used in the second embodiment. A plurality of wiring lands 24 and metal patterns 26 are formed on the circuit board 22 in the same manner as the circuit board (FIG. 3) described in the first embodiment.

  FIG. 8B is a plan view of the first flexible printed circuit board 14-1. A plurality of apertures 18 and wiring lands 20 are formed in the first flexible printed circuit board so as to align with the wiring lands 24 of the circuit board 22.

  FIG. 8C is a plan view of the second flexible printed circuit board 14-2. In the second flexible printed circuit board, a plurality of openings 18X and wiring lands 20X are formed so as to align with the wiring lands 24 of the circuit board 22 and the openings 18 of the first flexible printed circuit board 14-1. .

  As shown in FIG. 8, the area | region to which the same code | symbol A of the 1st flexible printed circuit board 14-1 and the 2nd flexible printed circuit board 14-1 is attached | subjected is 1st according to the above-mentioned 1st form. The area where the flexible printed circuit board 14-1 and the second flexible printed circuit board 14-2 are joined to the circuit board 22, and the area denoted by the same symbol B is in accordance with the second embodiment described above. The region where the bonding is performed only between the first flexible printed circuit board 14-1 and the circuit substrate 22, and the region denoted by the same reference symbol C is the number according to the third embodiment described above. 2 is a region where bonding is performed only between the flexible printed board 14-2 and the circuit board 22.

  When the first flexible printed circuit board 14-1 and the second flexible printed circuit board 14-2 are correctly stacked with respect to the circuit board 22, the above-described A, B, And the region C are bonded to the circuit board 22 according to the above-described embodiment.

  FIG. 9 is a cross-sectional view of the circuit board 22, the first flexible printed circuit board 14-1, and the second flexible printed circuit board 14-2 showing the process of obtaining the first bonding form described above. As shown in FIGS. 9A and 9B, solder 30 is preliminarily deposited on the circular copper foil wiring land 24 of the circuit board 22, and then the first flexible printed board 14- If 1 is piled up, as shown in (3) of Drawing 9, solder will enter into opening 18 of the 1st flexible printed circuit board.

  Next, as shown in (4), when the solder 30 is heated from above the first flexible printed circuit board 14-1 with the soldering iron, the solder is melted, and as described in the first embodiment, the solder is the first. One flexible printed circuit board 14-1 wraps around the surface of the wiring land 20 and solidifies. At this time, the solder 30 is added to the opening 18, and the solder having a mountain shape protrudes from the surface of the first flexible printed board 14-1.

  Next, as shown in (5), when the second flexible printed circuit board 14-2 is stacked on the first flexible printed circuit board 14-1, the solder 30 having a mountain shape becomes the second flexible printed circuit board. It enters into the opening 18X of 14-2.

  Since the diameter of the opening 18X of the second flexible printed circuit board 14-2 is larger than the diameter of the opening 18 of the first flexible printed circuit board 14-1, the first flexible printed circuit board 14-1 has a first interval between (4) and (5). The crests of the solder 30 whose diameter is increased by going around the wiring land 20 of the flexible printed board 14-1 can be accommodated in the opening 18 of the second flexible printed board 14-2. It is more desirable that the diameter of the opening 18X is substantially the same as the diameter of the wiring land 20.

  The tip of the mountain-shaped solder 30 is located at a position slightly protruding from the surface of the second flexible printed circuit board 14-2. Next, as shown in (6), when the soldering iron heats the solder 30, The distal end side region melts, and the melted solder wraps around the wiring land 20X of the second flexible printed board 14-2 and solidifies.

  As described above, the wiring land 24 of the circuit board 22, the wiring land 20 of the first flexible printed board 14-1, and the wiring land 20X of the second flexible printed board 14-2 are joined together by the solidified solder 30. And electrical connection between these wirings is also realized.

  Next, the 2nd form of joining is demonstrated based on FIG. 10 (1) to 10 (4) are the same as FIG. 9 showing the first form of bonding. (5) shows a state where the mountain-shaped solder 30 enters the opening 18X of the second flexible printed circuit board 14-2.

  Since no electrical connection is required between the second flexible printed circuit board 14-2 and the circuit board 22, the opening end 20A on the conductor side of the conductor opening 18X of the second flexible printed circuit board 14-2. Is receding toward the outside of the diameter of the opening 18X from the opening end 23A on the insulating layer side of the opening 18X of the insulating layer on the front and back surfaces of the substrate.

  The mountain-shaped solder 30 shown in (4) and (5) does not have a role of joining the second flexible printed board 14-2 to the first flexible printed board 14-1 and the circuit board 22. Furthermore, the height of the solder 30 may be such that it can enter the second flexible printed circuit board 14-2. If the height of the solder 30 does not disturb the structure, the solder 30 may protrude beyond the height of the insulating layer 23 of the flexible printed board 14-2.

  The second bonding mode is completed when the second flexible printed circuit board 14-2 is overlapped with the first flexible printed circuit board 14-1. At this time, the first form of joining and the third form of joining are completed when the solder 30 entering the second flexible printed board 14-2 is heated and solidified.

  Next, the 3rd form of joining is demonstrated based on FIG. As shown in (1), the first flexible printed circuit board 14-1 is overlaid on the circuit board 22 and then over the opening 18 of the first flexible printed circuit board 14-1 on the wiring land 24 of the circuit board 22. Then, the solder 30 is stacked at a height that exceeds the surface of the second flexible printed circuit board 14-2.

  Since the 1st flexible printed circuit board 14-1 is not joined with the circuit board 22, it does not have the wiring land similarly to the 2nd flexible printed circuit board 14-2 of (5) of FIG.

  The second flexible printed circuit board 14-2 is overlapped with the first flexible printed circuit board 14-1 so that the solder 30 having a mountain shape enters the opening 18X of the second flexible printed circuit board 14-2.

  Next, as shown in (3), when the solder 30 is heated with a soldering iron, the solder melts and wraps around the wiring land 20X of the second flexible printed circuit board 14-2, so that the solder is connected to the wiring land of the circuit board 22. 24 and the wiring land 20X of the second flexible printed circuit board 14-2 are joined together. The flexible printed board 14-1 may be a plurality of sheets instead of one.

  Unlike FIG. 3, the formation pattern of the wiring lands 24 of the circuit board shown in FIG. 8A is not uniform. That is, in the arrangement of each of the plurality of wiring lands 24, the relative intervals and positions of the wiring lands 24 are also nonuniform or irregular. In FIG. 3, there are a plurality of ways of overlapping the flexible printed circuit board with respect to the circuit board, but there is an advantage that the method of overlapping the flexible printed circuit board 14-1 with respect to the circuit board 22 in FIG. Because there is.

  According to the above-described embodiment, since the joint portion of the flexible printed circuit board to the circuit board can be formed without using a connector, the height of the joint portion can be clearly reduced as compared with the case where the connector is used. it can.

  In addition, since the solder in the opening wraps around the wiring land of the flexible printed circuit board and the solder is combined with the side surface and the plane of the wiring land, the wiring land formed on the circuit board and the wiring of the flexible printed circuit board are flat. The bonding strength between the circuit board and the flexible printed board is excellent while electrically and physically connecting the land.

  In addition, in order to form a junction part with a flexible printed circuit board in a circuit board, what is necessary is just to form the area | region where a flexible printed circuit board is joined to the flexible printed circuit board side edge part of a circuit board.

  In the above-described embodiment, the example in which the flexible printed board is bonded to the fixed board has been described. However, the board to which the present invention is applied is not limited thereto. Moreover, although the flexible wiring was demonstrated as an example as a flexible printed circuit board, it is not restricted to this.

  Furthermore, although the wiring lands 20 and 24 have been described as having a circular shape, the shape of the wiring land may be other than a circle, for example, a quadrangle or a polygon such as a triangle. It is desirable that they are almost the same.

  Furthermore, in the embodiment described above, the flexible printed circuit board is laminated on the circuit board after the solder is previously deposited on the wiring land of the circuit board. However, the solder is previously deposited on the wiring land. Alternatively, the flexible printed circuit board may be stacked on the circuit board, and then solder may be put into the opening 18 of the flexible printed circuit board.

1 is a perspective view illustrating an optical disk drive to which a joining structure according to the present invention is applied, being enlarged obliquely from the back surface thereof. It is a top view of a flexible printed circuit board. It is a top view of a circuit board. It is sectional drawing which shows the state which accumulated the flexible printed circuit board on the circuit board. It is sectional drawing of the state in which the flexible printed circuit board overlapped with the circuit board after completion | finish of soldering. It is sectional drawing which shows the modification of FIG. It is sectional drawing which shows the modification of FIG. (1) is a plan view of the circuit board 22 used in the second embodiment, (2) is a plan view of the first flexible printed board, and (3) is a plan view of the second flexible printed board. It is. It is sectional drawing of the circuit board, the 1st flexible printed circuit board, and the 2nd flexible printed circuit board which show the process of obtaining the 1st joining form. It is sectional drawing of the circuit board, the 1st flexible printed circuit board, and the 2nd flexible printed circuit board which show the process of obtaining the 2nd joining form. It is sectional drawing of the circuit board, the 1st flexible printed circuit board, and the 2nd flexible printed circuit board which show the process of obtaining the 3rd joining form.

Explanation of symbols

  14 Flexible printed circuit board, 20, 24 Wiring land, 18 Open hole, 22 Circuit board, 30 Solder.

Claims (8)

In a bonding structure between a plurality of substrates, in which a second substrate is stacked on a first substrate and both are bonded by a conductive bonding material,
The first substrate includes a first wiring land formed on a surface thereof,
The second substrate is
An opening facing the first wiring land;
A second wiring land formed around the opening;
With
The conductive bonding material filled in the opening wraps around the second wiring land from the opening to be bonded to the second wiring land, and is further bonded to the plane of the first wiring land. A bonding structure between a plurality of substrates, wherein the first substrate and the second substrate are bonded to each other.   The joint structure between a plurality of substrates according to claim 1, wherein a diameter of the opening is larger than a diameter of the first wiring land.   The bonding structure between a plurality of substrates according to claim 2, wherein the bonding material is bonded to a side surface of the first wiring land.   2. The bonding structure between a plurality of substrates according to claim 1, wherein the bonding material is bonded to a side surface facing the opening of the second wiring land and a plane of the second wiring land. A second substrate is stacked on the first substrate, a third substrate is stacked on the second substrate, and the first substrate, the second substrate, and the third substrate are connected to each other by a conductive bonding material. In the bonding structure of a plurality of substrates formed by bonding with
The first substrate includes a plurality of first wiring lands formed in a flat shape,
The second substrate includes a plurality of first openings facing each of the plurality of first wiring lands,
The third substrate includes a plurality of second openings facing each of the first openings,
In the bonding mode of the first substrate, the second substrate, and the third substrate, there is at least one mode of the first mode to the third mode,
In the first aspect, the first substrate, the second substrate, and the third substrate are bonded to each other with the bonding material,
In the second aspect, the first substrate and the second substrate are bonded to each other without bonding the third substrate to the first substrate,
In the third aspect, the first substrate and the third substrate are bonded to each other without bonding the second substrate to the first substrate,
In the first aspect, the conductive bonding material filled in the first opening and the second opening is formed around the first opening of the second substrate. The second wiring land and the third wiring land formed around the second opening of the third substrate, and further bonded to the plane of the first wiring land. A first substrate, a second substrate, and the third substrate,
In the second aspect, the conductive bonding material filled in the first opening and the second opening is bonded to the second wiring land, and further, the first wiring land By joining to a plane, the first substrate and the second substrate are joined,
In the third aspect, the conductive bonding material filled in the first opening and the second opening wraps around the third wiring land and bonds to the third wiring land. Furthermore, a bonding structure between a plurality of substrates, wherein the first substrate and the second substrate are bonded by bonding to the plane of the first wiring land. Depositing solder on the wiring land of the first substrate;
Aligning and overlapping the second substrate to the first substrate while inserting the solder into the apertures of the second substrate;
Heating the solder in the apertures of the second substrate;
A plurality of substrates joining method, wherein the wiring lands facing the opening of the second substrate and the wiring lands of the first substrate are joined by the solder.   A wiring land facing the opening of the second substrate is exposed on the surface of the second substrate, and the heated and melted solder wraps around the exposed surface of the wiring land and solidifies. The method of claim 6.   The method according to claim 6, wherein the third substrate is overlaid on the second substrate so that the solder in the opening of the second substrate enters the opening of the third substrate.