JP2002093851A - Mounting structure of board, electro-optical device, and electronic appliance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable mounting structure, where two boards are connected with each other by soldering them to each other, in a state of their being superimposed on each other. SOLUTION: In the mounting structure of boards for superimposing first and second boards 90, 3 on each other to connect them with each other, there are formed on the first board 90 a land 94 for connecting therewith the second board 3 and on the side surface of the second board 3, a conductive layer 324a connected with conductive patterns 322, 323 formed on the surface of the second board 3, to connect with each other the land 94 of the first board 90 and the conductive layer 324a of the second board 3 by soldering them to each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a first substrate and a second substrate.
The present invention relates to a mounting structure of a substrate which is connected by being superimposed on a substrate.

[0002]

2. Description of the Related Art A mounting structure for forming an electric circuit of an electronic device using a plurality of printed circuit boards is known. Generally, as a method of connecting printed circuit boards, connectors may be connected. In the case of a flexible printed circuit board, a structure called a pre-punch, in which a single-sided copper foil with its upper and lower surfaces exposed, is used for soldering.

[0003]

However, when soldering two printed circuit boards in an overlapping state, it is difficult to arrange terminals or lands to be soldered in a positional relationship suitable for soldering. Therefore, it was difficult to secure a highly reliable connection state.

For example, in a liquid crystal device, in order to reduce the size of an electronic device on which the liquid crystal device is mounted, a mounting method in which a printed circuit board is stacked in parallel on the back side of a liquid crystal panel may be adopted. In such a case, an illuminating device for a liquid crystal panel to be arranged on the back side of the liquid crystal panel, a so-called backlight illuminant, and a space for avoiding interference with the printed circuit board are required, and the liquid crystal device is enlarged. There is a problem. Such a problem is solved by soldering a mounting board of the light emitting body on the printed board,
At present, it is not possible to perform reliable soldering with sufficient strength in a state where the mounting board of the light emitting body and the printed board are overlapped.

An object of the present invention is to provide a highly reliable mounting structure which is soldered and connected to each other in a state where two substrates are superposed.

[0006]

A board mounting structure according to the present invention is a board mounting structure in which a first substrate and a second substrate are overlapped and connected to each other. A land for connection with the second substrate is formed, and a conductive layer connected to a conductive pattern formed on a surface of the second substrate is formed on a side surface of the second substrate; The land of the first substrate and the conductive layer of the second substrate are connected to each other by soldering.

According to the mounting structure of the substrate, the lands of the first substrate and the conductive layers provided on the side surfaces of the second substrate are connected to each other by soldering. The reliability of the connection can be improved. Note that as the second substrate, a so-called flexible printed board including a flexible base can be used.

[0008] A side surface of the second substrate may be formed along a periphery of a notch formed in the second substrate. By forming the notch in the second substrate, the area of the side surface is increased, so that the soldering strength can be increased. A notch may be formed so that a part of the side of the second substrate is depressed. As a shape that depresses a part of the substrate side of the second substrate, for example, a semicircular shape, a partial shape of a circle, a slit shape, or the like can be adopted. It is preferable that the notch is formed so that the peripheral edge of the conductive layer formed on the side surface covers the land of the first substrate. It should be noted that the “notch” of the second substrate merely means that the second substrate is formed in a shape like a notch, and the “notch”
It is not limited to the one formed through the step of notching the substrate.

[0009] The side surface of the second substrate may be formed along a peripheral edge of a through hole formed in the second substrate. By forming a through hole in the second substrate, a side surface can be formed at an arbitrary position. Any shape such as a circular shape and a rectangular shape can be adopted as the shape of the through hole. It is preferable that the notch is formed so that the peripheral edge of the conductive layer formed on the side surface covers the land of the first substrate.

By forming a notch or a through hole in the second substrate, it is possible to increase the area of the side surface at the soldered portion. Therefore, the strength of the solder can be increased by the notch or the through hole. it can.

[0011] The conductive pattern of the second substrate may be formed on a surface of the second substrate opposite to the first substrate.

[0012] The conductive pattern of the second substrate may be formed on a surface of the second substrate on a side facing the first substrate. A conductive pattern may be formed on both surfaces of the second substrate, and a structure in which the conductive patterns on both surfaces are connected by a conductive layer, that is, a so-called through hole may be formed. In this case, a common conductive layer is used to connect the conductive patterns on both surfaces, and the reliability of soldering can be improved.

In the electro-optical device according to the present invention, the first substrate and the second substrate are mounted so as to be superimposed substantially in parallel with an electro-optical panel. Item 1. It has a mounting structure of the substrate described in Item 1. The second substrate may be a flexible printed circuit board connected to the electro-optical panel, and the first substrate may have a light emitter for illuminating the electro-optical panel.

In this case, since the first substrate on which the light emitter is mounted can be mounted in a state of being superimposed on the second substrate, the space efficiency around the electro-optical panel can be improved. Further, since the light-emitting body can be controlled by connecting an external circuit to the terminal formed on the first substrate, it is not necessary to provide a terminal for connecting the external circuit to the second substrate.

[0015] The conductive layer may be formed by plating.

An electronic apparatus according to the present invention includes the above-described electro-optical device. As electronic equipment, for example,
Mobile devices such as mobile phones are included.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a substrate mounting structure according to the present invention will be described below with reference to FIGS. In the present embodiment, the substrate mounting structure according to the present invention is applied to a liquid crystal device.

FIG. 1 is a sectional view showing the structure of the liquid crystal device. As shown in FIG. 1, a liquid crystal device 100 includes a liquid crystal panel 1 having a first substrate 10 and a second substrate 20, and a plastic light guide disposed along the liquid crystal panel 1 on the back side of the liquid crystal panel 1. The liquid crystal panel 1 includes a body 2, a flexible printed board 3 connected to the liquid crystal panel 1, and an LED mounting board 90 on which an LED (light emitting diode) 92 as a light emitting body for illuminating the liquid crystal panel 1 is mounted. The flexible printed board 3 connected to the liquid crystal panel 1 is bent so as to go around the back side of the light guide 2. As described later, the LED mounting board 90 is a flexible printed board 3
Implemented above.

FIG. 2 is a perspective view showing the liquid crystal panel, and FIG. 3 is an exploded perspective view showing the liquid crystal panel in an exploded manner. Note that FIG.
3 and FIG. 3 schematically show electrode patterns and terminals, and actual electrodes and terminals are formed at a finer pitch than shown.

Referring to FIGS. 2 and 3, a liquid crystal panel 1 used in a passive matrix type liquid crystal display device mounted on an electronic device such as a mobile phone has a first gap made of glass or plastic or the like with a predetermined gap therebetween. Substrate 1
The second substrate 20 and the second substrate 20 are bonded to each other with a sealant 30 interposed therebetween. Liquid crystal is sealed in a liquid crystal sealed area 30A partitioned by the sealing material 30.

In the liquid crystal panel 1, the polarizing plate 5 is attached to the outer surface of the second substrate 20 with an adhesive or the like, and the polarizing plate 6 is also attached to the outer surface of the first substrate 10 with an adhesive or the like. .

A plurality of rows of electrodes 40 extending in parallel with each other are formed on the first substrate 10, and a plurality of rows of electrodes 50 extending in a direction perpendicular to the electrodes 40 are formed on the second substrate 20. Pixels for displaying an image are formed at intersections between the electrodes 40 and the electrodes 50.

At the end of the second substrate 20 on the substrate side 201 side, there is provided an area 25 projecting from the first substrate 10.
The terminal 80 is formed in the region 25. The terminals 80 include a terminal 81 connected to the electrode 40 formed on the first substrate 10 and a terminal 82 connected to the electrode 50 formed on the second substrate 20. As shown in FIG.
0 is connected to the terminal 82 so as to go around the outside of the area where the image is displayed. The electrode 40 extends to the terminal portion 60 formed at a position facing the end portion 70 of the terminal 81 of the first substrate 10. First substrate 10
And the second substrate 20, the sealing material 30
When the conductive particles contained in the terminal 70 are crushed between the end 70 and the terminal 60 of the terminal 81, the end 70 and the terminal 6
0 to the first substrate 10
Is connected to the electrode 40. Note that, as the conductive particles, particles obtained by plating the surface of elastically deformable plastic beads or the like are used.

FIG. 4 is a plan view showing the flexible printed circuit board 3. Components (not shown) such as a liquid crystal driving IC are mounted on the back surface of the flexible printed board 3 in FIG. As shown in FIG. 4, the flexible printed circuit board 3 has terminals 31 connected to terminals 80 of the liquid crystal panel 1.
And a connection part 32 for mounting the LED mounting board 90,
33 and terminals 34 and 35 for connection to an external circuit are formed. The terminals 31 and 34 are shown in FIG.
, And the terminal 35 is formed on the back surface in FIG. The holes 36a to 36c formed in the flexible printed board 3 are used for fixing the flexible printed board 3 with screws or the like at the time of mounting.

FIG. 5 shows an LED mounting board 90.
FIG. 5A is a perspective view of the LED mounting board 90, and FIG.
FIG. 5A is a view of the back surface of the LED mounting board 90 viewed from below in FIG.

As shown in FIG. 5A, the LED mounting board 9
In the case of 0, three LEDs 92 are mounted on the surface of the substrate 91 (the upper surface in FIG. 5A). FIG. 5 (b)
As shown in FIG. 5, on the back surface of the substrate 91, lands 94 connected to the anode of each LED 92 and lands 95 connected to the cathode of each LED 92 are formed. The lands 94 and 95 are formed, for example, as a part of a conductive pattern formed of copper or the like. Note that in FIG. 5B, LE
The illustration of the conductive pattern formed on the D mounting board 90 is omitted.

As shown by the dotted lines in FIG. 4, the LED mounting board 90 has the front surface of the flexible printed circuit board 3 (the front surface in FIG. 4) and the back surface of the LED mounting board 90, that is, lands 94 and 95. It is mounted with its surface facing.

FIG. 6 is an enlarged view of the periphery of the land 94 of the LED mounting board 90 from the back side of the flexible printed board 3 in FIG. 4, and FIG. 7 is a sectional view taken along the line VII-VII of FIG. As shown in FIGS. 4, 6, and 7, a substantially semicircular notch 321 is formed in the flexible printed circuit board 3 at the connection portion 32 of the flexible printed circuit board 3.
A conductive pattern 322 formed of copper or the like in a shape surrounding the notch 321 is formed on the back surface (the upper surface in FIG. 7) of the base film 37 of the flexible printed board 3.
However, a conductive pattern 323 formed of copper or the like in a shape surrounding the notch 321 is provided on the surface (the lower surface in FIG. 7) of the base film 37, respectively. In FIG. 6, the area of the conductive pattern 322 is indicated by oblique lines.

As shown in FIG. 7, gold (A) is formed on the surface of the flexible printed circuit board 3 around the notch 321.
The plating layer 324 is formed by u) or the like. Plating layer 3
Reference numeral 24 is also formed on the side surface of the flexible printed circuit board 3. The conductive pattern 32 formed on the opposite side of the base film 37 by the side surface region 324 a of the plating layer 324 formed on the side surface of the flexible printed board 3.
2 and the conductive pattern 323 are short-circuited.

As shown in FIGS. 6 and 7, the plating layer 3
24 and land 94 are connected by solder 325. At this time, since the solder 325 also adheres to the side surface area 324a of the plating layer 324, the flexible printed circuit board 3 and the LED mounting board 90 are firmly fixed, and in particular, the resistance to the force applied in the horizontal direction in FIG. it can.

The connection between the land 95 and the connection portion 33 is made in the same manner as the connection between the land 94 and the connection portion 32 described above.

By bending the flexible printed circuit board 3 on which the LED mounting board 90 is mounted, the LED 92 is housed in the housing 2a of the light guide 2 as shown in FIG. Light from the LED 92 is guided by the light guide 2 to the entire liquid crystal panel 1. The LED 92 is controlled by applying a predetermined signal to the terminal 34 or the terminal 35 of the flexible printed board 3, and there is no need to draw out terminals other than the terminals of the flexible printed board 3.

FIGS. 8 and 9 show another embodiment, and each of them is a sectional view corresponding to FIG. In the above embodiment, the conductive patterns formed on both sides of the flexible printed board 3 are short-circuited by plating.
The present invention is not limited to such a case.

In FIG. 8, the flexible printed circuit board 3A
Conductive pattern 32 only on the lower surface of base film 37A.
3A is formed, and a plating layer 324A is formed from the conductive pattern 323A to the side surface of the flexible printed circuit board 3. Solder 325A is plated layer 324A
And adhere to the land 94A on the substrate 91A. In the example shown in FIG. 8, since the solder 325A adheres to the plating layer 324A formed up to the side surface of the flexible printed circuit board 3A, a strong connection by soldering is possible as in the above embodiment.

On the other hand, in FIG. 9, the conductive pattern 322A is formed only on the upper surface of the base film 37B of the flexible printed circuit board 3B, and the plating layer 324B is formed from the conductive pattern 322A to the side surface of the flexible printed circuit board 3. Solder 325B is plating layer 3
24B and the land 94B on the substrate 91B.
In the example shown in FIG. 9, since the solder 325B adheres to the plating layer 324B formed up to the side surface of the flexible printed circuit board 3B, a strong connection by soldering is possible as in the above embodiment.

In the above embodiment, the case where the notch is formed in the flexible printed board (the second substrate) and the conductive layer is formed on the side surface around the notch has been described, but the conductive layer is formed on the side surface of the second substrate. Is formed, and it is not always necessary to form the notch. Also, instead of the notch,
The side surface of the second substrate may be formed at a connection site by soldering by forming a through hole in the substrate.

The present invention is not limited to application to a mounting structure of a liquid crystal device, but is widely applied to a mounting structure of an electronic circuit.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a structure of a liquid crystal device.

FIG. 2 is a perspective view showing a liquid crystal panel.

FIG. 3 is an exploded perspective view showing an exploded liquid crystal panel.

FIG. 4 is a plan view showing a flexible printed circuit board.

FIGS. 5A and 5B are diagrams showing an LED mounting board, wherein FIG.
FIG. 3B is a perspective view of the D mounting board, and FIG.

FIG. 6: LED from the back side of the flexible printed circuit board
The enlarged view which looked around the land of the mounting board.

FIG. 7 is a sectional view taken along line VII-VII of FIG. 6;

FIG. 8 is a cross-sectional view showing another embodiment.

FIG. 9 is a sectional view showing still another embodiment.

[Explanation of symbols]

 3 Flexible printed board (second board) 90 LED mounting board (first board) 94 Land 324A, 324B Plating layer (conductive layer) 324a Side area (conductive layer)

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H05K 3/34 501 H05K 3/34 501E F term (Reference) 2H089 HA40 QA02 QA11 QA12 QA13 RA05 TA04 TA07 TA18 2H092 GA33 GA41 GA42 GA44 GA49 GA50 GA51 GA57 GA60 NA25 NA27 NA29 PA05 PA13 5E319 AC03 AC11 AC20 CC33 GG03 5F044 NN12 NN18 5G435 AA16 AA17 BB12 EE40 EE43 EE47 KK05

Claims (10)

[Claims] 1. A mounting structure for a substrate, wherein a first substrate and a second substrate are overlapped and connected to each other, wherein a land for connection to the second substrate is provided on the first substrate. A conductive layer connected to a conductive pattern formed on the surface of the second substrate is formed on a side surface of the second substrate, and a land of the first substrate and a conductive layer of the second substrate are formed. A mounting structure for a substrate, wherein a conductive layer and a conductive layer are connected to each other by soldering. 2. The substrate mounting structure according to claim 1, wherein a side surface of the second substrate is formed along a peripheral edge of a notch formed in the second substrate. . 3. The mounting structure according to claim 1, wherein a side surface of the second substrate is formed along a peripheral edge of a through hole formed in the second substrate. . 4. The device according to claim 1, wherein the conductive pattern of the second substrate is formed on a surface of the second substrate opposite to the first substrate. A mounting structure for a substrate according to the item. 5. The semiconductor device according to claim 1, wherein the conductive pattern of the second substrate is formed on a surface of the second substrate on a side facing the first substrate. 1
A mounting structure for a substrate according to the item. 6. The substrate according to claim 1, wherein the first substrate and the second substrate are mounted so as to be superimposed substantially in parallel with an electro-optical panel. An electro-optical device having the mounting structure of (1). 7. The first substrate is a flexible printed circuit board connected to the electro-optical panel.
7. An electro-optical device having a substrate mounting structure according to claim 6, wherein a light emitting body for illuminating the electro-optical panel is mounted on the substrate. 8. The mounting structure for a board according to claim 1, wherein the conductive layer is formed by plating. 9. The electro-optical device according to claim 6, wherein the conductive layer is formed by plating. 10. An electronic apparatus comprising the electro-optical device according to claim 6. Description: