JPH11317568A - Reinforcing method for wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a reinforcing method, through which a flexible printed board mounted with electronic components is kept flat so as not to be bent and protected against breakages due to an external force. SOLUTION: Electronic components 2, 3, and 4 are mounted alternately on the front and rear of a flexible printed board 1, so as to make the mounting surfaces of the electronic components 2, 3, and 4 overlap partially with each other. A common electrode board, a circuit, solder and others are arranged on the intermediate space between the mounting planes of the electronic components 2 and 4 arranged in a line on the flexible printed board 1 or straddling the sideways extensions of the mounting planes so as to serve as reinforcing materials.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for reinforcing a wiring board, and more particularly, to a method for reinforcing a flexible printed board or a thin rigid board after mounting electronic components.
The present invention relates to a reinforcing method for maintaining flatness on a printed circuit board and a reinforcing method for making a ceramic substrate hard to be broken by an external force.

[0002]

2. Description of the Related Art In a memory board, that is, a wiring board on which a plurality of large electronic components such as a semiconductor device for memory are mounted, electronic components are placed at the same position on the front and back of the wiring board in order to increase the mounting density. Often worn. FIG. 7 is a side view in the case where the wiring substrate is a flexible printed circuit board. A substrate electrode 10 is provided so that the mounting position is symmetrical on the front and back of the flexible printed circuit board 1, and a lead 9 is fixed to this. Electronic components 2, 4 on the front side
Are mounted, and electronic components 3 and 5 are mounted on the back side. However, when such mounting is performed, due to an artificial external force in the assembling process, the electronic components 2, 3,.
As shown in FIG. 7, there is a problem that the flexible printed circuit board 1 is bent between adjacent electronic components 2 (3) and 4 (5) due to their own weights 4 and 5, and the flatness is not maintained. . 7 is an example, and may be slack depending on a method of fixing both ends of the flexible printed circuit board 1. When the flexible printed board 1 is bent, the electronic components 2, 3,.
4 and 5 come into contact with other mechanical components and electronic components on other substrates, causing trouble. Therefore, in order to avoid such a problem, a mechanism or a member for supporting the flexible printed circuit board 1 at the center thereof is provided in a case where the slackness occurs, for example. Is increasing.

[0003] These facts indicate that the wiring board has a thickness of, for example, 0.3 mm.
The same applies to a thin rigid printed circuit board of about 6 mm or less. FIG. 8 is a side view when the wiring substrate is a ceramic substrate 11 having a thickness of about 1 mm or less. The same reference numerals are given to the same components as those in FIG. When an external force acts on the ceramic substrate 11 as shown by an arrow F, the ceramic substrate 11 is easily cracked starting from the notch A, leading to cracking.

[0004] The following prior art has been disclosed for reinforcing a wiring board.

(Conventional Example 1) Japanese Patent Application Laid-Open No. 57-148391 discloses a "flexible printed circuit board and a method for manufacturing the same". Since the polyester base material is slightly stretched in the longitudinal direction, a manufacturing method that takes measures to prevent unnecessary shrinkage and elongation of the flexible printed wiring board manufactured from the element body 21 is taken. ing. FIG. 10 is a perspective view of a flexible printed wiring board in the course of manufacture. After the guide holes 28 and 29 are provided on both sides of the element body 21 and the insertion hole 31 for the electronic component is provided, etching and solder resist liquid are applied to the front and back of the hatched portions on both sides to etch and solder resist layers. After providing 33 and 34, an etching resist solution is applied to a portion to be a conductive foil 41 for a circuit and a portion to be a conductive foil 42 for reinforcement which forms a frame by connecting the etching and solder resist layers 33 and 34 on both sides. Thereafter, the circuit conductive foil 41 and the reinforcing conductive foil 42 are formed by immersion in an etching solution. And the electronic component 47 with the lead,
Flexible printing in which the leadless electronic component 48 is positioned and temporarily held in the specific guide hole 29, soldered, cut along the frame 43, and the electronic components 47 and 48 are connected as shown in FIG. The wiring board 51 is manufactured. During this time, the element body 21 is intermittently sent in the direction of arrow B by the engagement of the sprocket wheel 53 with the guide holes 28 and 29.

If the conductive foil is not left on the guide holes 28 and 29, the edges of the guide holes 28 and 29 are deformed,
Engagement with the sprocket wheel 53 becomes extremely unstable, and the element body 21 does not travel smoothly, or the electronic components 47, 4
8 is not accurately positioned for attachment. Further, even when the reinforcing conductive foil 42 between the frames 43 is not provided, the element body 21 expands and contracts, so that an accurate reference position cannot be obtained. That is, the guide holes 28 and 29
The conductive foil and the reinforcing conductive foil 42 remaining in the portion are only for smooth running and positioning of the element body 21 and are cut and separated from the final flexible printed wiring board 51. However, it does not reinforce the flexible printed wiring board 51 itself.

(Conventional example 2) The following substrate is disclosed in "double-sided flexible printed circuit board" disclosed in Japanese Patent Application Laid-Open No. 60-79795. That is, a flat package of electric circuit elements for control is mounted on the surface of a flexible substrate incorporated in a small space of precision equipment such as a camera, and a circuit pattern for checking the electric circuit elements is provided on another surface of the same surface. Attaching a reinforcing backing plate to the back side of the circuit pattern, or attaching the circuit pattern so that it does not damage the circuit pattern or the flexible substrate when checking the circuit pattern by contacting the probe pins, The flexible substrate is routed and arranged so as to be located on the surface of a flat member such as the device body and the ground plane.

However, attaching a backing plate involves an increase in the number of components and man-hours, and drawing a flexible substrate reduces the mounting density of components, increases the size of the flexible substrate, and increases the cost. A flexible board in which a flat package of elements is placed on the back side of the flexible board where the backing plate is placed, and a circuit pattern is attached to the front side of the flexible board opposite to the flat package is described as one example. Have been. In other words, the flat package and the circuit pattern attached to the front and back of this flexible substrate use the flatness of the flat package to prevent damage to the circuit pattern and the flexible substrate when the probe pins are brought into contact with the circuit pattern. This is not for maintaining the flatness of the flexible substrate.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and a method of reinforcing a flexible printed board or a thin rigid printed board on which electronic components are mounted so as not to bend, and an electronic component. It is an object of the present invention to provide a reinforcing method for preventing a ceramic substrate provided with a substrate from being easily broken by an external force.

[0010]

Means for Solving the Problems The above problem is solved by the structure of claim 1 or claim 3. To solve the problem, the invention of claim 1 comprises a plurality of electronic devices on both sides of a wiring board. When mounting components, the electronic components are alternately staggered on the front and back surfaces of the wiring board, and the mounting surface occupied by the electronic components on the front side on the wiring board and the electronic components on the back side are mounted on the wiring board. This is a method of arranging and mounting so that the occupied mounting surfaces partially overlap each other. By mounting the electronic components in this manner, the flexible wiring board is prevented from being bent and the flatness is maintained, and the brittle wiring board is prevented from being cracked by an external force.

According to a third aspect of the present invention, when a plurality of electronic components are arranged side by side in one direction on one or both surfaces of the wiring board, an intermediate portion between the respective mounting surfaces occupied by the adjacent electronic components on the wiring board. Or a method of arranging a reinforcing member on the wiring board so as to straddle a laterally extending portion of the intermediate portion. By arranging the reinforcing material in this manner, the flexible wiring board is prevented from being bent and the flatness is maintained, and the brittle wiring board is prevented from being cracked by an external force. The reinforcing material may be a substrate electrode shared by adjacent electronic components on the same surface of the wiring board. Further, a circuit provided on the mounting surface of the electronic component or the surface opposite thereto, or an interlayer circuit when the wiring board has a multilayer structure may be used. Further, a circuit simulated product which is manufactured in the same manner as the circuit but does not constitute the circuit may be used. Further, the solder may be placed on a circuit or a circuit dummy.

[0012]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows mounting of electronic components 2, 3, and 4 alternately in a zigzag pattern on the front and back surfaces of a flexible printed circuit board 1, and the electronic components 2 and 4 on the front surface occupy the flexible printed circuit board 1. The mounting surface A occupied by the surfaces A ₂ and A ₄ and the electronic component 3 on the back side on the flexible printed circuit board 1
₃ and is a side view when mounted to partially overlap each other, by attaching by placing the electronic component 2, 3, 4 in this manner, rigid wiring board is a flexible printed circuit board or thin In the case of a printed board, the flatness is maintained without bending, and in the case of a fragile ceramic substrate, the wiring board is not easily broken by external force.

FIG. 4 shows an intermediate portion B between the respective mounting surfaces A ₂ and A ₄ occupied on the flexible printed circuit board 1 by the electronic components 2 and 4 mounted on the surface of the flexible printed circuit board 1, or the side thereof. so as to straddle the extension towards the reinforcement member 7 to the flexible printed circuit board 1 _1, 7
FIG. 4 is a side view showing that ₂ and 7 ₃ can be provided, and as a reinforcing material, a substrate electrode shared by adjacent electronic components 2 and 4, a circuit manufactured in the same manner as the substrate electrode, and an interlayer of a multilayer substrate. May be an inter-layer circuit provided in the device. Further, a circuit simulated product that is manufactured in the same manner as the circuit and does not configure the circuit may be used. In addition, it may be solder placed on a circuit or a circuit dummy. Hereinafter, specific examples will be described.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Among the practically used wiring boards, there are a flexible printed board and a thin rigid printed board having a thickness of about 0.6 mm or less which are easily deformed. About 1mm thick
The following ceramic substrates are available. Hereinafter, the reinforcing method for these will be described sequentially by examples.

(Embodiment 1) FIG. 1 shows a structure in which electronic components 2, 3, and 4 are alternately arranged in a zigzag pattern on the front and back surfaces of a flexible printed circuit board 1, and respective leads 9 are fixed to a board electrode 10. FIG. 3 is a side view of the electronic component 2,
The positional relationship between 3 and 4 is that the mounting surface A ₃ occupied by the electronic component 3 on the back side on the flexible printed circuit board 1 and the mounting surface A ₂ occupied by the electronic components 2 and 4 on the front surface on the flexible printed circuit board 1. , and the A ₄ are arranged so as to partially overlap each other. FIG. 2 is a perspective view thereof.

By arranging and mounting the electronic components 2, 3, and 4 in this manner, for example, the electronic component 2 and the electronic component 4
Even when an external force acting to bend the flexible printed circuit board 1 acts between them, the electronic component 3 prevents bending, so that the flexible printed circuit board 1 does not bend as shown in FIG. Flatness is maintained.

Note that the electronic components 2, 3, and 4 are
As shown in the partial cross-sectional view of FIG. 9A, the substrate electrode 10 is made of a flexible strip having a thickness of about 0.5 mm or less, such as polyester or polyimide, which is a raw material of the flexible printed circuit board 1. Conductive foil adhered to both sides of an insulating substrate 19 made of a synthetic resin sheet of
For example, a portion other than the portion that becomes the substrate electrode 10 from the copper foil 20 is removed by a known etching technique, and the substrate electrode 10 is left on the insulating substrate 19.

(Embodiment 2) FIG. 3 shows electronic components 2, 3, 4 on the front and back surfaces of a ceramic substrate 11 made of, for example, alumina.
Are alternately arranged in a zigzag pattern, and each of the leads 9 is fixedly mounted on the substrate electrode 10 and is a side view. The electronic components 2, 3, and 4 are mounted in exactly the same manner as in FIG. 1 of the first embodiment except that the wiring substrate is a ceramic substrate 11. By arranging and mounting the electronic components 2, 3, and 4 in this manner, for example, even if there is a notch A between the electronic component 2 and the electronic component 4 and an external force F acts, the electronic component 3 can be mounted on the ceramic substrate. Since the deformation of the ceramic substrate 11 is prevented, the ceramic substrate 11 does not break. The substrate electrode 10 on the ceramic substrate 11 is formed by, for example, printing a thick film.

(Embodiment 3) FIG. 4 shows an intermediate portion between mounting surfaces A ₂ and A ₄ occupied on the flexible printed circuit board 1 by electronic components 2 and 4 mounted on the surface of the flexible printed circuit board 1. FIG. 9 is a side view showing that reinforcing members 7 ₁ , 7 ₂ , and 7 ₃ can be provided in a direction in which the electronic components 2 and 4 are arranged so as to straddle a portion B or an extended portion to the side thereof;
By arranging at least one of them as a reinforcing material, the flexible printed circuit board 1 can be prevented from being bent.

[0021] Among the above, the reinforcing member ₇₁ is intended to be created in the same manner as in the case of making a substrate electrode 10 on the surface of the flexible printed circuit board 1, the electronic component 2 and the electronic component 4 It may be a common substrate electrode or a part of the circuit of the electronic components 2 and 4. FIG. 5 is a perspective view showing the electronic components 2 and 4 mounted on the surface of the flexible printed circuit board ₁ together with a normal board electrode 10 and a reinforcing member 71 as a circuit. That is, in the circuit formed entirely, a portion that straddles the intermediate portion B between the mounting surfaces A ₂ and A ₄ of the electronic components 2 and 4 or the extended portion to the side thereof is provided. Contributes to reinforcement. Although in FIG. 5 shows a reinforcing member 7 ₁ as a circuit of the electronic components 2 and 4, without the need for reinforcement is a circuit, for example, a circuit mimetics are prepared in the same manner as the circuit Is also good. Although the wiring board in FIGS. 4 and 5 has been described as the flexible printed board 1 in the above description, bending can be similarly prevented even with a thin rigid printed board. When the wiring substrate is a ceramic substrate, cracks can be effectively prevented.

Further, on the back side of the reference stiffener 7 ₂ are flexible printed circuit board 1 to FIG. 4, similarly to the reinforcing member _71, i.e., is created in the same manner as in the method of making a substrate electrode 10 Things. Reinforcement 7 ₂ electronic parts 2 and 4
Independent not connected by plating are connected by the through hole 6 may be those constituting the circuit and plated-through holes 6 that are created by known techniques between the reinforcing member ₇₁ included in a circuit Circuit mimics may be used.

Further, the insulating substrate 19 of the flexible printed circuit board 1 shown in FIG. 9A is replaced with two insulating substrates 19 ₁ , like a flexible printed circuit board 1 ′ shown in a partial sectional view of FIG. 9B. shall insulating substrate 19 ₂ is glued, can be sandwiched conductive foil at a predetermined position therebetween, for example, a copper foil as a reinforcing material 7 _3. As shown in FIG. 4, the reinforcing member 7 _3, an intermediate portion between the electronic component 2 and the electronic component 4 each mounting surface A ₂ which occupies on the flexible printed circuit board 1, A ₄ B or the sides thereof, in so long as it cross the extension of, similarly to the reinforcing member 7 _2, plated through-holes 6 constitutes a circuit connected to the stiffener ₇₁ by, or plated through separate circuits which are not connected by holes 6 Any of the imitations is similarly effective.

[0024] (Embodiment 4) FIG. 6 is the same perspective view as Figure 5, but the common elements denoted by the same reference numerals, and the circuit as a reinforcing member _71, the electronic components 2 and 4 Mounting surface A ₂ ,
So as to straddle the extension to the side of the intermediate portion B between A _4, in which carrying as a reinforcing material 8 by a long solder fusion, solidification in the direction in which the electronic components 2 and 4 aligned. In FIG. 6, the solder as the reinforcing member 8 is placed on the circuit. However, the reinforcing member 8 may be placed on a circuit dummy created in the same manner as the circuit. In any case, the reinforcing members 7 ₁ , 7 ₂ , and 7 ₃ are used. It is equally effective.

That is, the above-mentioned reinforcing members 7 ₁ , 7 ₂ , 7
₃ and the reinforcing material 8 prevent bending of the rigid printed circuit board and effectively maintain flatness even when applied to a thin rigid printed circuit board in addition to the flexible printed circuit board 1. Further, the reinforcing members 7 ₁ , 7 ₂ , 7 ₃ and the reinforcing members 8
Is similarly effective even when the wiring substrate is a ceramic substrate, and prevents cracking of the ceramic substrate due to external force.

The method of reinforcing a wiring board according to the present embodiment is constructed and operates as described above. Of course, the present invention is not limited to this, and various modifications are possible based on the technical idea of the present invention. It is.

For example, in the present embodiment, the case where the electronic components 2, 3, and 4 are mounted in a single row as shown in FIG. 2, for example, has been exemplified. The present invention is also effectively applied to a case where electronic components are mounted side by side in multiple rows. Also, in the present embodiment, the case where the electronic components 2, 3, and 4 are arranged and mounted is illustrated. However, the method for reinforcing the wiring board of the present invention is such that the electronic components are displaced laterally and mounted. It is also effectively applied when it is done.

Further, in the present embodiment, in the case where the reinforcing member is provided, for example, as shown in FIG. 4, the case where the electronic components 2 and 4 are arranged and mounted on one surface of the wiring board has been described. The method of providing the reinforcing material of the present invention is also effective when the component 2 and the electronic component 4 are mounted on opposite surfaces.

In this embodiment, the DIP (dual in-line package) electronic components 2, 3, and 4 having a plurality of leads on both sides are illustrated. Quad Flat
Package) and other package electronic components,
It goes without saying that the method for reinforcing a wiring board of the present invention is effective.

[0030]

The method for reinforcing a wiring board according to the present invention is implemented in the above-described embodiment, and has the following effects.

When electronic components are mounted on a flexible printed circuit board, they are prevented from being bent between the electronic components and the flatness is maintained, so that troubles in contact with other materials are avoided without providing a separate support member. can do. In addition, even if the ceramic substrate on which the electronic component is mounted is subjected to vibration or impact, cracks are less likely to occur.

[Brief description of the drawings]

FIG. 1 is a side view of a flexible printed circuit board on which electronic components are mounted according to the method of the present invention.

FIG. 2 is a perspective view of the same.

FIG. 3 is a side view of a ceramic substrate on which electronic components are mounted according to the method of the present invention.

FIG. 4 is a side view showing locations where a reinforcing material can be provided on a flexible printed circuit board.

FIG. 5 is a perspective view showing a case where a circuit is provided as a reinforcing material on a flexible printed circuit board.

6 is a perspective view showing a case where solder is provided as a reinforcing material in the circuit of the flexible printed circuit board in FIG. 5;

FIG. 7 is a side view when electronic components are symmetrically arranged and mounted on the front and back of a flexible printed circuit board.

FIG. 8 is a side view when electronic components are symmetrically arranged and mounted on the front and back of a ceramic substrate.

9A and 9B are cross-sectional views illustrating a configuration of a flexible printed circuit board, where A illustrates a case where the insulating substrate has a single layer, and B illustrates a case where the insulating substrate is a multilayer structure with a reinforcing material interposed therebetween.

FIG. 10 is a perspective view of a flexible printed wiring board in the course of manufacture according to Conventional Example 1.

FIG. 11 is a plan view of a flexible printed wiring board manufactured according to Conventional Example 1.

[Explanation of symbols]

1 ... Flexible printed circuit board, 2 ... Electronic components,
3 ... Electronic component, 4 ... Electronic component, 6 ... Plating through hole, 7 ₁ ... Reinforcement (circuit), 7 ₂ ... Reinforcement (circuit), 7 ₃ ... Reinforcement (circuit), 8 ... reinforcing material (solder), 9 ... lead, 10 ... board electrode, 11 ... ceramic board, 19 ... insulating board, 20 ... copper foil.

Claims (8)

[Claims] When mounting a plurality of electronic components on both surfaces of a wiring board, the electronic components are alternately staggered on a front surface and a back surface of the wiring substrate, and the electronic components on the front surface are connected to the wiring. A method of reinforcing a wiring board, comprising arranging the electronic components such that a mounting surface occupying on a substrate and a mounting surface occupied by the electronic component on the back side on the wiring board partially overlap each other. . 2. The method according to claim 1, wherein the wiring board is a flexible printed board, a thin rigid printed board having a thickness of 0.6 mm or less, or a ceramic substrate. 3. When mounting a plurality of electronic components in one direction on one or both surfaces of a wiring board, an intermediate portion between respective mounting surfaces occupied by the adjacent electronic components on the wiring board, or a part thereof. A method of reinforcing a wiring board, comprising: arranging a reinforcing member on the wiring board so as to straddle an intermediate portion extending laterally. 4. The method for reinforcing a wiring board according to claim 3, wherein the reinforcing member is a board electrode used for mounting the adjacent electronic components on the same surface of the wiring board. 5. The electronic component according to claim 3, wherein the reinforcing member is a part of a circuit of the electronic component disposed on at least one of a front surface, a back surface, and inside the substrate. 5. The method for reinforcing a wiring board according to the above. 6. The method for reinforcing a wiring board according to claim 3, wherein the reinforcing material is a circuit imitation that is formed in the same manner as the circuit, but does not constitute the circuit. 7. The method according to claim 3, wherein the reinforcing member is solder placed on the circuit or the circuit dummy on at least one of the front surface and the back surface of the wiring board. The method for reinforcing a wiring board described in the above. 8. The method according to claim 3, wherein the wiring board is a flexible printed board, a thin rigid printed board having a thickness of 0.6 mm or less, or a ceramic substrate.