JP2010212542A - Circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circuit board which improves the strength of the board without having an effect on the performance of an electric component even though the board becomes thinner in response to a demand for densely mounting a component on a circuit board. <P>SOLUTION: The circuit board 1 in which electronic components 3 to 11 are mounted on the board 2 includes belt-like adhesive layers 20 and 21 on the board 2 along at least part of the peripheries 3a and 4a of the electronic components 3 and 4. The strength of the board 2 is improved without having an effect on the performance of the electronic components 3 and 4. The lifting of the electronic components 3 and 4 from the board 2 and the strain of the board 2 are prevented. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a circuit board on which components are mounted, and more particularly to a technique for improving mounting strength and increasing the rigidity of a board.

  In recent years, demands for miniaturization, high performance, and environmental protection measures are rapidly advancing in audio / video equipment and information equipment. In response to such demands, circuit boards with components mounted on the board are promoted to reduce the thickness of the board, to reduce the pitch of the circuit due to the high-density mounting of the parts, and to lead-free as an environmental measure. Therefore, the strength of the circuit board is required to be improved.

  As a conventional technique related to the strength of the circuit board, on the solder resist layer, which is the outermost protective layer of the printed wiring board, against the problem that cracks are likely to occur in the solder resist layer under conditions such as heat cycle, Furthermore, a method of covering by forming a reinforcing layer having a thickness of about 5 μm to 50 μm made of a resin containing a thermoplastic resin is disclosed. (For example, see Patent Document 1).

In addition, in a card-like electronic device such as a memory card, a tape-like electronic device that surrounds the mounting part of the electronic component on the circuit board is provided for the problem that the circuit board is warped or distorted by heat applied during reflow. A method for attaching a heat-resistant member is disclosed (for example, see Patent Document 2).
Japanese Patent Laid-Open No. 11-251724 JP 2000-200330 A

  However, a tape or the like has a problem that bending rigidity is small as a reinforcing member, and a necessary effect cannot be exhibited with respect to a problem in strength of the circuit board. In addition, when bonding electronic parts using epoxy resin or the like to reinforce the circuit board, the bonded part affects the oscillation frequency and performance of the oscillation parts such as ceramic capacitors. This may cause functional degradation or failure of the parts. In addition, there is a problem that the substrate is deformed by stress such as an epoxy resin at the bonded portion, and the electronic component is easily peeled off from the substrate.

  An object of the present invention is to provide a circuit board that improves the strength of a substrate without affecting the performance of an electronic component even if the substrate is thinned. is there.

  In order to achieve the above-described object, a circuit board according to the present invention is a circuit board in which an electronic component is mounted on a substrate, and is a strip-shaped adhesive on the substrate along at least a part of the peripheral edge of the electronic component. With layers. With such a configuration, the board strength can be improved without affecting the performance of the electronic component, and the circuit can be mounted in a small size and with high density by preventing the peeling of the electronic component from the board and the distortion of the board. A substrate can be realized.

  Furthermore, it is desirable to provide the belt-like adhesive layer with a predetermined distance from the peripheral edge of the electronic component. According to such a configuration, the strength of the substrate can be improved without affecting the mounting conditions and performance of the electronic component to be mounted.

  Furthermore, it is desirable that the electronic component is an oscillation component. According to such a configuration, it is possible to realize a high-quality and high-function circuit board without affecting the oscillation frequency or the like even for the oscillation component.

  According to the present invention, it is possible to improve the substrate strength without affecting the performance of the electronic component, and to prevent the peeling of the electronic component from the substrate and the distortion of the substrate, and to achieve a small and high-density mounting circuit. A substrate can be realized.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 and 2.

(Embodiment)
First, the configuration of the circuit board in the embodiment of the present invention will be described. FIG. 1 is a plan view showing a main configuration of a circuit board according to an embodiment of the present invention, FIG. 2 is a diagram showing details of a portion A in FIG. 1, and FIG. 2 (b) is a cross-sectional view taken along line BB in FIG. 2 (a).

  In FIG. 1, a circuit board 1 has a printed wiring board (hereinafter abbreviated as a board) 2 on which electronic components 3 to 11 are mounted at predetermined positions. The substrate 2 has a known structure, and includes a solder resist layer and the like as outermost layers on the front and back surfaces. Of the electronic components 3 to 12, the electronic component 3 and the electronic component 4 are oscillation components such as a ceramic capacitor, and the others are electronic components such as a resistor and a CPU.

  Further, as shown in FIGS. 1 and 2, strip-like adhesive layers 20 and 21 are provided on the substrate 2 along at least a part of the peripheral edge 3 a of the electronic component 3 and the peripheral edge 4 a of the electronic component 4. . As shown in FIG. 2, connection terminals 3c and 3d are extended from the peripheral edge 3a of the electronic component 3 and connected to a wiring pattern (not shown) of the substrate 2 by bonding or the like. Further, the substrate 2 has a thin thickness T of several tens to several hundreds of μm in order to make the entire circuit board 1 thin.

  The electronic component 3 includes a belt-like adhesive layer 20 formed by protruding like a bank on the substrate 2 along one side of the peripheral edge 3a, and the electronic component 4 surrounds the four sides of the peripheral edge 4a. Thus, a belt-like adhesive layer 21 formed by protruding like a bank is provided. Further, the belt-like adhesive layer 20 is formed on the substrate 2 separated from the peripheral edge portion 3a by a predetermined distance S1, and the belt-like adhesive layer 21 is also separated from the peripheral edge portion 4a of the electronic component 4 by a predetermined distance S2 on the substrate 2. Is formed. In addition, as shown in FIG. 2B, these strip-like adhesive layers 20 and 21 have a shape having a substantially semicircular or substantially semicircular cross section.

  The band-shaped adhesive layers 20 and 21 are formed by mounting a thermosetting resin on a solder resist layer (not shown) which is the outermost layer of the substrate 2 after mounting the electronic components 3 to 11 on the substrate 2. It is formed by coating at the position of and then heat-curing. As the material of the belt-like adhesive layers 20 and 21, a material having a high resin hardness after fixing, such as an epoxy compounded resin, is desirable. In the embodiment of the present invention, the circuit board 1 uses a known thermosetting epoxy resin, and the board 2 and the belt-like adhesive layer 20 are made of the same material as the board 2 and the belt-like adhesive layers 20 and 21. , 21 is reduced in physical property difference.

  That is, according to the embodiment of the present invention, the band-shaped adhesive layers 20 and 21 increase the rigidity of the substrate 2 having a small thickness in the region where the electronic component 3 and the electronic component 4 are mounted, thereby increasing the bending strength of the substrate 2. It becomes possible to improve. Therefore, the distortion that occurs when the electronic component 3 or the electronic component 4 is directly bonded to the substrate 2 with an adhesive, the vibration that occurs because the substrate 2 is thin, and the electronic components 3 and 4 that are generated due to the distortion. The peeling from the substrate 2 can be prevented.

  In the circuit board 1 according to the embodiment of the present invention, of the electronic components 3 to 12, the band-shaped adhesive layer 20 is formed in the region of the peripheral portion 3 a and the peripheral portion 4 a of the electronic component 3 that is an oscillation component and the electronic component 4. 21 are provided.

  When the electronic component mounted on the circuit board 1 is an oscillating component, the method of reinforcing the substrate by directly bonding the peripheral edge of the electronic component and the substrate with a bonding material, characteristics such as the transmission frequency of the electronic component Changes under the influence of the substrate and bonding material.

  On the other hand, in the circuit board 1 in the embodiment of the present invention, the strip-like adhesive layers 20 and 21 for increasing the rigidity of the board 2 are formed on the board 2 so as to be separated from the electronic component 3 or the electronic component 4. . At that time, the length L, height H, width W, or separation distances S1 and S2 of the belt-like adhesive layers 20 and 21 are determined according to the substrate conditions and the physical properties of the belt-like adhesive layers 20 and 21 and the electronic component 3. 4 and the like can be arbitrarily optimized. Of the above-mentioned distances, the length L depends on the size of the electronic component 3 or 4 including the belt-like adhesive layer 20 or 21. For example, it is preferable that the length L of the strip-shaped adhesive layer 20 in the electronic component 3 is equal to or longer than the length facing the strip-shaped adhesive layer 20 of the electronic component 3, and the upper limit is that of the adjacent electronic component (electronic component 5 or 10). Can be determined depending on the distance. Since the width W also depends on the distance from the adjacent electronic component, it cannot be defined unconditionally. However, if the width W is 0.5 mm or more, an effect is seen. Among the separation distances S1 and S2, the distances that are most effective are the separation distances S1 and S2. The shorter the distance, the higher the effect is, and about 0.5 mm to 4 mm. In this embodiment, the separation distances S1 and S2 are 3 mm. It was. In addition, the effect was seen if the height H was about the mounting height of the electronic components 3 and 4. As a result, even if the belt-like adhesive layers 20 and 21 are formed on the substrate 2, a circuit having high bending rigidity even if the substrate 2 is thin without affecting the characteristics such as the oscillation frequency of the electronic components 3 and 4. The substrate 1 can be realized.

  Moreover, about the shape of the strip | belt-shaped adhesive bond layers 20 and 21, the length direction is made into linear shape, and the cross section is made into the shape provided with the substantially semicircle or the substantially semicircle part. Thus, by making the cross-section of the strip-shaped adhesive layers 20 and 21 into a shape having a large cross-sectional second coefficient, the bending rigidity of the strip-shaped adhesive layers 20 and 21 can be increased, and the rigidity of the substrate 2 can be increased.

  On the other hand, in forming the band-shaped adhesive layers 20 and 21, after mounting the electronic components 3 to 11 on the substrate 2, for example, scanning is performed while discharging a thermosetting epoxy resin or the like from a nozzle. Can be formed. Therefore, the electronic component mounting process is not affected and can be easily formed with simple manufacturing equipment.

  As described above, the belt-like adhesive layer 20 is disposed by arranging the belt-like adhesive layers 20 and 21 having a large secondary coefficient along the peripheral edges 3a and 4a of the electronic components 3 and 4 mounted on the substrate 2. , 21 can be increased in rigidity in the substrate 2. Thereby, generation | occurrence | production of distortion can be relieve | moderated with respect to the impact applied to the board | substrate 2, the vibration generate | occur | produced from an oscillation component, etc., and generation | occurrence | production of destruction or peeling of the mounted electronic component can be prevented. In addition, by optimizing the shape, size, and arrangement position of the belt-like adhesive layers 20 and 21, it is possible to prevent functional degradation such as a change in oscillation frequency in the oscillation component. In addition, even with respect to electronic components other than the oscillation component, the impact resistance of the component can be improved by increasing the rigidity of the substrate 2 in the vicinity of the electronic component. As a result, it is possible to realize a circuit board 1 on which high-quality electronic components that can be mounted with a high degree of honey are mounted, and it is possible to realize a circuit board suitable for small and high-performance video equipment and information equipment.

  Note that the shape, size and arrangement of the belt-like adhesive layer can be arbitrarily optimized according to the design requirements of the circuit board 1. That is, a method of disposing a plurality of linear strip adhesive layers on the periphery of an electronic component, a method of disposing and printing strip adhesive layers in an island shape, and a curved strip adhesive layer. Is possible.

  The circuit board of the present invention is useful as a circuit board for small, high-performance video equipment and information equipment that require high-density mounting of components.

The top view which shows the main structures of the circuit board in embodiment of this invention The figure which shows the detail of the A section in FIG.

DESCRIPTION OF SYMBOLS 1 Circuit board 2 Board | substrate 3,4,5,6,7,8,9,10,11,12 Electronic component 3a, 4a Peripheral part 3c, 3d Connection terminal 20,21 Band-shaped adhesive layer

Claims (3)

A circuit board having electronic components mounted on a board,
A circuit board comprising a belt-like adhesive layer on the substrate along at least a part of a peripheral edge of the electronic component. The circuit board according to claim 1, wherein the belt-like adhesive layer is provided at a predetermined distance from the peripheral edge of the electronic component. The circuit board according to claim 1, wherein the electronic component is an oscillation component.

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