JP2011138802A - Surface mounting electronic component with cover where creepage distance of printed circuit board is increased using fixing structure of cover - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make a surface mounting electronic component more compact by increasing a creepage distance between the conductive patterns formed on the side surface of a printed circuit board by using a fixing structure of a resin cover, thereby removing the cause of short circuit or leakage. <P>SOLUTION: In the surface mounting electronic component which is assembled as one electronic component by mounting electronic elements and electronic components on a small surface mounting printed circuit board, electrode recesses are formed on the side surface of the printed circuit board, conductive patterns which electrically connect the wiring pattern on the component mounting surface side of the printed circuit board with the electrode pattern on the backside are formed in the electrode recesses, fitting notches are provided on the side surface between the adjoining electrode recesses and protrusions provided on the lower side of a cover are fitted therein, and the creepage distance between the conductive patterns is increased by the fitting notches. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to the structure of a cover and a printed circuit board for a surface-mounting electronic component with a cover using a surface-mounted printed circuit board, and more specifically, formed on a side surface of the printed circuit board using a cover mounting structure. The present invention relates to a structure in which a creepage distance between the conductive patterns is increased to prevent short circuit and leakage.

  There is an electronic component assembly in which a circuit having a target function is formed on a small printed circuit board and supplied as a single component. For example, in a control DC / DC converter, a plurality of electronic elements and electronic components are mounted on a printed circuit board of about 20 mm square and formed as one electronic component assembly, and this DC / DC converter is a parent unit along with other components. Mounted on a printed circuit board.

  At present, the surface mounting type using a chip-type electronic element or electronic component (hereinafter referred to as a chip component) is mainly used as a printed circuit board for an electronic circuit, and the printed circuit board of the electronic component assembly is also a parent printed circuit board. However, surface mounting type printed circuit boards are often used without exception.

Surface mounting is a mounting method in which the planar terminal electrodes formed on the bottom and side surfaces of the chip component body and the wiring pattern of the printed circuit board are connected by soldering, and the electrode terminals to be inserted into the through holes of the printed circuit board are used as components. Since there is no need to provide a component, the size of the component can be reduced, and the printed circuit board on which the component is mounted can be further reduced by eliminating the need for an extra space for the through-hole for inserting the electrode terminal of the component to be mounted. It is.
In this surface mounting, the chip solder is temporarily fixed using cream solder applied by printing or the like on the printed circuit board pattern as an adhesive, and the cream solder is melted and solidified by a reflow process.

  When the electronic component assembly is used for surface mounting to support a surface mount type parent printed circuit board, terminal electrodes for soldering to the parent printed circuit board are formed on the back surface of the printed circuit board together with the wiring pattern of the printed circuit board. In many cases, a cover is attached to the component mounting surface side of the printed circuit board to protect circuits and components.

Here, in the surface mount type parent printed circuit board, the component main body is placed so as to be in contact with the printed circuit board, and therefore, between the printed circuit board and the electronic component, a conventional through-hole type printed circuit board is used. There is no space.
In other words, since the side surface of the cover cannot protrude below the back surface of the printed circuit board of the electronic component assembly, a structure is provided in which a claw or a step is provided near the lower end of the cover side surface and engaged with the lower surface of the printed circuit board. I can't.

  Therefore, as shown in FIGS. 9 and 10, there is a structure in which a cover 32 having the same outer shape as the printed board 31 is arranged on the printed board 31 (Patent Document 1). This surface-mounting electronic component is formed by pressing and firing a ceramic printed board 31 and a side wall 32a, and fixing a metal lid portion 32b to the upper side of the side wall 32a by bonding or the like.

The printed circuit board 31 and the cover 32 of Patent Document 1 are manufactured by the following process.
(1) Through holes such as electrode recesses 33 are formed in ceramic green sheets to be a plurality of printed boards 31 to form wiring patterns 34, terminal electrode patterns 35, and conductive patterns 36.
(2) A ceramic green sheet to be a plurality of side walls 32a is punched to form a space to be inside the side wall 32a, and a through hole to be a recess 37 is formed.
(3) The ceramic green sheet to be the printed circuit board 31 and the ceramic green sheet to be the side wall 32a are aligned, pressed, fired and fixed.
(4) The surface of the wiring pattern 34, terminal electrode pattern 35 and conductive pattern 36 is plated.
(5) Cut along a boundary line passing through the center of the through hole and divide into individual substrates.
(6) The component 41 is mounted on the printed circuit board 31.
(7) The lid portion 32b is fixed to the upper side of the side wall 32a by adhesion or the like.

Japanese Patent No. 3286717

  In the surface-mounting electronic component shown in FIGS. 9 and 10, the side surface 38 of the printed board 31 is provided with the concave portion 33 in which the conductive pattern 36 is formed, but the other portions are flat. In the surface mount electronic component, the wiring pattern is formed with a minimum insulation distance for miniaturization. Therefore, if the creeping distance between the conductive patterns 36 formed on the side surface 38 is short as described above, the pattern may be formed depending on the situation. There was a problem that it might cause short circuit and electric leakage. Further, there has been a problem that this distance needs to be further reduced in order to further reduce the size of the surface mount electronic component.

  The present invention has been made in view of the above-mentioned problems, and a creepage distance between conductive patterns formed on a side surface of a printed board using a resin cover mounting structure is increased to cause a short circuit or a leakage. An object of the present invention is to obtain a surface-mounting electronic component capable of further reducing the size of the surface-mounting electronic component.

  The invention of the present application is a surface mount electronic component assembled as a single electronic component by mounting an electronic element or electronic component on a small surface mount type printed circuit board, and an electrode recess is formed on the side surface of the printed circuit board. In this electrode recess, a conductive pattern that electrically connects the wiring pattern on the component mounting surface side of the printed circuit board and the electrode pattern on the back surface is formed, and a fitting notch is formed on the side surface between adjacent electrode recesses. The convex side provided on the lower side of the cover is fitted and the creeping distance between the conductive patterns is increased by the fitting notch.

  According to the invention of the present application, it is possible to increase the creepage distance between adjacent conductive patterns provided in the recesses on the side surface of the printed circuit board. There is an effect that downsizing can be performed. Moreover, since the cover mounting structure is used, positioning and orientation of the printed circuit board and the cover can be simultaneously performed.

It is the disassembled perspective view seen from the partially notched lower part which shows the electronic component for surface mounting by this invention. It is a perspective view which shows the printed circuit board and cover of the electronic component for surface mounting by this invention. It is a bottom view which shows the cover of the electronic component for surface mounting by this invention. It is a top view which shows the printed circuit board of the electronic component for surface mounting by this invention. It is a bottom view which shows the back surface of the printed circuit board of the electronic component for surface mounting by this invention. 1 is a partially cutaway front view showing a surface mount electronic component according to the present invention. 1 is a partially cutaway side view showing a surface mount electronic component according to the present invention. It is explanatory drawing which shows the positional relationship of a locking member and a printed circuit board. It is a disassembled perspective view which shows a prior art example. It is sectional drawing which shows a prior art example.

  An electrode recess is formed on the side surface of the printed circuit board, and a conductive pattern for electrically connecting the wiring pattern on the component mounting surface side and the electrode pattern on the back surface side of the printed circuit board is formed in the electrode recess, and adjacent electrodes A fitting notch is provided on the side surface between the recesses to fit the convex side provided on the lower side of the cover, and the creeping distance between the conductive patterns is increased by the fitting notch.

A configuration for attaching a cover to the electronic component for surface mounting according to the present invention and increasing the creeping distance between the conductive patterns 6 formed on the side surface of the printed circuit board 1 will be described with reference to the drawings.
FIG. 4 is a plan view showing a component surface of a printed circuit board 1 of an electronic component for surface mounting according to the present invention. Has been implemented.
A cutout 3 is formed at the center of the lower side surface of the printed board 1, and a fitting cutout 4 and an electrode recess 5 are formed on the left and right side surfaces.

In the electrode recess 5, a conductive pattern 6 for electrically connecting the wiring pattern on the component mounting surface and the electrode pattern 9 on the bottom surface side is formed.
The electrode recess 5 is formed by a long hole formed in a boundary portion between adjacent printed circuit boards 1 in a state before separation where a large number of printed circuit boards 1 are connected in the manufacturing process of the printed circuit board 1. The electrode recess 5 is formed in such a shape as a result of forming and separating the conductive pattern 6 by through-hole plating as described later, and the conductive pattern 6 is formed on the side surface of the printed circuit board 1 by other methods. If it can be formed, it does not have to be such a shape.

A flat or bar-like first locking member 14 is surface-mounted on the component mounting surface side of the notch 3 of the printed circuit board 1, and a U-shaped is faced down at the center of the upper edge of the drawing for soldering. A second locking member 15 having a leg extended left and right is surface-mounted. These first and second locking members 14 and 15 are not mounted so as to be closely aligned with the side surface of the printed circuit board 1, but have a slight margin d from the side surface as shown in FIG. Has been implemented.
The locking members 14 and 15 are usually made of a metal material in order to be soldered together with the other components 7 and 8 through a reflow process. A metal layer may be formed on the surface by plating or vapor deposition.
FIG. 5 is a bottom view showing the back side of the printed circuit board 1, and an electrode pattern 9 is formed as a terminal electrode of a surface mounting electronic component connected to the conductive pattern 6.

FIG. 3 is a bottom view showing the cover 2 that covers the printed circuit board 1.
The cover 2 is molded from a heat-resistant synthetic resin such as glass-filled plastic, and the first locking step 10 is located at the inner center of the side surface 18 on the lower side of the drawing along the lower edge of the side surface 18. A second locking step portion 11 is formed so as to protrude inwardly at a position in the center of the upper side surface 19 and spaced from the lower edge of the side surface 19 by the thickness of the printed circuit board 1. The second locking step 11 is tapered so as to become thinner toward the bottom of the cover 2.
The vertical positional relationship between the members 14 and 15 and the locking step portions 10 and 11 is such that the upper surface of the locking step portions 10 and 11 is not pressed against the lower surface of the locking members 14 and 15. It is set so that there is a slight gap.

By forming a notch 20 for exposing the conductive pattern 6 of the printed circuit board 1 at the time of soldering on the lower sides of the left and right side surfaces 17 of the cover 2, the cover 2 is fitted into the fitting notch 4 of the printed circuit board 1. Convex sides 12 are provided.
Positioning step portions 13 are provided at the four corners inside the cover 2 to contact the component surface of the printed circuit board 1 and perform positioning in the height direction.

Next, the manufacturing process of the electronic component assembly of Example 1 having the above configuration will be described. Since the manufacturing process of the printed circuit board 1 is not particularly different from that of a conventional surface-mount type printed circuit board, the description thereof is omitted.
First, as shown in FIGS. 2 and 4, the first locking member 14 and the second locking member 15 together with the electronic element 7 and the electronic component 8 are soldered to the printed circuit board 1 by surface mounting. The surface mounting here is not different from the conventional surface mounting, and the only difference is that the first and second locking members are mounted in the same manner as other components.

Next, as shown by a chain line in FIG. 6, the cover 2 is tilted so that the first locking step portion 10 of the cover 2 enters the notch 3 of the printed circuit board 1. The first locking member 14 is locked.
Subsequently, by pushing the opposite side of the cover 2 downward, the second locking step 11 is locked to the second locking member 15, and the positioning step 13 is the component surface of the printed circuit board 1. Is held in contact with. At this time, the side surface of the cover 2 on the second locking step portion 11 side is bent outward by the taper provided on the second locking step portion 11, so that the second locking step portion 11 is second. The engagement notch 4 of the printed circuit board 1 and the convex side 12 of the cover 2 are engaged with each other.

  As described above, since the recess by the fitting notch 4 is provided on the side surface of the printed circuit board 1, the creeping distance between the conductive pattern 6 provided in the electrode recess 5 and the adjacent conductive pattern 6 is equivalent to the depth. It becomes larger and the possibility of short circuit and leakage is reduced.

  The surface-mounting electronic components formed as described above are surface-mounted by being connected to the parent printed circuit board 23 with solder 24 as shown in FIG.

The locking members 14 and 15 are mounted with a slight margin from the side surface of the printed circuit board 1, and the positional relationship is set such that the lower side of the locking members 14 and 15 and the locking step portions 10 and 11 are not pressed against each other. The reason is as follows.
The surface mounting electronic component according to the present invention is supplied as one chip component and is surface mounted on the parent printed circuit board 23. At this time, there is a reflow process for soldering parts to the parent printed circuit board 23, and the solder of the printed circuit board 1 may be melted again by this reflow process. This is because if the stress is generated between the covers 2, the locking members 14 and 15 may be lifted or peeled off. In order to prevent such a situation from occurring, this is a configuration for preventing excessive stress from being generated in the locking members 14 and 15 and the cover 2.

  In the above embodiment, the cover 2 molded with a heat-resistant synthetic resin is used. However, the present invention is not limited to this, and a metal cover may be used when a shield is required. it can.

  DESCRIPTION OF SYMBOLS 1 ... Printed circuit board, 2 ... Cover, 3 ... Notch, 4 ... Fitting notch, 5 ... Electrode recessed part, 6 ... Conductive pattern, 7 ... Electronic element, 8 ... Electronic component, 9 ... Electrode pattern, 10 ... 1st Locking step 11, second locking step 12, convex side 13, positioning step 14, first locking member 15, second locking member 17, 18, 19,. Side of cover, 20 ... notch, 23 ... parent printed circuit board, 24 ... solder.

Claims (2)

In surface mount electronic components assembled as a single electronic component by mounting electronic elements and electronic components on a small surface mount printed circuit board,
Forming an electrode recess on a side surface of the printed circuit board;
In this electrode recess, a conductive pattern that electrically connects the wiring pattern on the component mounting surface side of the printed circuit board and the electrode pattern on the back surface side is formed,
A fitting notch is provided on a side surface between adjacent electrode recesses to fit a convex side provided on a lower side of the cover, and a creeping distance between the conductive patterns is increased by the fitting notch. Covered electronic components for surface mounting.   2. The electronic component for surface mounting with a cover according to claim 1, wherein the cover is formed of a non-metallic material such as a synthetic resin.

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