JP2010258178A - Structure and method for mounting electronic component on circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure and a method for mounting an electronic component on a circuit board having the electronic component mounted on a circuit on the board, capable of preventing the positional deviation of the electronic component without deteriorating the mounting reliability of the electronic components and causing an increase in manufacturing cost. <P>SOLUTION: The length of a width direction of a pad 31b corresponding to a lead 11b not electrically used matches the length of a width direction of the lead 11b and the length of a lead-out direction of a lead corresponding to the pad 31b matches the length of a lead-out direction of the lead 11b. Thus, in soldering, a force acts to the lead 11b so that the position of the lead 11b matches that of the pad 31b by surface tension of the solder. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a mounting structure and mounting method of an electronic component on a circuit board, and more particularly, to an electronic circuit board that mounts an electronic component having a vacant electrode that is not electrically used among a plurality of electrodes on the circuit board. The present invention relates to a component mounting structure and a mounting method.

  In recent years, with the reduction in size and weight of electronic devices, circuit boards mounted on electronic devices and electronic components mounted on circuit boards have been reduced in size and weight, and when electronic components are mounted on circuit boards. The mounting accuracy required for this is also increasing.

  Accordingly, when mounting electronic components with solder or the like, it has become a big problem that the electronic components are displaced by sliding on the pads before the solder is cured.

  Therefore, in order to improve the mounting accuracy of electronic components, silk printing is performed around the contact points (pads) with the leads derived from the electronic components on the circuit board, and the leads derived from the electronic components are held by the silk. A method for preventing misalignment has been proposed (see, for example, Patent Document 1).

  There has also been proposed a misregistration prevention method in which an electronic component is pre-applied on a circuit board, the electronic component is mounted on the circuit board, and the electronic component is momentarily attached to the circuit board to prevent misalignment of the electronic component. Yes.

JP 2002-111184 A

  However, in the misalignment prevention method in which the silk printing is performed around the pad on the circuit board so that the lead derived from the electronic component does not deviate from the pad, the silk printing applied on the circuit board itself is misaligned. There is a problem that the effect of preventing the displacement of the lead of the electronic component is reduced.

  Further, the silk is applied to a position very close to the pad on the circuit board because of the property of preventing the displacement of the electronic component by the silk applied to the circuit board.

  Therefore, when the applied silk bleeds, the silk may be applied to the pad, and there is a problem that the mounting reliability of the electronic component may be reduced by the applied silk.

  In addition, in the method of preventing the electronic components from being displaced by instantly attaching the electronic components to the circuit board with the adhesive, if the electronic components are mounted in the state of being displaced in the first place, the electronic components will be instantly attached and the positional displacement will be caused. There is a problem that the electronic component is mounted on the circuit board as it is.

  Further, there has been a problem that the mounting cost increases due to an increase in the process of applying the adhesive and the material cost of the adhesive.

  The present invention has been made in view of the above points, and to a circuit board capable of preventing displacement of an electronic component without lowering the mounting reliability of the electronic component and without increasing the manufacturing cost. It is an object of the present invention to provide a mounting structure and mounting method for electronic components.

  In order to solve the above-described problem, the present invention provides a mounting structure in which an electronic component having a vacant electrode that is not electrically used among a plurality of electrodes is mounted on a circuit board, wherein the electrode is provided on the circuit board. A plurality of pads to be mounted are provided, and at least one of the pads on the circuit board corresponding to the vacant electrode is used as a position adjustment pad for the electronic component and corresponds to an electrode to be used electrically Provided is a structure for mounting an electronic component on a circuit board, wherein the electronic component is mounted on the circuit board by forming electrodes smaller than the pads on the circuit board and soldering electrodes to the respective pads.

  Thus, when mounting an electronic component having a vacant electrode that is not electrically used among a plurality of electrodes on the circuit board, the pad on the circuit board corresponding to the vacant electrode is provided on the circuit board. At least one of them is formed as a position adjustment pad of the electronic component smaller than the pad on the circuit board corresponding to the electrode to be used electrically.

  In the present invention, among the plurality of electrodes, there is provided a mounting method for mounting an electronic component having an unused electrode that is not electrically used on a circuit board, wherein the plurality of electrodes are placed on the circuit board. The pad on the circuit board corresponding to the electrode to be used electrically as at least one of the pads on the circuit board corresponding to the empty electrode is used as a position adjustment pad for the electronic component. It is formed smaller and formed in the same plane shape as the connection portion of the empty electrode that contacts the position adjustment pad, and the electronic component is mounted on the circuit board by soldering the electrode to each pad. Method of mounting electronic components on a circuit board

  Thus, when mounting an electronic component having a vacant electrode that is not electrically used among a plurality of electrodes on the circuit board, the pad on the circuit board corresponding to the vacant electrode is provided on the circuit board. At least one of them is used as a position adjustment pad for the electronic component, and soldering is performed on each lead in a state of being formed smaller than the pad on the circuit board corresponding to the electrode to be used electrically.

  According to the circuit board of the present invention, during soldering, force is applied to the empty electrode so that the position of the empty electrode and the corresponding pad coincide with each other due to the surface tension of the solder. Even when the electronic component is misaligned when mounting the component, the misalignment is corrected during soldering.

  Further, since a special process such as applying silk is not required, it is possible to prevent displacement of the electronic component at a low cost.

  In addition, since mounting reliability is not required for empty electrodes, misalignment can be prevented by pads corresponding to empty electrodes, and pads corresponding to other leads can be made sufficiently large. Reliability can be ensured.

It is a figure which shows a mode that an 8-pin electronic component is mounted in the circuit board of this Embodiment. It is a figure which shows a mode that the electronic component of 8 pins which has two empty electrodes on a circuit board is mounted.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram illustrating a state in which an 8-pin electronic component is mounted on the circuit board according to the present embodiment, and FIG. 1A is a diagram illustrating an 8-pin electronic component mounted on the circuit board. FIG. 1B is a diagram showing pads corresponding to 8-pin electronic components formed on the circuit board of the present embodiment, and FIG. 1C is formed on the circuit board of the present embodiment. It is a figure which shows the state which mounted the electronic component of 8 pins on the done pad.

  In FIG. 1, as an example, eight leads 11 connected to an electronic arithmetic circuit formed in the electronic component 10 are each an 8-pin IC (Integrated Circuit) derived from the main body 12 of the electronic component 10 as a circuit board 20. An example of mounting on the pad 31 formed in FIG.

  At this time, the lead 11b, which is a hatched lead, is not connected to the electronic arithmetic circuit formed in the electronic component 10 (hereinafter, the pins not connected to the electronic arithmetic circuit are vacant as described above). Called electrodes).

As shown in FIG. 1, the pad 31b is a pad having a special shape.
Specifically, the length in the width direction of the pad 31b matches the length in the width direction of the corresponding lead 11b. Further, the length in the lead-out direction of the lead corresponding to the pad 31b matches the length in the lead-out direction of the corresponding lead 11b.
That is, the sizes of the lead 11b and the pad 31b are completely the same.
More specifically, in the lead 11b, the width direction of the contact portion that contacts the pad 31b and the length in the lead-out direction of the lead 11b are the same. In the following description, it is assumed that the length in the width direction of the contact portion matches the length in the width direction of the lead 11 and the contact portion is provided at the leading end portion in the lead-out direction of the lead 11.

  When the lead 11 corresponding to the pad 31 is connected by placing the electronic component 10 at a predetermined position on the circuit board 20, the length in the width direction of the lead 11b and the length in the width direction of the pad 31b Therefore, even if the lead 11b is placed at a position displaced from the corresponding pad 31b, the lead-out direction of the lead 11b corresponds to the pad 31b due to the surface tension of the solder between the lead 11b and the corresponding pad 31b. A force acts so as to align with the lead-out direction.

In addition, since the length of the lead 11b in the lead-out direction matches the length of the lead in the lead-out direction corresponding to the pad 31b, even if the lead 11b is placed at a position shifted from the corresponding pad 31b, the lead 11b corresponds to the lead 11b. The force acts so that the width direction of the lead 11b is aligned with the width direction of the pad 31b by the surface tension of the solder between the pads 31b to be performed.
Since the force acting on the lead 11b also acts on the electronic component 10, the displacement of the electronic component 10 is eliminated. That is, the pad 31b functions as a position adjustment pad for adjusting the shifted position.

  Since the sizes of the lead 11b and the pad 31b are completely the same, a fillet is not formed between the lead 11b and the pad 31b, but the electrical connection reliability is not required for the empty electrode. The mounting reliability for the entire 10 is not lowered.

  Up to this point, the case where there is one empty electrode has been described as an example. However, if there are two or more empty electrodes, a pad having a special shape may be provided in accordance with the position of the empty electrode.

  FIG. 2 is a diagram showing a state where an 8-pin electronic component having two empty electrodes is mounted on a circuit board, and FIG. 2A is an 8-pin electronic component having two empty electrodes mounted on the circuit board. FIG. 2B is a diagram illustrating an electronic component, and FIG. 2B is a diagram illustrating a pad corresponding to an 8-pin electronic component having two empty electrodes formed on a circuit board, and FIG. It is a figure which shows the state which mounted the electronic component of 8 pins which has two empty electrodes in the pad formed in the board | substrate.

In FIG. 2, leads 11b and 11f, which are the hatched leads, are vacant electrodes.
As shown in FIG. 2, the pads 32b and 32f are specially shaped pads.
Specifically, the lengths of the pads 32b and 32f in the width direction match the lengths of the corresponding leads 11b and 11f in the width direction. Further, the lengths of the leads in the lead-out direction corresponding to the pads 32b and 32f are the same as the lengths of the leads 11b and 11f in the lead-out direction.
That is, the sizes of the leads 11b and 11f and the pads 32b and 32f are completely the same.

  When the lead 11 corresponding to the pad 31 is connected by placing the electronic component 10 at a predetermined position on the circuit board 20, the length in the width direction of the leads 11b and 11f and the width of the pads 32b and 32f Since the lengths in the directions match, even if the leads 11b and 11f are placed at positions shifted from the corresponding pads 32b and 32f, the surface tension of the solder between the leads 11b and 11f and the corresponding pads 32b and 32f A force acts so that the lead-out directions of the leads 11b and 11f are aligned with the lead-out directions of the leads corresponding to the pads 32b and 32f.

In addition, since the length in the lead-out direction of the leads 11b and 11f matches the length in the lead-out direction of the lead corresponding to the pads 32b and 32f, the leads 11b and 11f are placed at positions shifted from the corresponding pads 32b and 32f. Even so, force acts so that the width direction of the leads 11b and 11f is aligned with the width direction of the pads 32b and 32f due to the surface tension of the solder between the corresponding pads 32b and 32f.
Since the force acting on the leads 11b and 11f also acts on the electronic component 10, the displacement of the electronic component 10 is eliminated. That is, the pads 32b and 32f function as position adjustment pads for adjusting the shifted positions.

  Since the sizes of the leads 11b and 11f and the pads 32b and 32f are completely the same, no fillet is formed between the leads 11b and 11f and the pads 32b and 32f. Therefore, the mounting reliability for the entire electronic component 10 is not lowered.

10 Electronic Component 11 Lead 12 Body 20 Circuit Board 31, 32 Pad

Claims (3)

  Among the plurality of electrodes, a mounting structure for mounting an electronic component having an empty electrode that is not electrically used on a circuit board, wherein the circuit board is provided with a plurality of pads on which the electrodes are placed, At least one of the pads on the circuit board corresponding to the vacant electrode is formed smaller than the pad on the circuit board corresponding to the electrode to be electrically used as a position adjustment pad for the electronic component, An electronic component mounting structure on a circuit board, wherein an electrode is soldered to the pad and the electronic component is mounted on the circuit board.   The structure for mounting an electronic component on a circuit board according to claim 1, wherein the position adjustment pad has the same planar shape as a connection portion of the empty electrode that contacts the position adjustment pad.   Among the plurality of electrodes, a mounting method for mounting an electronic component having an unused electrode that is not electrically used on a circuit board, wherein the circuit board is provided with a plurality of pads on which the electrodes are placed, At least one of the pads on the circuit board corresponding to the empty electrode is formed as a position adjustment pad of the electronic component smaller than the pad on the circuit board corresponding to the electrode used electrically, Forming in the same plane shape as the connection portion of the empty electrode that contacts the position adjustment pad, soldering the electrode to each pad, and mounting the electronic component on the circuit board Electronic component mounting method.

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