JPH11177223A - Electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To check the joining condition of componenta with a printed wiring board for an electronic component which is difficult to check by visual or X-ray examination, and prevent warp of the electronic component caused by thermal stress. SOLUTION: An electronic component 1 has terminals 3c and 3d for checking a joining state with a printed wiring board. The terminals 3c and 3d are alternately connected with a pattern wiring 4. A measuring pad to be joined with a measuring device for measuring continuity resistance is provided. After the electronic component 1 is mounted on the printed wiring board, the continuity between the examination pads is detected easily so as to check the joining state between the electronic component 1 and the printed wiring board. At the same time warp of the electronic component caused by thermal stress can be prevented by the pattern wiring 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improving the reliability of electronic components mounted on a printed wiring board.

[0002]

2. Description of the Related Art Conventionally, a visual method has been employed as one of the methods for inspecting the bonding state of terminals of an electronic component mounted on a printed wiring board by a general bonding method such as a reflow soldering method. . This is to visually inspect the bonding state between the terminal of the electronic component in the visible range and the corresponding solder pad on the printed wiring board.

However, with the rapid development of miniaturization in recent years, electronic parts whose terminals are not in the visible range have been manufactured. 13 and 14 show, for example, Ball Grid Ar
FIG. 11 is a diagram showing a conventional example of an electronic component such as a ray type, which is not in a visible range because a terminal is hidden by the electronic component itself. 13 and 14, reference numeral 1 denotes an electronic component having a precision circuit therein, which is entirely sealed and molded with a resin such as an epoxy resin, and has a substantially square shape in this example. Numeral 2 is a spherical terminal provided on the bottom surface 1a side of the electronic component 1 for performing the original function of the electronic component, and is arranged vertically and horizontally at equal intervals. Reference numeral 5 denotes a printed wiring board on which the electronic component 1 is mounted on the upper surface, and reference numeral 7 denotes a solder pad to which a terminal 2 of the electronic component 1 to be mounted and mounted on a predetermined area surface of the printed wiring board 5 is joined. When such an electronic component 1 is mounted on the printed wiring board 5 as shown in FIG. 13, the visual inspection becomes difficult because the terminal 2 is hidden by the electronic component itself. In such a case, a method of inspecting the bonding state between the electronic component and the printed wiring board using X-rays has been adopted, as introduced in page 42 of the surface mounting technology, March 1997 issue. I have.

[0004] As another method, as described on page 48 of the same document, it is difficult to inspect the appearance, and a method of optimizing the bonding conditions so as not to inspect the bonding state has been adopted.

[0005] On the other hand, in mounting electronic components on a printed wiring board, it is required that the electronic components themselves have no warpage (small). Since a stress due to heating is applied, for example, a heat treatment using a heating furnace such as a reflow furnace or an oven for solder reflow, warpage of the electronic component occurs.

However, even in these cases, Bal
l In the case of a Grid Array type electronic component, a self-alignment effect at the time of reflow (soldering) can be effectively obtained, so that it is not necessary to have a strict mounting position accuracy. It is enough. Therefore, as described in JP-A-59-182595, it is unnecessary to confirm the positional accuracy by using an electronic component and an inspection bump provided on a printed wiring board before reflow.

[0007]

As described above, as described above, Bal
In mounting a 1 Grid Array type electronic component, it is more important to determine whether the terminals of the electronic component are securely joined after reflow than to the positional accuracy at the time of mounting the electronic component.

FIGS. 11 and 12 show a conventional electronic component inspected by X-rays. Figures 11 and 1
In 2, reference numeral 8 denotes a pattern wiring for electrically connecting the pads 7 on the printed wiring board 5, and is formed of a conductor such as copper. Reference numeral 10 indicates the direction of X-ray irradiation, and reference numeral 11 indicates a defective terminal in a bonded state. In such X-ray inspection, FIG.
Even if the terminal 11 is not joined due to its outer diameter being smaller than the other terminals like the terminal 11, the electronic component 1 and the printed wiring board 5 are moved in the direction of arrow 10, that is, on the surface of the electronic component 1. As seen in the transparent state in the direction, the pad 7 on the printed wiring board 5 and the terminal 2 of the electronic component 1 can be seen only in an overlapping state as shown in FIG. 12, and it is impossible to determine a defect in the joint state of the terminal 11. .

Further, surface mounting technology, March 1997 issue 42
As described on the page, if the printed wiring board is a multilayer board, not only the terminals of the electronic components and the pads on the printed wiring board, but also the outer layer pattern and the inner layer pattern of the printed wiring board will be seen at the same time It is even more difficult to clearly determine only the joint.

Also, on page 48 of the document, there is a method of eliminating the inspection of the bonding state by optimizing the bonding conditions. However, there are many vague points such as what to do without inspection. It is still impossible to judge the joining state.

In the manufacturing process and the mounting process of the electronic component, the heat treatment for solder reflow shrinks the sealing resin of the electronic component made of epoxy resin or the like. As indicated by a broken line 15, the electronic component 1 is distorted and bows outward, or warps spherically. For this reason, there is a high possibility that the mounting of the electronic component 1 on the printed wiring board 5 becomes difficult.

The present invention facilitates the inspection of an electronic component whose bonding state with a printed wiring board is difficult to inspect as described above, and prevents warpage of the electronic component caused by stress such as heat treatment. The purpose is to do.

[0013]

According to the first aspect of the present invention,
An electronic component is provided with a terminal for confirming a bonding state with a printed wiring board and a pattern wiring for connecting the terminals, in addition to a terminal for operating an original function of the electronic component.

According to a second aspect of the present invention, there are provided a plurality of pairs of terminals for confirming a bonding state of the electronic component with a printed wiring board and a pattern wiring for connecting the terminals. It is a thing.

According to a third aspect of the present invention, the pattern wiring for preventing warpage is extended from the pattern wiring connecting the terminals.

According to a fourth aspect of the present invention, in order to prevent warpage caused by thermal stress of the electronic component, a pattern wiring not related to the original function of the electronic component is provided inside or on the surface of the electronic component. .

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Embodiment 1 of the present invention will be described below with reference to FIGS. FIG. 1 is an electronic component according to Embodiment 1,
13 and 14 have the same reference numerals. In FIG. 1, reference numeral 1 denotes an electronic component having a precision circuit therein, which is entirely sealed and molded with a resin such as epoxy resin, and reference numeral 2 denotes a terminal for performing an original function of the electronic component. Are arranged at equal intervals vertically and horizontally except for the corners. Reference terminals 3a to 3d are inspection terminals provided separately from the terminals 2 arranged on the bottom surface side of the electronic component 1 for checking a bonding state with the printed wiring board, and are located at four corners of the aligned terminals 2. Have been. The two test terminals 3c and 3d provided on the electronic component 1 are electrically connected to the test pattern wiring 4 not related to the original function of the electronic component. The inspection pattern wiring 4 connects a pair of inspection terminals 3c and 3d facing each other, and the electronic component 1
Out of the sides 1m and 1n, a straight portion 4a extending parallel to one side 1n, and bent portions 4b and 4b bent from both ends of the straight portion 4a in the direction of the inspection terminals 3c and 3d, It is composed of a conductor such as copper which constitutes a wiring in the electronic component.

FIG. 2 shows an upper surface of a printed wiring board on which the electronic component 1 is mounted. In FIG. 2, reference numeral 5 denotes a printed wiring board on which the electronic component 1 is mounted on the upper surface;
Reference numeral 6d denotes an inspection pad for connecting a measuring instrument or the like for reading a conduction state with the component. Reference numeral 7 denotes a soldering on a predetermined area surface of the printed wiring board 5 to which the terminals 2 of the electronic component to be mounted and mounted are joined. Pads 7a to 7d are inspection terminals 3a to
3d is a soldering pad for inspection to be joined, and one set of soldering pads for inspection 7a to 7d is connected to the inspection pads 6a to 6d by the pattern wirings 8a to 8d on the printed wiring board 5.
d is electrically connected. Each of the above pads 7a to 7d
Are arranged leaving four corners so as to face the aligned terminals 2, and the inspection soldering pads 7a to 7d which are not related to the original function are provided at the four corners. The pattern wirings 8a to 8d extend linearly from the solder pads 7a to 7d for inspection and are connected to the pads 6a to 6d for inspection provided opposite to the solder pads 7a to 7d for inspection. Have been.

Next, a method of inspecting the bonding state between the printed wiring board 5 and the electronic component 1 using the electronic component according to the first embodiment will be described with reference to FIG. First, the electronic component 1 is mounted on a predetermined area surface of the printed wiring board 5, and the terminals 2 and the inspection terminals of the electronic component 1 are formed using a general bonding method, for example, an electrical bonding method such as a reflow soldering method. 3a-3
d is joined to the soldering pad 7 and the inspection soldering pads 7a to 7d on the printed wiring board 5. FIG. 3 shows a state where electronic component 1 according to the first embodiment is mounted on printed wiring board 5. In this state, the inspection pads 6c,
When a measuring device (not shown) for reading a conduction state with the component is connected to 6d, a test terminal 3c of the electronic component 1 passes through the test pattern wiring 4 of the electronic component 1 via the pattern wiring 8c, and then the other test device. The conduction between the inspection pads 6c and 6d is observed from the terminal 3d via the pattern wiring 8d on the printed wiring board.

As a result, if conduction between the test pads 6c and 6d is obtained, it is understood that the test terminals 3c and 3d and the test pads 6c and 6b are normally joined. It can be seen that the test terminals 3a, 3b and the test pads 6c, 6d are not properly joined. The presence or absence of continuity between the inspection pads 6c and 6d represents the original state of the connection between the other terminal 2 and the soldering pad 7. That is, if there is continuity between the inspection pads 6c and 6d, it can be inferred that the original other terminals 2 are also normally joined. Further, the inspection pattern wiring 4 having a fixed width is used.
Due to a, the warpage preventing effect of the electronic component 1 can be obtained based on the reason described later.

The inspection terminals 3a and 3b that are not connected by the pattern wiring 4 are idle terminals, but these inspection terminals 3a and 3b are connected by external lead wires (not shown) as necessary. The electrical connection allows the inspection pad 6 to be connected similarly to the case of the inspection terminals 3c and 3d.
The connection state can be inspected by connecting a measuring device or the like (not shown) to the terminals a and 6b.

Second Embodiment In the first embodiment, the set of the two test terminals 3c and 3d and the test pattern wiring 4 is one set, but as shown in FIG. , 3b may be connected by an inspection pattern wiring 4 composed of a straight portion 4a and a bent portion 4b to provide two sets. Alternatively, more sets may be provided.

FIG. 5 shows a state in which the electronic component 1 according to the second embodiment is mounted on a printed wiring board 5. In this case, in the inspection of the bonding state between the electronic component 1 and the printed wiring board 5, both the presence / absence of conduction of the inspection pads 6c and 6d and the presence / absence of conduction of the inspection pads 6a and 6b are inspected. It is possible to increase the reliability of the inspection of the bonding state between the original terminal 2 and the soldering pad 7. In addition, if the inspection pads 6a to 6d and the pattern wirings 8a to 8d corresponding to any one of the inspection terminals 3c and 3d and the inspection terminals 3a and 3b are provided on the printed wiring board 5,
Since the same inspection as that of the first embodiment can be performed, the arrangement positions of the inspection pads 6a to 6d and the pattern wirings 8a to 8d can be set freely, and it is possible to cope with higher-density mounting. Further, the effect of preventing warpage of the electronic component 1 can be increased by the plurality of pattern wirings 4 provided on the electronic component 1, and the effect of preventing warpage can be further improved by increasing the width of the pattern wiring 4. Can be. In FIG. 5, the inspection terminals are provided in the outermost row, but not limited to the outermost row, an inner terminal may be used as the inspection terminal, or an outer terminal and an inner terminal may be combined. .

Third Embodiment FIG. 6 shows an electronic component according to a third embodiment. In FIG. 6 which is a plan view, reference numerals 9a to 9d denote linear warp preventing patterns provided along the outer periphery of the surface of the electronic component 1 to prevent the warpage of the electronic component itself and which are not related to the original function of the electronic component. The wiring is made of a conductor such as copper which forms the wiring in the electronic component. Each of the warp prevention pattern wirings 9a to 9d has a length slightly shorter than each side 1m, 1n, 1u, 1v of the rectangular electronic component 1.

For the electronic component 1, a printed wiring board 5
Thermal stress is added by heat treatment using a heating furnace at the time of reflow soldering in the mounting process to the
As a result, the sealing resin of the electronic component 1 shrinks, and the stress causes a distortion in the base substrate. Therefore, as shown in FIG. However, by providing the pattern wirings 9a to 9d for preventing warpage on the surface of the electronic component 1 along the four sides 1m, 1n, 1u and 1v, the substantial thickness of the base substrate is 18 μm.
Since the thickness increases the strength of the base substrate, the strength of the base substrate increases, so that it is possible to withstand the stress generated by the shrinkage of the sealing resin constituting the package of the electronic component 1 and suppress the warpage of the electronic component 1. can do.

Further, the first embodiment or the second embodiment
In the same manner, the effect of preventing warpage can be obtained by the pattern wiring 4 provided on the electronic component 1 according to (1), but the pattern wirings 9a to 9d for preventing warpage are provided separately from the pattern wiring 4.
Is provided, a more powerful warpage prevention effect can be obtained, and also the warp prevention effects can be obtained for the sides 1u and 1v of the electronic component 1 where the pattern wiring 4 is not provided.

Fourth Embodiment FIG. 7 is a bottom view of an electronic component according to a fourth embodiment.
As shown in FIG. 7, as the pattern wiring for preventing warpage, the inspection pattern wiring 4 on the side 1n is moved from the inspection terminal 3a to the side 1u.
, And the inspection pattern wiring 4 on the side 1m side is linearly extended from the inspection terminal 3d along the side 1v to provide warp prevention pattern wirings 4x and 4y. Is also good. By arranging in this way, Embodiment 3
Similarly to the electronic component 1 according to the first or second embodiment, in the electronic component 1 according to the first or second embodiment, the sides 1u and 1v to which the effect of preventing the warp is not provided are provided with the effect of preventing the warp. Become.

Fifth Embodiment FIGS. 8 to 10 are cross-sectional views showing an electronic component according to a fifth embodiment. The warp preventing pattern wiring 9 or the inspection pattern wiring 4 may be wired on either the surface or the inside of the electronic component as shown in FIGS. 9 and 10. In any case, the warpage is the same as in the third to fifth embodiments. The prevention effect is obtained. In addition, as shown in FIG. 11, the surface and the internal wiring may be combined, and in this case, by further increasing the thickness of the base substrate, a stronger warp prevention effect than in the third to fifth embodiments can be obtained. Will be obtained.

[0029]

As described above, according to the first aspect of the present invention, the terminal for checking the bonding state with the printed wiring board is provided on the electronic component, and the terminals are interconnected by the pattern wiring. Therefore, by checking the presence or absence of conduction between the test pads provided on the printed wiring board at the time of mounting the electronic component, it is possible to check the bonding state between the test terminals and the test pads. The bonding state of the inspection terminal and the inspection pad is representative of the bonding state of a normal terminal, the overall bonding state can be analogized, and the inspection of the bonding state between the electronic component and the printed wiring board can be facilitated. Can be planned. Further, the effect of preventing warpage of the electronic component can be obtained by the pattern wiring for connecting the terminals for confirming the bonding state, and the reliability of the electronic component can be improved.

According to the second aspect of the present invention, a plurality of pairs of terminals for confirming the bonding state with the printed wiring board and the terminals interconnected by pattern wiring are provided. In addition, not only can the connection state between the printed wiring board and the electronic component be easily confirmed, but also the arrangement of the test pads can be flexibly performed, and this has the effect of being able to cope with higher-density mounting. Further, the plurality of pattern wirings can more effectively prevent the warpage of the electronic component, and can improve the reliability of the electronic component.

According to the third aspect of the present invention, the pattern wiring for preventing warpage is extended from the pattern wiring for connecting the terminals for checking the bonding state with the printed wiring board. Also, even on the side where there is no pattern wiring for connecting the inspection terminal, the effect of preventing warpage can be given without providing a separate pattern wiring,
This will contribute to the miniaturization of electronic components.

According to the fourth aspect of the present invention, in order to prevent warpage caused by thermal stress of the electronic component, apart from the pattern wiring for connecting the inspection terminal, the inside of the electronic component or Since the pattern wiring for preventing warpage is provided on the surface, a stronger warpage prevention effect can be obtained against thermal stress due to heat treatment such as reflow soldering, and the reliability of electronic components Can be improved.

[Brief description of the drawings]

FIG. 1 is a bottom view of an electronic component according to Embodiment 1 of the present invention.

FIG. 2 is a top view showing mounting pads of a printed wiring board on which electronic components according to the first embodiment are mounted.

FIG. 3 is a side view showing a state where the electronic component according to the first embodiment is mounted on a printed wiring board.

FIG. 4 is a bottom view of another example of the electronic component according to the second embodiment.

FIG. 5 is a perspective view showing a state in which the electronic component according to the second embodiment is mounted on a printed wiring board.

FIG. 6 is a bottom view of the electronic component according to the third embodiment.

FIG. 7 is a bottom view showing another example of the electronic component according to the fourth embodiment.

FIG. 8 is a sectional view of an electronic component according to a fifth embodiment.

FIG. 9 is a sectional view of another example of the electronic component according to the fifth embodiment.

FIG. 10 is a sectional view of another example of the electronic component according to the fifth embodiment.

FIG. 11 is a side view showing an inspection method according to a conventional method.

FIG. 12 is an image diagram showing a state after X-ray transmission by the method of FIG. 11;

FIG. 13 shows a side view of a conventional electronic component.

FIG. 14 is a bottom view of a conventional electronic component.

FIG. 15 is a side view showing a warped state of a conventional electronic component.

[Explanation of symbols]

1 electronic components, 2 terminals, 3a-3d inspection terminals, 4
Inspection pattern wiring, 5 printed wiring board, 6a-6
d Inspection pad, 7 Soldering pad, 8 Pattern wiring, 9a-9d Pattern wiring for warpage prevention, 10
X-ray irradiation direction, 11 joint failure

Claims (4)

[Claims] In an electronic component mounted by connecting a terminal provided on a bottom surface side to a pad of a printed wiring board, the electronic component is connected to a printed wiring board separately from a terminal for operating an original function of the electronic component. An electronic component, comprising: a terminal for checking a state; and a pattern wiring connecting the terminals. 2. A semiconductor device according to claim 1, wherein said electronic component has a plurality of pairs of terminals for checking a bonding state with a printed wiring board and a pattern wiring connecting said terminals. The electronic component according to claim 1. 3. The electronic component according to claim 1, wherein a pattern wiring for preventing warpage is extended from the pattern wiring connecting the terminals. 4. An electronic component, wherein a pattern wiring which is not related to the original function of the electronic component is provided inside or on the surface of the electronic component in order to prevent warpage caused by thermal stress of the electronic component.