JP4036017B2 - Electronic component mounting structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is an electronic component connected to the one surface of the substrate, the connection portion between the electronic component and the substrate about the mounting structure of an electronic component comprising resin reinforced with.
[0002]
[Prior art]
FIG. 10 shows a general cross-sectional configuration of a conventional electronic component mounting structure. An electronic component 10 such as a flip chip, a CSP (chip size package), a ceramic component, or a molded component is connected to one surface of a substrate 20 such as a ceramic substrate or a printed substrate via a connection member 30.
[0003]
Here, the connection member 30 employs solder, a conductive adhesive, or the like, and the connection member 30 electrically connects the component electrode 11 of the electronic component 10 and the substrate electrode 21 of the substrate 20. A resin 40 is provided to reinforce the connecting portion between the electronic component 10 and the substrate 20 formed by the connecting member 30.
[0004]
The resin 40 is, for example, an epoxy resin, a silicon resin, a polyamide resin, an acrylic resin, or the like that covers the connection member 30 or is filled between the electronic component 10 other than the connection member 30 and the substrate 20. Or the like is used to reinforce the connecting portion.
[0005]
[Problems to be solved by the invention]
However, in the conventional mounting structure described above, there is a problem that voids are generated in the resin 40 depending on a method of applying the resin 40 and a method of wrapping the resin 40 under the electronic component 10 at the time of injection.
[0006]
In particular, in the electronic component 10 having the recess 12 at the lower portion as shown in FIG. 10, it is very difficult to inject the resin 40 into the recess 12 without generating voids. This will be described with reference to a conventional mounting method.
[0007]
FIG. 11 is a process diagram showing a conventional mounting method for forming the conventional mounting structure shown in FIG. 11A to 11D are views seen from one surface of the substrate 20, but for convenience, the region of the resin 40 is hatched. FIG. 11E is a cross-sectional view along the thickness direction of the substrate 20.
[0008]
First, as shown in FIGS. 11A and 11B, the electronic component 10 is mounted on one surface of the substrate 20 via the connection member 30, and the substrate electrode 21 of the substrate 20 and the component electrode 11 of the electronic component 10 are Connect. Next, as shown in FIG. 11C, a resin 40 is applied onto one surface of the substrate 20 from one side of the electronic component 10 using a dispenser K1 or the like.
[0009]
Then, the applied resin 40 is injected between the electronic component 10 and the substrate 20 by capillary action. Then, after the injection is completed, the mounting structure is completed by curing the resin 40 by heating or the like.
[0010]
However, the gap between the electronic component 10 and the substrate 20 is generally small, and depending on how the resin wraps around, the resin 40 is formed directly under the electronic component 10 as shown in FIGS. As a result, air is trapped and a void 100 is generated.
[0011]
In particular, as shown in FIGS. 11 (d) and 11 (e), when the concave portion 12 exists in the portion immediately below the electronic component 10, the gap between the electronic component 10 and the substrate 20 in the portion other than the concave portion 12 is usually 10 μm to There is only about 40μm. For this reason, at the time of resin injection, the resin 40 wraps around faster than the part between the electronic component 10 and the substrate 20 and the part between the recess 12 and the substrate 20. Therefore, the void 100 is likely to occur.
[0012]
Such a void 100 weakens the effect of reducing leakage current between terminals, contact failure due to corrosion of the electrode portion, and distortion generated in the solder connection portion in the reliability test of the electronic device. This may cause a significant decrease in the reliability of the electronic device, such as generation of solder cracks.
[0013]
As means for suppressing the generation of voids, conventionally, as described in JP-A-11-26483, JP-A-2001-210462, etc., a through-hole for venting air is provided in a substrate and filled with resin. There is a technique for removing voids.
[0014]
However, in this method, it takes a lot of man-hours to process the resin dripping from the air vent through hole, and after the resin is cured, the difference in the thermal expansion coefficient between the resin buried in the through hole and the substrate can cause In this case, there is a problem that the substrate is cracked.
[0015]
In view of the above problems, an object of the present invention is to appropriately suppress the occurrence of voids in a resin in a mounting structure in which a connecting portion between an electronic component and a substrate is reinforced with resin.
[0016]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, the electronic component (10) is connected to one surface of the substrate (20), and the connection portion between the component electrodes provided at both ends of the electronic component and the substrate. In the mounting structure of the electronic component formed by reinforcing the resin with the resin (40), the electronic component has a concave portion (12) that does not communicate with the outer portion of the electronic component on the surface facing the one surface of the substrate. And a groove (22) formed continuously from the area where the electronic component is projected onto the one surface to the outside of the area is provided on one surface of the substrate. And the groove is filled with resin.
[0017]
According to this, between the connected electronic component and the substrate, due to the presence of the groove provided in the substrate, the portion directly under the electronic component communicates with the outer portion of the electronic component, and an air passage is formed. It will be.
[0018]
Therefore, when the resin is placed on the substrate in order to reinforce the connection between the electronic component and the substrate with the resin, bubbles in the resin that are generated immediately below the electronic component are released through the groove, so It is hard to remain as a void. Then, when performing the arrangement of the resin is a form of the resin (40) is filled in the groove portion (22).
[0019]
Therefore, according to the present invention, in the mounting structure in which the connecting portion between the electronic component and the substrate is reinforced with the resin, it is possible to appropriately suppress the generation of voids in the resin.
[0030]
In addition, the code | symbol in the bracket | parenthesis of each said means is an example which shows a corresponding relationship with the specific means as described in embodiment mentioned later.
[0031]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments shown in the drawings will be described below. In the following embodiments, the same parts are denoted by the same reference numerals in the drawings.
[0032]
(First embodiment)
FIG. 1 is a schematic sectional view showing a mounting structure of an electronic component according to the first embodiment of the present invention. The electronic component 10 is connected to one surface of the substrate 20 via the connection member 30, and the resin 40 is filled between the electronic component 10 and the substrate 20 in order to reinforce the connection portion between the electronic component 10 and the substrate 20. ing.
[0033]
As the electronic component 10, a flip chip, a CSP (chip size package), a ceramic component, a molded component, or the like can be adopted. In this example, a molded diode is used. Single unit diagrams of the electronic component 10 are shown in FIGS. 2A is a cross-sectional view corresponding to FIG. 1, and FIG. 2B is a view taken in the direction of arrow A in FIG.
[0034]
The electronic component 10 has component electrodes 11 at both ends thereof, and a recess 12 made of mold resin is formed on a surface facing one surface of the substrate 20. Here, as shown in FIG. 2, in the electronic component 10 of this example, the distance W11 between the component electrodes 11 is about 2 mm, and the recess 12 has a round hole shape with a diameter D1 of about φ1 mm. Further, the width W12 of the electronic component 10 is about 2 mm.
[0035]
Moreover, the board | substrate 20 shown in FIG. 1 can employ | adopt the ceramic board | substrate, a printed circuit board, etc., such as an alumina board | substrate and an AlN board | substrate, In this example, it is set as the alumina board | substrate. The single-piece | unit structure figure of this board | substrate 20 is shown to Fig.3 (a), (b). 3A is a cross-sectional view corresponding to FIG. 1, and FIG. 3B is a view taken in the direction of arrow B in FIG.
[0036]
On one surface of the substrate 20, a substrate electrode 21 made of Au, Ag, Cu or the like is formed at a position corresponding to the component electrode 11 of the electronic component 10. Also, in FIG. 3B, a region R where the electronic component 10 to be mounted is projected onto one surface of the substrate 20, that is, the component projection region R is indicated by a broken line.
[0037]
A groove portion 22 is formed on one surface of the substrate 20 continuously from the component projection region R to the outside of the region R. As shown in FIG. 3B, the width W <b> 21 of the groove 22 in the direction separating the substrate electrodes 21 can be not less than the diameter D <b> 1 of the recess 12 of the electronic component and not more than the distance between the substrate electrodes 21.
[0038]
In this example, the width W21 of the groove portion 22 can be about 1.1 mm to 2.0 mm. Further, the width W22 of the groove portion 22 in the direction orthogonal to the width W21 can be about 1.5 mm to 3.0 mm in this example. Furthermore, the depth D2 of the groove part 22 shown by Fig.3 (a) can be about 0.1 mm-0.4 mm.
[0039]
As shown in FIG. 1, the electronic component 10 and the substrate 20 are mechanically and electrically connected by connecting the component electrode 12 and the substrate electrode 22 via a connection member 30. . As the connection member 30, solder, a conductive adhesive, or the like is employed.
[0040]
As shown in FIG. 1, the resin 40 is provided on one surface of the substrate 20 in order to reinforce the connection portion between the electronic component 10 formed by the connection member 30 and the substrate 20. The resin 40 is, for example, an epoxy resin, a silicon resin, a polyamide resin, an acrylic resin, or the like.
[0041]
In this example, the resin 40 covers the connection member 30, and the recess 12 and the groove portion 22 are filled with almost no gap between the electronic component 10 and the substrate 20 in a portion other than the connection member 30. By arranging the resin 40 in this way, the connection portion between the electronic component 10 and the substrate 20 is reinforced.
[0042]
Incidentally, in this example, the thermal expansion coefficient α of the substrate 20 as the alumina substrate is about 7 ppm, and the thermal expansion coefficient α of the electronic component 10 as the mold part is about 23 ppm. Thus, since the difference in thermal expansion coefficient is large, cracks are likely to occur in the connection portion by the connection member 30 in a temperature cycle environment. Therefore, the resin 40 is reinforced.
[0043]
According to such a mounting structure of the present embodiment, between the connected electronic component 10 and the substrate 20, due to the presence of the groove portion 22 provided in the substrate 20, the portion immediately below the electronic component 10 and the electronic component 10. The outside portion communicates with each other, and an air passage is formed.
[0044]
Therefore, when the resin 40 is disposed on the substrate 20 in order to reinforce the connection portion between the electronic component 10 and the substrate 20 with the resin 40, bubbles in the resin 40 that are generated immediately below the electronic component 10 pass through the groove 22. Therefore, it is difficult to remain as a void in the resin 40. Therefore, in this mounting structure, generation of voids in the resin 40 can be appropriately suppressed.
[0045]
Next, the mounting method of this embodiment will be described based on the mounting structure shown in FIG. 4 to 7 are process diagrams showing the mounting method. 5A to 7A, the region of the resin 40 is hatched for convenience.
[0046]
First, the electronic component 10 shown in FIG. 2 and the substrate 20 shown in FIG. 3 are prepared. At this time, in the substrate 20, as described with reference to FIG. 3, the groove portion 22 formed continuously on one surface of the substrate 20 from the component projection region R to the outside of the region R with respect to the one surface. Is provided.
[0047]
Here, the groove portion 22 is continuously formed from the component projection region R to the outside of the end portion on the side opposite to the end portion on the resin injection portion side when the resin 40 described later is injected. The
[0048]
For example, when the substrate 20 is a multilayer ceramic substrate, the groove 22 is formed by punching the green sheet by pressing or the like before firing the green sheet disposed on one side of the substrate 20 or firing the green sheet. It can be formed by performing groove processing later by laser processing, milling, or the like.
[0049]
Similarly, when the substrate 20 is a multilayer printed circuit board, the groove 22 is formed by punching the outermost layer sheet by pressing or the like before the thermocompression pressing, or by performing grooving by milling or the like after the thermocompression pressing. can do.
[0050]
In this way, using the substrate 20 on which the groove 22 is formed, a component assembling step for assembling the electronic component 10 to the substrate 20 as shown in FIG.
[0051]
[Steps shown in FIG. 4]
4A is a view from one surface of the substrate 20, and FIG. 4B is a cross-sectional view taken along the line CC in FIG. In this component assembly step, the electronic component 10 is mounted on one surface of the substrate 20 via the connection member 30, and the component electrode 11 of the electronic component 10 and the substrate electrode 21 of the substrate 20 are connected. Next, the process shown in FIG. 5 is performed.
[0052]
[Steps shown in FIG. 5]
5A is a diagram viewed from one surface of the substrate 20, and FIG. 5B is a cross-sectional view taken along the line DD in FIG. This process is a resin coating process in which the resin 40 is coated on one surface of the substrate 20. For example, the resin 40 is applied onto one surface of the substrate 20 using a dispenser, a stamp method, a printing method, a spraying method, or the like.
[0053]
At this time, in the case where the groove portion 22 is formed to protrude from only one side of the electronic component 10 as in this example, the resin 40 is not applied to the side of the periphery of the electronic component 10 where the groove portion 22 protrudes. . That is, as described above, the groove portion 22 is continuously formed on the one surface of the substrate 20 from the component projection region R to the outside of the end portion of the region R opposite to the end portion on the injection portion side of the resin 40. It is a thing.
[0054]
[Steps shown in FIG. 6]
6A is a view as seen from one surface of the substrate 20, and FIG. 6B is a cross-sectional view taken along line EE in FIG. This process is a resin injection process in which the applied resin 40 is injected and filled between the electronic component 10 and the substrate 20 by capillary action.
[0055]
In this example, as a preferred mode, as shown in FIG. 6B, the resin 40 is injected in a state where the substrate 20 is positioned above the electronic component 10. At this time, the substrate 20 is further inclined at an angle θ (for example, 0 to 90 °) with respect to the horizontal plane so that the injection portion of the resin 40 is higher than the protruding side of the groove portion 22 from the electronic component 10. Of course, it may be performed with the substrate 20 positioned below the electronic component 10.
[0056]
In this step, the groove 22 provided in the substrate 20 is present between the connected electronic component 10 and the substrate 20 so that the portion directly below the electronic component 10 communicates with the outer portion of the electronic component 10. In addition, a communication portion 22a is formed as an air escape path.
[0057]
Therefore, when the applied resin 40 is injected between the electronic component 10 and the substrate 20, bubbles in the resin 40 that are generated immediately below the electronic component 10 are exposed to the outside via the communication portion 22 a of the groove portion 22. Since it escapes, it is hard to remain as a void in the resin 40.
[0058]
In particular, when the groove portion 22 is formed in the substrate 20 as in this example, if the substrate 20 is positioned above the electronic component 10 at the time of resin injection, the resin 40 is efficiently filled in the recess 12 of the electronic component 10. it can. In addition, since the resin 40 is injected to the side of the electronic component 10 located on the lower side, the communication portion 22a of the groove portion 22 can be widened, so that air can be more easily released.
[0059]
[Steps shown in FIG. 7]
7A is a view from one surface of the substrate 20, and FIG. 7B is a cross-sectional view taken along the line FF in FIG. 7A. This step is a resin curing step in which the resin 40 that has been injected is cured by heat treatment or the like. With the completion of this process, the mounting structure shown in FIG. 1 is completed.
[0060]
And according to the mounting method of this embodiment described above, according to it, in the resin injection | pouring process, it becomes difficult for a void to remain in the resin 40 by presence of the groove part 22 provided in the board | substrate 20. FIG. Therefore, according to the present embodiment, in the mounting structure in which the connection part between the electronic component 10 and the substrate 20 is reinforced with the resin 40, it is possible to appropriately suppress the generation of voids in the resin 40. An implementation method can be provided.
[0061]
(Second Embodiment)
FIG. 8 is a diagram showing a main part of the mounting structure according to the second embodiment of the present invention. In the first embodiment, the groove portion 22 is provided on the substrate 20 side. In this embodiment, instead of the groove portion 22 of the substrate 20, the concave portion 13 is provided on the electronic component 10 side. The same function as that of the groove portion 22 is provided.
[0062]
FIG. 8 shows a facing surface that opposes one surface of the substrate 20 in the electronic component 10 of the present embodiment. On this facing surface, a recess formed continuously from the inner peripheral portion to the outer edge portion of the facing surface. 13 is provided. The concave portion 13 is formed continuously from the inner peripheral portion of the facing surface to the outer edge portion on the side opposite to the outer edge portion on the injection portion side of the resin 40.
[0063]
A mounting structure according to the present embodiment is obtained by connecting the electronic component to the substrate 20 using the electronic component 10 as in FIG. According to this, even if the substrate 20 does not have the groove portion 22, the concave portion 13 of the electronic component 10 plays the same role as the groove portion 22.
[0064]
That is, between the connected electronic component 10 and the substrate 20, due to the presence of the concave portion 13 provided in the electronic component 10, the portion immediately below the electronic component 10 and the outer portion of the electronic component 10 communicate with each other. A loophole has been formed.
[0065]
Therefore, when the resin 40 is arranged on the substrate 20 in order to reinforce the connection part between the electronic component 10 and the substrate 20 with the resin 40, bubbles in the resin 40 generated immediately below the electronic component 10 pass through the recess 13. Therefore, it is difficult to remain as a void in the resin 40. When the resin 40 is arranged, in the present embodiment, the recess 13 is filled with the resin 40.
[0066]
Therefore, it is possible to appropriately suppress the generation of voids in the resin 40 also by the mounting structure of the present embodiment. Such a recess 13 can be formed in the electronic component 10 by molding or cutting.
[0067]
Further, the mounting method of this embodiment uses the electronic component 10 shown in FIG. 8 and the substrate 10 on which no groove is formed, as in the first embodiment, the component assembly step, the resin coating step, the resin An injection process and a resin curing process can be performed. Thereby, the mounting structure of this embodiment is appropriately formed.
[0068]
And also in the mounting method of this embodiment, the presence of the recess 13 of the electronic component 10 makes it difficult for voids to remain in the resin 40. Therefore, even in this embodiment, in the mounting structure in which the connection portion between the electronic component 10 and the substrate 20 is reinforced with the resin 40, the mounting that can appropriately suppress the generation of voids in the resin 40. A method can be provided.
[0069]
Also in this embodiment, the substrate 20 may be positioned above the electronic component 10 in the resin injecting step, but it is not necessary.
[0070]
(Other embodiments)
Various modifications of the groove 22 formed in the substrate 20 are shown in FIGS. 9 (a), 9 (b), and 9 (c). FIG. 9 is a diagram of the substrate 20 as viewed from one side, and the positions of the respective parts in the component projection region R and the electronic component 10 are indicated by broken lines. As shown in FIGS. 9A and 9B, the groove 22 only needs to overlap with a part of the recess 12 of the electronic component 10, if not all.
[0071]
The groove 22 may be formed continuously from the component projection region R to the outer surface of the end of the region R opposite to the end of the resin injection portion on the one surface of the substrate 20. However, as shown in FIG. 9C, the component projection region R, that is, the outside of the end portion of the electronic component 10 on the resin injection portion side may be continuously formed.
[0072]
The same thing as FIG. 9C can be said in the second embodiment. That is, the concave portion 13 of the electronic component 10 is formed continuously from the inner peripheral portion of the facing surface to the outer edge portion on the injection portion side of the resin 40 and both outer edge portions on the opposite outer edge portion. Also good.
[0073]
Further, the shape of the groove portion 22 and the recess portion 13 that function as a passage for air can be any shape even if it is not a flat rectangular shape as in the above example.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing a mounting structure for an electronic component according to a first embodiment of the present invention.
FIG. 2 is a unit configuration diagram of the electronic component in FIG. 1;
FIG. 3 is a unit configuration diagram of a substrate in FIG. 1;
FIG. 4 is a process diagram showing the electronic component mounting method according to the first embodiment.
FIG. 5 is a process diagram showing a mounting method following FIG. 4;
6 is a process diagram illustrating a mounting method subsequent to FIG. 5. FIG.
7 is a process diagram illustrating a mounting method subsequent to FIG. 6; FIG.
FIG. 8 is a diagram showing a main part of a mounting structure according to a second embodiment of the present invention.
FIG. 9 is a view showing various modified examples of groove portions formed on a substrate.
FIG. 10 is a diagram showing a general cross-sectional configuration of a conventional electronic component mounting structure;
FIG. 11 is a process diagram showing a conventional general mounting method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Electronic component, 13 ... Recessed part, 20 ... Board | substrate, 22 ... Groove part, 40 ... Resin.

Claims (1)

Electronic component mounting structure in which an electronic component (10) is connected to one surface of a substrate (20), and a connection portion between the component electrode provided at both ends of the electronic component and the substrate is reinforced with a resin (40) In
The electronic component is formed with a concave portion (12) that does not communicate with an outer portion of the electronic component on a surface facing one surface of the substrate,
One surface of the substrate is provided with a groove portion (22) continuously formed from a region where the electronic component is projected onto the one surface to the outside of the region, and the width of the groove portion is the electronic component. A mounting structure for an electronic component, wherein the groove is filled with the resin.

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