JP3593879B2 - Substrate for mounting electronic components - Google Patents

Description

[0001]
【Technical field】
The present invention relates to a substrate for mounting electronic components, and more particularly to a structure for improving the bonding stability of an electronic component to a mounting portion.
[0002]
[Prior art]
Conventionally, as a board for mounting an electronic component, as shown in FIG. 8, there is a board having an insulating substrate 91 and a mounting portion 911 provided on the insulating substrate 91 for mounting an electronic component. The mounting section 911 is covered with a metal pad 92. An electronic component 94 is bonded to the metal pad 92 with an adhesive 93. The mounting portion 911 is provided with a connection hole 912 made of resin, into which a solder ball 95 is joined. The solder ball 95 is connected to a metal pad 92 covering the upper opening of the connection hole 912. Further, the legs of the solder balls 95 are connected to external terminals.
[0003]
A conductor pattern 96 is provided on the front side surface of the insulating substrate 91 so as to surround the mounting portion 911. The conductor pattern 96 is electrically connected to the electronic component 94 by a bonding wire 941. The electronic component 94 and the conductor pattern 96 are sealed with a sealing resin 97.
[0004]
[Problem to be solved]
However, the conventional electronic component mounting board has a problem that the electronic component 94 is peeled off from the mounting portion 911 due to the popcorn phenomenon of the adhesive 93. That is, as shown in FIG. 9, since the adhesive 93 for bonding between the electronic component 94 and the metal pad 92 is a resin, it absorbs moisture after bonding.
[0005]
This moisture thermally expands due to the adhesion of the solder ball 95 to the connection hole 912 and the heating for joining the solder ball 95 to the external terminal. For this reason, as shown in FIG. 9, the popcorn peels off between the metal pad 92 and the adhesive 93 as if the popcorn pops, and an unbonded portion 939 occurs. For this reason, there is a problem that the adhesiveness of the electronic component 94 to the mounting portion 911 decreases, and the electronic component 94 comes off.
[0006]
SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an electronic component mounting substrate which can suppress a decrease in adhesiveness of an electronic component to a mounting portion due to heating.
[0007]
[Means for solving the problem]
The present invention relates to an electronic component mounting substrate having a substrate and a mounting portion for mounting electronic components provided on the substrate.
The mounting part is provided with a metal die pad for bonding electronic components.
The aforementioned mounting portion, an opening hole is provided et is capable of passing the water that may be included in the mounting side of the electronic component,
The die pad has a relief hole opened in the opening hole,
The opening of the substrate is larger than the escape hole of the metal die pad .
[0008]
In the present invention, the mounting portion is provided with an opening through which moisture that may be contained on the mounting side of the electronic component can pass. Therefore, even if moisture is absorbed by the adhesive bonding the mounting portion and the electronic component, the moisture can be released to the outside of the mounting portion through the opening. Therefore, the popcorn phenomenon that occurs during heating can be suppressed. Therefore, even if there is a step of heating the electronic component mounting substrate after the electronic component is bonded, the bonding strength of the electronic component to the mounting portion does not decrease, and the electronic component does not peel off from the mounting portion.
[0009]
The opening preferably has a diameter of 0.1 to 0.5 mm. Thereby, the water on the mounting side can be efficiently released to the opening. On the other hand, when the thickness is less than 0.1 mm, the efficiency of releasing moisture decreases, and the popcorn phenomenon of the adhesive may not be suppressed. On the other hand, if the thickness exceeds 0.5 mm, moisture will invade from the outside through the opening holes, and the adhesive on the mounting portion will absorb moisture, so that it is difficult to expect a reduction in the popcorn phenomenon.
[0010]
The substrate is not particularly limited as long as it is a base material on which a mounting portion for mounting an electronic component can be provided. The substrate is, for example, an insulating substrate. As the insulating substrate, for example, a resin substrate such as a glass epoxy substrate, a glass polyimide substrate, or a glass bismaleimide triazine substrate can be used.
Further, the substrate may be a heat sink. This is because the heat sink can also serve as a mounting portion for the electronic component. The heat radiating plate is not particularly limited as long as it is a substrate having a high heat radiating property. For example, a metal plate or the like is used.
[0011]
The aforementioned mounting portion, that has a die pad is provided for the electronic parts adhering. The die pad, for example, metal foil, ing of a metal material such as a metal plating film. Metals, moisture absorption almost no Ru can prevent moisture from being absorbed into the mounting side of the mounting portion.
[0012]
The die pad, escape hole that opens to the opening hole that provided. As a result, since the electronic component is bonded to the die pad via the adhesive, the moisture absorbed by the adhesive can be released to the mounting hole of the mounting portion through the relief hole of the die pad. to enable you suppress the popcorn phenomenon.
[0013]
The relief hole preferably has a diameter of 0.1 to 0.5 mm. Thereby, the water on the mounting side can be efficiently released to the opening. On the other hand, when the thickness is less than 0.1 mm, the efficiency of releasing moisture decreases, and the popcorn phenomenon of the adhesive may not be suppressed. On the other hand, if the thickness exceeds 0.5 mm, moisture will invade from the outside through the escape hole, and the adhesive on the die pad will absorb the moisture, and it is difficult to expect a reduction in the popcorn phenomenon.
[0014]
Preferably, the opening of the substrate is larger than the clearance hole of the metal pad. Thereby, moisture can be smoothly released from the escape hole toward the opening hole.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiment 1
An electronic component mounting board according to an embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 1, the electronic component mounting board 100 of this example includes an insulating substrate 1 and a mounting portion 11 provided on the insulating substrate 1 for mounting the electronic component 4. The mounting portion 11 is provided with an opening 10 through which moisture that may be included on the mounting side of the electronic component 4 can pass.
[0016]
The mounting portion 11 is provided with a metal die pad 2. The die pad 2 is provided with a relief hole 20 opened to the opening hole 10. The diameter of the opening 10 is 0.3 mm, the diameter of the relief hole 20 is 0.1 mm, and the opening 10 is larger than the relief hole 20. As shown in FIG. 4, the relief holes 20 are provided in the die pad 2 in a scattered manner. As shown in FIG. 5, the opening holes 10 are provided in the mounting portion 11 at positions corresponding to the escape holes 20 in a scattered manner.
[0017]
The insulating substrate 1 is provided with connection holes 12 for joining the solder balls 5. The bottom of the connection hole 12 is opened in the die pad 2 to electrically connect the solder ball 5 and the die pad 2. As shown in FIG. 5, a plurality of connection holes 12 are provided in the mounting portion 11 between the opening holes 10 in a scattered manner.
[0018]
In manufacturing the electronic component mounting substrate 100, as shown in FIG. 2, first, a glass epoxy resin substrate is prepared as an insulating substrate 1, and an opening 10 and a connection hole 12 are formed in the glass epoxy resin substrate. Next, as shown in FIG. 3, a metal foil such as a copper foil is attached to the insulating substrate 1, and the die pad 2 having the clearance hole 20 and the conductor pattern 6 are formed by etching. Thereby, the electronic component mounting substrate 100 is obtained.
[0019]
An electronic component 4 is bonded to the electronic component mounting substrate 100 on the die pad 2 by an adhesive 3 made of epoxy resin. The adhesive 11 may be partially transferred to the opening 10 through the escape hole 20 (FIG. 6). After that, the electronic component 4 is electrically connected to the conductor pattern 6 by the bonding wire 41, these are sealed by the sealing resin 7, and the solder balls 5 are melt-bonded to the external terminals 81 of the motherboard 8.
[0020]
Next, the operation and effect of this embodiment will be described.
In this example, as shown in FIG. 6, the mounting portion 11 is provided with an opening 10 through which moisture A that may be contained on the mounting side of the electronic component 4 can pass. The mounting portion 11 is covered with the die pad 2, and the die pad 2 is provided with a relief hole 20 at a position corresponding to the opening hole 10. Therefore, even if the moisture A is absorbed by the adhesive 3 that adheres between the mounting portion 11 and the electronic component 4, the moisture A can be discharged to the outside of the mounting portion 11 through the escape hole 20 and the opening 10. . Therefore, peeling of the electronic component 4 due to the popcorn phenomenon that occurs during heating can be suppressed. Therefore, even when the solder ball 5 is heated when the solder ball 5 is joined to the die pad 2 or the external terminal 81, the adhesiveness of the electronic component 4 to the mounting portion 11 does not decrease and the electronic component 4 does not come off from the mounting portion 11.
[0021]
Embodiment 2
In this example, as shown in FIG. 7, a mounting portion 251 for mounting electronic components is provided on a heat sink 25, and an opening 250 is provided therein.
The electronic component mounting board 100 of the present embodiment is provided with a mounting hole 15 for mounting the electronic component 4 on the insulating substrate 1. One opening of the mounting hole 15 is covered with a heat sink 25. The radiator plate 25 is adhered to the insulating substrate 1 with a resin adhesive 39. The heat sink 25 has a mounting portion 251 for mounting the electronic component 4. The mounting portion 11 has one or more opening holes 250.
Others are the same as the first embodiment.
[0022]
Next, the moisture resistance of the electronic component mounting substrate 100 was evaluated.
The evaluation was performed by setting the heating temperature, humidity, and heating time at the time of solder ball bonding to each of the moisture resistance levels proposed by JEDEL. As a result, the popcorn phenomenon of the adhesive did not occur until 85 ° C./60%/196 hours (level 2).
On the other hand, when the same measurement was performed without making an opening hole in the heat sink, the popcorn phenomenon of the adhesive did not occur up to 30 ° C./60%/240° C. (level 4). A phenomenon has occurred.
[0023]
In this example, the heat dissipation plate 25 is provided with an opening 250. Therefore, as in the first embodiment, the popcorn phenomenon of the adhesive 3 due to heating can be suppressed, and peeling of the electronic component 4 can be prevented. Further, in this example, since the electronic component 4 is bonded to the metal (iron, copper, etc.) heat radiating plate 25, it is possible to prevent moisture from entering the electronic component from the mounting portion side.
[0024]
【The invention's effect】
As described above, according to the present invention, it is possible to provide an electronic component mounting substrate that can suppress a decrease in the adhesiveness of an electronic component to a mounting portion due to heating.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an electronic component mounting board on which electronic components are mounted according to a first embodiment.
FIG. 2 is a cross-sectional view of the insulating substrate according to the first embodiment in which an opening hole and a connection hole are formed.
FIG. 3 is a cross-sectional view of the electronic component mounting board according to the first embodiment.
FIG. 4 is a plan view of the electronic component mounting board according to the first embodiment.
FIG. 5 is a rear view of the electronic component mounting board according to the first embodiment.
FIG. 6 is an essential part cross-sectional view of the electronic component mounting board for describing the opening hole in the first embodiment;
FIG. 7 is a sectional view of an electronic component mounting board according to a second embodiment.
FIG. 8 is a cross-sectional view of a conventional electronic component mounting substrate.
FIG. 9 is a cross-sectional view of a main part of an electronic component mounting board showing a popcorn phenomenon of an adhesive in a conventional example.
[Explanation of symbols]
1. . . Insulating substrate,
10,250. . . Opening hole,
11,251. . . Mounting part,
12. . . Connection holes,
100. . . Electronic component mounting board,
2. . . Die pad,
25. . . Heat sink,
3,39. . . Adhesive,
4. . . Electronic components,
41. . . Bonding wire,
5. . . Solder balls,
6. . . Conductor pattern,
7. . . Sealing resin,
8. . . Motherboard,
81. . . External terminal,

Claims (3)

An electronic component mounting board having a substrate and a mounting portion for mounting electronic components provided on the substrate,
The mounting part is provided with a metal die pad for bonding electronic components.
The aforementioned mounting portion, an opening hole is provided et is capable of passing the water that may be included in the mounting side of the electronic component,
The die pad is provided with a relief hole opened in the opening hole.
An electronic component mounting substrate, wherein an opening of the substrate is larger than a clearance hole of the metal die pad . 2. The electronic component mounting substrate according to claim 1, wherein the substrate is an insulating substrate. 2. The electronic component mounting substrate according to claim 1, wherein the substrate is a heat sink.

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