JP2009026982A - Electronic device and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic device provided with at least a wiring substrate 20, including at least an IC mounting part and a wiring film 22 connected to terminals 11 of an IC 10 mounted on the IC-mounting part, and the IC 10 mounted thereon, capable of preventing migration in the electronic device in which the respective terminals 11 of the IC 10 and the wiring film 22 corresponding to them are connected, improving the moisture resistance, water resistance, dust tightness, and corrosion resistance, so as to improve the reliability and prolong the service life of the electronic device, and reduce the environmental pollution associated with the manufacture of the electronic device. <P>SOLUTION: A double film formed of a solder resist film 28 and a coating film 30, mainly having silica protects between at least the wiring films 22 and 22 of at least the wiring substrate 20. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is connected to a semiconductor integrated circuit device mounting portion (hereinafter referred to as “IC mounting portion”) and a plurality of terminals of a semiconductor integrated circuit device (hereinafter referred to as “IC”) mounted on the IC mounting portion. The present invention relates to an electronic device including at least a wiring board having a wiring film and an IC mounted on the IC mounting portion of the wiring board, and connecting each terminal of the IC to a corresponding wiring film, and a method for manufacturing the same.

As an electronic device, for example, as disclosed in JP-A-6-310844, there is one in which an IC, for example, a QFP type IC and other electronic components are mounted on a wiring board.
FIGS. 3A to 3F are cross-sectional views showing the main part of an example of such an electronic device, where FIG. 3A is a perspective view of a QFP type IC, and FIG. 3B is a wiring on which the IC is mounted. The perspective view of a board | substrate, (c) is a perspective view which shows the state which mounted IC in the wiring board, (d) is sectional drawing of the aa line direction of (c), (e) is bb of (c). Sectional drawing of a line direction, (f) is sectional drawing of the cc line direction of (c).

  In FIG. 3, 10 is a QFP type IC mounted on a wiring board, 11 is an outer lead (terminal) of the IC 10, 20 is a wiring board on which the IC 10 is mounted, and 22 is an electrode of a wiring film formed on the wiring board 20. A pad portion 23 is a through hole formed in the electrode pad portion 22, and 24 is an adhesive for fixing the resin sealing portion of the IC 10 to the wiring substrate 20.

In this electronic device, as shown in FIG. 3, a wiring film (only the electrode pad portion 22 appears in the drawing) is formed, and a wiring board in which an adhesive 24 is applied to a portion corresponding to a resin sealing portion of the IC 10 The IC 10 is aligned with the surface of 20 so that each outer lead (terminal) 11 is positioned on the electrode pad portion 22 corresponding thereto, and the resin-sealed portion is adhered to the wiring board 20 with the adhesive 24, Each terminal 11 is connected to the corresponding electrode pad portion 22 by soldering.
JP-A-6-310844

By the way, the above-described conventional technique has a problem that a failure due to migration occurs when the IC is multi-functional, downsized, highly integrated, multi-terminal, and narrowed in the terminal interval.
Migration is a phenomenon in which the metal used as wiring or electrodes moves over the insulator by using electronic parts such as ICs for a long time, which is undesirable because it reduces the insulation resistance between the electrodes, and the progress of the decrease As a result of this, failure such as insulation failure or short circuit failure occurs.

By the way, migration includes electromigration in which the metal component moves over and inside non-metallic media due to the influence of electric fields, and migration in which corrosive products are generated by corrosion regardless of the presence or absence of electric fields, resulting in reduced insulation. Both have basically different generation mechanisms, but both are not preferable because they reduce the insulation resistance between the electrodes, and are common in that they need to be prevented.
Various technologies have been developed for preventing migration, but no perfect technology exists. Therefore, if the inter-terminal spacing becomes narrower due to the multi-function, miniaturization, high integration, and multi-terminal of the IC, the current technology may not be able to completely prevent the problem of failure due to migration. is there.

  The present invention has been made to solve such problems, and includes a wiring board having at least a wiring film connected to an IC mounting portion and an IC terminal mounted on the IC mounting portion, and the wiring substrate mounted thereon. In addition, at least one IC is provided, and migration of an electronic device in which each terminal of this IC is connected to a corresponding wiring film is prevented, and further, moisture resistance, water resistance, dust resistance, and corrosion resistance are improved. The purpose of the present invention is to improve the reliability of the device and extend its life, and to reduce the environmental pollution associated with the manufacture of electronic devices.

  In the present invention, at least the wiring film on the surface of the wiring board and the space between the wiring films are double protected with a solder resist film and a coating film mainly composed of silica.

According to the present invention, at least the wiring film on the surface of the wiring board of the electronic device and the space between the wiring films are protected by the solder resist film and the coating film mainly composed of silica. The space is double protected not only by the solder resist film but also by a coating film that is an inorganic substance.
Therefore, it is possible to prevent the movement between metals and the generation of corrosion products between the wirings.
Therefore, migration between the wiring films can be effectively prevented.

Furthermore, according to the coating agent made of an inorganic substance, the moisture resistance, water resistance, dust resistance and corrosion resistance of the coated part can be improved, so that the moisture resistance, water resistance, dust resistance and corrosion resistance of the electronic device are improved. Thus, the reliability of the electronic device can be improved and the life can be extended.
Since the coating agent contains silica, which is an inorganic substance, as a main component, there is less environmental pollution than when an organic material is used, and environmental pollution associated with the manufacture of electronic devices can be reduced.

In the present invention, basically, at least the surface of a wiring board having a solder resist film formed on the surface thereof is further covered with a coating film containing silica (SiO ₂ ) as a main component, and the solder resist film and silica are used as main components. Although the protective film is double-protected, the thickness of the solder resist film is, for example, 10 to 15 μm, and is patterned by applying the solder resist over the entire surface, then exposing and developing. .

Patterning is performed so that the portion of the wiring film connected to the terminals of the semiconductor integrated circuit device and other various electronic components is exposed. Conventionally, it is formed by screen printing. Along with the increase in the number of pins and the increase in the density of wiring, it has been formed by a photolithography technique by exposure and development. In this invention, it can implement in any form.
The coating film is optimally mixed with powdered silica in isopropyl alcohol (silica is, for example, 80 to 95% by weight, isopropyl alcohol is, for example, 20 to 5% by weight) and liquefied. However, alcohols other than isopropyl alcohol may be used.

Here, the characteristics of the coating agent containing 90% by weight of powdered silica and 10% by weight of isopropyl alcohol will be described. Coating film thickness is 10μm ~ 20μm, heat resistance temperature is 700 ° C, hardness is 9H, specific gravity (specific gravity at 25 ° C) is 1.05, pH is 5.0, refractive index (Beckeline method) is 1.43, volume specific The resistance (volume specific resistance at 25 ° C.) is 10 ¹⁴ Ω / cm or more, the glass component in the liquid is 57%, the appearance is a pale yellow liquid, and the viscosity is 40 cp.

Note that water may be used as a diluent for the coating agent instead of isopropyl alcohol.
The coating film is preferably formed by diluting powdered silica with a diluent to form a liquid, for example, by spraying or coating on the surface of the wiring board and drying it.

The present invention is not limited to an electronic device in which one or a plurality of ICs are mounted on a wiring board, but in addition to one or a plurality of ICs, an electronic device in which electronic components other than ICs, for example, electronic components such as resistors and capacitors, are mounted. It can also be applied to.
The coating film is preferably formed not only on the surface of the wiring board but also on the surface of the IC and other electronic components mounted thereon. That is, the coating film is formed on the entire surface of the wiring board including the surface of the mounted electronic components, and in this way, the mounted electronic components can be protected.

Hereinafter, the details of the present invention will be described based on illustrated embodiments.
1 and 2 (a) to 2 (c) show an electronic device 1a according to one embodiment of the present invention. FIG. 1 is a perspective view, and FIG. 2 (a) is a view taken along the line aa in FIG. Sectional drawing, (b) is also a sectional view in the bb line direction, and (c) is a sectional view in the same cc line direction.

  This Example 1a is completely different from the conventional example shown in FIG. 3 in that a solder resist film (28) and a thin coating agent (30) are formed on the surface of the wiring board 20, but in other points. Since common points and common points have already been described, the same reference numerals are given to portions common to FIG. 3 in FIG. 1, and detailed descriptions are omitted, and new portions are used only for different portions. I will explain. Further, the perspective view of the IC 10 to be mounted and the wiring board 20 on which the IC 10 is mounted is the same as (a) and (b) of FIG.

Reference numeral 28 denotes a solder resist film formed on the surface of the wiring board 20. After the wiring film 22 is formed, a liquid solder resist is applied to the entire surface of the wiring board 20, and then patterned by exposure and development. A portion of the wiring film 22 connected to the terminal of the IC 10 is exposed.
A coating film 30 is formed on the surface of the solder resist film 28 of the wiring board 20. After the terminals 11 of the IC 10 are connected to the wiring film 22 by soldering using a flux, the IC 10 is formed on the surface of the wiring board 20. In this case, the powdered silica is applied over the entire surface including a surface obtained by diluting with liquefied silica such as isopropyl alcohol or water, and then dried.

Specifically, the wiring film 22 is formed on the surface, and the wiring substrate 20 whose surface is covered with the solder resist film 28 except for each portion connected to the terminal 11 such as the IC 10 of the wiring film 22 is prepared. Each terminal 11 is connected to a portion of the wiring film 22 that is not covered with the solder resist film 28 by soldering using a flux, and then the entire surface of the wiring substrate 20 including the surface of the IC 10 is entirely covered. The coating film 30 can be formed by applying (or spraying) a coating agent (a liquid material obtained by diluting powdered silica with a diluent such as alcohol such as isopropyl alcohol or water) and drying.
Since the coating film 30 is formed by applying a coating agent after the electronic component such as the IC 10 is mounted and drying, the coating film 30 is also formed on the surface of the mounted electronic component such as the IC. Accordingly, the mounted electronic component such as the IC 10 can be protected by the coating film 30.

According to such an electronic device 1a, the solder resist film 28 that directly covers the wiring board 20 between the wiring films 22 and 22 of the wiring board 20, and the coating film mainly composed of silica on the solder resist film 28. Since the double film 30 is interposed, the solder resist film 28 and the coating film 30 which is an inorganic substance can prevent the movement between metals and the generation of corrosion products between the wirings.
Therefore, migration between the wiring films can be effectively prevented.

Furthermore, according to the coating film 30 made of an inorganic substance, the moisture resistance, water resistance, dust resistance, and corrosion resistance of the coated portion can be improved, so that the moisture resistance, water resistance, dust resistance, and corrosion resistance of the electronic device can be improved. Thus, the reliability of the electronic device can be improved and the life can be extended.
And since a coating film has as a main component silica which is an inorganic substance, compared with the case where an organic material is used, there is little environmental pollution, and environmental pollution accompanying manufacture of an electronic device can be reduced.

  The present invention includes at least an IC mounting portion and a wiring substrate having at least a wiring film connected to a plurality of terminals of the IC mounted on the IC mounting portion, and an IC mounted on the IC mounting portion of the wiring substrate, There is a wide industrial applicability to an electronic device in which each terminal of this IC and its corresponding wiring film are connected, and a method for manufacturing the electronic device.

It is a perspective view which shows the principal part of the electronic device of one Example of this invention. (A)-(c) is sectional drawing of one Example of this invention, (a) is sectional drawing of the aa line direction of FIG. 1, (b) is sectional drawing of a bb line direction similarly. (C) is also a cross-sectional view in the direction of the line cc. (A)-(f) is sectional drawing which shows the principal part of an example of the prior art example of the electronic device for demonstrating the background art of this invention, (a) is a perspective view of QFP type IC, (b). Is a perspective view of a wiring board on which the IC is mounted, (c) is a perspective view showing a state in which the IC is mounted on the wiring board, (d) is a cross-sectional view in the direction of the aa line of (c), and (e). (C) is a cross-sectional view in the bb line direction, (f) is a cross-sectional view in the cc line direction of (c).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a ... Electronic device (Example), 10 ... IC,
11 ... Terminal (outer lead), 20 ... Wiring board,
22 ... Wiring film (electrode pad portion thereof),
30: Coating film.

Claims (5)

A semiconductor integrated circuit device mounting portion, a wiring substrate having at least a wiring film connected to a plurality of terminals of the semiconductor integrated circuit device mounted in the semiconductor integrated circuit device mounting portion, and the semiconductor integrated circuit device mounting portion of the wiring substrate In an electronic device comprising at least a semiconductor integrated circuit device mounted and connecting each terminal of the semiconductor integrated circuit device and a corresponding wiring film,
A solder resist film is formed on the wiring board to cover the surface except at least a portion of the wiring film connected to the terminal of the semiconductor integrated circuit device,
An electronic device, wherein a coating film mainly composed of silica is formed on at least a portion of the solder resist film covering the wiring film. 2. The electronic device according to claim 1, wherein the coating film is formed by coating a surface of the wiring board with a powdered silica mixed with alcohol to be liquefied, and then drying. 3. . The electronic device according to claim 2, wherein the alcohol is isopropyl alcohol. 2. The electronic device according to claim 1, wherein the coating film is formed by coating the wiring substrate with a powdered silica mixed with water to be liquefied, and then drying. 3. The semiconductor integrated circuit device having the wiring film on the surface of the wiring substrate having at least a wiring film connected to a plurality of terminals of the semiconductor integrated circuit device mounted on the semiconductor integrated circuit device mounting portion. Forming a solder resist film covering at least a portion connected to the terminal of
Thereafter, the wiring film and at least a terminal of the semiconductor integrated circuit device are connected to mount the semiconductor integrated circuit device,
Thereafter, at least a portion of the solder resist film covering the wiring film is coated on the surface of the wiring substrate with a powdered silica mixed with alcohol or water, and dried to dry the main component of silica. A method for manufacturing an electronic device, comprising: forming a coating film.

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