JP2796043B2 - Electronic components - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic component in which a ceramic substrate on which a predetermined circuit including an electronic element is formed is covered with a sealing member.

[0002]

2. Description of the Related Art Conventionally, an electronic component in which a predetermined circuit pattern is formed on a ceramic substrate, electronic elements such as semiconductor elements and capacitors are mounted on the circuit pattern, and the ceramic substrate is covered with a sealing member such as a resin. It is heavily used. This is commonly called a hybrid integrated circuit.

[0003] Such a sealing member is formed by coating a sealing resin obtained by dissolving additives such as a thermosetting resin, a filler and a pigment with a solvent around a ceramic substrate by a dipping method or the like, and drying the solvent. It was formed by removing and curing.

[0004] By controlling the material of the thermosetting resin and the filler constituting the sealing member and the composition ratio thereof,
It is dense and excellent in water resistance, is free from cracks and peeling, and has a small difference in thermal expansion coefficient from the ceramic substrate.

In general, when the proportion of the filler in the sealing member is increased in order to reduce the difference in thermal expansion coefficient from the ceramic substrate, the proportion of the thermosetting resin interposed between the fillers and acting as an adhesive is increased. Is relatively small, the mesh of the sealing member is coarse, and sufficient characteristics of water resistance cannot be obtained.

On the other hand, if the proportion of the filler is reduced and the mesh of the sealing material is made finer, the difference in thermal expansion coefficient from the ceramic substrate increases, and cracks or peeling of the sealing member occurs when a thermal shock is applied. A problem such as the occurrence of a problem occurs.

[0007] Therefore, in order to satisfy both of the above-mentioned contradictory characteristics, conventionally, the sealing member has a multilayer structure, and the sealing layer having a large number of filling members is impregnated with wax to improve water resistance and moisture resistance. In order to improve both properties (Japanese Unexamined Patent Publication No. 64-44052) and to satisfy both characteristics, the undersealing sealing layer and the exterior sealing layer are made of different kinds of resins (Japanese Unexamined Patent Publication No. 2-134892).

[0008]

However, the sealing member impregnated with the wax can be used to solder the electronic component to a printed wiring board or to perform other heat treatments.
Further, when used at a high temperature, there is a problem that the wax is melted and the water resistance is significantly deteriorated.

Further, in a sealing member having a multilayer structure in which different types of resins are combined, different types of resins are used in the respective sealing layers. There is a problem that blisters are easily generated, thermal shock resistance is deteriorated, and a curing process of the resin is complicated due to fundamentally different resin curing conditions.

The present invention has been devised in view of the above-mentioned problems, and has as its object to perform a curing step by using an epoxy resin as a thermosetting resin for each layer of a sealing member having a multilayer structure. An object of the present invention is to provide an electronic component having a sealing member that is easy and has good water resistance and thermal shock resistance.

[0011]

According to the present invention, there is provided an electronic component comprising a ceramic substrate on which an electronic element is mounted, covered with a sealing member having a multilayer structure, wherein the sealing member is a thermosetting resin. 80% by weight or more of fused silica glass containing resin and fused silica glass as a filler, and being in contact with the ceramic substrate (hereinafter referred to as a base sealing layer); Is an electronic component containing 77.5% by weight or less of fused silica glass, preferably, the sealing member has a two-layer structure,
The film thickness is 0.5 to 2.5 mm, and the thickness of the sealing layer on the exterior side is 66% or more of the whole.

[0012]

According to the present invention, when forming a sealing member having a multi-layer structure, each layer is formed by using an epoxy resin which is the same type of thermosetting resin. This makes it possible to simplify the manufacturing process and obtain a sealing member that does not cause swelling or peeling at the interface between the layers.

Further, since the fused silica glass as a filler is added to the base sealing layer on the side in contact with the ceramic substrate at 80% or more, the difference in thermal expansion coefficient between the base sealing layer and the ceramic substrate is small. This improves the thermal shock resistance.

Further, since the outer sealing layer contains 77.5% or less of fused silica glass as a filler, the amount of the filler is relatively small and the amount of the resin is relatively large, so that the sealing member has a fine mesh. And the water resistance becomes good.

As a result, an electronic component having a sealing member which is easy to manufacture and has excellent water resistance and impact resistance is achieved.

When the sealing member has a two-layer structure, its thickness is desirably 0.5 to 2.5 mm as a whole. 0.5
If the thickness is less than 2.5 mm, the sealing member becomes extremely thin at the edge of the ceramic substrate, and the ceramic substrate may be exposed. High-density mounting on a wiring board becomes difficult.

In the above-mentioned thickness of the sealing member, the thickness of the exterior sealing layer is set to 66.6% or more of the whole. 66.
If it is less than 6%, the water resistance is greatly deteriorated.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an electronic component according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic view in which a sealing member is omitted in a part of the electronic component of the present invention.

In the drawing, 1 is a ceramic substrate, 2 is a conductor pattern for forming a circuit, 3 is a semiconductor element as an example of an electronic element, and 4 is a chip component such as a chip resistor and a chip capacitor as an example of an electronic element. ,... Are lead terminals, and 6 is a sealing member. In the drawing, the sealing member 6 is shown.
Has a two-layer structure, and includes a sealing layer on the side in contact with the ceramic substrate 1, that is, a base sealing layer 61, and a sealing layer on the exterior side, that is, an exterior sealing layer 62.

On the surface of the ceramic substrate 1, a conductor pattern 2 for forming a predetermined circuit is formed by a thick film technique, for example, printing and baking of a conductive paste. A semiconductor element 3 as an electronic element and various chip components 4 are mounted on the conductor pattern 2. The bonding between the semiconductor element 3 and the conductor pattern 2 is performed by wire bonding or face bonding using solder bumps, and the bonding between the chip component 4 and the conductor pattern 2 is performed by solder bonding or the like. Also, at the end of the ceramic substrate 1,
A plurality of lead terminals 5.
.. are joined.

Around such a ceramic substrate 1,
The sealing member 6 is covered.

The sealing member 6 is composed of a base sealing layer 61 and an outermost sealing layer 62, and is mainly composed of an epoxy resin as a thermosetting resin and a fused silica glass as a filler.

The base sealing layer 61 contains at least 80% by weight of a fused silica glass as a filler, and the remainder is substantially an epoxy resin which is a thermosetting resin.

On the other hand, the outer sealing layer 62 is set so that the content of the fused silica glass as a filler is 77.5% by weight or less, and the remainder is substantially an epoxy resin which is a thermosetting resin. It is.

The sealing member 6 having such a two-layer structure is manufactured by the following manufacturing method.

First, a resin dissolved by a solvent for the base sealing layer 61 and the exterior sealing layer 62 is prepared. For example, the melted resin serving as the base sealing layer 61 may be added with an additive such as an epoxy resin, a fused silica glass, or a pigment so that the fused silica glass becomes 80% by weight or more after curing, that is, after the solvent is removed. Is dissolved in a solvent. In addition, the dissolving resin which becomes the exterior sealing layer 62 is similarly prepared.

Next, the ceramic substrate 1 on which the semiconductor element 3 and the chip component 4 are mounted on the conductor pattern 2 and to which the lead terminals 5 are joined is immersed in a bath of a molten resin to be a base sealing layer 61. After pulling up, air dry. In order to set the thickness of the base sealing layer 61 to a predetermined value, this immersion, pulling up, and air drying may be repeated a plurality of times.

Next, the ceramic substrate 1 coated with the resin to be the base sealing layer 61 is immersed in a bath of a molten resin to be the exterior sealing layer 62, pulled up, and air-dried.
In order to set the thickness of the exterior sealing layer 62 to a predetermined value, the immersion, lifting, and air drying may be repeated a plurality of times.
Thereby, the thickness of the sealing member 6 is set to 0.5 to 2.5 mm, and the thickness ratio of the exterior sealing layer 62 to the whole is 6 mm.
6.6% or more.

Thereafter, the epoxy resin which is a thermosetting resin is completely cured by a heat treatment at 150 ° C. for 30 to 3 hours.

As a result, the sealing member 6 including the base sealing layer 61 and the exterior sealing layer 62 is formed around the ceramic substrate 1.

In the sealing member 6 described above, the base sealing layer 6
No. 1 contains a large amount of fused silica glass as a filler. Therefore, since there are many fused silica glass having a value relatively close to the coefficient of thermal expansion of the ceramic substrate 1, the ceramic substrate 1
The thermal shock resistance is improved, and peeling between the ceramic substrate 1 and the sealing member 6 due to the thermal shock and breakage of the thin wires of the semiconductor element 3 can be effectively prevented. Can be prevented.

Since the exterior sealing layer 62 contains less fused silica glass and contains a relatively large amount of an epoxy resin as a thermosetting resin as compared with the base sealing layer 61,
Since a sufficient amount of epoxy resin acting as an adhesive is interposed around the fused silica glass, a dense sealing layer is formed. As a result, the water absorption in 1 g becomes 4 mmg or less, and the sealing member 6 as a whole has excellent water resistance.

Further, both sealing layers 61 and 62 are made of the same type of thermosetting resin, ie, an epoxy resin. In addition, structurally, both sealing layers 6
The interfaces 1 and 62 are joined in a strong state, and no separation occurs between them.

In order to improve the above-mentioned water resistance and thermal shock resistance, the thickness of the sealing member 6 should be 0.5 to 2.5 mm.
And the thickness ratio of the exterior sealing layer 62 is 66.6%.
It is important to do the above.

If the thickness of the sealing member 6 is less than 0.5 mm, the sealing member becomes extremely thin at the edge of the ceramic substrate 1, exposing the ceramic substrate 1 and deteriorating the moisture resistance. On the other hand, if the thickness exceeds 2.5 mm, the thickness of the entire electronic component becomes large, making it difficult to use the printed wiring board for high-density mounting, and the time required for the curing step becomes extremely long. Further, when the thickness ratio of the exterior sealing layer 62 is less than 66.6%, the water resistance is greatly deteriorated.

As shown in Table 1, the present inventors set the weight ratio of the fused silica glass after curing of the base sealing layer 61 and the exterior sealing layer 62 and the thickness ratio of the exterior sealing layer 62, respectively. An electronic component was prepared, and the water resistance and thermal shock resistance of the sealing member 6 were examined.

Here, the thermal shock resistance refers to the number of cycles at which cracking or peeling of the sealing member 6 occurs by immersing an electronic component in water at 0 ° C. and 100 ° C. for 6 minutes each, and repeating this. evaluated. Good products can withstand 1000 cycles.

The water resistance was evaluated by immersing the electronic components in water at 65 ° C. and saturated saline at 0 ° C. for 1 hour, and repeating the procedure 6 times to evaluate the water absorption. Good product is 1g
It has a water absorption of 4 mmg or less.

In Samples Nos. 7 to 11 in Table 1, although the sealing member 6 had a single-layer structure, the thickness was 2.5
mm is achieved by repeating immersion and air drying in a bath of the same molten resin a plurality of times, which can be said to be the same as having multiple layers of sealing layers having the same composition. The thickness of the sealing member 6 was 2.5 mm in total.

[0040]

[Table 1]

As is clear from Table 1, Sample Nos. 7-1
1, the thickness of the single-layered sealing member is 2.5 mm.
However, a material satisfying both water resistance and thermal shock resistance cannot be obtained.

In the sealing member having the two-layer structure, the base sealing layer 61
When the fused silica glass is 80% by weight or more (Sample Nos. 1 to 4 and 6), the thermal shock resistance becomes good, and when the fused silica glass of the exterior sealing layer 62 is 77.5% by weight or less. (Sample number 1 to 5), 1 g of the sealing member 6
The water absorption per unit is 1 to 4 mg, and the water resistance is good.

Therefore, the content of the fused silica glass as the filler of the base sealing layer 61 is 80% by weight or more, and the content of the fused silica glass of the exterior sealing layer 62 is 7% or more.
It is understood that when the content is 7.5% by weight or less, the water resistance and the thermal shock resistance are satisfied. However, in Sample Nos. 3 and 6 in which the content of the fused silica glass in the sealing member 6 is the same, Sample No. 6 has a thickness ratio of the exterior sealing layer 62 of 33 even though the composition ratio is satisfied. When it is as thin as 0.3%, the water resistance deteriorates. Therefore, it is important that the thickness ratio of the exterior sealing layer 62 be 66.6% or more.

In the above-described embodiment, the sealing member 6 has a two-layer structure including the base sealing layer 61 and the exterior sealing layer 62.
During this time, an intermediate sealing layer may be formed to perform multilayering. In this case, it is important to use an epoxy resin as the thermosetting resin.

[0045]

As described above, according to the present invention, there is provided an electronic component formed so as to cover a ceramic substrate with a sealing member containing a thermosetting resin and a filler, wherein the thermosetting resin is an epoxy-based resin. Resin, the filler is fused silica glass, and contains 80% by weight or more of the fused silica glass of the base sealing layer on the side in contact with the substrate, and 77.5% by weight or less in the exterior sealing layer. Prevents swelling between layers,
It is possible to obtain a sealing member which has a simple curing process and good water resistance and thermal shock resistance, and can stably protect a circuit pattern on a ceramic substrate.

[Brief description of the drawings]

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Ceramic substrate 2 ... Conductor pattern 3 ... Semiconductor element 4 ... Chip component 5 ... Lead terminal 6 ... Sealing member 61 ... Underlayer 62 ... Outermost layer Sealing layer

Claims (1)

(57) [Claims] An electronic component comprising a ceramic substrate on which an electronic element is mounted and covered with a sealing member having a multilayer structure, wherein the sealing member is an epoxy resin as a thermosetting resin and a fused silica as a filler. It is composed of glass and contains 80% by weight or more of fused silica glass on the side in contact with the ceramic substrate and 77.5% by weight or less of fused silica glass on the exterior side. Stopper thickness
An electronic component, wherein the thickness is 66% or more of the thickness of the sealing member .