JP2770043B2 - Substrate for mounting electronic components - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electronic component mounting board using a package board such as a pin grid array or a hybrid IC board which requires high density mounting.

[Prior Art] Conventionally, as substrates for mounting electronic components, FIGS.
As shown in the figure, a conductor circuit 3 extending radially is provided on a substrate 4, and an electronic component 5 such as a semiconductor element is mounted in a concave portion 2 formed at a substantially central portion thereof as an electronic component mounting portion. Things are known.

The electronic component 5 is electrically connected to the conductor circuit 3 by a bonding wire 6, and is mounted with high density. That is, the bonding wire 6 is a circuit terminal.
It is connected between 35 and the component terminal 55 of the electronic component 5. As the bonding wire 6, an ultrafine wire (for example, 25 μm) made of gold, aluminum, or the like is generally used.
Reference numeral 51 in the figure denotes a connection pin of the electronic component 5.

[Problem to be solved]

 However, the above prior art has the following problems.

That is, since the bonding wire 6 is a very thin wire, the strength is not excellent, and the length tends to be longer as the density is increased. Therefore, the bonding wires 6 may be deformed and come into contact with each other, or may come into contact with the bonding terminals 55 adjacent to the bonding wires 6 to cause a short circuit, thereby stopping the function of the electronic component 5.

The present invention has been made in view of such a conventional problem, and an object of the present invention is to provide an electronic component mounting substrate in which a short circuit due to deformation of a bonding wire does not occur.

[Solutions to solve the problem]

The present invention relates to a substrate having a concave electronic component mounting portion and a conductive circuit, wherein an insulating material formed of an insulating material such as paint or resin is provided on the surface of the substrate near the concave electronic component mounting portion. An electronic component mounting board characterized in that a convex portion is provided and a stepped substrate space is provided between the insulating convex portion and the concave electronic component mounting portion.

In the present invention, examples of the insulating material include a paint or a resin made of a polymer material having excellent comparative heat resistance, such as a white epoxy resin, a polyimide resin, a triazine resin, and a resin obtained by modifying these resins. . Further, the insulating material is preferably a material having high thixotropy, for example, a material having 7.0 or more. The term "cyclotropic property" as used herein generally refers to the ratio of ease of movement between static and flowing states. For example, using a B-type viscometer No. 7 rotor at 2 rpm
An index determined by the ratio of viscosity at 10 rpm.

Further, it is preferable that the insulating convex portion is formed by using the insulating material so as to have a height of 0.01 to 0.50 mm by, for example, a silk printing method (see Examples). Such a height prevents deformation of the wires during wire bonding and prevents contact between the wires.

Further, the insulating convex portion may be formed using a photo-curing resin or a thermosetting resin such as epoxy acrylate or epoxy resin in a B-stage state using a dispenser (molding frame). It is preferable that the insulating convex portion is formed up to the vicinity of the end of the circuit terminal of the conductor circuit, that is, the connection terminal of the bonding wire (see FIGS. 2 and 4).

Further, the electronic component mounting portion is provided with the concave portion as described above (see the embodiment).

[Action and effect]

In the electronic component mounting board according to the present invention, an insulating convex portion is formed around the electronic component mounting portion of the substrate. Therefore, when the bonding wire is bonded between the terminal on the conductor circuit side and the terminal on the electronic component side, the bonding wire comes into contact with the upper part of the insulating convex portion. At the time of this bonding, since the substrate including the projections is in a heated state, the insulating projections are slightly melted. Therefore, it is also possible to fix the wire while slightly biting into the insulating convex portion.

Therefore, the deformation of the bonding wire is prevented,
The occurrence of a short circuit due to mutual contact of the bonding wires can be prevented.

Therefore, according to the present invention, it is possible to provide an electronic component mounting substrate in which a short circuit due to deformation of a bonding wire does not occur.

In the electronic component mounting board of the present invention, since a stepped substrate space is provided between the insulating convex portion and the concave electronic component mounting portion, the concave electronic portion is formed when the insulating convex portion is formed. It is possible to prevent the resin from dripping to the component mounting portion. Also, even when the bonding wire comes into contact with the resin constituting the insulating convex portion at the time of connection and the portion is slightly melted, the resin does not hang down or enter the concave electronic component mounting portion. .

〔Example〕

First Embodiment An electronic component mounting board according to the present embodiment will be described with reference to FIGS. 1 and 2. FIG.

That is, as shown in FIG. 2, the mounting substrate of this embodiment has a substrate 4 having a concave portion 2 as an electronic component mounting portion and having a conductor circuit 3, and an electronic component mounted in the concave portion 2 of the substrate 4. 5 and a bonding wire 6 for connecting the conductor circuit 3 and the electronic component 5.

That is, the mounting substrate is provided on the surface of the substrate 4 and in the vicinity of the concave portion 2 by the screen printing method.
11 is provided, and an intermediate portion 60 of the bonding wire 6 is fixed to the insulating convex portion 11.

The bonding wire 6 is an ultrafine gold wire having a diameter of 25 μm. The bonding wire 6 connects between the circuit terminal 35 and the component terminal 55.

The recess 2 is an electronic component mounting portion formed by counterboring using an end mill. In addition, as shown in FIG.
May form 25. The conductor circuit 3 is a circuit portion made of copper foil, copper plating, nickel plating, gold plating, or the like formed by photoetching.

The substrate 4 is made of a glass epoxy substrate, has a thickness of about 1.6 mm, and has a size of about 30 mm square. The electronic component 5 is a semiconductor element and has a size of about 10 mm square.

Also, as shown in FIG.
It has a conductor circuit 3 extending radially around the vicinity. The conductor circuit 3 has a circuit terminal 35 on the concave portion 2 side. A substantially terminal portion of the conductor circuit 3 has a through hole 8, and a large number of connection pins 7 in the through hole 8. The substrate is usually a pink lit array (PG
A) substrate.

In addition, the insulative convex portion 11 has a thixotropic property of 7.0.
It was formed of a white epoxy acrylate resin of the type which is cured by light irradiation in a relatively short time as described above.

The height of the insulating convex portion 11 is in the range of about 0.14 to 0.24 mm, and this height is substantially the same as the loop height of the bonding wire 6.

Also, what should be noted in this example is that, as shown in FIG. 2, the insulating convex portion 11 has a substrate space portion 41 at a peripheral portion 110 adjacent to the concave portion 2. That is, the board space 41 has a space which is approximately half the space called pullback, which is a gap between the end 31 of the conductor circuit 3 and the end 40 of the board 4 on the side of the concave portion 2. The insulating convex portion 11 is formed so as to cover the conductor circuit 3 at the peripheral portion 111 on the conductor circuit 3 side.

Since the mounting substrate of this example is formed as described above, it has the following operational effects.

That is, in the mounting substrate, the middle portion 60 of the bonding wire 6 is fixed on the insulating convex portion 11, so that the bonding wire 6 is not deformed and the other bonding wire 6 and the other bonding wire 6 are not deformed. There is no contact with the component terminal 55 of the bonding wire.

Therefore, according to the present embodiment, it is possible to provide an electronic component mounting board having excellent insulation and reliability.

Further, in the electronic component mounting apparatus of the present embodiment, since the substrate space 41 is provided in the peripheral portion 110 of the insulating convex portion 11 on the concave portion 2 side, the bonding wire 6 is connected to the insulating convex portion 11 at the time of connection. The resin does not hang down or enter the concave portion 2 even if the resin comes into contact with the resin and slightly melts.

Second Embodiment A mounting board according to this embodiment will be described with reference to FIGS. 3 and 4. FIG.

That is, the mounting substrate of the present embodiment has the insulating convex portions 12 provided only at the four corners instead of the insulating convex portions 11 in the first embodiment. Other configurations were the same as those in the first embodiment.

As shown in FIG. 3, the insulating convex portion 12 is provided with the concave portion 2.
Are formed only in the vicinity of the four corners. The insulating convex portion 12 has a peripheral portion on the concave portion 2 side as in the first embodiment.
120 has a board space portion 42 and a peripheral portion 1 on the conductor circuit 3 side.
In 21, the conductor circuit 3 is covered.

According to the present embodiment, in addition to the effects of the first embodiment, the material and the like forming the insulating convex portion 12 can be saved, so that the cost can be reduced.
The reason why the insulating convex portion is not provided in the central portion other than the four corners of the concave portion 2 in the present insulating convex portion 12 is that the bonding wire 6 in the central portion is relatively short, This is because a short circuit due to mutual contact is unlikely to occur.

Third Embodiment A mounting board according to this embodiment will be described with reference to FIGS.

That is, the mounting substrate of the present embodiment has the following insulating protrusions 14 instead of the insulating protrusions 11 in the first embodiment. Other configurations were the same as those in the first embodiment.

In other words, the insulating convex portion 14 is provided at the peripheral portion 140 on the concave portion 2 side.
And board space portions 44 and 45 at the peripheral portion 141 on the conductor circuit 3 side.
Having.

According to this embodiment, the following effects are obtained in addition to the effects of the first embodiment.

That is, since the insulating convex portion 14 has the substrate space portion 44 at the peripheral portion 140 on the concave portion 2 side, even when the resin forming the insulating convex portion 14 is melted when the bonding wire 6 is connected. , The resin hangs in the recess 2,
It does not enter again.

Further, the insulating convex portion 14 is formed on the peripheral portion 141 on the conductor circuit 3 side.
Has a substrate space 45, so that the substrate space 45
The insulating convex portion 14 and the conductor circuit 3 are separated from each other via.
Therefore, even if a minute external stress due to heating occurs in the insulating convex portion 14 during resin sealing or the like, it is not transmitted to the conductor circuit 3. Therefore, the bonding wires 6 are not deformed in the vicinity of the end of the conductor circuit 3 and do not come into contact with each other to cause a short circuit.

[Brief description of the drawings]

1 and 2 show an electronic component mounting board according to a first embodiment, FIG. 1 is a perspective view thereof, FIG. 2 is an enlarged sectional view of a mounting apparatus, and FIGS. 3 shows a mounting board according to the second embodiment, FIG. 3 is a plan view thereof, FIG. 4 is an enlarged sectional view thereof, and FIGS. 5 and 6 show mounting boards according to the third embodiment. FIG. 6 is a plan view thereof, FIG. 6 is an enlarged sectional view thereof, and FIGS. 7 and 8 show a conventional mounting substrate.
FIG. 7 is a perspective view thereof, and FIG. 8 is a sectional view thereof. 11,12,14 …… Insulating convex, 2… Recess, 3… Conductor circuit, 4…
... substrate, 5 ... electronic parts, 6 ... bonding wire, 7 ...
… Connection pins, 8 …… Through holes,

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01L 21/60 301

Claims (1)

(57) [Claims] 1. A substrate having a concave electronic component mounting portion and a conductor circuit, comprising: an insulating material formed of an insulating material such as paint or resin on a surface of the substrate and near the concave electronic component mounting portion. An electronic component mounting substrate, comprising: a conductive convex portion; and a stepped substrate space portion provided between the insulating convex portion and the concave electronic component mounting portion.