JPH0476945A - Substrate for mounting electronic component - Google Patents

Abstract

PURPOSE:To facilitate the injection of sealing resin by putting the shape of an insulating base material into the shape where chamfered parts are made by cutting angles off four corners. CONSTITUTION:For a board 10 for mounting electronic components, chamfered parts 15 are positively formed at the corners of an insulating base material 12, which is usually formed in a quadrangle, whereby the periphery of the insulating base material 12 opens wide by these chamfered parts 15. Accordingly, when it is supported in the molds of a transfer molding device after mounting electronic components 30 on this board 10 for mounting electronic parts, a passage for fluidified sealing resin 20 is made largely. Hereby, when sealing the board 10 for mounting electronic parts with sealing resin 20, the flow of this sealing resin 20 improves, and also the drop of the resin pressure at the corners of the insulating base material 12 can be prevented, and the occurrence of voids is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a substrate for mounting electronic components, and in particular, to a substrate for mounting electronic components, in particular, after mounting electronic components, almost the entire substrate is molded with a sealing resin with an outer lead protruding. The present invention relates to a board for mounting electronic components.

(Prior Art) In order to protect the mounted electronic components, their conductor circuits, or the connecting parts of bonding wires, the circuit board for mounting electronic components as shown in FIG. As shown, it is common to mold with a sealing resin so as to enclose almost the entire part. Molding with this sealing resin is usually done by a transfer molding method, in which an electronic component mounting board with electronic components mounted is fixedly placed in a mold, and a heated fluid seal is placed around it. This is done by injecting resin.

On the other hand, when looking at the electronic component mounting board, it is formed by integrating an insulating base material on both sides of the inner end of each outer lead, with the tips of many outer leads protruding outward. The above-mentioned sealing resin must be reliably injected between these many outer leads.

In other words, with respect to electronic component mounting boards in which insulating base materials are integrated on both sides of outer leads, transfer molding has to be carried out without considering the following points.

As electronic component mounting boards in recent years have become more compact in response to higher density electronic components, the spacing between each outer lead has become extremely small, and the length has also become extremely short. There is. Therefore, the gap between the insulating base material integrated on both sides of the outer lead and the mold becomes narrower, making it difficult for the resin to flow, and at the same time, it becomes difficult for the resin to flow into the mold, especially in parts of the mold away from the resin injection part or in particularly narrow gaps. Since it becomes difficult to apply resin pressure, defects such as voids are more likely to occur. In this case, no matter how fluid the resin is, it will not be possible to mold it reliably unless the pressure is increased or the resin is injected over time. If the molding with this sealing resin is not reliable,
This leaves voids that adversely affect electronic components and the like.

In addition, if the sealing resin is not completely integrated by adhering to both sides of each outer lead, cracks or peeling may occur at the sealing resin itself or at the interface between it and the outer lead due to heat stress applied from the outside, for example. This may occur. This phenomenon may occur because the sealing resin on both sides of each outer lead is not completely integrated, or it may easily occur if the distance between each outer lead is very small as described above. be.

In particular, if the distance between the outer leads is small, the passage for the sealing resin becomes small, which makes voids more likely to occur, as well as peeling and cracking.

In light of the above, conventional molding of electronic component mounting substrates with sealing resin has had problems, such as the need to be very careful and spend a lot of time.

Therefore, in order to improve the above-mentioned situation, the inventors of the present invention have conducted intensive studies on how to devise ways to improve the electronic component mounting substrate side in order to ensure that molding with sealing resin can be performed reliably and efficiently. As a result of repeated efforts, the present invention was completed.

(Problems to be Solved by the Invention) The present invention has been made based on the above-mentioned circumstances, and the problem to be solved is to securely seal an electronic component mounting board with a sealing resin. .

An object of the present invention is to make it possible to reliably and quickly inject the sealing resin into the entire outer lead even when the spacing and length of the outer leads become smaller, and to make it possible to reliably and quickly inject the sealing resin into the entire outer lead after sealing with the sealing resin. The object of the present invention is to provide a substrate for mounting electronic components with a simple structure that does not cause voids or peeling from the sealing resin.

(Means for Solving the Problems) In order to solve the above problems, the means taken by the present invention are as follows:
To explain with reference numerals used in the examples, [a large number of outer leads (11) whose inner ends are concentrated toward the mounting portion (14) of the electronic component (30), and each of these outer leads (11)] an insulating base material (12) integrated on both sides of the inner end of the insulating base material (12), and a conductor circuit (13) formed on this insulating base material (12) and electrically connected to each outer lead (11). In the electronic component mounting board (10), the insulating base material (12) has a polygonal shape with at least one square corner cut off to form a chamfered part. This is a component mounting board (10)J.

That is, in the electronic component mounting board (10) according to the present invention, chamfered portions (15) are actively formed at the corners of the insulating base material (12), which is usually formed in a square shape, so that the chamfered portions (15) are Toribe (1
5), the periphery of the insulating base material (12) is largely open.

(Operation of the invention) In the electronic component mounting board (10) according to the present invention configured as described above, the chamfered portion (15) formed on the insulating base material (12) The surrounding area is wide open. Therefore, when the electronic component (30) is mounted on the electronic component mounting board (10) and then supported in the mold of a transfer molding device, the path of the fluidized sealing resin (20) is wide. It will be formed.

Thereby, when this electronic component mounting board (10) is sealed with the sealing resin (20), the sealing resin (20)
), it is possible to prevent the resin pressure from decreasing at the corners of the insulating base material (12), and the generation of voids can be prevented. That is, fluidized sealing resin (20
) from one side of the mold of the transfer molding device to the other, the flow of the sealing resin (20) is controlled by each outer lead (11) and insulating base material (12) present in the mold. In the electronic component mounting board (10) according to the present invention, since the chamfered part (15) is formed at the corner of the insulating base material (12), the sealing at least in that part is prevented. This ensures the fluidity of the resin (20).

Therefore, the sealing resin (20) injected from one side of the mold is
The resin is passed around each arator (11) and the insulating base material (12) under sufficiently uniform resin pressure, and the air that causes voids is not pushed out to the other side of the mold, so that the mold is sufficiently filled. It is.

Furthermore, in the electronic component mounting board (10) according to the present invention, the chamfered portions (15) are formed at the corners of the insulating base material (12) as described above. When the entire substrate (lO) is sealed with the sealing resin (20), the sealing resin (20) that has flowed into both sides of each outer reed (11) covers each chamfered portion (
15) are also integrated with each other. In other words, if the conventional board does not have this chamfered part (15), there will be a part of the insulating base material (12) facing outward in that part, and the upper and lower sides of that part will be The reason is that the sealing resin (20) of the electronic component mounting substrate (20) of the present invention is not integrated with each other closely.
In 10), the sealing resin (20) is integrated with each other in this part.

Therefore, according to this electronic component mounting board (10), the adhesiveness of the sealing resin (20) that has flowed into both sides of the board is sufficient, and the integration of the entire sealing resin (20) is promoted. There is no possibility of peeling off from the component mounting substrate (10) or cracking of the sealing resin (20) itself.

In particular, in the electronic component mounting board (10) according to the embodiment shown in FIG. 6, which will be described later, the chamfered portion (
A plurality of outer leads (11) also protrude from the chamfered part (15). ) protrudes from the outer lead (
11) and open the gaps between them. Therefore, in this embodiment, it is possible to sufficiently wrap the sealing resin (20) around the outside of the chamfered portion (15) of the insulating base material (12), and furthermore, the outer lead (
This improves the integration of the sealing resins (20) located on both sides of the substrate 11) compared to conventional substrates.

(Example) Next, the electronic component mounting board (10) according to the present invention will be described in detail according to the examples shown in the drawings.

FIG. 1 shows an electronic component mounting board (10) according to the present invention.
A plan view of this electronic component mounting board (10
), as shown in Fig. 3, includes a lead frame (IIA) in which a large number of outer leads (11) are integrated on one plane, and a lead frame (IIA) integrated on both sides of this lead frame (IIA). Insulating base material (12) on the front and back, conductor circuit (13) formed on this insulating base material (12) and mounting part (1
4) and each outer lead (1
The inner end of 1) is formed so as to be concentrated toward the mounting portion (14) on the insulating base material (12). Further, in the electronic component mounting board (10) according to this example, the insulating base material (
12) Connect the upper conductor circuit (13) and each outer lead (11)
) is electrically connected by a through hole (16) formed through an insulating base material (12).

Conventional insulating base materials have been formed in a rectangular shape as shown in the imaginary line in FIG. 1 or as shown in FIG. 7 for reasons such as simplifying the manufacturing process. In the electronic component mounting board (10) according to the present invention, the corner portions of the insulating base material (12) are cut off to positively form chamfered portions (15). In the embodiment shown in FIG. 1, chamfered portions (15) are formed at the upper left and lower right corners of the insulating base material (12), but in the embodiment shown in FIG. shows an example in which chamfered portions (15) are formed on all four corners. The original purpose of such a chamfer (15) can be achieved by forming at least one chamfer (15) on the insulating base material (12), as shown in FIG. 1 or 4. It is easy to manufacture and convenient for positioning the electronic component mounting board (10) within a mold of a transfer molding device. It should be noted that if the technical idea of the present invention is carried out several lines to its limit, the shape of the insulating base material (12) will become a perfect circle.

For the electronic component mounting board (10) configured as described above, the insulating base material (12) and the electronic components (30) mounted thereon are provided with the following structure as shown in FIGS. 2 and 3. Thus, sealing is performed using the sealing resin (20).

In this way, when the entire electronic component mounting board (lO) is sealed with the sealing resin (20), the insulating base material (
12), but also the front and back surfaces of each outer lead (11) protruding outward from these insulating base materials (12), and in particular, the sealing resin (20) is in close contact with each outer lead (11). ) through the gap between the upper and lower sealing resins (20
) are integrated. The above also applies to the electronic component mounting substrate (10) shown in FIG. 4, and as shown in FIG. 5, the sealing resin (20) and become integrated.

FIG. 6 shows an electronic component mounting board (lO) according to the present invention.
Another example is shown, and this electronic component mounting board (
In 10), the chamfered portion (15) of the insulating base material (12)
No outer leads are placed on the outer lead (11) near the lead frame (IIA).
) The sealing resins (20) located on both sides of the sealing resin (20) are more firmly integrated.

(Effects of the Invention) As detailed above, in the present invention, as exemplified in the above embodiment, "a large number of outer leads whose inner ends are concentrated toward the mounting portion (14) of the electronic component (30)" (11), an insulating base material (12) integrated on both sides of the inner end of each outer lead (11), and an electrical In the electronic component mounting board (10), the insulating base material (12) is shaped so that at least one square corner is cut off to form a chamfered part. Its structural feature is that it has a polygonal shape, and as a result, even if the spacing and length of the outer leads become smaller, the sealing resin can be injected reliably and quickly throughout the entire lead. Therefore, it is possible to provide a substrate for mounting electronic components with a simple structure that does not cause voids or peeling from the sealing resin after sealing with the sealing resin.

[Brief explanation of drawings]

FIG. 1 is a plan view of a substrate for mounting electronic components according to the present invention, FIG. 2 is a plan view showing the substrate for mounting electronic components molded with a sealing resin, and FIG. Fig. 4 is a plan view showing another embodiment of the electronic component mounting board, and Fig. 5 is an enlarged cross-sectional view taken along the m-line, and Fig. 5 shows the electronic component mounting board shown in Fig. 4 molded with a sealing resin. FIG. 6 is a partially enlarged plan view showing still another embodiment of the electronic component mounting board according to the present invention, FIG. 7 is a plan view of a conventional electronic component mounting board, and FIG. The figure is a plan view of this electronic component mounting board molded with a sealing resin. Explanation of symbols 10... Electronic component mounting board, 11... Outer lead, 12... Insulating base material, 13. Conductor circuit, 14... Mounting section, 15... Chamfered section, 20. ... Sealing resin, 30... Electronic components.

Claims (1)

[Scope of Claims] A large number of outer leads whose inner ends are concentrated toward the mounting portion of electronic components, an insulating base material integrated on both sides of the inner end of each of these outer leads, and this insulating base material. and a conductor circuit electrically connected to each of the outer leads, the insulating base material having a shape such that at least one square corner is cut off to form a chamfered part. A board for mounting electronic components, characterized in that it has a polygonal shape.