JPH07120730B2 - Resin board with electronic components - Google Patents

Description

The present invention relates to a resin substrate on which electronic parts are mounted, a timepiece,
It is used for inner layer substrates such as cameras, chip carriers, pin grid arrays, etc.

[Conventional technology]

Conventionally, when mounting an electronic component such as a semiconductor element, a printed wiring board on which a circuit is formed is often provided with a recess, and the semiconductor element is fixedly mounted in the recess for use. The formation of the recesses in the substrate as described above is performed in the case where there is a demand for high circuit density, when the height of component mounting is limited, and a large number of connection conductors are provided in a high-density thin substrate or a very limited portion. This is because the recess can be effectively used in various cases, such as when it has to be formed and when the semiconductor element has to be packaged together with the substrate.

However, in this recess, the formation is performed by counterboring (milling by moving a rotating bite or the like in a direction orthogonal to the rotation axis) and various subsequent processing. As a result of the application or the like, the cross-sectional shape of this recess is usually as shown in FIGS. 6 and 7. The various treatments mentioned here include various liquid treatments such as plating and solvent cleaning for forming a circuit on the substrate after forming the recesses, and further various heat treatments thereafter.

The recess 30 shown in FIG. 6 has been subjected to a liquid treatment such as a plating process in the spot facing process, and has an opening edge 31 of the recess 30.
Intersects from. On the other hand, the recess 30 shown in FIG.
In that case, liquid treatment such as plating process after spot facing,
It shows a state after a step such as heat treatment for forming a multilayer structure is added, and in this concave portion 30, swelling or heat shrinkage of the base material itself which constitutes the substrate by various treatments is shown. Due to the difference in stress inside the base material due to the above, the side surface 34 extending from the opening edge 31 of the recess 30 to the bottom surface 32 and the bottom surface 32 intersect at an acute angle.

[Problems to be Solved by the Invention]

In any case, the cross-sectional shape of the recess formed in the conventional substrate is the above-described shape, that is, whether the surface 33 and the bottom surface 32 vertically downward from the opening edge 31 of the recess 30 intersect at a right angle, Alternatively, when the recess 30 and the side surface 34 extending from the opening edge 31 to the bottom surface 32 and the bottom surface 32 intersect at an acute angle, the following problem is likely to occur. That is, internal stress is likely to concentrate at the intersection, and cracks or cracks starting from the intersection are likely to occur inside the base material of the printed wiring board.

Further, when it is desired to separately form a conductor layer made of a metal film in the recess 30, since the formation of the conductor layer is often performed by plating, the bottom surface 32 of the recess 30 is formed in such plating operation. If there is a cross-sectional shape or a crossing of a right angle or an acute angle, the plating liquid or the plating treatment liquid is likely to remain in this portion. Furthermore, since the current density of plating is low at this intersection, the formed plating layer is partially thin. Therefore, this plating layer is inferior in adhesiveness to the concave portion 30 and the strength of the plating layer itself is weakened, which may cause a problem of peeling or breaking from the base material.

For this reason, for example, in Japanese Patent Publication No. 49-47978, as shown in FIG. 8, "the first surface 35 and the bottom of the bottomed recess formed in the first surface 35 are formed. Second surface 36 and this first
An insulating package substrate having the above-described peripheral wall surface 37 of the recess which is continuous with the surface 35 at an obtuse angle is proposed. According to this substrate, not only the wiring member 38 can be formed on the peripheral wall surface 37 that intersects the first surface 35 with an obtuse angle while avoiding the risk of disconnection, but also on the wiring member 38 and the second surface 36. The electrical connection to the mounted semiconductor element 14 by the bonding wire 39 can be easily performed.

However, in the conventional package substrate shown in FIG. 8, since the peripheral wall surface 37 is formed continuously so as to intersect the first surface 35 at an obtuse angle, the effective area on the first surface 35 becomes small. Thus, the degree of freedom of wiring on the first surface 35 is greatly limited. Also, the surrounding wall
Although the wiring member 38 is formed on the wiring 37, it is a very difficult work in practice to accurately form the etching resist or the plating resist on such an inclined surface. Furthermore, since it is very difficult to form the insulating base material having the peripheral wall surface 37 in such an inclined state from a plate-like laminated plate which is generally commercially available, for example, the peripheral wall surface inclining. The special mold corresponding to 37 must be prepared in advance, and the cost of the package board becomes very high.

The present invention is to overcome the above problems, cracks near the recess, cracks and peeling of plating are less likely to occur, prevent moisture absorption of electronic components mounted, increase the effective area on the substrate, short distance In order to provide a resin substrate on which an electronic component is mounted, the electronic component and the wiring member can be connected to each other and which has a recess easily manufactured.

[Means for Solving the Problems]

A resin substrate on which an electronic component of the present invention is mounted includes a resin substrate having a recess for mounting an electronic component, a wiring member formed on the upper surface of the resin substrate, and an electronic component housed in the recess of the resin substrate. In the resin substrate on which the electronic component is mounted, including a connection thin wire that electrically connects the electronic component and the wiring member, and a sealing member for sealing the electronic component in the recess, A projecting portion that extends toward the center of the internal space of the recess from the intersection of the vertical bottom surface that is perpendicular to the opening edge of the recess, the planar bottom surface, and the extension surface of the vertical bottom surface and the bottom surface. The protrusion has a triangular cross section, the recess is formed by counterboring, and the entire inner circumference is covered with a metal plating film. The top surface of the substrate is smooth and The continuous thin line is characterized by connecting the wiring board formed on the smooth surface and the electronic component.

[Action]

In the present invention, the projection has a vertical lower surface that is perpendicular to the opening edge of the concave portion, and the projecting portion extends toward the center of the internal space of the concave portion from the intersection of the vertical lower surface and the extension surface of the bottom surface. It has a flat surface (inclined surface) exposed to the inside and its longitudinal section is a triangle. Therefore, the effective area of the upper surface of the substrate is increased, which increases the degree of freedom of wiring of the wiring member. Further, even if the stress is concentrated in this portion by reinforcing the vicinity of this protruding portion, this stress is dispersed, and further,
It is possible to form a plating layer having a predetermined thickness without the plating solution or the pretreatment solution for plating remaining on this portion and the current density of the plating not decreasing.

Further, since the concave portion is formed by counterboring, it can be easily and inexpensively formed, and a generally commercially available plate-shaped laminated plate can be used.

Further, since the wiring member in the present invention is formed on the upper surface of the substrate, this connection wiring will protrude above the recess. Therefore, the depth of this recess can be reduced.

In the present invention, the metal plating film is formed on the entire inner wall surface of the recess (that is, the peripheral wall surface and the bottom surface). This coating is
This is mainly for preventing the electronic components from absorbing moisture, and thus it is possible to prevent the electronic component arranged in the recess from absorbing moisture via the resin substrate.

〔Example〕

Next, the present invention will be described in more detail according to the specific examples shown in the drawings.

FIG. 1 is a vertical cross-sectional view of a pin grid array 10A on which electronic components are mounted, which is formed by adopting an electronic component (semiconductor element) mounting substrate 11 according to the present invention.

In the recess 12 of the electronic component mounting substrate (hereinafter simply referred to as “mounting substrate”) 11, a protrusion 20 integral with the mounting substrate 11 is provided at the center of the recess 12 as shown in FIG. It is issued to the part. The protrusion 20 has a flat surface (inclined surface) exposed in the recess and a triangular cross section.

The pin grid array 10A is manufactured as follows. That is, first, in the recess 12 of the mounting substrate 11,
The semiconductor element 14 is fixedly supported. Then this semiconductor element
The bonding wires 14a connect the 14 and the conductor circuit formed on the mounting substrate 11 to each other. Next, the upper portion of the semiconductor element 14 was covered with a metal cap 15 adhered to the mounting substrate 11. Further, in this electronic component mounting pin grid array 10A, the heads of the conductor pins 16 are forcibly fitted into the through holes formed in the mounting substrate 11 so that the pin as its name implies. It is a grid array.

The protrusion 20 formed on the mounting board 11 is
Has the following relationship. That is, as shown in FIG. 2, in the vicinity of the bottom surface 13 of the recess 12, a portion (vertical bottom surface) 21 vertically lower than the opening edge 12a of the recess 12 and an extension surface 22 of the bottom surface 13 of the recess 12 intersect. The protrusion 20 is formed from 23 toward the center of the internal space of the recess 12.

FIG. 5 illustrates this relationship in more detail. As is apparent from FIG. 5, when looking at the intersection 23 of the hanging lower surface 21 and the extension surface 22 of the bottom surface 13 from the opening edge 12a of the recess 12, the protrusion 20 is located at least in the internal space of the recess 12. It means that it is directed toward the center. As a result, in the vicinity of the bottom surface 13 of the recess 12, there is no right angle portion or acute angle portion.

The projecting portion 20 is for eliminating the presence of a right angle portion or an acute angle portion in the vicinity of the bottom surface 13 of the recess 12 as described above. The recessed portion 12 has an inner surface of the recessed portion 12 that extends vertically from an opening edge 12a of the recessed portion 12, a planar bottom surface 13 of the recessed portion 12, and an intersection of the suspended lower surface and an extension surface of the bottomed surface. The inclined surface is directed toward the center (direction) of the space. As described above, the protrusion 20 protrudes into the recess 12, and it is easy to form in this way. For example, when a plating layer is formed in the recess 12, the strength of the plating layer becomes strong.

In order to satisfy such conditions, as shown in FIGS. 2 and 5, the surface of the protrusion 20 exposed in the recess 12 is formed as a flat surface (inclined surface). As a method of eliminating the right-angled portion or the acute-angled portion, as shown in FIG. 3 (reference drawing), it may be possible to form a spherical surface which is concave toward the central portion of the concave portion 12. However, in this case, it cannot be said that the strength of the intersecting portion between the vertically lower surface and the bottom surface is sufficient.

To form the protrusion 20 under the above conditions, the protrusion 20
Counterboring is performed by a rotary blade (bite) having a cutting surface corresponding to the surface exposed in the concave portion (12). Mounting board 11
As the material of the above, a base material made of glass epoxy resin, glass polyimide resin or glass triazine resin was used. Since this is a resin, it is also convenient for counterboring.

The surface of the protrusion 20 exposed in the recess 12 and the other surface (that is, the entire inner peripheral surface of the recess) are covered with a metal plating film. This is done by providing a metal coating on the inner surface of the recess 12 to prevent moisture from penetrating through the inside of the base material and improving sealing reliability, and the metal coating itself is used as a conductor circuit for the ground conductor. In addition, this coating is designed and wired so as to be connected to the external leads, so that the heat generated from the semiconductor element can be quickly dissipated to the outside by the coating.

In the substrate on which the electronic component used in this example is mounted, since the predetermined recess is formed in the recess formed in the mounting substrate used therein, cracks and cracks are less likely to occur in the vicinity of the recess, and The conductor layer formed on the inner surface is less likely to cause a phenomenon such as peeling. Further, since a predetermined concave portion is formed by counterboring and a plate-like laminated plate which is generally commercially available is used as an insulating base material for the substrate, it can be formed by the simplest and most effective method at a low cost. I was able to.

Further, since the plated coating is formed on the entire inner peripheral surface of the recess, moisture does not enter the recess through the resin substrate after the metal cap is fixed by coating. Therefore, the reliability and life of the electronic component can be improved.

In addition, since the concave portion has the hanging bottom surface, it is possible to increase the effective area on the mounting substrate 11 and increase the degree of freedom of wiring on the effective area. Moreover, since the surface of the semiconductor element and the surface of the mounting substrate are at substantially the same height and are in a close distance, it is very convenient to connect the semiconductor element and the wiring member with a bonding wire.

The present invention is not limited to the specific examples described above, and various modifications may be made within the scope of the present invention depending on the purpose and application. That is, FIG. 4 (the metal coating covering the inner peripheral surface of the recess is omitted),
Pin grid array 10A for mounting electronic components shown in FIG.
In a different type of chip carrier package 10B,
It is a longitudinal section showing the state where the present invention was implemented. Also in this chip carrier package 10B, the bottom surface 13 of the recess 12 is
A protruding portion 20 is formed in the periphery from the opening edge 12a of the concave portion 12 and an intersecting portion 23 of the extending surface 22 of the bottom surface 13 of the concave portion 12 toward the center of the internal space of the concave portion 12. ing. In this chip carrier package 10B, in order to prevent the sealing resin 17 from flowing out to the periphery by dropping the sealing resin 17 around the electronic component 14 grounded and fixed in the concave portion 12, A resin sealing frame 18 is fixed to the upper surface of the mounting substrate 11.

〔The invention's effect〕

The resin substrate on which the electronic component of the present invention is mounted is less likely to cause cracks in the vicinity of the recess, cracks and peeling of the plating, prevents moisture absorption of the electronic component, increases the effective area on the substrate, and provides freedom of wiring of the wiring member. It is possible to increase the connection efficiency, facilitate the connection between the electronic component and the wiring member, and have a recess that is easily manufactured.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a pin grid array on which an electronic component is mounted in an embodiment, FIG. 2 is a vertical cross-sectional view showing an electronic component mounting substrate according to the present invention, and FIG. 3 is a mounting substrate as a reference example. FIG. 4 is a vertical cross-sectional view of a chip carrier package embodying the present invention, FIG. 5 is an enlarged vertical cross-sectional view of a main part of a protrusion shown in FIG. 2, and FIG. 6 is a conventional electronic component. FIG. 7 is a vertical cross-sectional view showing a mounting substrate, FIG. 7 is a vertical cross-sectional view showing a state after the substrate shown in FIG. 6 is subjected to heat treatment as a post-treatment, and FIG. 8 is another conventional electronic component. It is a longitudinal cross-sectional view showing a mounted substrate. [Description of Reference Signs] 10a; electronic component mounting pin grid array, 10B; chip carrier package, 11; electronic component mounting substrate, 12; recess,
12a; opening edge, 13; bottom surface, 14; semiconductor element, 20; protruding portion, 21;
Vertically lowered surface, 22; bottom extension, 23; intersection.

Continuation of the front page (56) References JP-A-59-67686 (JP, A) JP-A-49-47978 (JP, A) Supervised by Japan Metal Surface Technology Association, "Electric plating guide '83", April 1, 1983, National Federation of Plating Industry Associations, Luminescence, pp. 30-31, Eiichita, "Plastic Metallizing," November 15, 1985, CMC, Inc., 7th- Page 14 Keiji Oshima, 2 ed., “Pressure molding / transfer molding of thermosetting resin”, November 15, 1964, issued by Plastic Age Co., Ltd., pp.163-171

Claims (1)

[Claims] 1. A resin substrate having a recess for mounting an electronic component,
A wiring member formed on the upper surface of the resin substrate, an electronic component housed in the recess of the resin substrate, a connection thin wire for electrically connecting the electronic component and the wiring member, and the electronic component. A resin substrate having an electronic component mounted thereon, comprising: a sealing member for hermetically sealing the inside of the recess, wherein the recess has a hanging bottom surface perpendicular to an opening edge of the recess, a planar bottom surface, and the hanging surface. An inclined surface forming a surface of a protruding portion that extends from the intersection of the lower surface and the extension surface of the bottom surface toward the center of the inner space of the recess, and the vertical cross section of the protruding portion is a triangle. The concave portion is formed by counterboring, the entire inner circumference is covered with a metal plating film, the upper surface of the resin substrate is a smooth surface, and the connection thin wire is a wiring board formed on the smooth surface. Is characterized by connecting the Equipped with a resin substrate the electronic components.