JPH10189818A - Electronic component-mounting substrate and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic component-mounting substrate, having superior reliability in connection of a lead and the pad on a mother board, without contamination by the adhesion of solder on an electronic part mounting substrate, by adhering solder on the lead only. SOLUTION: A lead is adhered to the surface of an insulated substrate 7 through an adhesive layer 52 in a state, wherein a lead 1 is arranged in such a manner that it is electrically connected to a conductive circuit 4. The conductive circuit 4 and the lead 1 are connected by a solder 5. a solder-plate film 11 is formed in advance on the surface of the lead 1 prior to the adhesion to the insulated substrate 7. When the lead 1 is adhered to the insulated substrate 7 through an adhesive layer 52, the adhesive layer 52 is arranged in a non-hardened state on the outer circumferential part of the conductive circuit 4 on the surface of the insulated substrate, the lead 1 and a frame-like dam 2 are arranged thereon, and the adhesive layer 52 is hardened. As a result, the lead 1 is pinchingly attached and retained by the adhesive layer 52 and the frame-like dam 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate for mounting electronic components and a method for manufacturing the same, and more particularly, to a method for joining leads.

[0002]

2. Description of the Related Art Conventionally, as a board for mounting an electronic component, for example, as shown in FIG.
It is called QFP. ). The electronic component mounting board 9 has a mounting portion 973 provided substantially at the center of the insulating substrate 97 for mounting the electronic component 93, and a conductor circuit 94 provided around the mounting portion 973. Electronic component 93 and conductor circuit 9
4 is electrically connected by a bonding wire 931.

The mounting portion 973 is, for example, an opening penetrating the insulating substrate 97, and one of the openings is covered with, for example, a heat slug 96 as shown in FIG. The heat slug 96 is bonded and fixed to the insulating substrate 97 with an adhesive 953. Mounting part 97
3, a through hole 977 for electrically connecting the upper and lower surfaces of the insulating substrate 97 is provided.

As shown in FIG. 16, the leads 91 are adhered and fixed to an insulating substrate 97, and are electrically connected to a conductor circuit 94 through solder through holes 975 filled with solder 95 (Japanese Patent Laid-Open Publication No. 6-295962).
That is, the leads 91 are physically bonded and fixed by the adhesive 952 disposed on the outer peripheral portion of the conductor circuit 94. The lead 91 is electrically connected to the conductor circuit 94 by filling the solder 95 into a solder through hole 975 that conducts with the conductor circuit 94. Separating the physical holding / fixing with these adhesives from the electrical connection can greatly improve the connection reliability.

The surface of the electronic component mounting board 9 is
In a state where 1 is projected, it is covered with a sealing resin 99 by a transfer molding method. After molding the sealing resin, the leads 91 protruding from the sealing resin 99 are covered with a solder plating film 92. The protruding tip of the lead 91 is soldered to a pad 981 on the motherboard 98 by a solder paste 982.

In this conventional example, the mounting portion 973
Is an opening penetrating the insulating substrate 97, and one of the openings is covered with the heat slug 96. However, when the mounting portion 973 is a concave portion which is not formed through the insulating substrate 97 but is formed in a concave shape, Alternatively, the pad may be a pad adhered to the surface of the insulating substrate 97 without forming the insulating substrate 97. Further, in this conventional example, the heat slug 96 is used, but it may not be used.

[0007]

However, due to recent market demands, as shown in FIG.
Instead of covering the entire surface of the mounting portion 973 with the sealing resin 99, as shown in FIG.

However, in this case, as shown in FIG. 17, when the solder plating film 92 is formed on the leads 91, there arises a problem that the surfaces of the insulating substrate 97 and the heat slug 96 are contaminated by the solder. That is, in the electronic component mounting substrate 90 shown in FIG.
On the surface of the heat slug 96 and the surface of the heat slug 96.
There is an uncoated portion that is not covered by 9. Therefore, in this state, the solder plating film 92
Is formed, the solder adheres to the uncovered portions of the insulating substrate 97 and the heat slug 96.

Therefore, the solder plating film 9 is formed on the surface of the lead 91 while the uncovered portion is covered with the mask 98.
2 is conceivable. However, the solder may intrude from between the electronic component mounting substrate 90 and the mask 98, and the solder may adhere to the above-mentioned uncovered portion, so that solder soaking may occur.

Therefore, as shown in FIG.
It is conceivable that a solder plating film 92 is formed on the surface of the lead 91 before the substrate is bonded to the insulating substrate 97. However, as described above, the solder plating film 92 is
Is formed, the entire surface of the lead 91 is covered with the solder plating film 92. The adhesive 94 for bonding the leads 91 and the insulating substrate 97 is an epoxy resin or the like.

Therefore, at a high temperature, the adhesive force of the adhesive 952 to the solder plating film 92 decreases. Therefore, the adhesive 952 is exposed to a high temperature by the high-temperature solder 95 melted when the solder 95 is filled in the through-hole 975 for the solder. When the electronic component mounting substrate is sealed with the sealing resin, the adhesive 9
52 is exposed to high temperatures.

When exposed to such a high temperature, the adhesive 95
In No. 2, the adhesion to the solder plating film 92 is reduced, and poor adhesion occurs between the insulating substrate 97 and the leads 91.
There is a possibility that the lead 91 may be displaced such as a lateral displacement, or the lead 91 may come off the insulating substrate 97.

The present invention has been made in view of the above-mentioned conventional problems, and does not contaminate an electronic component mounting board by solder adhesion, and only solders are applied to the leads, thereby improving the connection reliability between the leads and the pads on the motherboard. And a method of manufacturing the same.

[0014]

According to a first aspect of the present invention, a mounting portion for mounting an electronic component on an insulating substrate and a conductive circuit are formed, and then leads are arranged so as to be electrically connected to the conductive circuit. Then, the lead is adhered to the surface of the insulating substrate via an adhesive layer, and then the conductor circuit and the lead are joined by soldering. Before bonding to the surface of the insulating substrate, a solder plating film is formed in advance, and when bonding the lead to the surface of the insulating substrate via an adhesive layer, the outer periphery of the conductor circuit on the surface of the insulating substrate is required. Placing an uncured adhesive layer on the part, then placing the lead on the adhesive layer, then placing a frame dam on the lead, and then curing the uncured adhesive layer As a result, De The, sandwiching the adhesive layer and the frame-shaped dam, a manufacturing method of the electronic component mounting board, characterized in that the holding.

The operation and effect of the present invention will be described.
In the present invention, since the solder plating film is formed on the surface of the lead, the wettability between the lead and the solder paste is improved. Therefore, the leads can be reliably connected to the pads on the motherboard using the solder paste. After a solder plating film is formed on the lead in advance, the lead is bonded to the insulating substrate. Therefore, there is no possibility that the solder will adhere to the surfaces of the conductor circuit, the insulating substrate, the heat slug, and the like, and the electronic component mounting substrate will not be contaminated by the solder.

Further, in the present invention, the bonding portion of the lead is not only bonded to the insulating substrate, but is also sandwiched between the bonding layer formed on the surface of the insulating substrate and the frame-shaped dam.
keeping. Therefore, the leads are in a state of being firmly bonded and fixed by the adhesive layer. Therefore, even when the lead is exposed to high temperature and the solder plating film is melted at the time of solder bonding between the lead and the conductor circuit or at the time of resin sealing of the mounting portion, the lead is displaced laterally with respect to the insulating substrate. And it does not come off. Also, the frame dam is
During resin sealing of the electronic component, resin flow of the sealing resin can be prevented.

The following method is used for joining the above-mentioned conductor circuit and the lead by soldering. For example, as in the second aspect of the present invention, the soldering of the conductor circuit and the lead is performed by first forming a through hole for solder that is electrically connected to the conductor circuit on an insulating substrate, and then forming the solder through hole. Placing the above lead on the through hole, and then raising the jet solder from the side opposite to the side where the lead is placed inside the solder through hole, and soldering the lead on the solder through hole and the conductor circuit It is preferable to carry out. This makes it possible to electrically connect the lead and the conductor circuit easily and reliably. Also, the conductor circuit and the lead can be directly joined by soldering.

Next, a third aspect of the present invention provides an insulating substrate provided with a mounting portion for mounting an electronic component and a conductive circuit, and electrically connected to the conductive circuit provided on an outer peripheral portion of the conductive circuit. In an electronic component mounting board comprising a lead bonded by an adhesive layer formed on the surface of the insulating substrate, a solder plating film is formed on the surface of the lead, and the lead is An electronic component mounting substrate characterized in that it is sandwiched and held between an adhesive layer formed on a surface of an insulating substrate and a frame-shaped dam.

In the electronic component mounting board of the present invention,
Since the solder plating film is formed on the surface of the lead, the wettability with the solder paste is improved. Therefore, the leads can be reliably connected to the pads on the motherboard by the solder paste. Further, since the bonding portion of the lead to the insulating substrate is sandwiched and held by the bonding layer and the frame-shaped dam, the bonding strength between the lead and the insulating substrate is high. In addition, the solder connection between the lead and the conductor circuit is good, and the electrical connection reliability between the two is high.

For example, it is preferable that the lead is soldered by solder in a solder through hole electrically connected to the conductor circuit.
Thereby, the reliability of the electrical connection between the lead and the conductor circuit can be further increased. Further, the conductor circuit and the lead may be directly joined by soldering.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION

First Embodiment An electronic component mounting board according to an embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the electronic component mounting board of the present embodiment includes an insulating substrate 7 provided with a mounting portion 73 for mounting the electronic component 3 and a conductor circuit 4.
And a lead 1 provided on the outer periphery of the conductor circuit 4 and joined to the conductor circuit 4 by solder 5 and adhered to the insulating substrate 7.

On the surface of the lead 1, a solder plating film 11 is formed. The lead 1 is sandwiched and held between the adhesive layer 52 formed on the surface of the insulating substrate 7 and the frame dam 2. The mounting portion 73 is a concave portion, and includes an opening 730 provided in the insulating substrate 7 and a heat slug 6 adhered to the insulating substrate 7 so as to cover one of the openings 730.

Next, an outline of a method of manufacturing the electronic component mounting board will be described. First, a solder plating film 11 is formed on the entire surface of the lead 1 (FIG. 3). The lead 1 is disposed on the adhesive layer 52 disposed on the surface of the insulating substrate 7, and then the frame dam 2 is disposed on the adhesive layer 52. Pinched by
Hold (FIG. 10). Thereafter, the conductor circuit 4 and the lead 1 are joined by solder 5 (FIG. 11).

Next, this will be described in detail. First, as shown in FIG. 2, a copper lead 1 is prepared. A total of 160 leads 1 are connected from the square frame-shaped lead frame 10 toward the center, with 40 leads on each side. Next, the lead is immersed in a solder plating bath. This gives
As shown in FIG. 3, a solder plating film 1
1 is formed.

Further, an insulating substrate made of a glass bismaleimide triazine substrate is prepared. Copper foil is bonded to the insulating substrate in advance. Next, as shown in FIG. 4, a through hole 75 for solder is formed in the outer peripheral portion of the insulating substrate 7, and an opening 730 is formed substantially in the center of the insulating substrate 7. A plurality of solder through holes 75 are provided at regular intervals near the edge of the insulating substrate 7.

Next, panel plating is performed on the entire surface of the insulating substrate 7 to form a panel plating film. Next, an etching process using a mask is performed to etch the panel plating film. As a result, the conductor circuit 4 is formed on the surface of the insulating substrate 7, and the inner walls of the through holes 75 and the through holes 74 for solder are coated with the metal plating film 40. Next, the surface of the conductive circuit 4 is covered with a resist film 58 except for the wire bonding part 41 and the land part 42 in the conductive circuit 4.

Next, as shown in FIG. 5, a band-shaped adhesive layer 52 is provided on the periphery of the insulating substrate 7. The adhesive layer 52 is a thermosetting epoxy resin. Next, as shown in FIGS. 6 to 8, the leads 1 are arranged on the surface of the adhesive layer 52 such that the leads 1 are arranged on the through holes 75 for solder. At this time, it is preferable that the adhesive portion 17 of the lead 1 that adheres to the insulating substrate 7 is pressed against the adhesive layer 52 on the insulating substrate 7. Thereby, the bonding portion 17 of the lead 1
Slightly bites into the uncured adhesive layer 52, and the lead 1 is temporarily bonded to the insulating substrate 7.

Next, an epoxy resin having a high viscosity suitable for thick film printing is applied to the bonding portion 17 of the lead 1 by a screen printing method using a metal mask, and a heat treatment is performed at 175 ° C. As a result, as shown in FIGS. 9 and 10, the insulating frame dam 2 having a thickness of about 0.3 mm is formed. The frame dam 2 is formed in a frame shape around the opening 730 along the bonding portion 17 of the lead 1. Frame dam 2
Has a width of 1.0 mm and a thickness of 0.3 mm. Next, the insulating substrate 7 is heated to 175 ° C.
2 is cured. As a result, the lead 1 is attached to the adhesive layer 52.
Is adhered to the insulating substrate 7, and is sandwiched and held by the adhesive layer 52 and the frame-shaped dam 2.

Next, as shown in FIG.
A solder bath 50 of 230 ° C. is placed under the
11, the solder 5 is brought into contact with the through-hole 75 for solder as shown in FIGS. Then, the solder 5 becomes the solder through hole 7 due to the capillary phenomenon.
5 and joined to the lead 1 located on the solder through hole 75. As a result, the solder through hole 75 and the lead 1 are connected.

Next, as shown in FIG. 1, the heat slug 6 is adhered to the insulating substrate 7 using an adhesive 53 so as to cover the opening 730, and a concave shape comprising the upper surface of the heat slug 6 and the opening 730 is formed. Is formed. Thus, the electronic component mounting board 70 shown in FIG. 1 is obtained.

Next, as shown in FIG. 1, the electronic component 3 is mounted in the mounting portion 73 on the electronic component mounting substrate 70 by the adhesive 54. Next, the bonding wire 31 is connected to the electronic component 3 and the wire bonding portion 41 of the conductor circuit.
Connect with Next, the mounting part 73 is filled with a sealing resin 38 to seal the electronic component 3. Next, the protruding tip of the lead 1 is bent, and the lead and the lead frame are cut. Thereafter, the protruding tip of the lead 1 is joined to the surface of the pad 81 on the motherboard 8 using a solder paste 82.

Next, the operation and effect of this embodiment will be described. In the present embodiment, as shown in FIG. 1, since the solder plating film 11 is formed on the surface of the lead 1, the wettability between the lead 1 and the solder paste 82 is improved. Therefore, the leads 1 can be reliably connected to the pads 81 on the motherboard 8 using the solder paste 82.

After the solder plating film 11 is formed on the lead 1 in advance, the lead 1 is bonded to the insulating substrate 7 using the bonding layer 52. Therefore, there is no possibility that the solder adheres to the surface of the conductive circuit, the insulating substrate, the heat slug, or the like, and the electronic component mounting substrate 70 is not contaminated by the solder.

As shown in FIG. 10, the bonding portion 17 of the lead 1 is a portion bonded to the insulating substrate 7 by the bonding layer 52, and the bonding portion 17 is
Between the adhesive layer 52 formed on the surface of the substrate and the frame-shaped dam 2. Therefore, the lead 1 is connected to the insulating substrate 7
Strongly adhered and fixed to Therefore, as shown in FIG. 11, when the solder 5 is filled in the solder through-hole 75, the lead 1 is exposed to a high temperature by the molten high-temperature solder 5, and the solder plating formed on the surface of the lead 1 is performed. Membrane 1
Even if the lead 1 is melted, the lead 1 will not be displaced from the insulating substrate 7 and will not come off.

Further, as shown in FIG. 1, when the electronic component 3 is sealed, the solder plating film 11 formed on the bonding portion 17 of the lead 1 is formed by curing the sealing resin 38 at a high temperature. In addition, since the lead 1 is sandwiched and held between the adhesive layer 52 and the frame-shaped dam 2, the lead does not shift laterally and does not come off. Also, the solder bonding state between the lead 1 and the through hole 75 for solder is good, and the reliability of the electrical connection between the two is high. Furthermore, the frame-shaped dam 2 can prevent resin flow of the sealing resin 38 when the electronic component 3 is sealed with resin.

Embodiment 2 This embodiment is different from Embodiment 1 in that the frame-shaped dam 21 is a resin molded body as shown in FIGS. The frame dam 21 is a frame along the outer shape of the insulating substrate 7 and is formed by resin molding. The width of the frame dam 21 is 1.0 mm and the thickness is 0.5 mm.

In bonding the frame-shaped dam 21, an adhesive layer 52 is provided on the insulating substrate 7, and a lead bonding portion 17 is provided thereon. Then, a frame-shaped frame-shaped dam 21 is further placed thereon, and the frame-shaped dam 21 is pressed against the insulating substrate 7. As a result, the frame dam 21 comes into close contact with the adhesive layer 52. Thereafter, the adhesive layer 52 is heated and thermoset in the state of the close contact. As a result, the leads 1 are adhered to the surface of the insulating substrate 7 by the adhesive layer 52, and are held and held by the adhesive layer 52 and the frame-shaped dam 21. Other configurations are the same as those of the first embodiment. In this example, too, Embodiment 1
The same effect as described above can be obtained.

[0038]

According to the present invention, an electronic component mounting board excellent in connection reliability with a pad on a motherboard can be obtained by applying solder only to the lead without contaminating the electronic component mounting board by solder adhesion. A substrate and a method for manufacturing the same can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an electronic component mounting board according to a first embodiment.

FIG. 2 is a perspective view of a lead connected to a lead frame, showing a method of manufacturing the electronic component mounting board in the first embodiment.

FIG. 3 is a sectional view of the lead on which a solder plating film is formed, following FIG. 2;

FIG. 4 is a cross-sectional view of the insulating substrate formed with a conductor circuit, an opening, and a through hole for solder, following FIG. 3;

FIG. 5 is a sectional view of the insulating substrate on which an adhesive layer is arranged, following FIG. 4;

FIG. 6 is a sectional view of the insulating substrate to which the leads are adhered, following FIG. 5;

FIG. 7 is a sectional view taken along line AA of FIG. 6;

FIG. 8 is a plan view of a main part of the insulating substrate to which the leads have been adhered, following FIG. 5;

FIG. 9 is a plan view of the insulating substrate to which the frame dam is adhered, following FIG. 6;

FIG. 10 is a sectional view of the insulating substrate to which the frame-shaped dam is adhered, following FIG. 6;

FIG. 11 is a sectional view of the insulating substrate, showing a method of filling the through holes with solder, following FIG. 10;

FIG. 12 is a sectional view taken along line BB of FIG. 11;

FIG. 13 is a sectional view of an electronic component mounting board according to the second embodiment.

FIG. 14 is a sectional view taken along line CC of FIG. 13;

FIG. 15 is a plan view of an electronic component mounting board in a conventional example.

FIG. 16 is a cross-sectional view of an electronic component mounting board in a conventional example.

FIG. 17 is a cross-sectional view of an electronic component mounting board in another conventional example.

FIG. 18 is an explanatory view showing a problem when a solder plating film is previously formed on the surface of a lead.

[Explanation of symbols]

 1. . . Lead, 11. . . Solder plating film, 17. . . Bonded part, 2,21. . . 2. framed dam; . . Electronic components, 38. . . 3. resin for sealing; . . 4. conductor circuit; . . Solder, 52. . . Adhesive layer, 6. . . Heat slug, 7. . . Insulating substrate, 70. . . Electronic component mounting substrate, 73. . . Mounting part, 75. . . 7. Through hole for solder; . . Motherboard,

Claims (4)

[Claims] 1. A mounting portion for mounting an electronic component on an insulating substrate and a conductor circuit are formed. Then, a lead is arranged so as to be electrically connected to the conductor circuit. In the method for manufacturing an electronic component mounting board, in which the leads are bonded through an adhesive layer, and then the conductor circuit and the leads are joined by soldering, the surface of the leads is bonded to the surface of the insulating substrate before bonding. When a solder plating film is formed in advance and the leads are bonded to the surface of the insulating substrate via an adhesive layer, an uncured adhesive layer is formed on the outer peripheral portion of the conductor circuit on the surface of the insulating substrate. The lead is then placed on the adhesive layer, and the frame-shaped dam is placed on the lead, and then the uncured adhesive layer is cured. And frame dam A method for manufacturing an electronic component mounting substrate, wherein the substrate is sandwiched and held by: 2. The method according to claim 1, wherein the soldering of the conductor circuit and the lead is performed by first forming a through hole for solder that is electrically connected to the conductor circuit on an insulating substrate. By placing the above lead on the hole and then raising the jet solder from the side opposite to the side where the lead is placed inside the solder through hole, and soldering the lead on the solder through hole and the conductor circuit A method for manufacturing a substrate for mounting electronic components. 3. An insulating substrate provided with a mounting portion for mounting an electronic component and a conductive circuit, and provided on an outer peripheral portion of the conductive circuit and electrically connected to the conductive circuit, and a surface of the insulating substrate. An electronic component mounting board comprising a lead bonded by an adhesive layer formed on a substrate, wherein a solder plating film is formed on a surface of the lead, and the lead is formed on a surface of the insulating substrate. An electronic component mounting substrate, which is sandwiched and held between a layer and a frame dam. 4. The electronic component mounting board according to claim 3, wherein said leads are soldered by solder in a solder through hole electrically connected to a conductor circuit.