JPH07183339A - Electronic component mounting board and electronic component mounting method - Google Patents

Abstract

(57) [Summary] [Purpose] When joining outer leads to electrode pads,
It is an object of the present invention to provide an electronic component mounting board which is not damaged by ultrasonic vibration applied to the outer lead. An electrode pad 11 to which an outer lead 4 of an electronic component is joined by a bonding tool 1 which vibrates ultrasonically.
The surface of the electrode pad 11 to be joined to the outer lead 4 is provided with a plurality of concave grooves 15 orthogonal to the ultrasonic vibration applied by the bonding tool 1 at predetermined intervals. The substrates 2 are provided in parallel with each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic component mounting board and an electronic component mounting method for joining an outer lead of an electronic component to an electrode pad provided on the electronic component mounting board.

[0002]

2. Description of the Related Art Electronic component mounting methods for mounting a semiconductor electronic component having a large number of outer leads on a substrate such as a printed circuit board include a gang bonding method and a single point bonding method.

The former is a method in which all the outer leads are pressed against the electrode pads provided on the printed circuit board substantially at the same time to join them collectively, and the latter is a method of individually joining the outer leads one by one. It is a method of joining to.

[0004] The gang bonding method has the advantage of being superior in product productivity because all outer leads can be bonded at once by moving the bonding tool up and down once. However, there is a drawback that the bonding state varies between the outer leads due to the parallelism of the substrate and the flatness of the substrate.

Therefore, when mounting an electronic component, such as a semiconductor electronic component having a multi-pin, multi-terminal, narrow pitch outer lead, which requires severe conditions for joining the outer leads, the reliability of the product is improved. It may not be suitable because it deteriorates the sex.

Therefore, in recent years, such semiconductor packages have been used.
When bonding the wires, each outer
There is a tendency to use a single-point bonding method that can reliably bond the cords.

This single point bonding method is
As shown in FIG. 8, a needle-shaped bonding tool 1 having a small tip diameter is used, and each electrode pad 3 formed on the substrate 2 is provided with one outer lead 4 protruding from the semiconductor package device. We will join each one individually.

When the outer lead 4 is joined, a predetermined load is applied to the outer lead 4 by using the bonding tool 1 and the bonding tool 1 is moved in the direction indicated by an arrow (a) in the figure. Reciprocating vibration (hereinafter referred to as "ultrasonic vibration") at a frequency in the ultrasonic range. Further, the substrate 2 is preheated to a predetermined temperature.

By this operation, ultrasonic energy and heat energy are applied between the outer lead 4 and the electrode pad 3, so that the outer lead 4 and the electrode pad 3 are bonded to each other.

[0010]

The conventional single point bonding method has the following problems to be solved. In the single point bonding method, as described above, ultrasonic vibration is applied to the outer lead 4 so that the outer lead 4 and the electrode pad 3 are joined.

However, when the ultrasonic vibration is applied in this manner, the ultrasonic vibration is transmitted to the electrode pad 3 and vibrates the electrode pad 3, so that a load having a very high repetition rate is applied to the substrate 2. (Impact load) is applied, and the resulting impact stress may damage the portion indicated by A in the drawing of the substrate 2.

In particular, when the substrate 2 is formed of a material which is fragile to impact such as silicon, such a phenomenon occurs remarkably, and the outer lead 4 together with the electrode pad 3 is provided on the substrate 2 There is a risk of peeling from.

Further, in the case of a multi-layer wiring board, there is a risk of damaging the underlying wiring. On the other hand, in order to prevent such a defect, the outer lead 4 may be joined with a low pressure load and a small ultrasonic vibration amplitude, but a good joining state cannot be obtained by such a joining method. There is a thing.

The present invention has been made in view of the above circumstances, and it is possible to effectively prevent an electronic component mounting board that is not damaged when mounting an electronic component and an electronic component mounting board from being damaged. It is intended to provide an implementation method.

[0015]

According to a first aspect of the present invention, in an electronic component mounting board having an electrode pad to which a lead of an electronic component is joined, the substrate is joined to the lead of the electrode pad. The electronic component mounting board is characterized in that unevenness is provided on its surface.

A second means is the electronic component mounting board according to the first means, wherein the irregularities are composed of a plurality of concave grooves and convex portions formed between the concave grooves. Is.

A third means is characterized in that, in the electronic component mounting board of the second means, the plurality of concave grooves are provided substantially in parallel at a predetermined interval. A fourth means is characterized in that, in the electronic component mounting board according to the second means, the plurality of concave grooves are provided in a grid pattern.

A fifth means is that, in the electronic component mounting board of the second means, the plurality of concave grooves are provided in a direction substantially orthogonal to the ultrasonic vibration applied to the lead. It is a feature.

A sixth means is an electronic component mounting method in which an outer lead is joined to an electrode pad provided on an electronic component mounting board, the outer lead is pressed against the electrode pad, and the electrode is also attached. The electronic component mounting method is characterized in that the two are joined by applying ultrasonic vibration in a direction orthogonal to the concave groove provided in the pad.

[0020]

According to such means, ultrasonic vibration is transmitted to the unevenness formed on the surface of the electrode pad to be joined to the outer lead, so that the electrode pad and the outer lead are joined together. You can

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. The same components as those described in the section of the conventional example are designated by the same reference numerals, and the description thereof will be omitted.

Reference numeral 10 in FIG. 3 denotes a substrate as an electronic component mounting substrate. The substrate 10 is made of, for example, silicon. A wiring pattern (not shown) is previously formed on the surface of the substrate 10 by a method such as etching, and each outer portion of the semiconductor electronic component is mounted on the portion of the wiring pattern where the semiconductor electronic component is mounted. A plurality of electrode pads 11, ... Corresponding to the cathode 4 are provided.

In the case where the semiconductor electronic component is an electronic component in which the outer lead 4 projects in four directions, such as QFP or TCP, the electrode pads 11 are indicated by X1, X2, Y1 in the figure.
, Y2, the outer leads 4 are formed so as to correspond to the respective protruding directions.

As shown in FIG. 2, the electrode pad 11 has a three-layer structure in which first to third layers 12 to 14 are sequentially laminated on the substrate 10. The first layer 12 is, for example, Al (aluminum), the second layer 13 is, for example, Ti (titanium), and the third layer 14 is, for example, Au.
(Fri) is adopted.

Then, the third layer 1 of the electrode pad 11
A plurality of concave grooves 15 ... Are formed on the surface of No. 4 as shown in the figure. As shown in the figure, the groove 15 is provided with its longitudinal direction orthogonal to the vibration direction (a) of the bonding tool 1, and is formed by etching, for example.

The pitch of the concave grooves 15 is set to be 1/2 or less of the width of the outer lead 4 and the convex portion between the concave grooves 15 that supports the lower surface of the outer lead 4 ( (Indicated by 16 in the figure) is at least two or more.

Next, the operation of mounting the semiconductor electronic component on the substrate 10 will be described. Board 1
When the semiconductor electronic component is positioned and mounted at a predetermined position of 0, the outer lead 4 of the semiconductor electronic component is placed on the upper surface of the electrode pad 11, that is, the plurality of convex portions, as shown in FIG. It will be stably supported by 16.

In this state, the bonding tool 1 is driven, a load is applied to the outer lead 4, and ultrasonic vibration in the direction shown in FIG. As a result, the concave groove 15, the convex portion 16 and the outer lead 4 are solid-phase diffusion bonded by the ultrasonic energy and the thermal energy as shown in FIG.

Then, such an operation is individually performed for each outer lead 4, and first, the outer lead 4 is joined to each electrode pad 11 indicated by X1 in FIG. If the outer lead 4 is joined to the electrode pad 11 indicated by X1, the outer lead 4 is connected to the respective electrode pads 11 indicated by Y1, X2 and Y2 in this order. In the embodiment, Y1, Y
The concave groove 15 formed in each electrode pad 11 shown by 2 is provided so that the longitudinal direction is orthogonal to the concave groove 15 formed in the electrode pad 11 shown by X1.

Therefore, when the outer lead 4 is joined to the respective electrode pads 11 indicated by Y1 and Y2, the vibration direction of the bonding tool 1 is such that it is orthogonal to the concave groove 15. Direction indicated by (b) in the figure ((b)
The bonding tool 1 is vibrated in a direction (perpendicular to the direction).

As a result, all the outer leads 4 of the semiconductor electronic component are joined to the respective electrode pads 11 provided on the substrate, and the semiconductor electronic component is attached to the substrate 1.
0 can be implemented.

According to this structure, the following effects can be obtained. As described above, as shown in FIG. 2, the surface of each electrode pad 11 provided on the substrate 10 of the present invention is provided with a plurality of concave grooves 15 in parallel at a predetermined interval to form unevenness. Formed.

When the outer lead 4 is joined to the electrode pad 11, as shown in FIG. 1 (a), the outer lead 4 is formed with a convex portion 16 formed between the concave grooves 15. The above-mentioned bonding tool 1
In a direction orthogonal to the direction in which the groove 15 is provided (a)
It was made to vibrate ultrasonically.

As a result, the convex portion 16 is easily vibrated, and the ultrasonic vibration transmitted from the outer lead 4 to the electrode pad 11 is effectively absorbed by the convex portion 16 and the substrate is It rarely reaches 10.

Since the applied ultrasonic energy is efficiently transmitted only to the upper portion of the electrode pad 11, the outer lead 4 and the electrode pad 11 are satisfactorily joined in a short time. be able to.

Further, the outer lead 4 and the electrode pad 11
Since the joint area is increased, a stronger joint can be obtained. Therefore, it is possible to effectively prevent the substrate 10 from being damaged by an impact load as in the conventional example, and it is possible to more effectively connect the outer lead 4 and the electrode pad 11.

The present invention is not limited to the above-mentioned embodiment, but can be variously modified without departing from the spirit of the invention. In the above-described embodiment, the direction of the groove 15 is offset by 90 ° between the electrode pads 11 indicated by X1 and X2 and the electrode pads 11 indicated by Y1 and Y2.
Alternatively, they may be provided in the same direction as shown in FIG.

In this case, even when the outer lead 4 is joined to the electrode pads 11 indicated by Y1 and Y2, the bonding tool 1 is made to vibrate in the direction indicated by the arrow (a).

With such a structure, the same effect as that of the above-described embodiment can be obtained. Further, in the substrate 10 shown in FIG. 4, the concave groove 15 formed in the electrode pad 11 indicated by X1 and X2 may be formed in the same direction as the concave groove 15 formed in the electrode pad 11 indicated by Y1 and Y2. good.

In this case, when the outer lead 4 is joined to the electrode pads 11 indicated by X1 and X2, the bonding tool 1 is vibrated in a direction orthogonal to the arrow (a).

This also makes it possible to obtain the same effects as those of the first and second embodiments. In short, the groove 1
It suffices that the direction in which 5 is provided is substantially orthogonal to the vibration direction of the bonding tool 1.

Further, as shown in FIG. 5, the concave groove 15 is formed.
May be provided in a grid pattern on the surface of the electrode pad 11. With such a configuration, even if the bonding tool 1 is vibrated in any direction, the convex portion 16 is always in a state in which it is easy to vibrate.
It is possible to obtain the same effect as that of the embodiment.

In this way, the outer lead 4 can be satisfactorily joined regardless of the operation of the bonding apparatus, so that the substrate 1 with a wide range of application can be obtained.
You can get 0.

Further, in the above-mentioned one embodiment, the concave and convex are formed by forming the concave groove on the electrode pad 11, but
As shown by 18 and 19 in FIGS. 6 and 7, respectively, even if unevenness is provided by forming the surface of the electrode pad 11 into a corrugated or sawtooth shape, substantially the same effect as that of the above-described first embodiment is obtained. Obtainable.

Further, in FIG. 8 and FIG. 9, respectively 20,
As shown by reference numeral 21, the same effect can be obtained by providing unevenness in the central portion of the electrode pad 11.
Further, although the substrate 10 is formed of silicon in the above-described embodiment, the substrate 10 is not limited to this and may be formed of another material.

Further, the material of the electrode pad 11 is not limited to that of the above embodiment, and the same effect can be obtained even if other material such as aluminum is used. Further, in the above-mentioned one embodiment, the electronic component mounting substrate is not particularly limited and may be, for example, a liquid crystal glass substrate.

Further, in the above-mentioned one embodiment, the electronic component is QF.
The electronic component has an outer lead protruding in four directions such as P and TCP, but is not limited to this, and an SOP having an outer lead protruding in only two directions or an outer lead only in one direction. It may be a protruding liquid crystal driving TAB component.

[0048]

As described above, according to the first structure of the present invention, in the electronic component mounting board having the electrode pad to which the lead of the electronic component is joined, the lead of the electrode pad and the lead of the electronic component are provided. The electronic component mounting board is provided with irregularities on the surfaces to be joined.

In the second structure, in the electronic component mounting board of the first structure, the unevenness is composed of a plurality of concave grooves and convex portions formed between the concave grooves. According to a third configuration, in the electronic component mounting board of the second configuration, the plurality of recessed grooves are provided substantially in parallel at a predetermined interval.

In the fourth structure, in the electronic component mounting board of the second structure, the plurality of concave grooves are provided in a grid pattern. A fifth structure is the electronic component mounting board of the second structure, wherein the plurality of concave grooves are provided along a direction substantially orthogonal to the ultrasonic vibration applied to the lead. .

A sixth structure is an electronic component mounting method in which an outer lead is joined to an electrode pad provided on an electronic component mounting board, and the outer lead is pressed against the electrode pad and the electrode is also attached. This is an electronic component mounting method in which both are joined by applying ultrasonic vibration in a direction orthogonal to the longitudinal direction of the concave groove provided in the pad.

According to this structure, it is possible to effectively prevent the electronic component mounting board from being damaged by an impact load at the time of joining the outer leads, and to improve the connection between the outer leads and the electrode pads. There is an effect that can be done.

[Brief description of drawings]

1A and 1B are process diagrams showing a longitudinal section of an electrode pad, which is a main part of a first embodiment of the present invention, and a joint structure of an outer lead.

FIG. 2 is a plan view and a vertical sectional view of an electrode pad.

FIG. 3 is likewise a plan view of the substrate.

FIG. 4 is a plan view of a substrate showing another embodiment.

FIG. 5 is a plan view, a front view, and a side view of an electrode pad showing another embodiment.

FIG. 6 is a front view of an electrode pad showing another embodiment.

FIG. 7 is a front view of an electrode pad showing another embodiment.

FIG. 8 is a perspective view of an electrode pad showing another embodiment.

FIG. 9 is a perspective view of an electrode pad showing another embodiment.

FIG. 10 is a front view showing a conventional example.

FIG. 11 is likewise a front view showing a joining step.

[Explanation of symbols]

1 ... Bonding tool, 4 ... Outer lead (lead)
10) Substrate (electronic component mounting board), 11 ... Electrode pad, 15 ... Recessed groove, 16 ... Convex portion.

Claims (6)

[Claims] 1. An electronic component mounting board comprising an electrode pad to which a lead of an electronic component is joined, wherein the surface of the electrode pad to be joined to the lead is provided with irregularities. Characteristic electronic component mounting board. 2. The electronic component mounting board according to claim 1, wherein the irregularities are composed of a plurality of concave grooves and convex portions formed between the concave grooves. 3. The electronic component mounting board according to claim 2, wherein the plurality of concave grooves are provided substantially in parallel at a predetermined interval. 4. The electronic component mounting board according to claim 2, wherein the plurality of concave grooves are provided in a grid pattern. 5. The electronic component mounting board according to claim 2, wherein the plurality of concave grooves are provided in a direction substantially orthogonal to ultrasonic vibration applied to the lead. Component mounting board. 6. An electronic component mounting method for bonding an outer lead to an electrode pad provided on an electronic component mounting board, wherein the outer lead is pressed against the electrode pad and provided on the electrode pad. An electronic component mounting method characterized in that both are joined by applying ultrasonic vibration in a direction orthogonal to the concave groove.