JPH07147427A - Manufacture of optically coupled element - Google Patents

Abstract

PURPOSE:To improve insulation breakdown strength between elements by separating the positions of the summits of metal wire loops from the top planes and the facing planes of a light receiving element and a light emitting element when the plane of a lead frame that fixes the light receiving element and the light emitting element through metal wire is permitted to be the reference. CONSTITUTION:A light receiving element 3 and a light emitting element 4 are firmly adhered to lead frames 5 and 6, respectively, and metal wire 1 is bonded between the elements 3, 4 and the lead frames 5, 6 for electrical continuity. At that time, especially the metal wire 1 is ball-bonded on the lead frame 5 and then wedge-bonded on a pad 2 on the light emitting element 4 so as to take away the summit 1B of the loop of the metal wire 1 from the light emitting element 4. The metal wire 1 is bonded to the light receiving element 3 in the same manner. Thus, insulation breakdown strength between the elements 3 and 4 is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical coupling element, and more particularly to a method for connecting metal wires.

[0002]

2. Description of the Related Art As shown in FIG. 4, a conventional optical coupling element is connected to a lead frame by bonding pads (hereinafter referred to as pads) 2 fixed on a lead frame 6, for example, on a light receiving element 3. In order to minimize the force applied to the wire neck portion due to friction between the bonding tool and the metal wire 1 during bonding, ball bonding is performed on the lead frame 6 side and then wedge bonding is performed on the lead frame 6 side. In addition, the apex 1B of the metal wire loop was formed near the ball bond portion 1A. Therefore, as shown in FIG. 3, in the optical coupling element in which the light receiving element 3 and the light emitting element 4 are vertically opposed to each other and sealed with the epoxy resin 7, the apex 1B of the loop of the metal wire is
The structures are close to each other in the central portions of the elements facing each other.

[0003]

In the optical coupling element manufactured by the above-mentioned conventional ball bonding method, the apexes 1B of the loops of the metal wires 1 of the respective elements are close to each other, as shown in FIG. There is a drawback of lowering the electrical withstand voltage on the input side and the output side. Therefore, the miniaturization of the package is limited, and it is necessary to take measures such as inserting a translucent insulating film between the metal wires.

[0004]

According to a method of manufacturing an optical coupling element of the present invention, a light emitting element and a light receiving element, which are fixed to a lead frame and whose pads and lead frame are connected by metal wires, are made to face each other and sealed with a resin. In the method for manufacturing an optical coupling element that is stopped, the pad of each element and one end of the metal wire are respectively connected by wedge bonding, and the other end of the metal wire and the lead frame are respectively connected by ball bonding, Each position of the apexes of the loops of the metal wires when the lead frame surface on which each element is fixed is used as a reference is separated from the upper surface and the facing surface of the light emitting element and the light receiving element. It is what

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.
FIG. 1 is a sectional view for explaining a first embodiment of the present invention.

In FIG. 1, the lead frames 5 and 6 are
The light receiving element 3 and the light emitting element 4 are fixed to each other by die bonding, and the metal wire 1 for obtaining electrical conduction is bonded between each element and the lead frame. At this time, particularly for the bonding of the metal wire 1, a method of performing ball bonding on the lead frame 5 and then wedge bonding on the pad 2 on the light emitting element 4 is used.
The apex 1B of the loop is moved away from the light emitting element 4. Bonding of the metal wire 1 connected to the light receiving element 3 is similarly performed.

After the wire bonding is completed, the light emitting element 4 is coated with a silicon resin 8 in order to prevent the deterioration of the light emission output due to the stress of the exterior resin described later. After that, the lead frame 6 having the light receiving element 3 and the lead frame 5 having the light emitting element 4 are opposed and combined and fixed by means such as a welding method, and the exterior is covered with an epoxy resin 7 by a known transfer molding method. Mold. Further, the optical coupling element is completed after the leads are shaped and cut, and the predetermined electrical characteristics are selected.

According to the first embodiment constructed as described above, the apex 1 of the loop of the metal wire 1 is formed in the facing surface of each element.
Since there is no B, the withstand voltage between elements is improved.

FIG. 2 is a sectional view for explaining a second embodiment according to the present invention.

FIG. 1 shows an optical coupling element having a structure in which a light transmission path for an optical signal is formed of a transparent silicon resin 8 and a silicone resin 9 containing a filler, and the light receiving element 3 and the light emitting element 4 face each other on a plane. The same bonding method as in the case of the first embodiment is applied to the structure in which the height of each metal wire 1 from the lead frames 5 and 6 is kept low, and the apex of the loop of each metal wire 1 The position of 1B is separated behind the facing surface of each element. Therefore, similarly to the first embodiment, there are advantages that the withstand voltage between elements is improved and the optical coupling element can be thinned.

[0011]

As described above, according to the present invention, in the method of manufacturing an optical coupling element in which a light emitting element and a light receiving element are opposed to each other and sealed, the pad of each element and one end of a metal wire are connected by wedge bonding. Then, by connecting the other end of the metal wire and the lead frame by ball bonding, it is possible to separate the vertex positions of the loops of the respective metal wires from the upper surface portion and the facing surface portion of the element facing each other. It is possible to improve the electric breakdown voltage with respect to the output side element. In addition, under a certain standard of electric withstand voltage, there is an effect that the package itself can be downsized.

[Brief description of drawings]

FIG. 1 is a cross-sectional view for explaining a first embodiment of the present invention.

FIG. 2 is a sectional view for explaining a second embodiment of the present invention.

FIG. 3 is a sectional view of a conventional optical coupling element.

FIG. 4 is a sectional view of a light receiving element for explaining a conventional wire bonding method.

[Explanation of symbols]

 1 Metal Wire 1A Ball Bond Section 1B Loop Apex 2 Pad 3 Light-Receiving Element 4 Light-Emitting Element 5, 6 Lead Frame 7 Epoxy Resin 8 Transparent Silicon Resin 9 Filled Silicon Resin

Claims (1)

[Claims] 1. A method of manufacturing an optical coupling element, wherein a light emitting element and a light receiving element, in which a pad and a lead frame are connected to each other by a metal wire, are fixed to each other on a lead frame, and the light receiving element and the light receiving element are opposed to each other and sealed with resin. Connect the pad and one end of the metal wire by wedge bonding,
The other end of the metal wire is connected to the lead frame by ball bonding, and the positions of the vertices of the loop of the metal wire when the lead frame surface on which the elements are fixed are used as the reference are the light emitting elements. And a method for manufacturing an optical coupling element, characterized in that it is separated from an upper surface portion and a facing surface portion of the light receiving element.