JPS6360565B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lead wire connection method for a crystal resonator in which a small crystal resonator having a fine electrode structure is held by the lead wire itself drawn out from the electrodes.

Recently, wristwatches using crystal oscillators have been released. This wristwatch is equipped with an oscillation circuit using a crystal oscillator, and operates a timekeeping mechanism using a signal obtained by dividing the frequency of this oscillation to a predetermined value. By the way, this crystal resonator for a wristwatch is a so-called tuning fork type crystal resonator that uses a "flexural vibration" crystal plate. Even if the crystal oscillator has the same vibration frequency, its shape can be made large or small as long as the ratio of the length and width of the vibrating tuning fork portion is kept constant.
Therefore, it has become possible to manufacture a small watch that can be stored inside a wristwatch even though the vibration frequency is relatively low.

On the other hand, due to its structure, a tuning fork type crystal resonator requires four lead wires to be drawn out from the crystal resonator.
Even if electrode connection wiring is provided on the surface of the crystal resonator, at least two lead wires must be drawn out. Moreover, it is not possible to draw out the lead wires from both ends of a circular or square diaphragm like in a thickness-slide type crystal oscillator, and all four lead wires come from the base.
A book or two leads must be drawn out. The electrodes and lead wires are usually connected using soldering or conductive adhesive, but for small models, the electrode spacing is a fraction of a millimeter or several tenths of a millimeter.
Because the size is only 1 mm, the solder or conductive adhesive may spread over multiple electrodes when connecting the lead wires due to carelessness, causing a short circuit between each electrode, resulting in a very poor manufacturing yield. Not only that, but the connection of the lead wires had to be done manually, making it impossible to fully automate the manufacturing process.

Furthermore, the above-described connection method uses extremely thin lead wires in order to facilitate delicate manual work. Therefore, this lead wire cannot be used also as a holding member for the crystal resonator, and a holding member must be provided separately.

The present invention is a novel invention that improves the conventional drawbacks as described above, and its purpose is to ensure mutual insulation from fine electrodes and to allow multiple lead wires to be drawn out in a firmly fixed state. An object of the present invention is to provide a lead wire connection method for a crystal resonator.

Next, one embodiment of the present invention will be described in detail using the drawings.

FIG. 1 is a partial perspective view showing the base of a tuning fork-type crystal resonator. In the figure, 1 is the base, 2 and 3 are vibrating pieces extending in parallel from the base 1, and 4a to 4d are these vibrating pieces. The electrodes 5 and 6 provided around the periphery are connection pads and are electrically connected to each electrode. Each electrode and electrode pad is made of evaporated gold (Au)
It is formed from a thin film. 5' and 6' are indium (Iu) layers thinly deposited on electrode pads 5 and 6.

The lead wire used in this embodiment is a thin copper wire plated with thin gold.

Next, a method of connecting the lead wire to the connection pad provided at the base of the tuning fork type crystal resonator as described above will be explained.

As shown in FIG. 2, lead wires 7 and 8 are placed on connection pads 5 and 6, respectively. Since the lead wires 7 and 8 must be parallel to each other and kept at a constant distance, they are attached to a suitable jig to keep them parallel to each other at a constant distance. Thereafter, as shown in FIGS. 2 and 3, pressure is applied from above the lead wires 7 and 8 to press the lead wires 7 and 8 against the connection pads 5 and 6, thereby separating the lead wire 7 and the connection pads 5 and 6. Strong contact is made between the lead wire 8 and the connection pad 6. At this time, the indium deposited on the connection pads 5 and 6 is diffused into the gold layers 7' and 8' plated on the lead wires 7 and 8, and as shown in FIG. a thin layer of gold-indium low-melting alloy D
As a result, the gold layer 7' of the lead wire 7 and the indium layer 5' on the connection pad 5 are integrally connected, and the lead wire 7 and the connection pad 5 are completely electrically connected. Note that D' is a thin layer of a low melting point alloy of gold and indium formed on the surface of the connection pad. or,
Similarly, electrical connection is made between the lead wire 8 and the connection pad 6.

Then, with the lead wires 7 and 8 firmly pressed against the connection pads 5 and 6, as shown in FIG.
Apply epoxy adhesive 9 around the lead wires 7, 8 and the connection pads 5, 6, and apply the epoxy adhesive 9 to ensure electrical connection between the lead wires 7, 8 and the connection pads 5, 6. 9 is solidified. When the adhesive 9 is solidified, a temperature of more than 100 degrees Celsius is usually applied.
Due to this heating, indium is increasingly diffused into the gold layer on the surface of the lead wire, forming a thin alloy layer with a low melting point between the lead wire and the connection pad, which melts and creates an electrical connection between them. becomes complete.

After the adhesive 9 has completely hardened, connect the lead wires 7 and 8.
Remove the pressure that was applied to the

In this way, the lead wires 7 and 8 physically fix and hold the crystal resonator at its base 1, and are electrically connected to each connection pad 5 and 6 by the insulating adhesive 9 that hardens while in electrical contact with the lead wires 7 and 8. The connection is also secure.

According to the above embodiment, a diffusion layer D is formed at the contact portion of the lead wires 7, 8 on the connection pads 5, 6 drawn out from the electrodes 4a to 4d to the base 1 of the crystal resonator, and electrically connected. After that, an insulating adhesive 9 is applied to this connection part and solidified, and the crystal resonator is fixed and held by the lead wires 7 and 8. Even with a minute electrode structure, the lead wire 7,8
Since mutual insulation is ensured and they are firmly fixed, it is easy to hold the crystal resonator by the lead wires themselves.

In the above embodiment, adhesive is applied to the contact area between the lead wire and the connection pad after the lead wire is pressed against the connection pad. There is a possibility that air bubbles may be generated in some parts, which has the disadvantage of reducing the connection strength of the lead wire. These drawbacks can be overcome by the following embodiment. That is, even if a drop of adhesive is applied to the tip of the lead wire in advance and then placed on the connection pad, the strength of the bonded portion is improved in the same way as described above.

Furthermore, after applying liquid epoxy adhesive 9 to the connection pads 5 and 6 of the crystal resonator and their surroundings as shown in FIG. Press it onto the connecting pads 5 and 6 from above. At this time, the lead wire pushes away the adhesive and reaches the indium layer on the connection pad, making strong contact with it, and as in the previous example, the indium on the connection pad diffuses into the gold layer of the lead wire.
A thin layer of low melting point alloy is formed to ensure electrical connection between the connection pad and the lead wire.

While maintaining this state, the entire piece is heated to solidify the adhesive. During this heating, as described in the description of the above embodiment, diffusion into the indium alloy takes place and a thin alloy layer with a low melting point is formed. After the adhesive has completely solidified, the pressure applied to the lead wires is removed to complete the connection of the lead wires.

In the present invention, when electrically connecting the connection pad and the lead wire, the diffusion effect of metal is used, and the above two embodiments both use a combination of gold and indium, which facilitates diffusion. .
However, other combinations such as silver-gold, aluminum-cobalt, aluminum-chromium, silver-tin, and gold-tin can also be used; If tin is used, care must be taken to avoid short circuits due to whiskers.

In addition, in order to maintain a stable connection between the lead wire and the connection pad for a long period of time, it is preferable to mix a reducing agent and, if necessary, a catalyst into the adhesive.

Further, the present invention is not only applicable to the tuning fork type crystal resonator as in the above embodiment, but also to the lead wire extraction portion of other crystal resonators such as the thickness-slide type crystal resonator.

As explained in detail above, when the lead wire is drawn out from the crystal resonator, the present invention electrically connects the connection pad drawn out from the electrode and the lead wire using the diffusion effect of metal, and then Since we use a process that stably maintains this state by solidifying the adhesive, it is not complicated to solder the lead wires to each connection pad or use conductive adhesive to fix them. No manual work is required, which makes connecting the lead wires much easier. In addition, since an insulating adhesive can be used, unlike conventional bonding methods using conductive adhesives, even if the distance between multiple lead wires is narrowed, the gap between each lead wire will not be insulated. Because the adhesive penetrates and solidifies, the insulation between the lead wires is extremely good, and even if the crystal unit is made smaller, there will be no short circuit between the lead wires due to conductive adhesive or solder as in the past. No accidents occurred at all, and it became possible to fully automate the production of crystal resonators. Furthermore, since a large amount of adhesive can be applied to the contact portion between the crystal resonator and the lead wire, the lead wire and the crystal resonator can be firmly connected. Therefore, in the case of a bending vibrator, the manufacturing method according to the present invention brings about various effects, such as the ability to use the lead wire connected to the base as a holding member.

[Brief explanation of the drawing]

Figures 1 and 2 are partial perspective views showing the base of a tuning fork-shaped crystal resonator, Figures 3 to 5 are process explanatory diagrams explaining the steps of the connection method, and Figure 6 is another example of the connection method. It is an explanatory view explaining an example process. In the figure, 1 is the base, 2 and 3 are vibrating pieces, 4a to 4d are electrodes, 5 and 6 are connection pads, 5' and 6' are indium layers, 7 and 8 are lead wires, 7' and 8' are gold Layer 9 is adhesive.

Claims (1)

[Claims] 1. In a lead wire connection method in which the crystal resonator is held in the case by connecting the ends of lead wires extending from the case to a plurality of electrodes provided on the surface of the crystal resonator, the electrodes are connected to the base of the crystal resonator. A step of providing a thin layer of metal with a diffusion effect on the pulled-out connection pad, and electrically and mechanically contacting the thin metal layer with a diffusion effect formed on the connection pad with the lead wire, The process of applying pressure to the contact surface between the connection pad and the lead wire to maintain electrical continuity, and the contact between the lead wire and the thin metal layer with a diffusion effect formed on the connection pad. Apply pressure to the surface to maintain electrical continuity while heating and solidifying the liquid insulating adhesive that spans the connection pad and lead wire, excluding the areas in contact with the thin metal layer. and forming a thin alloy layer at the contact area between the lead wire and the connection pad by heating, and after the insulating adhesive has solidified, the pressure applied to the contact surface between the connection pad and the lead wire is reduced. 1. A method for connecting lead wires in a crystal resonator, the method comprising the step of removing lead wires.