JPH0461411A - Manufacture of resin sealing type piezoelectric resonator - Google Patents

Abstract

PURPOSE:To eliminate fall-off of a piezoelectric substrate entirely, to enhance the bonding strength between a piezoelectric element and a terminal and to excellent contact state by pressing and holding the piezoelectric substrate to the holding part of an external lead terminal prolonged from a lead frame so at to make the position of the piezoelectric almost constant with respect to the terminal holding part. CONSTITUTION:A piezoelectric element 1 is pressed and held to the holding parts 7a, 7b of terminals 4a, 4b prolonged from a lead frame 12. Thus, the position of the piezoelectric element 1 with respect to the holding parts 7a, 7b of the terminals 4a, 4b is set almost constant. Thus, the fall-off of the piezoelectric element 1 up to the solder bonding thereafter is eliminated entirely and solder is uniformly soldered to both major faces at the ends of the piezoelectric element 1, the bonding strength is improved and the contact state between the piezoelectric element 1 and the terminals 4a, 4b is main tained excellently.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a resin-sealed piezoelectric resonator, and more specifically, a method for manufacturing a frame terminal that improves the bonding reliability of a frame terminal that is bonded to a piezoelectric element. Regarding the method.

[Conventional technology]

FIG. 3 is a cross-sectional view of a typical resin-sealed piezoelectric resonator.

In the figure, 31 is a piezoelectric element, 32 is a piezoelectric substrate, 33 is an electrode,
34a and 34b are terminals, 35 is a resin layer, and 36 is a cavity.

In the piezoelectric element 31, electrodes 33 are formed on both main surfaces of a piezoelectric substrate 32. Note that an electrode symmetrical to the electrode 33 is also formed on the other main surface of the piezoelectric substrate 32, which does not appear in the figure.

The piezoelectric substrate 32 is made of PZT (lead zirconate titanate) piezoelectric ceramic that is processed into a predetermined shape and subjected to polarization treatment. The electrode 33 is made of Ag or the like and is formed in a predetermined shape on the piezoelectric substrate 32. For example, a vibrating electrode is formed at the center of the piezoelectric substrate 32 and mainly contributes to resonance, and a terminal electrode section 33a is formed at the end of the piezoelectric substrate 32 and connected to the terminals 34a and 34b (a terminal electrode on the other side). Part 33a
It doesn't even appear in the diagram. ). Also, terminal 3
At one end of 4a, 34b, a fourth electrode is provided at one end of the piezoelectric element 31 to connect with the terminal electrode part 33a of the piezoelectric element 31 and to hold the piezoelectric element 31.
Holding means 37 bent as shown in Figure (a)
Cup portions a and 37b are formed.

Specifically, as shown in FIG. 4(b), the frame 40
The piezoelectric element 3 is attached to the holding means 37a, 37b formed at one end of the terminals 34a, 34b... extending at a predetermined interval from the
Place 1. Subsequently, solder H is applied to join the holding means 37a, 37b and the terminal electrode portion 33a of the piezoelectric element 31.

Thereafter, as a sealing step, paraffin is dripped onto the central portions of both main surfaces of the piezoelectric substrate 31, and after curing, the entire piezoelectric substrate 31 is covered with a resin 35 capable of absorbing paraffin. Then, by heating, the bluff-in is impregnated with resin and a cavity 36 is formed.

[Problems with conventional technology]

However, according to the above manufacturing method, the holding means 37a, 3
Since a predetermined gap is created between 7b and the end of the piezoelectric element 31, the piezoelectric element 31 is tilted within the holding means 37a and 37b. When soldered in this state, the terminal 34a
, 34b and the ends of both main surfaces of the piezoelectric element 31 cannot be evenly bonded with solder, making it impossible to achieve strong bonding and good contact. As a result, the joint may come apart due to mechanical shock or stress during the process after soldering.

In addition, dripping paraffin to form the cavity 36,
It becomes difficult to drip the same amount onto the center portions of both main surfaces of the piezoelectric substrate 32, resulting in variations in characteristics.

[Purpose of the invention]

The present invention has been devised in view of the above-mentioned problems, and its purpose is to provide a method for manufacturing a resin-sealed piezoelectric resonator that improves the bonding strength and contact state between a piezoelectric substrate and a terminal, and has stable characteristics. It provides:

[Specific Means for Solving the Problems] A specific means proposed by the present invention for solving the above-mentioned problems is to form a holding part at one end of the external lead terminal extending from the frame at a predetermined distance. Using a terminal in which the interval between the holding parts of two external lead terminals is smaller than the width of the piezoelectric substrate, a piezoelectric substrate with electrodes formed on both opposing main surfaces is connected to both ends of the piezoelectric substrate using external lead terminals. This method of manufacturing a resin-sealed piezoelectric resonator is characterized in that the piezoelectric substrate and external lead terminals are soldered together while being held in pressure contact with each other, and the piezoelectric substrate is sealed with resin.

[Effect]

According to the above-described manufacturing method, the piezoelectric substrate is pressure-connected and held from both ends of the external lead terminal holding portion extending from the lead frame, so that the terminal holding portion and the piezoelectric substrate can be firmly held. The holding position of the piezoelectric substrate can be set approximately constant.

As a result, there is no chance of the piezoelectric substrate falling off during transportation during subsequent steps.

Further, since solder bonding is performed in this state, the solder can be uniformly bonded to both main surfaces of the end portion of the piezoelectric substrate, and the bonding strength can be improved and a good contact state can be maintained.

In addition, the paraffin dripped to form a cavity in the center of both main surfaces of the piezoelectric substrate can be reliably formed at the desired position, making it possible to manufacture resin-sealed piezoelectric resonant elements with less variation in characteristics. .

〔Example〕

Hereinafter, a method for manufacturing a resin-sealed piezoelectric resonator according to the present invention will be explained with reference to the drawings.

FIG. 1(a) is a schematic front sectional view of a resin-sealed piezoelectric resonator of the present invention, and FIG. 1(b) is a top view, in which the resin is shown by dotted lines for the sake of explanation.

The resin-sealed piezoelectric resonator of the present invention has a piezoelectric element having an energy-trapped thickness longitudinal vibration or thickness shear vibration mode and electrodes 3 formed on a piezoelectric substrate 2 bonded to terminals 4a and 4b. It is constructed by being covered with an exterior resin 5. In addition, 6 is a cavity, and the cavity is formed by forming paraffin and impregnating a part of the exterior resin 5. Further, the electrode formed on the other main surface of the piezoelectric substrate 1 does not appear in the figure.

When the resonant frequency of the resonator is 4MHz, the piezoelectric substrate 2 is
For example, it is made of piezoelectric ceramic such as PZT (lead zirconate titanate), and has a length of 6.4 mm and a radius of 1. It has a roughly rectangular shape of 0 mm.

Electrodes 3 made of Ag are provided on the front and back surfaces of the piezoelectric substrate 2.
is formed. Further, the electrode 3 is a vibrating electrode that is located in the center of the piezoelectric substrate 1 and mainly contributes to the resonance operation, and holding portions 7a and 7b that are formed on parts of the terminals 4a and 4b at the ends of the piezoelectric substrate 1. and a terminal electrode portion 3a to be connected.

The terminals 4a and 4b are connected to the terminal electrode portion 3a by solder, and a predetermined alternating voltage is applied from the outside.Holding portions 7a and 7b are formed at one end of the terminals 4a and 4b. Specifically, a metal plate such as nickel silver is pressed into a predetermined shape to form terminals 4a and 4b, and then bent into a cup shape to form holding parts 7a and 7b at one end.
is formed. The terminals 4a, 4b are provided with standoff portions 9a, 9b and the solder sockets are provided with protruding portions 11a, llb. The standoff parts 9a and 9b are for providing a predetermined gap between the external printed circuit board and the exterior resin 5 when the resonator is mounted on an external printed circuit board (not shown), and the solder sockets are provided on the protruding parts. 11a and Ilb are the terminals 4a and 4b when the piezoelectric element 1 and the holding parts 7a and 7b are soldered together.
, 4b, due to the heat capacity and thermal conductivity of the solder or terminal 4a.
, 4b side, the solder pool, the standoff protrusions 9a, 9b, and the solder receiver are the protrusions 11a, 11b.
A narrow portion of the terminals 4a, 4b is formed between the terminals 4a and 4b, and is provided so that the solder is not exposed to the outside of the exterior resin 5.

The exterior resin 5 has a two-layer structure of a porous resin and a hard resin. For example, the porous resin has sufficient pores to absorb the cavity-forming resin. The hard resin protects from external moisture and mechanical stress, and is formed by heating a powdered epoxy resin to about 150°C.

Next, the manufacturing method of the present invention will be explained.

First, the terminals 4a and 4b are molded into a predetermined shape.

The terminals 4a, 4b... extend substantially perpendicularly from the frame 12 at a predetermined interval, and are pressed into a predetermined shape such that holding portions 7a, 7b... of the piezoelectric substrate 1 are formed by bending at one end thereof. Processed.

Further, the holding portions 7a, 7b, . . . are bent into a cup shape.

In addition, the piezoelectric element 1 is made by polarizing piezoelectric ceramic in the length direction, and by depositing metal such as Ag on electrodes 3 and terminal electrodes 3.
It is obtained by forming a and then cutting it into a predetermined shape.

The piezoelectric elements 1 formed in this manner are held between terminals 4a, 4b extending from the frame 12 and having holding portions 7a, 7b, . . . at one end thereof.

That is, the piezoelectric elements 1 are pressed and held from both ends to the holding portions 7a of the terminals 4a and the holding portions 7b of the terminals 4b.

At this time, the holding portion 7a is not holding the piezoelectric element 1.
As shown in FIG. 2, the distance l between the piezoelectric element 1 and the holding portion 7b is set to be slightly shorter than the length L of the piezoelectric element 1. Therefore, the piezoelectric element 1 is held in a press-contact state between the holding part 7a and the holding part 7b, and the terminals 4a, 4b
Due to the springiness of the piezoelectric element 1, both ends of the holding parts 7a, 7
b, and is held accurately and firmly without tilting or misalignment.

Next, in this state, the terminal electrode 3a and the terminal 4a of the piezoelectric element
, 4b and the holding parts 7a, 7b are joined using solder.

For this solder joint, as mentioned above, solder or terminal 4
It is conceivable that the solder may flow to the standoff portions 9a and 9b of the solder sockets a and 4b, but since the solder receiver is provided with the protruding portions 11a and Ilb, the solder does not flow to the standoff portions 9a and 9b. Furthermore, since the piezoelectric element 1 is firmly held, the piezoelectric substrate 1 will not shift or fall off even if the whole is tilted.

After the piezoelectric element 1 and the terminals 4a, 4b are soldered together, paraffin for forming a cavity 6 is dripped into the center of both main surfaces of the piezoelectric element 1 and hardened.

Furthermore, a cavity 6 is formed at the same time as the exterior resin 5 is coated. First, with paraffin formed on the piezoelectric substrate 2,
The above-mentioned porous resin, which is the exterior resin 5, is formed. Specifically, it is formed by dipping into a resin bath in which porous resin is dispersed and then drying. Subsequently, a hard resin is formed. Specifically, a powdered epoxy resin as a hard resin is applied to a porous resin, and then heat of about 150° C. is applied.

This heating hardens the hard resin. At the same time, paraffin melts and is absorbed into the porous resin. As a result, a cavity 6 and an exterior resin 5 are formed in the center portions of both main surfaces of the piezoelectric substrate I.

Finally, the terminals 4a and 4b are each cut from the lead frame 12 to separate each element.

As described above, since the piezoelectric element 1 is pressed against and held by the holding parts 7a and 7b of the terminals 4a and 4b extending from the lead frame 12, the holding parts 7a and 7b of the terminals 4a and 4b,
The position of the piezoelectric element 1 relative to the piezoelectric element 7b can be set substantially constant. As a result, the piezoelectric element 1 will not fall off at all until the subsequent solder joining, and the solder can be uniformly joined to both main surfaces of the end of the piezoelectric element 1 during soldering. , the bonding strength is improved, and the piezoelectric element 1
Good contact between the terminals 3a and 3b can be maintained.

Furthermore, in the resin-sealed piezoelectric resonant element 10, it is easy to drip paraffin at a predetermined position in the central portions of both main surfaces of the piezoelectric substrate 2, and a resonant element with less variation in characteristics can be manufactured.

In addition, according to the above-mentioned embodiment, whether the terminals 4a, 4b, . . . extend substantially perpendicularly to the lead frame 12, or
As shown in FIG. 2(b), the terminals 4a, 4b, etc. may be extended at a slight angle with respect to the lead frame 12, and as shown in FIG. The standoff parts 9a, 9b may extend perpendicularly to the lead frame 12, with only the upper part slightly inclined from the standoff parts 9a, 9b.

〔Effect of the invention〕

As described above, according to the present invention, since the piezoelectric element is pressed against and held by the holding part of the external lead terminal extending from the piezoelectric substrate or the lead frame, the position of the piezoelectric element relative to the holding part of the terminal can be kept approximately constant. Moreover, there is no chance of the piezoelectric substrate falling off. As a result, solder bonding and paraffin dripping can be performed easily and reliably, resulting in a manufacturing method that reduces variation in element characteristics, improves the bonding strength between the piezoelectric element and the terminal, and provides a good contact state. Become.

[Brief explanation of the drawing]

FIG. 1(a) is a schematic front cross-sectional view of a resin-sealed piezoelectric resonator according to the present invention, and FIG. 1(b) is a top view, in which the exterior resin is shown by dotted lines for purposes of illustration. FIGS. 2(a) to 2(C) are schematic external views of terminals used in the present invention. FIG. 3 is a schematic perspective view of a typical resin-sealed piezoelectric resonator, and for the purpose of explanation, the exterior resin is shown by dotted lines. FIG. 4(a) is a schematic diagram of a terminal used in a conventional resonator, and FIG. 4(b) is a schematic diagram of a conventional terminal with a piezoelectric substrate placed thereon. 1 . . . . . . 2 .・・・Terminal・Exterior resin・Cavity・Holding part

Claims (1)

[Claims] (1) A piezoelectric substrate with electrodes formed on both opposing principal surfaces is held in pressure contact with external lead terminals from both ends of the piezoelectric substrate, and the piezoelectric substrate and external lead terminals are soldered together, and the piezoelectric substrate is attached to a resin. 1. A method for manufacturing a resin-sealed piezoelectric resonator, characterized in that it is sealed with a resin-sealed piezoelectric resonator.