JPH02211705A - Piezoelectric oscillator - Google Patents

Abstract

PURPOSE:To reduce cost and to obtain high reliability by using glass for a base body to surely seal up it and equalizing the outside shape to that of a semiconductor integrated circuit. CONSTITUTION:A shell-shaped glass base body 12 is formed on one side plate surface of a lead frame 11, and holding pieces 13 are cut and raised and are projected from the bottom of the base body 12 to hold a piezoelectric piece 14, and electrodes are led out, and the aperture of the base body 12 is closed with a cover body 15 to airtightly seal up the piezoelectric piece 14, and an integrated circuit is arranged on the other side plate surface of the lead frame 11, thus constituting an oscillating circuit. The base body 12 and the integrated circuit are molded into one body by a molding material 19. Consequently, the piezoelectric piece 14 is surely sealed up, and the outside periphery is molded with a resin to obtain the same outside shape as the IC. Thus, an inexpensive and high-reliability quartz oscillator is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a piezoelectric oscillator that can have the same external shape as a so-called dual-in-line integrated circuit element in a mold package and that can provide high reliability.

(Technical background of the invention and its problems) Recently, integrated circuit elements (hereinafter referred to as "integrated circuit elements") are used in various electronic devices.

In order to use a large amount of
If it has the same external shape as C, it is easy to manage the parts, and it has the advantage that it is relatively easy to introduce automatic equipment for testing, assembly, etc.

For this reason, it is desired that piezoelectric oscillators such as crystal oscillators, which have conventionally been housed in their own containers, be housed in the same container as the IC.

FIG. 3 is a sectional view showing an example of a conventional crystal oscillator using a so-called dual in-line package.

That is, the semiconductor chip 2 is mounted on the upper surface of the lead frame 1 and electrically wired by wire bonding with thin metal wires 3 or the like.

Then, the upper and lower surfaces of this lead frame l are integrally molded with molding resin to form a container 5 having a hollow portion 4 on the lower surface.
form.

Then, electrodes are formed on the plate surface, and a crystal piece 6 adjusted to a predetermined resonance frequency is placed in the hollow part 4 of the container 5. This crystal piece 6 is held by a holding part 7 provided on the lower surface of the lead frame l, and its electrodes are electrically led out to form an oscillation circuit.

After the hollow part 3 is covered with a metal cap 8 and sealed, a molding material 9 is filled in the hollow part 3 to improve airtightness.

However, the crystal piece used in such an oscillator has electrodes made of silver, aluminum, etc. formed on its plate surface. On the other hand, the molded container 5 has low moisture resistance and has the disadvantage that moisture easily penetrates into the container 5.

Therefore, in a crystal oscillator having a structure as shown in FIG. 3, frequency stability cannot be maintained if moisture or the like enters the hollow part of the container and adheres to the electrodes of the crystal piece, or if the electrode material is altered.

However, in conventional oscillators as shown in Figure 3, it is difficult to maintain airtightness at the interface between the mold material and the lead frame, and the intrusion of moisture causes frequency changes and, in rare cases, oscillation stops, resulting in reliability problems. There was a low problem.

(Object of the Invention) The present invention has been made in view of the above circumstances, and it is possible to reliably seal the crystal piece, thereby obtaining high reliability, and furthermore, by molding the outer periphery with resin, the IC
The purpose of this invention is to provide an inexpensive and highly reliable crystal oscillator that can have the same external shape as the oscillator.

(Summary of the Invention) The present invention includes forming a shell-shaped glass base on one side plate surface of a lead frame, and cutting and raising a holding piece to protrude from the bottom of the base to hold a piezoelectric piece and lead out an electrode. The piezoelectric piece is hermetically sealed in the opening of the base with a lid, an integrated circuit is arranged on the other side of the lead frame to form an oscillation circuit, and the base and the integrated circuit are molded together. It is characterized by being molded with.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the sectional view shown in FIG.

In the figure, 11 is a lead frame, which is made of a thin plate of 4270 mm, Kovar, copper, etc., and processed into a predetermined pattern shape. A shell-shaped base body 12 made of glass is formed on an example plate surface of this lead frame 11. Further, when molding the base body 12, a predetermined portion of the lead frame 11 is cut and raised to form a holding piece 13, which protrudes from the bottom surface of the base body 12.

Furthermore, reference numeral 14 is a crystal piece having electrodes formed on its plate surface and adjusted to a predetermined resonance frequency, which is held by the holding piece 13 and the electrodes on the plate surface are electrically led out.

Then, a glass cover 15 made of Kovar glass or the like is welded to the frontage of the base body 12 with a low melting point glass 16 to airtightly seal it. Note that if the lid body I5 has a transparent structure, for example, using a high energy beam such as a laser beam,
By irradiating the electrode surface of the crystal blank 14 with this, fine adjustment of the frequency can be performed while the crystal blank 14 is sealed.

Then, an integrated circuit chip 17 is attached to the other side plate surface of the lead frame 11, and electrical connection is made by wire bonding using a thin metal wire 18 to form an oscillation circuit.

Then, the center portions of both side plate surfaces of the lead frame 11 are integrally molded with a molding material 19 to form the outer shape into the same shape as, for example, a dual in-line type integrated circuit.

In this way, it has the same external shape as a dual in-line integrated circuit and can be handled in the same manner as a so-called semiconductor integrated circuit, so automatic inspection equipment, automatic assembly equipment, etc. can be easily used. Moreover, since the crystal piece is hermetically sealed in a glass container, there is no risk of moisture intrusion, and it has good heat resistance and can maintain high reliability. The base made of glass can be easily formed into a desired shape by pouring molten glass into a mold and solidifying it, making it relatively inexpensive and suitable for mass production, reducing the price of the entire oscillator. There are advantages that can be achieved.

Note that the present invention is not limited to the above embodiments,
For example, as shown in FIG. 2, a metal lid may be used.

That is, a metal ring 20 may be fixed to the opening of the base 12, and a metal plate-shaped lid 21 may be welded thereto by seam welding or the like.

Further, induction heating or the like may be used during this welding.

Further, as the piezoelectric piece, a ceramic resonator made of niobium oxide, tantalum oxide, or the like can also be used.

(Effects of the Invention) As described in detail above, according to the present invention, it is possible to use glass for the substrate, which has good heat resistance and reliable sealing, and which can have the same external shape as a semiconductor integrated circuit. It is possible to provide a piezoelectric oscillator that is possible, suitable for mass production, and inexpensive.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view showing one embodiment of the present invention, FIG. 2 is a side sectional view showing another embodiment of the present invention, and FIG. 3 is a side sectional view showing an example of a conventional piezoelectric oscillator. be. 11 ・ 12 ・ 13 ・ 14 ・ 15 19 φ Lead frame base holding piece piezoelectric piece lid integrated circuit chip molding material

Claims (1)

[Scope of Claims] A glass base formed into a shell shape on one side plate surface of a lead frame, a holding piece cut out from the lead frame and protruding from the bottom of the base, and a plate surface held by the holding piece. a piezoelectric piece from which an electrode formed on the piezoelectric piece is led out; a lid body that closes the opening of the base body and hermetically seals the piezoelectric piece; and an integrated circuit that constitutes an oscillation circuit that is disposed on the other side plate surface of the lead frame. A piezoelectric oscillator comprising: a molding material for integrally molding the base and the integrated circuit;