JPH07162236A - Piezoelectric oscillator and its manufacture - Google Patents

Abstract

PURPOSE:To obtain a piezoelectric oscillator for surface mounting which is small in size and thin by mounting a piezoelectric vibrator and a semiconductor integrated circuit on a lead frame and integrally molding them. CONSTITUTION:An IC chip 2 is mounted on the island part 1 of the lead frame 13 with a conductive adhesive, etc., and respective pads of the IC chip and inner lead terminals 3, etc., are connected by Au wire bonding wires 4. Then a cylinder type crystal vibrator 6 which has a crystal vibrator piece 5a or 5b internally is positioned at the space part 14 of the lead frame 13 and connected and fixed to the lead frame 13 by resistance spot welding, etc. This mounted lead frame 13 is set in a transfer mold 31, transfer molding except outward parts such as the terminals 3, etc., is carried out, and a plastic package main body 19 is molded with resin. Further, tie bars connecting the terminals 3, etc., are cut away and the remaining outward parts such as the terminals 3, etc., are bent to obtain a package type crystal oscillator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric oscillator incorporating a semiconductor integrated circuit and a piezoelectric vibrator and a method for manufacturing the same.

[0002]

2. Description of the Related Art An example of a conventional piezoelectric oscillator will be described with reference to the crystal oscillator shown in FIG. A CMOS type IC chip 101 is bonded and fixed to an island 103 which is a part of a lead frame 102 by a conductive adhesive or the like, and electrically connected to an input / output lead terminal 105 by an Au wire bonding wire 104. . Further, the crystal oscillator 106, which has a crystal oscillator piece built in a cylindrical case, is fixed to the inner lead 107 and electrically connected to the gate terminal 108 and the drain terminal 109 of the IC chip 101. Then, the IC chip 101 and the crystal unit 10
6. Part of the input / output lead terminal 105 is sealed with an epoxy resin molding material 110 by a transfer molding method or the like.

[0003]

The conventional piezoelectric oscillator described above has a built-in piezoelectric vibrator having a cylindrical case with a diameter of about φ3 mm, and the height of the piezoelectric oscillator is about 4.4.
mm, and its volume is about 0.5 cc as a whole, which is relatively large. It is difficult because of restrictions.

The object of the present invention is to solve the above problems of the prior art. The object of the present invention is to provide a small, thin and highly reliable surface mount resin package type piezoelectric oscillator. Is to provide at low cost.

[0005]

The piezoelectric oscillator of the present invention comprises:
In a piezoelectric oscillator incorporating a semiconductor integrated circuit and a piezoelectric vibrator, the semiconductor integrated circuit is mounted on an island of a lead frame and electrically wired by wire bonding. It is positioned and fixed in the space portion 14, electrically connects the lead of the piezoelectric vibrator and a part of the lead frame, and molds the semiconductor integrated circuit, the piezoelectric vibrator, and the lead frame integrally with resin. Characterize.

Further, in a piezoelectric oscillator incorporating a semiconductor integrated circuit and a piezoelectric vibrator, the tip of the piezoelectric vibrator is held and positioned by a part of the lead frame.

In a piezoelectric oscillator having a semiconductor integrated circuit and a piezoelectric vibrator built-in, at least one through hole reaching the tip of the piezoelectric vibrator is provided on the upper surface of the resin package corresponding to the tip of the piezoelectric vibrator. Characterize.

In a piezoelectric oscillator incorporating a semiconductor integrated circuit and a piezoelectric vibrator, the lead frame holding and positioning the tip of the piezoelectric vibrator is a lead terminal of the ground (Vss) potential of the piezoelectric oscillator. To do.

Further, in a transfer mold type for manufacturing a piezoelectric oscillator having a semiconductor integrated circuit and a piezoelectric vibrator built-in, the tip of the transfer mold type pin forming a through hole provided on the upper surface of a resin package has a cylindrical case of the piezoelectric vibrator. It is characterized by being manufactured by a transfer mold which is formed in a shape having a radius equal to the radius.

Further, in a piezoelectric oscillator having a semiconductor integrated circuit and a piezoelectric vibrator built-in, the piezoelectric vibrator is a crystal vibrator enclosed in a cylindrical case having a diameter of 2 mm or less.

Further, in a piezoelectric oscillator incorporating a semiconductor integrated circuit and a piezoelectric vibrator, a cylindrical case of the piezoelectric vibrator is formed of a metal material having a linear expansion coefficient close to that of a resin material for molding the piezoelectric oscillator. It is characterized by

[0012]

EXAMPLE An example of a piezoelectric oscillator of the present invention is an SOJ (Small Outl) in which a crystal oscillator is used as a piezoelectric oscillator.
As an example, a crystal oscillator in a plastic package in the form of in J-Lead Packages) is shown in FIG.
This will be described with reference to the plan view of [a] and the sectional view of FIG. 1 [b].

An IC chip 2 of CMOS type or the like is mounted on the island portion 1 made of a highly conductive metal material such as 42 alloy or Cu alloy by a conductive adhesive or the like. Inner lead terminals 3 surrounding the periphery are electrically connected by Au bonding wire wires 4. Rectangular AT crystal unit 5a or 32.768 KHz
A cylinder-type crystal unit 6 having a low-frequency crystal unit 5b as a typical example is a gate terminal 8 for causing the lead 7 to oscillate the crystal unit 6 of the IC chip 2.
And inner lead terminals 10a, 1 electrically connected to the drain terminal 9 by the Au wire bonding wire 4.
It is fixed to the mount areas 11a and 11b in the middle of 0b by resistance spot welding or the like, and is electrically connected at the same time. Here, the lead 7 is OE (Output Enable).
The inner lead terminal 12 for e) and the inner lead terminal 10a are crossed and connected to the mount areas 11a and 11b, so that they are bent as shown in FIG. 1 [b], and the lead 7 is further mounted on the mount areas 11a and 11b. Is cut so that it overhangs. The crystal unit 6 thus processed is positioned in the space 14 of the lead frame 13 in parallel with the IC chip 2.

The inner lead terminal 16 connected to the ground (Vss) terminal 15 of the IC chip 2 by the Au wire bonding wire 4 has a crystal oscillator 6 in the middle thereof.
It has support parts 17a and 17b that support the tip of the device at two points. The supporting portions 17a and 17b are formed in a shape having a spring effect by constricting the roots of the supporting portions 17a and 17b so as not to damage the bonding portion of the inner lead terminal 16.

Further, in this embodiment, the maximum outer shape of the cylinder type crystal unit 6 is about φ2 mm. The cylinder-shaped case 18 of the crystal unit 6 is made of an inexpensive metal of copper-nickel-zinc alloy.

The above is set in a transfer mold 31 shown in FIG. 2 and resin molding is performed on the plastic package body 19 by transfer molding while leaving the outer side of the inner lead terminals 3 and the like. After that, a tie bar or the like connecting the inner lead terminals 3 or the like is cut and removed, and leads of the outer portions of the inner lead terminals 3 or the like are bent. As described above, the SOJ package-shaped crystal oscillator is obtained.

FIG. 2 is a structural diagram showing a manufacturing method when the piezoelectric oscillator of the present invention is molded by the transfer mold 31. Cylinder case 1 for crystal unit 6
8 is set on the transfer mold 31 while being supported by the supporting portions 17a and 17b. Then, the tip portion of the crystal resonator 6 is fixed by the pin 32 formed on either the upper mold or the lower mold of the transfer mold 31. That is, the crystal unit 6 is molded in a state of being sandwiched from above and below by the supporting portions 17a and 17b and the pins 32, and the plastic package body 19 is formed.

In this way, the cylindrical case 18 of the crystal unit 6 is positioned in parallel with the outer surface of the plastic package body 19 and is molded with the outer surface of the plastic package body 19 kept at a constant thickness of about 0.2 mm. To be done.

Further, as shown in FIG. 2, the pin 32 is formed with a radius equal to the radius of the crystal unit 6, and serves to fix the position of the crystal unit 6. Further, the support portions 17a and 17b have a shape having a spring effect, and have a structure in which the crystal oscillator 6 is not loaded when the crystal oscillator 6 is pressed by the pin 32.

In the crystal oscillator thus molded, the through hole 20 has a plastic package body 19
Is formed on the upper surface of. This through hole 20 has a diameter of about 1 mm
And a pin 32 that forms the through hole 20.
Fixes the arc portion of the cylindrical case 18 of the crystal unit 6. Further, after the molding, the cylindrical case 18 of the crystal unit 6 is in a state where the through hole 20 is exposed to the outer surface of the plastic package body 19.

A cylinder-shaped case 1 for the crystal unit 6
No. 8 uses a copper-nickel-zinc alloy having a linear expansion coefficient of 16.7 × 10 ⁻⁶ / ° C., and the linear expansion coefficient of the epoxy resin molding material used in the present invention (α1: a line having a glass transition temperature or lower). (Expansion coefficient) 16.0 × 10 ^-6 / ° C.

The piezoelectric oscillator of the present invention thus constructed has a minimum resin mold wall thickness of 0.2 mm as shown in FIG. 1A, and can be designed to be extremely thin and compact. Has become.

FIG. 3 is an external view of the piezoelectric oscillator of the present invention.

With the structure described above, the height of the piezoelectric oscillator is about 2.5 mm and the volume thereof is about 0.13 cc.
The height of the conventional piezoelectric oscillator is about 57%, and the volume is about 2%.
It is 6% thinner and smaller.

FIG. 4 is a layout diagram when the piezoelectric oscillator of the present invention is set in a transfer mold. In the manufacturing process of the piezoelectric oscillator of the present invention, first, the IC chip 2
Are mounted on the island portion 1 of the lead frame 13 with a conductive adhesive, and then the pads of the IC chip 2 and the inner lead terminals 3 and the like are connected by Au wire bonding wires 4. Next, the crystal unit 6 is connected and fixed to the lead frame 13 by resistance spot welding. The lead frame 13 mounted as described above is set in the transfer mold 31, and an epoxy type molding material is injected from the molding gate 41 and cured at a high temperature. In this way, the crystal oscillator of the plastic package is molded. Further, a tie bar 4 for connecting the inner lead terminals 3 etc.
2 is cut and removed, and the outer portion of the remaining inner lead 3 and the like is lead-bent. With the above, the piezoelectric oscillator of the present invention is completed.

[0026]

According to the piezoelectric oscillator of the present invention described above, the piezoelectric oscillator can be thinned by mounting the piezoelectric vibrator in parallel with the semiconductor integrated circuit.

Further, by holding the tip end of the piezoelectric vibrator by a part of the inner lead which constitutes the piezoelectric oscillator, and further by pressing and fixing the opposite side of the piezoelectric vibrator by the pin provided in the transfer mold, The position of the piezoelectric vibrator is fixed, and variation in the position of the piezoelectric vibrator is suppressed. As a result, the mold thickness of the piezoelectric oscillator is 0.2
It is possible to reduce the thickness to mm, which has an effect of reducing the height of the piezoelectric oscillator.

Further, by matching the transfer mold type pin shape with the R shape of the cylindrical case of the piezoelectric vibrator, it is possible to suppress variations in the plane of the piezoelectric vibrator, and to prevent short-circuiting with the inner leads, etc. This has the effect of providing a high piezoelectric oscillator.

Since the inner lead for holding the tip of the piezoelectric vibrator is also common to the ground (Vss) terminal of the piezoelectric oscillator, the heat to the piezoelectric vibrator, which is thermally conducted by the self-heating of the semiconductor integrated circuit, It has the effect of radiating heat to the outside.

Further, the inner lead for holding the piezoelectric vibrator is formed by a part of the lead frame forming the piezoelectric oscillator, and it is not necessary to separately form a holding structure, and a very inexpensive piezoelectric oscillator is provided. it can.

However, here, by reducing the thickness as described above, there is a problem of thermal stress when the piezoelectric oscillator is mounted on the substrate by solder reflow or the like.

Generally, when a resin package is left as it is, moisture is absorbed inside the package due to a storage environment or the like. When the substrate is mounted by solder reflow or the like in this state, the water accumulated around the cylinder-shaped case is vaporized and expanded, and the water vapor pressure of this portion rises, and the thermal stress concentrates on the thinnest portion of the mold. In the worst case, cracks occur in this thinnest part.

However, according to the present invention, the through hole provided on the upper surface of the resin package allows the moisture due to the moisture absorption of the resin package to be released to the outside by the heating of the resin package during the solder reflow, and the thermal stress during the solder reflow. It is possible to prevent the concentration of thermal stress due to the above and the generation of the package crack due to it, and to obtain a highly reliable thin piezoelectric oscillator.

Further, by adopting a metal material having a linear expansion coefficient close to that of a resin molding material such as a copper-nickel-zinc alloy as the material of the cylindrical case of the piezoelectric vibrator, the manufacturing process of the piezoelectric oscillator is performed. The thermal expansion and contraction of the cylinder-shaped case due to the heat stress applied inside and the heat stress during solder reflow are the same as those of the resin molding material, preventing peeling at the interface between the cylinder case and the resin molding material. Therefore, there is an effect that a thin piezoelectric oscillator with high reliability can be provided.

[Brief description of drawings]

FIG. 1 is a structural diagram showing an embodiment of a piezoelectric oscillator of the present invention.

FIG. 2 is a structural diagram when a lead frame and a piezoelectric vibrator are set and molded in a transfer mold for manufacturing the piezoelectric oscillator of the present invention.

FIG. 3 is an external view of a piezoelectric oscillator of the present invention.

FIG. 4 is a layout diagram in which the piezoelectric oscillator of the present invention is set in a transfer mold type.

FIG. 5 is a structural diagram showing a conventional piezoelectric oscillator.

[Explanation of symbols]

 1 Island Part 2 IC Chip 3 Inner Lead Terminal 4 Au Wire Bonding Wire 5a AT Crystal Resonator Piece 5b Low Frequency Crystal Resonator Piece 6 Crystal Resonator 7 Lead 8 Gate Terminal 9 Drain Terminal 10a, 10b Inner Lead Terminal 11a, 11b Mount Area 12 Inner lead terminal for OE 13 Lead frame 14 Space portion 15 Ground terminal 16 Inner lead terminal 17a, 17b Supporting portion 18 Cylinder type case 19 Plastic package body 20 Through hole 31 Transfer mold type 32 pin 41 Molding gate 42 Tie bar 101 IC chip 102 Lead frame 103 Island 104 Au wire bonding wire 105 Lead terminal 106 Crystal oscillator 107 Inner lead 108 Gate terminal 10 The drain terminal 110 resin mold

Claims (7)

[Claims] 1. A piezoelectric oscillator including a semiconductor integrated circuit and a piezoelectric vibrator, wherein the semiconductor integrated circuit is mounted on an island of a lead frame and electrically wired by wire bonding, and the piezoelectric vibrator is the semiconductor. The space portion 14 of the lead frame parallel to the integrated circuit
Is positioned and fixed to, the lead of the piezoelectric vibrator and a part of the lead frame are electrically connected, and the semiconductor integrated circuit, the piezoelectric vibrator, and the lead frame are integrally molded with resin. A piezoelectric oscillator characterized in that. 2. A piezoelectric oscillator having a semiconductor integrated circuit and a piezoelectric vibrator built-in, wherein a tip portion of the piezoelectric vibrator is held and positioned by a part of a lead frame. . 3. A piezoelectric oscillator including a semiconductor integrated circuit and a piezoelectric vibrator, wherein at least one through hole reaching the tip of the piezoelectric vibrator is provided on the upper surface of a resin package corresponding to the tip of the piezoelectric vibrator. The piezoelectric oscillator according to claim 2, wherein 4. In a piezoelectric oscillator including a semiconductor integrated circuit and a piezoelectric vibrator, a lead frame holding and positioning the tip of the piezoelectric vibrator is a lead terminal of the ground (Vss) potential of the piezoelectric oscillator. The piezoelectric oscillator according to claim 2. 5. A transfer mold for manufacturing a piezoelectric oscillator having a semiconductor integrated circuit and a piezoelectric vibrator built therein, wherein a tip of a pin of the transfer mold for forming a through hole provided on a top surface of a resin package is a cylinder of the piezoelectric vibrator. The method of manufacturing a piezoelectric oscillator according to claim 3, wherein the piezoelectric oscillator is formed in a shape having a radius equal to the radius of the shaped case. 6. A piezoelectric oscillator incorporating a semiconductor integrated circuit and a piezoelectric vibrator, wherein the piezoelectric vibrator is a crystal vibrator enclosed in a cylindrical case having a diameter of 2 mm or less. Piezoelectric oscillator. 7. A piezoelectric oscillator including a semiconductor integrated circuit and a piezoelectric vibrator, wherein a cylindrical case of the piezoelectric vibrator is made of a metal material having a linear expansion coefficient close to that of a resin material for molding the piezoelectric oscillator. The piezoelectric oscillator according to claim 1, wherein the piezoelectric oscillator is formed.