JPS6367340B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronic device such as an electronic watch with small mounting dimensions.

In general, in electronic devices such as electronic wristwatches, one of the challenges is how to reduce the space occupied by so-called modules that incorporate semiconductor elements and electronic components such as capacitors and batteries. On the other hand, another problem is how to simplify the assembly work of such electronic devices or modules, and how to reduce the number of parts for assembling them.

In recent years, in order to solve the above problems, attempts have been made to effectively utilize semiconductor integrated circuits (hereinafter abbreviated as IC), etc., which have a large number of built-in active elements and passive elements and interconnect them internally. However, the above-mentioned problems still remain, and various efforts are being made to solve them.

For example, Japanese Patent Application No. 51-62158 (Japanese Patent Application No. 51-145370)
In electronic watches using ICs, the IC is sealed with resin, and a part is provided to house the external electronic components (crystal oscillator, trimmer capacitor, battery, display device, etc.) of the resin-sealed IC. , electronic components are housed in that part, and these electronic components and the IC are electrically connected through a single lead frame to form a compact module.

However, in this type of electronic watch module, each of the electronic components described above has a large shape, so the area for accommodating them becomes large, and as a result, the resin sealing body is It will have a large shape. Therefore,
During and after resin encapsulation of an IC, stress caused by the difference in thermal expansion coefficient between the resin in the part that houses electronic components and the lead frame and thermal distortion during resin curing is directly transmitted to the IC. , which has the disadvantage of deteriorating the characteristics and reliability of the IC.

In addition, in this type of electronic watch module, it is necessary to use a highly reliable resin with excellent moisture resistance, shock resistance, and chemical stability for sealing the IC. Resins that satisfy the characteristics of seeds have poor moldability and mold releasability, making it impossible to microfabricate complex-shaped molds to accommodate electronic components with complex shapes, making it difficult to obtain moldability suitable for mass production. There is. On the other hand, considering molds with complex shapes for storing electronic components, we
When a resin with excellent mold releasability is used as an encapsulant, the resin that satisfies these properties has poor moisture resistance and chemical stability, which has the disadvantage of degrading the performance of the IC. Therefore, with conventional modules of this type, it has been difficult to obtain a sealed body that satisfies the above two contradictory requirements.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an electronic device such as a high-performance and highly reliable electronic watch that can solve the above-mentioned conventional problems.

That is, the present invention provides: (a) placing the integrated circuit chip on a lead frame on which electronic components and integrated circuit chips are to be placed, and sealing the integrated circuit chip with resin by transfer molding; (b) using the first resin forming body as a resin outflow prevention member and storing the electronic component in a state separated from the first resin forming body; (c) placing the electronic component on a predetermined portion of the second resin forming body where the lead frame is exposed; and (d) removing unnecessary portions of the lead frame.

In order to achieve such an object, an embodiment of the present invention includes a sealed body (first resin molded body) of a semiconductor element having an unstable surface such as an IC or a transistor, and an external electronic component thereof (for example, (crystal resonators, capacitors, batteries, display devices such as LCDs and LEDs)
The device is completely separated from the block body (second resin molded body) that houses the block body, so that deformation or distortion of the block body does not interfere with the characteristics of the element inside the sealing body, and is arranged at a distance from the sealing body. An electronic device in which two block bodies are connected together by a lead frame and their spatial positions are maintained, and in addition, electrical connections are made between electronic components housed in the latter block body and elements within the encapsulation body. The manufacturing method is as follows.

Therefore, the present invention is characterized in that the sealed body such as an IC and the block body housing external electronic components thereof are completely separated. Therefore, deformation or distortion of the block body has no effect on the elements within the sealing body, making it easy to prevent deterioration of element characteristics.

The material for sealing the element and the material for molding the block body can be made suitable for each purpose. Therefore, as a material for encapsulating elements, regardless of the block body, it has good moisture resistance, little deterioration, has few undesirable impurities such as Na and Cl, and has chemical stability, especially free of impurities that easily move as ions. Any good material (resin, glass, etc.) that has good adhesion to the lead portion can be used. On the other hand, as a material for molding a block body, it has excellent moldability, releasability, thermal deformability, thermal stability, and impact resistance, and has excellent thermal expansion with the lead frame, regardless of the aforementioned element sealing body. Materials (resin, ceramic, etc.) that have small coefficient differences and can be microfabricated can be used. Moreover, unlike the former sealing material, a low-cost material can be selected. Furthermore, since the element sealing material and the block molding material can be made different, there is greater freedom in selecting the materials to be used.

The material for sealing the element is generally thermosetting, and the material for molding the block is not limited to thermosetting, but may also be thermoplastic.

A light-shielding black resin is used as the element sealing material, and a transparent resin is used as the block molding material because it facilitates assembly of external electronic components and provides high product value. I can do it. In this way, the partner can be identified.

The block body alone can be separated and the sealed semiconductor element alone can be sold as a product, and the block body alone can be sold as a product.
Furthermore, if a defect occurs in any of them, the leads at the boundary between them can be cut and replaced with another good product.

The present invention uses an IC that occupies a small space as the main circuit element, uses small external electronic components for the IC, and installs them in storage areas such as grooves and through holes drilled in the block body. Since it can be structured so that it can be easily stored, it becomes an extremely compact device.

In manufacturing this type of module, since the sealing body and the block body are separated, various manufacturing methods can be employed. Therefore, the most suitable molding method or apparatus can be selected depending on the application.

For example, the following manufacturing method can be adopted.

(f-1) After attaching a semiconductor element such as an IC to a lead frame and sealing it, a block body is formed. Since the surface of a semiconductor element is unstable, it is desirable to perform sealing prior to molding the block body.

This method requires two molds, one for sealing the element and one for molding the block body. However, in this method, there is no need to provide a dam in the lead frame between the element sealing body and the block body to prevent resin from flowing during molding. This is because the pre-molded sealing body (or block body) acts as a stopper for the flow of resin flowing out of the mold during the next molding process of the block body (or sealing body). It is.
Therefore, this method has the advantage that there is no need to perform a dam cutting operation on the lead frame and that a lead frame with a simple shape can be used.

(f-2) According to method (f-1) described above, since there is no dam in the lead frame, it is necessary to remove unnecessary parts such as resin burrs that are created when encapsulating elements such as ICs. The frame may be deformed. Therefore, in order to prevent this, a dam is provided on the lead frame (f
-1) Form the element sealing body and block body according to the method.

(f-3) A dam is provided on the lead frame, and the element sealing body and block body are simultaneously formed using one molding die. this is,
This can be done by separately providing a pressurized injection port for the resin for sealing the element and a pressurized injection port for the resin for molding the block body. It is particularly advantageous when formed using This method consists of 1
Since one mold is used to simultaneously seal the element and mold the block, it is versatile and highly productive.

As described in detail above, the present invention provides an electronic device such as an electronic clock that occupies as little space as possible for the module, is easy to manufacture, has high productivity, and has high reliability and high performance. Applicable to devices.

Hereinafter, a method for manufacturing an electronic wristwatch using an IC, which is an embodiment of the present invention, will be specifically described with reference to the drawings. A package in which block bodies housing components are completely separated and connected by a single lead frame will be described.

FIG. 1 is a perspective view of a package according to the invention. As shown in the figure, in the package 1 according to the present invention, a sealing body 2 that seals an IC (not shown) and a block body 3 that houses external electronic components are formed by a single lead frame 4. Although they are connected and integrated, they are spaced apart from each other. Both of them are molded using resin material. Note that 4a to 4d indicate each exposed lead in the lead frame 4. The surface of the block body 3 made of resin is provided with grooves and through holes for storing electronic components. 5 is a through hole for storing a battery, 6 is a groove for storing a crystal resonator, 7 is a groove for storing a temperature compensation capacitor, 8
9 is a groove for accommodating a trimmer capacitor, and 9 is a groove for accommodating a chip capacitor. Also, 10-11
is a groove for electrically connecting the external terminal of the crystal resonator and the lead frame 4, and a part of the lead frame is provided at the bottom of the groove to be exposed. 12~
Reference numeral 13 denotes a groove for electrically connecting both external terminals of the trimmer capacitor and the lead frame. Reference numeral 14 indicates four through holes for screwing in order to attach the mounting plate of the display device to the package cage 1. 1
5 is a groove for storing the lamp, and 16 to 17 are grooves for electrically connecting the external terminal of the lamp and the lead frame. Furthermore, an LCD is used as the display device.
It is attached to the sealing body 2 made of resin of the IC via a zebra connector, and is adapted to engage with the guide groove 18 of the block body 3 made of resin.

Next, a method for manufacturing this type of package 1 is described.
Examples will be described in order of process.

(1) Prepare a lead frame 4 as shown in Figure 2 as a starting material. This lead frame 4 is made of a Kovar plate or the like with a thickness of about 0.15 mm, and each external lead of the IC and wiring leads of external electronic components are formed thereon.

4a is an external lead that is electrically connected to the pad electrode on the surface of the IC chip, 4b and 4c are wiring leads that are connected to the poles of the battery, 4d, 4e and 4f are wiring leads for the switch, and 4g is the IC chip that is die bonded. tabs, 4h and 4
j, 4k and 4l, 4m and 4n, 4p and 4q, 4
r and 4s are lead terminals to which the crystal resonator, temperature compensation capacitor, trimmer capacitor, chip capacitor, and lamp are electrically connected to the external leads of the IC. Further, 4t is a dam for preventing the resin from flowing during resin molding.

Note that the lead frame 4 shown in the figure is partially cut away for ease of illustration.

(2) After die bonding the IC chip 19 to the tab 4g on the lead frame 4, the pad electrodes on the IC chip 19 and the leads 4a on the lead frame 4 are interconnected using thin metal wires 20 made of Au, Al, etc. Figure 3). This can be easily wire bonded using well-known techniques such as nail head bonding.

(3) The IC chip 19 is encapsulated with resin by transfer molding or the like (FIG. 4). The resin material to be used is an epoxy resin having excellent moisture resistance, chemical stability, etc.

In this case, since a resin burr 2' is formed around the sealing body 2, this is removed along with the dam cutting (FIG. 5).

(4) A block body 3 for housing external electronic components of the IC is formed by injection molding, transfer molding, etc. (FIG. 6). As the resin used, a resin having excellent moldability, mold releasability, heat deformability, etc. is used. This block body 3 is provided with grooves and through holes for storing electronic components. 5 is a through hole for housing the battery. Also,
6, 7, 8, 9, and 15 are grooves that house the crystal resonator, temperature compensation capacitor, trimmer capacitor, chip capacitor, and lamp;
Numerals 1, 12 and 13, and 16 and 17 are grooves for electrically connecting the electronic components, and leads 4b to 4s are exposed at the bottoms of the grooves.

(5) Cut the outer frame of the lead frame 4 to obtain the package 1. A plan view of the package 1 is shown in FIG. 7, and a back view is shown in FIG.

Next, the mounting and assembly of the electronic wristwatch according to the present invention will be explained. As shown in schematic assembly diagrams in FIGS. 9a to 9b, each through hole and groove of the block body 3 made of resin in the package 1 includes a crystal resonator 21, a temperature compensation capacitor 22, a trimmer capacitor 23, and a chip capacitor 24. , lamp 25,
A battery 26 is housed, and each terminal thereof is fixed to a lead whose surface is exposed by spot welding, solder, silver paste, or the like. Before or after this assembly process, the leads extending to the side walls of the block body 3 made of resin are bent. Next, a zebra connector 27 is interposed on the resin sealing body 2 of the IC in the package 1 incorporating these electronic components, and the LCD 28 is inserted.
Then, the mounting plate 29 is placed and attached to the block body 3 made of resin using screws 30 and screw fasteners 31 to obtain a module 32. FIG. 10 is a cross-sectional view of the module 32 shown in FIGS. 9a-b.

In the present invention, the IC sealing body 2 and the block body 3 housing the crystal oscillator 21, capacitors 22 to 24, battery 26, etc. are spaced apart from each other, and the gap between them is sufficient to accommodate the LCD 28. This is used as a place for electrical connection through the zebra connector 27 to the IC. Since the leads (conductors) 4a exposed in this gap are mechanically reinforced by being buried at both ends by the sealing body 2 and the block body, the leads 4a will not bend even if pressed when the LCD 28 is attached. , no positional deviation occurs. Therefore, block 3 is IC
In addition to preventing the performance of the IC from deteriorating due to the block body 3 and having an effect from the molding surface, arranging the block body 3 at a distance from the sealing body 2 has the effect of arranging it at a distance from the sealing body 2. The gap can be used as a positioning and storage area for attaching the zebra connector 27, LCD 28, etc., and can also be used for mechanical reinforcement of the lead 4a, which has great effects.

11 and 12 are schematic perspective views showing a package in an electronic device according to the present invention. In the figure, numeral 33 is a sealing body made of resin for the IC, and numeral 34 is a block body made of resin for accommodating external electronic components. The one shown in FIG. 11 has two ICs mounted at predetermined locations on a block body 34 made of resin and a sealing body 3 made of the resin.
It incorporates 3. What is shown in FIG. 12 is a sealing body 3 consisting of three ICs and their resin.
3 and a block body 34 made of two resins are integrated by one lead frame.

FIG. 13 is a schematic perspective view of another device according to the present invention. In the example shown in the figure, a lead conductor 36 in a lead frame is led out from the periphery of a sealing body 35 that seals an IC with resin, and its tip is buried in a block body 37. This can be applied to an electronic device in which an electronic component such as an LCD is installed by interposing a connecting body such as a zebra connector on the lead conductor 36 between the sealing body 35 and the block body 37. Block 37
The lead conductor 4a is mechanically reinforced to prevent the lead conductor 36 from bending, and is spatially positioned with the sealing body 35 to form a housing section for external electronic components. .

As described above, the present invention can be applied to various types of electronic devices and can provide a compact and highly reliable electronic device.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a package in an electronic wristwatch according to the present invention, FIGS. 2 to 8 are plan views or back views showing the manufacturing process of the package according to the present invention, and FIGS. 9 a to b are views according to the present invention. A schematic assembly diagram showing the assembly of such an electronic wristwatch (module), FIG. 10 is a cross-sectional view of the module taken in the direction of arrows, and FIGS. 11 to 13 are schematic perspective views of other examples according to the present invention. 1... Package, 2, 33, 35... Sealing body made of IC resin, 3, 34, 37... Block body made of resin, 4... Lead frame, 4a
~4s, 36...Lead (conductor) in lead frame, 5-18...Block body 3 made of resin
Groove or through hole in 19...IC chip,
20...Thin metal wire, 21...Crystal resonator, 22...
... Temperature compensation capacitor, 23 ... Trimmer capacitor, 24 ... Chip capacitor, 25 ... Lamp, 26 ... Battery, 27 ... Zebra connector, 2
8...LCD, 29...Mounting plate, 30...Screw, 31...Screw stopper, 32...Module.

Claims (1)

[Claims] 1 (a) Mounting the integrated circuit chip on a lead frame on which electronic components and integrated circuit chips are to be mounted, and sealing the integrated circuit chip with resin by transfer molding. Therefore, the step of forming a first resin molded body and (b) using the first resin molded body as a resin outflow prevention member and in a state separated from the first resin molded body, forming the electronic component. (c) forming a second resin molded body to be housed with the above resin or a resin different from the above resin; A method for manufacturing an electronic device, comprising the steps of: placing a component; and (d) removing an unnecessary portion of the lead frame.