JP2002536894A - Packaged device - Google Patents

Abstract

The transducer comprises a lid component (16) and a peripheral component (17) made of plastics material fixed to the lid component (16) on one side and fixed to the substrate (13) on the other side. And a closure for the component mounted on the substrate (13), wherein the lid component (16) and the peripheral component (17) are hermetically sealed for the electrode structure (12). Serves to form the enclosure (18). The invention further includes a workpiece bearing the transducer that allows the resulting strain to be inspected by the transducer.

Description

DETAILED DESCRIPTION OF THE INVENTION

TECHNICAL FIELD The present invention relates to packaged devices, and more particularly, to packaged surface acoustic wave (hereinafter abbreviated as “SAW”) transducers.

BACKGROUND OF THE INVENTION European Patent No. 0518900 discloses, among other aspects of the invention,
Apparatus for measuring dynamic torque transmitted by a body having a rotating axis, wherein one or more SAW transducers are located on the body and a first signal input and low power induction on the signal input. A signal transmitter coupled by an inductive, capacitive or radio wave means; a second signal input and a signal coupled to the signal input by a low power inductive, capacitive or radio wave means A signal receiver common to the outputs of both transducers and a signal receiver coupled to the first signal output by low power inductive, capacitive, or radio wave means; each transducer comprising: Remotely located on or near the rotating shaft; each transducer has a pair of interdigitated (comb) electrodes mounted on one side One electrode of the pair is connected to the signal input; a first oscillator for applying an input signal at a predetermined frequency to the first signal input; and an input signal to the second signal input. And a mixer for receiving signals from the first and second oscillators, so that a change in signal output due to distortion applied to the substrate can be derived. Is described. Hereinafter, this type of SAW transducer will be referred to as "described type".

According to a first aspect of the present invention, there is provided a transducer of the described type in which a thin-film conductor electrode structure, such as aluminum, is mounted on a substrate, wherein one or more conductive tracks have electrodes. A closure for a component extending from the structure to the perimeter of the board boundary and mounted on the board is made of plastic material secured to the lid component and one side to the lid component and the other side to the board. Including the peripheral member, the peripheral member acts to separate the lid component from the substrate, the substrate, the lid component,
And the peripheral members combine to form a hermetic seal enclosure for the electrode structure, while leaving the area of each track outside the enclosure near the periphery of the substrate exposed outside the enclosure. An adapted transducer is provided.

[0004] According to a first preferred variant of the first aspect of the invention, the peripheral member is obtained from a single plastic adhesive film. As a typical example, the adhesive film is AB
LEFILM550.

[0005] According to a second preferred variant of the first aspect of the invention or a first preferred variant thereof, the area of the substrate opposite the side supporting the peripheral member is provided by means of a transducer. It is adapted to be attached to the surface of a component that is to be inspected and is subject to distortion. Typically, this area includes an adhesive layer, which allows the transducer to be attached to the surface of the component. Alternatively, this area includes a metallization layer, so that the transducer can be attached to the surface of the component.

[0006] According to a second aspect of the present invention, there is provided a workpiece for supporting a transducer according to the first aspect or any of its preferred variants, wherein the generated strain can be inspected by the transducer. Is done.

[0007] A development plan was implemented in accordance with the present invention to develop a method for packaging a SAW device in such a way as to form a hermetic seal and transmit maximum strain from the substrate into the SAW transducer. This method must be low cost and suitable for mass production.

[0008] Exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, in which a single drawing is a schematic cross-sectional view of a packaged SAW transducer.

BEST MODE FOR CARRYING OUT THE INVENTION A SAW transducer device 11 has an electrode structure 12 made of thin-film aluminum on a quartz substrate 13. The size of the substrate 13 is about 9 mm × 7 mm
X 250 m thick. An aluminum track 14 extends from the electrode structure 12 to the edge 15 of the substrate 13 to allow electrical connection of the device 11 to an external network. Also, the lid component 16 is made of quartz having a thickness of 250 m, but the outer dimension of the substrate 1 is set so that the end 14A of the aluminum track 14 is exposed.
It is slightly narrower than 3. This packaged design achieves sealing by a peripheral member 17 in the form of a 1 mm thick annular ring of material connecting the substrate 15 to the lid component 16, thereby forming a hermetically sealed chamber 18 for the substrate 12. Based on the assumption that. The lower surface R of the substrate 13 is adapted for mounting on a workpiece to be inspected by the structure 12.

Initial Steps Initially, the intention was to use a peripheral member 17 in the form of a metal joint to provide a wall between the SAW device and its quartz lid component. This approach has the advantage that the metal joints are clean (free of organic compounds), are very reliable and can form a sufficiently airtight enclosure for the electrode structure. Accordingly, the program of operations has begun to establish a process for forming the required diffusion bonded joint between the peripheral member 17 and the substrate 13 and lid component 16. It has been found that a simpler, lower cost approach to creating some functional SAW devices is to use plastic peripherals 17 instead. This involves using a peripheral member 17 consisting of a single adhesive film to form a ring frame to secure the 250 m thick quartz plate lid 16 components on each SAW device 12. . Initially, it was felt that plastic components could not provide the same degree of hermetic sealing that can be obtained from metal peripherals. However, it serves to facilitate electrical insulation and thus avoids the problem of bridging the SAW connection resulting from the use of the metal peripheral member 17. The adhesive component is physically suitable and is
Help maximize strain transfer to W device 12. Moreover, the use of the plastic peripheral member 17 is relatively simple to implement in mass production. The material and process costs are reduced and forming the plastic peripheral in the form of an adhesive sheet ring frame preform can be purchased off the shelf from adhesive film suppliers. In other applications, different plastic materials may be required.

Tests were conducted to find suitable sheet plastics for the peripheral components and to establish appropriate process conditions for the application. Although the maximum continuous service temperature is 150 ° C., the plastic components need to withstand intermittent exposure to 300 ° C. The latter feature is that the package type SAW device
Required when bonded on a steel shaft using silver tin solder that melts at 1 ° C. A proprietary adhesive known as ABLEFILM550 in the form of sheet material, which has been used in the electronics industry for about 20 years.
sive) was finally selected. The film can be used in various thicknesses, with the thinnest thickness being 0.125 mm. This provides a proper isolation distance between the SAW device and the package lid.

[0012] The adhesive material for the peripheral component was obtained in the form of a flexible translucent seed that was slightly tacky at room temperature. The preform was easily cut from the sheet using a standard metal punch or by hand using scissors and a modeling scalpel. A spare lid is used as a template to cut out a rectangle of the adhesive film of the correct shape, and a scalpel blade is used to prepare the peripheral member preform by cutting out the central part, and thus, A reproducible preform was prepared with negligible yield loss.

Activating and curing the plastic preform as a component,
It was stated that for a minimum time, simultaneous exposure to heating and compression loads was required. The conditions recommended by the manufacturer were a temperature of 150 ° C. and a pressure of 5 PSI for 0.5 hours, which were used first. Subsequent tests were based on gradually changing the parameters to achieve the required end product. The recommended conditions have been found to result in considerable flow of adhesive and the joint gap is almost completely destroyed.
Thus, to achieve complete cure, the pressure and temperature were continuously reduced and the time increased proportionally. During the course of this work, it was discovered that accurate regulation of temperature was important to control the flow of the adhesive. Using a high performance fan oven, it was possible to control the temperature within a set point range of +/- 0.1 ° C. This has been found to give adequate reproducible results.

The final set process conditions were 100 ° C., no load and maintained for at least 30 minutes. This process time is dependent on certain conditions, ie 30 minutes at 100 ° C., when further heating is continued at the same temperature (up to 16 hours) or when the temperature is increased to 150 ° C. in the last 30 minutes. It is necessary that no flow occurs. Prolonged heat treatment or short treatment at higher temperatures is required to fully cure the adhesive. The decision as to which approach to use and whether to perform the dual temperature process in a programmable temperature oven or in two separate ovens requires additional cost considerations. Technically, they are equally feasible.

In accordance with Military Standard 883E, Method A1, a sample device encapsulated in the proposed manner was tested for air tightness. In summary, this test involves placing the package in a chamber, evacuating to 5 mb, pressurizing to 60 psi with helium for 2 hours, and then measuring the rate of helium leakage at atmospheric pressure. Military specifications for hermetically sealed packages are such that the rate of helium leakage does not exceed 5 × 10 ⁻⁸ atm / cc / sec. The package volume was estimated to be 0.5 mm ³ .

After the leak test, the packaged SAW devices were tested for post-package functionality. The packaging process did not appear to have affected the electrical performance of the SAW device.

Industrial Applicability Experimental results show that the proposed method used to package SAW devices containing plastic adhesive preforms does not adversely affect the electrical performance of the components. It has been shown that a hermetic seal takes place. This process is
Includes the use of commercially available sheet and film adhesives and a simple heating process. Particular care was needed in controlling the process temperature so that satisfactory sealing was achieved without excessive flow of adhesive onto the SAW device.

Moreover, this experimental program shows that a highly marketable product can be realized by using a package having an upper part (corresponding to a substrate) made of quartz and a peripheral member made of a plastic preform. Was done. The selection of an appropriate assembly process also takes into account the intended use of the resulting transducer and the final operating position. The transducer packaging material and manufacturing process could provide one or more desired functions, such as the ability to maintain temperature or pressure conditions, electromagnetic shielding, chemical resistance, shock resistance, and vibration resistance. . This packaging, in addition to the electrode structure, allows the transducer to provide additional information or to extend or optimize the operation of the basic electrode structure,
Other components could be encapsulated.

In use, the packaged component is attached (eg, using an adhesive) via the backside R of the substrate 13 to the surface of the component susceptible to distortion that is tested by the transducer. it is conceivable that. In this manner, a non-contact process can be used to communicate information representative of the torque, strain, or pressure experienced by the component to the transducer and recover information therefrom. The transducer is small and lightweight, and thus, in addition to the contactless communication path provided by the present invention,
There is little noticeable effect on the component on which the transducer is mounted. In this packaged form, the invention of the proposed transducer provides a basis for measuring almost any amount of torque, strain, and pressure on any size component that rotates at almost any speed.

By metallizing the back surface R of the device, it is possible to better disperse the distortion. Adhesive mounting, on the other hand, suffers from creep in long-term use (such as may occur in automotive use).

──────────────────────────────────────────────────続 き Continuation of front page (81) Designated country EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE ), AU, BR, CA, CN, IN, JP, KR, US (72) Inventors Perry, James Anthony Harold OH, UK 63 HH Oxfordshire Vicestar Upper Hayford Hayford Park Charwell Innovation Center (No Address) Building 77 F-Term (Reference) 5J097 AA25 AA33 AA34 HA04 HA05 HA09

Claims (7)

[Claims] 1. A transducer of the described type in which an electrode structure of a thin-film conductor such as aluminum is mounted on a substrate, wherein one or more conductive tracks (14) are provided at the interface of the electrode structure (12) to the substrate (13). Extends to the periphery (15) of the
A closure for the component (12) mounted on the substrate (13) is secured to the lid component (16), and one side is secured to the lid component (16), and the other side is secured to the substrate (13). A peripheral member (17) made of plastic material, which acts to separate the lid component (16) from the substrate (13);
The combination of the substrate (13), the lid component (16), and the peripheral member (17) combines each track (14) outside the closure near the periphery (15) of the substrate (13).
A) forming a hermetic seal enclosure (18) for the electrode structure (12) while leaving the area (14A) exposed outside the enclosure. 2. Transducer according to claim 1, wherein the peripheral member (17) is obtained from a single plastic adhesive film. 3. The transducer according to claim 2, wherein the adhesive film is ABLEFILM550. 4. A region (R) opposite to a side supporting the peripheral member (17) of the substrate.
4. The transducer according to claim 1, wherein the first component is mounted on a surface of a component to be strained, which is to be inspected with the transducer. . 5. Region (R) comprises an adhesive layer, whereby the transducer (R)
5. The transducer according to claim 4, wherein 11) can be mounted on a surface of the component. 6. The region (R) comprising a metallization layer, so that the transducer (11) can be mounted on the surface of the component.
A transducer according to claim 1. 7. A workpiece for supporting a transducer (11) according to any of the preceding claims, wherein the generated strain can be checked by the transducer (11).