Detection method for determining air tightness of miniaturized packaging of surface acoustic wave filter

Abstract

The invention belongs to the technical field of miniaturized packaging processes, and particularly relates to a detection method for judging the air tightness of miniaturized packaging of a surface acoustic wave filter, which comprises the following steps of: loading a device to be detected into a container filled with a micro-corrosive liquid, and completely immersing the device to be detected into the micro-corrosive liquid; placing the container into the sealing cavity, and introducing compressed air into the sealing cavity, namely performing pressurized soaking treatment on the to-be-detected device; after soaking is completed, the to-be-detected device is taken out, cleaned and dried; and testing the electrical performance of the to-be-detected device, and removing the device with the electrical performance not meeting the requirement. According to the invention, manual detection is not needed for micro-corrosive liquid leakage detection, devices with poor sealing performance and deteriorated electrical performance are rejected through equipment electrical performance test, and the detection efficiency and reliability of air tightness detection of miniaturized packaging devices can be significantly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of miniaturized packaging technology, and specifically relates to a detection method for determining the air tightness of a miniaturized package of a surface acoustic wave filter. Background Art

[0002] Hermetic packaging plays an important role in protecting SAW filter chips from external environmental corrosion, thereby improving their reliability and stability. In the fields of communications, navigation, and special equipment, SAW filter chips need to have higher durability and corrosion resistance due to the particularity of the working environment. Therefore, the airtightness detection technology of miniaturized packaging is crucial. Through the airtightness detection method, it can be determined whether the sealing performance of the SAW filter meets the standard requirements, and the weak links in product design and process can be discovered and solved in time.

[0003] Conventional methods for testing the air tightness of SAW filter packages include coarse leak detection with fluorine oil and fine leak detection with helium mass spectrometry. The bubble method, weighing method and dyeing method are often used for coarse leak detection, among which the fluorocarbon bubble method is an effective method that can be combined with ordinary helium mass spectrometry leak detection. Fluorine oil is a medium with excellent dielectric properties, chemical inertness, electrical insulation and high and low temperature resistance. It will not corrode the SAW filter chip, nor will it affect its performance parameters. Coarse leak detection mainly includes two steps: pressing low-boiling point fluorine oil and heating high-boiling point fluorine oil for bubble leak detection. The principle is mainly to apply pressure to the low-boiling point fluorine oil to make it enter the interior of the device, and then place it in high-boiling point fluorine oil for heating. The low-boiling point fluorine oil is quickly vaporized, and the pressure in the internal cavity of the device rises sharply, so that the gas coming out of the leak hole will form bubbles in the high boiling point. This phenomenon can be used as an obvious indicator of the existence of a leak.

[0004] The principle of helium mass spectrometry leak detection is to use the principle that ions with different mass-to-charge ratios (m / e) move in different radii due to different Lorentz forces in a magnetic field. Ions with different mass-to-charge ratios are separated and tracer gas is collected at the corresponding radius. If the inspected part leaks, tracer gas ions will be detected, and the leak rate will be calculated accordingly. Helium has a low content in the air and is an inert gas, making it the most commonly used tracer gas.

[0005] The above two general leak detection methods are not suitable for small cavities (cavity size less than 1mm 3 ), it is impossible to quickly and effectively detect leaking devices, especially for a large number (more than tens of thousands of devices) of miniaturized SAW devices, the leak detection efficiency is extremely low and the missed detection rate is extremely high. Summary of the invention

[0006] In order to solve the problems of low efficiency of package airtightness detection in the prior art and easy omission of airtightness detection of large quantities of devices, the present invention proposes a detection method for determining airtightness of miniaturized package of surface acoustic wave filter, which specifically includes the following steps:

[0007] Place the device to be inspected into a container filled with micro-corrosive liquid, and make sure that the device to be inspected is completely immersed in the micro-corrosive liquid;

[0008] Place the container in the sealed cavity and introduce compressed air into the sealed cavity, that is, perform pressurized immersion treatment on the device to be inspected;

[0009] After soaking, take out the device to be inspected, clean it and dry it;

[0010] Conduct electrical performance tests on the devices to be inspected, and eliminate devices that do not meet the electrical performance requirements.

[0011] Preferably, the pressure condition for performing the pressurized immersion treatment on the device to be inspected is 0.6 MPa.

[0012] Preferably, when the device to be inspected is subjected to a pressurized immersion treatment, the pressurized immersion time is 1 hour.

[0013] Preferably, after soaking, the cleaning time is greater than 10 minutes.

[0014] Preferably, the micro-corrosive liquid is a liquid that is corrosive to the metal functional structure film layer of the SAW filter chip.

[0015] Compared with the coarse leak detection by fluorine oil, the micro-corrosive liquid leak detection method of the present invention does not need to observe the continuous bubble phenomenon generated by the leaking device with the naked eye, thus avoiding the error caused by manual observation; compared with the fine leak detection by helium mass spectrometry, the micro-corrosive liquid leak detection method of the present invention is more convenient and quicker, suitable for the air tightness detection of large-scale device packaging, and more suitable for miniaturized devices with microcavities inside, and can avoid the missed detection of miniaturized devices due to the small volume of the inner cavity and the small amount of helium in the cavity during the fine leak detection process. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The present invention is a flow chart of a method for determining the air tightness of a miniaturized package of a surface acoustic wave filter. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] The present invention proposes a method for determining the airtightness of a miniaturized package of a surface acoustic wave filter. Figure 1 , specifically including the following steps:

[0019] Place the device to be inspected into a container filled with micro-corrosive liquid, and make sure that the device to be inspected is completely immersed in the micro-corrosive liquid;

[0020] Place the container in the sealed cavity and introduce compressed air into the sealed cavity, that is, perform pressurized immersion treatment on the device to be inspected;

[0021] After soaking, take out the device to be inspected, clean it and dry it;

[0022] Conduct electrical performance tests on the devices to be inspected, and eliminate devices that do not meet the electrical performance requirements.

[0023] The present embodiment provides a method for detecting the air tightness of the miniaturized package of the surface acoustic filter using a high-pressure micro-corrosive liquid, so as to solve the problems of low efficiency of package air tightness detection and easy omission of air tightness detection in large quantities of devices in the prior art. The high-pressure micro-corrosive liquid used in the present embodiment is to place the packaged surface acoustic filter device in the micro-corrosive liquid for pressurized immersion (pressurized immersion conditions: 0.6MPa, 1h), and after immersion, cleaning and drying, the electrical performance of the device is tested, and then qualified devices with good package air tightness are screened out. The basic principle of this method is that the micro-corrosive liquid is corrosive to the metal functional structure film layer of the surface acoustic filter chip. After the micro-corrosive liquid enters the device with poor sealing, the device performance deteriorates, thereby eliminating the device with poor sealing in the electrical performance test link. In the present embodiment, the detection method for determining the air tightness of the miniaturized package of the surface acoustic filter of the present invention specifically includes the following steps:

[0024] Step 1) placing the device to be tested into a container;

[0025] Step 2) Pour the micro-etching solution into the container, immerse all devices in the micro-etching solution, and ensure that no device floats on the surface of the solution;

[0026] Step 3) placing the container inside a sealed chamber, introducing compressed air, and pressurizing and immersing the device;

[0027] Step 4) After the pressure immersion is completed, the device is taken out from the solution and then cleaned and dried;

[0028] Step 5) After drying, the device is subjected to an electrical performance test. During the process of immersing the device in a pressurized micro-corrosive solution, the micro-corrosive solution leaks into the device and reacts with the chip, causing performance deterioration. Thus, the device with poor sealing is eliminated during the electrical performance test.

[0029] The basic principle of the micro-corrosive liquid leak detection in the present invention is that the hydroxide in the micro-corrosive liquid chemically reacts with the metal aluminum film layer on the surface of the SAW filter chip, causing the device performance to deteriorate.

[0030] The device of the present invention is immersed in the micro-corrosive solution under a pressure of 0.6 MPa for 1 hour, and the cleaning time after immersion is greater than 10 minutes to fully remove the ion residues of the micro-corrosive solution on the device surface.

[0031] The micro-etching solution used in the embodiment of the present invention is tetramethylammonium hydroxide (TMAH) with a concentration of 2.38%.

[0032] In the description of the present invention, it is necessary to understand that the terms "coaxial", "bottom", "one end", "top", "middle", "the other end", "upper", "one side", "top", "inside", "outside", "front", "center", "both ends" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0033] In the present invention, unless otherwise clearly stipulated and limited, the terms such as "installation", "setting", "connection", "fixation" and "rotation" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. Unless otherwise clearly defined, ordinary technicians in this field can understand the specific meanings of the above terms in the present invention according to the specific circumstances.

[0034] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for determining the air tightness of a miniaturized package of a surface acoustic wave filter, characterized in that: The specific steps include: Place the device to be inspected into a container filled with micro-corrosive liquid, and make sure that the device to be inspected is completely immersed in the micro-corrosive liquid; Place the container in the sealed cavity and introduce compressed air into the sealed cavity, that is, perform pressurized immersion treatment on the device to be inspected; After soaking, take out the device to be inspected, clean it and dry it; Conduct electrical performance tests on the devices to be inspected, and eliminate devices that do not meet the electrical performance requirements.

2. A method for determining the air tightness of a miniaturized SAW filter package according to claim 1, characterized in that: The pressure condition for the pressurized immersion treatment of the device to be inspected is 0.6 MPa.

3. A method for determining the air tightness of a miniaturized SAW filter package according to claim 1, characterized in that: When the device to be inspected is subjected to a pressure immersion treatment, the pressure immersion time is 1 hour.

4. A method for determining the air tightness of a miniaturized SAW filter package according to claim 1, characterized in that: After soaking, the cleaning time is greater than 10 minutes.

5. The method for determining the air tightness of a miniaturized package of a surface acoustic wave filter according to claim 1, characterized in that: The micro-corrosive liquid is a liquid that is corrosive to the metal functional structure film layer of the SAW filter chip.

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