Active crystal oscillator and manufacturing method thereof

Abstract

The present invention discloses an active crystal oscillator and a manufacturing method thereof; belonging to the field of component technology; its technical key points are: comprising: a concave container formed on one side, and an IC carrier; the concave container comprising: a sidewall portion and a bottom portion; the sidewall portion and the bottom portion surrounding a concave storage space; a plurality of metal balls provided on the outer surface of the bottom portion, the IC carrier plate being welded and fixed to the metal balls, and a void space formed between the IC carrier plate and the sidewall portion; a low-viscosity solvent filled between the inner surface of the IC carrier plate and the outer surface of the bottom portion; a high-viscosity solvent coated on the outer surface of the low-viscosity solvent in the void space; neither the low-viscosity nor the high-viscosity solvent is coated on the outer surface of the IC carrier plate. The active crystal oscillator and its manufacturing method of the present application can effectively improve the corrosion resistance and impact resistance of the product, meeting the product requirements for high-reliability applications such as automotive applications.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic components, and more particularly to an active crystal oscillator and a manufacturing method thereof. Background Art

[0002] Crystal oscillators in electronic circuits can be divided into the following two types: quartz crystal resonators (Crystal) and active crystal oscillators (Oscillator).

[0003] For the active crystal oscillator 100, its typical structure is as follows: Figure 1 As shown, the upper structure: the chip 101 of the active crystal oscillator 100 is suspended and bonded to the substrate 102 through the conductive adhesive 103; the lower structure: a concave container 105 is formed on the lower side of the active crystal oscillator 100, and the IC carrier 104 (the active circuit exists in the form of an integrated circuit board) is arranged in the concave container 105.

[0004] The IC carrier 104 is directly exposed, which makes it susceptible to corrosion, and the product lifespan cannot meet the requirements. In addition, the adhesion between the IC carrier and the concave container is also lacking.

[0005] In response to the above problems, Figures 2 and 3 (The active crystal oscillator 100 is flipped 180°: the active crystal oscillator is inverted when the concave container 105 is filled with the solvent), the following improvements are made:

[0006] a. The circuit arranged on the bottom surface of the multilayer ceramic substrate 102 has several metal balls protruding (gold ball implantation process), and the IC carrier is soldered to the metal balls. The gap between the IC carrier and the multilayer ceramic substrate 102 is filled with an insulating solvent with good permeability.

[0007] b. The outer surface of the IC carrier is also coated with an insulating solvent with good permeability ( Figure 3 The glue on the IC carrier is black because it is the final product of the active crystal oscillator 100 after the baking process.

[0008] However, the R&D team discovered the following problems:

[0009] a. In order to allow the solvent to penetrate into the inner surface of the IC carrier, the insulating solvent must be a low-viscosity solvent with low viscosity and good permeability.

[0010] b. After coating, the active crystal oscillator 100 needs to be moved to the baking equipment for the next step of processing (baking and curing). During the baking process of low-viscosity solvents, the glue molecules will move more rapidly after being heated, which will also cause the flow, diffusion, and overflow to adhere to the test terminals of the concave container (the depth of the concave container is generally not more than 0.3mm). Figure 4 As shown, glue adheres to the test terminals in the concave container (there is a color difference on the test terminal surface). Since the solvent is an insulating solvent, this can cause errors in the test results.

[0011] c. Since the outer surface of the IC substrate is also covered by the low-viscosity solvent, the outer surface of the IC substrate (such as scratches) cannot be inspected after baking. Summary of the Invention

[0012] The object of the present invention is to provide an active crystal oscillator in view of the above-mentioned deficiencies in the prior art.

[0013] Another object of the present invention is to provide a method for manufacturing an active crystal oscillator in response to the above-mentioned deficiencies in the prior art.

[0014] The technical solutions of the present invention are as follows:

[0015] An active crystal oscillator comprises: a concave container formed on one side, and an IC carrier; the concave container comprises a sidewall portion and a bottom portion; the sidewall portion and the bottom portion surround a concave storage space; a plurality of metal balls are provided on the outer surface of the bottom portion, the IC carrier board is welded to the metal balls, and a gap is formed between the IC carrier board and the sidewall portion;

[0016] A low-viscosity solvent is filled between the inner surface of the IC carrier and the outer surface of the bottom;

[0017] A high viscosity solvent is coated on the outer surface of the low viscosity solvent in the void space;

[0018] Neither low-viscosity nor high-viscosity solvents are coated on the outer surface of the IC substrate.

[0019] A method for manufacturing an active crystal oscillator comprises inverting the active crystal oscillator so that the opening of the concave container faces upward;

[0020] Follow these steps to fill with low-viscosity solvent as well as high-viscosity solvent:

[0021] Step A, filling with a low-viscosity solvent: injecting a low-viscosity solvent into the gap formed between the IC carrier and the sidewall of the concave container, so that the low-viscosity solvent fills the gap between the IC carrier and the bottom of the concave container, and the height of the low-viscosity solvent does not exceed the outer surface of the IC carrier;

[0022] Step B, first baking and curing;

[0023] Step C, filling with high-viscosity solvent: Injecting high-viscosity solvent into the void space makes the outer surface of the low-viscosity solvent be wrapped by the high-viscosity solvent and the inner surface of the IC substrate, and the high-viscosity solvent cannot adhere to the outer surface of the IC substrate;

[0024] Step D, second baking and curing.

[0025] An active crystal oscillator produced using the aforementioned method for manufacturing an active crystal oscillator.

[0026] Furthermore, the viscosity difference between the low-viscosity solvent and the high-viscosity solvent is 40 Pa.S to 85 Pa.S. Furthermore, the low-viscosity solvent and the high-viscosity solvent are insulating solvents, the viscosity of the low-viscosity solvent at 25°C is 5 to 30 Pa.S, and the viscosity of the high-viscosity solvent at 25°C is 70 to 90 Pa.S.

[0027] Furthermore, the viscosity of the low-viscosity solvent at 25° C. is 10 Pa.S, and the viscosity of the high-viscosity solvent at 25° C. is 81 Pa.S.

[0028] Furthermore, direction-finding terminals are provided at the four corners of the side wall.

[0029] The beneficial effects of this application are:

[0030] First, the concave container of the active crystal oscillator is filled with a low-viscosity solvent, which will cover the IC carrier. This practice creates two problems: the low-viscosity solvent can easily overflow onto the direction-finding terminals under external forces (such as the heat effect during baking and curing); and the outer surface of the IC carrier is also covered with the low-viscosity solvent, making subsequent inspection inconvenient.

[0031] Second, the present application solves the two problems of "the low viscosity solvent is extremely easy to overflow onto the direction-finding terminal under external force conditions; and the outer surface of the IC carrier is also covered with a low viscosity solvent" by "filling a low viscosity solvent between the inner surface of the IC carrier and the outer surface of the bottom; coating the outer surface of the low viscosity solvent in the void space with a high viscosity solvent (that is, the outer surface of the low viscosity solvent is wrapped by the high viscosity solvent and the inner surface of the IC carrier), the viscosity of the low viscosity solvent is 5 to 25 Pa.S at 25°C, and the viscosity of the high viscosity solvent is 70 to 90 Pa.S at 25°C".

[0032] 2.1. The outer surface of the low-viscosity solvent is wrapped by the high-viscosity solvent and the inner surface of the IC carrier. By using the high-viscosity solvent to cover the low-viscosity solvent, its permeability is hindered, thereby preventing the low-viscosity solvent from climbing, thereby improving the test stability of the test terminal.

[0033] 2.2. Viscosity is the core indicator of low-viscosity solvents and high-viscosity solvents (both are insulating solvents).

[0034] The viscosity of the low-viscosity solvent filled between the inner surface of the IC carrier and the outer surface of the bottom cannot be too high, otherwise a cavity will be formed between the inner surface of the IC carrier and the outer surface of the bottom.

[0035] In order to prevent the high-viscosity solvent from overflowing onto the outer surface of the IC carrier and the test terminals, the viscosity of the high-viscosity solvent cannot be too low (which affects the lower viscosity limit of the high-viscosity solvent). In order to ensure that it has a certain fluidity, its viscosity should not be too high.

[0036] 2.3. High viscosity solvents can usually form a stronger adhesive layer after curing and drying, which has better durability.

[0037] Third, the method for filling the low-viscosity solvent and the high-viscosity solvent of the active crystal oscillator of the present application is: filling the low-viscosity solvent-curing-filling the high-viscosity solvent-curing. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The present invention will be further described in detail below with reference to the embodiments in the accompanying drawings, but this does not constitute any limitation to the present invention.

[0039] Figure 1 FIG. 1 is a cross-sectional structural diagram of an active crystal oscillator 100 in the prior art.

[0040] Figure 2 FIG. 1 is an X-ray image of the active crystal oscillator 100 after the gold implantation process and the filling of a low-viscosity solvent (curing).

[0041] Figure 3 This is an external view of the active crystal oscillator 100 after it is completely filled with a low-viscosity solvent (cured).

[0042] Figure 4 FIG. 1 is an external view of the concave container of the active crystal oscillator 100 .

[0043] Figure 5 It is a structural design diagram of the active crystal oscillator 100 of the present application.

[0044] Figure 6 This is the appearance after filling with low-viscosity solvent.

[0045] Figure 7 This is the appearance after filling with high-viscosity solvent.

[0046] The following are the descriptions of the reference numerals:

[0047] Active crystal oscillator 100, chip 101, substrate 102, conductive adhesive 103, IC carrier 104;

[0048] Concave container 105, side wall portion 106, inner surface 1041 of IC carrier, outer surface 1051 of bottom;

[0049] Low viscosity solvent 201 , high viscosity solvent 202 , void space 203 . DETAILED DESCRIPTION

[0050] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. However, the present disclosure may be embodied in many different forms and should not be construed as limited to the embodiments described herein. It is understood that these embodiments are provided to make the present disclosure more thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. In the drawings, the shapes and sizes of elements may be exaggerated for clarity, and the same drawings and reference numerals will be used throughout to represent the same or similar elements.

[0051] <1. Structural Design>

[0052] like Figure 4-5 As shown, an active crystal oscillator 100 has a concave container 105 formed on one side. The concave container 105 includes: a side wall portion 106 and a bottom portion; a concave storage space formed by the bottom portion and the side wall portion 106; a plurality of metal balls are arranged inside the concave storage space, and the IC carrier 104 is welded and fixed to the metal balls; and direction-finding terminals 107 are provided at the four corners of the side wall portion 106.

[0053] For structural design, there are several key points:

[0054] (1) For the IC carrier, the requirements for the inner and outer surfaces are different. Since the inner surface of the IC carrier is connected to the metal ball, and to ensure the integrity of the IC carrier and the concave container, the gap between the outer surface 1051 of the concave storage space and the inner surface 1041 of the IC carrier must be filled with an insulating solvent.

[0055] In order to fill the outer surfaces of the IC carrier and the recessed storage space with insulating solvent, a low-viscosity solvent 201 having low viscosity and good permeability as an insulator must be used.

[0056] (2) With the development of technology, many IC substrates (raw materials) have been provided with a silicon dioxide coating on their outer surface. Therefore, it is no longer necessary to apply an insulating solvent to the outer surface of the IC substrate. Moreover, if the outer surface of the IC substrate is coated with an insulating solvent, the insulating solvent will cover the outer surface of the IC substrate after baking, making it difficult to detect the outer surface of the IC substrate in subsequent inspections.

[0057] (3) The area of ​​the IC carrier 104 is smaller than the area of ​​the bottom, that is, a gap space 203 is formed between the IC carrier and the side wall portion; a high-viscosity solvent 202 is coated on the upper side of the low-viscosity solvent 201 in the gap space 203.

[0058] That is, the outer side of the low-viscosity solvent 201 contacts the inner surface of the IC carrier, the outer surface of the bottom of the concave container 105 , the side wall of the concave container 105 , and the high-viscosity solvent.

[0059] That is, in order to make the low viscosity solvent 201 penetrate only into the parts that need to be penetrated and prevent the low viscosity solvent 201 from penetrating into other parts, the low viscosity solvent is covered with a high viscosity solvent 202 to hinder its permeability, thereby preventing the insulating solvent from climbing and improving the test stability of the test terminal.

[0060] <2. Test Verification>

[0061] When the present application is implemented, its basic components are: the IC carrier is fixed to the metal ball. The active crystal oscillator 100 is turned upside down, that is, the concave container 105 is opened upward;

[0062] Follow these steps to produce:

[0063] Step A, injecting a low-viscosity solvent: injecting a low-viscosity solvent from the void space 203 so that the low-viscosity solvent fills the space between the IC carrier and the bottom of the concave container, and the height of the low-viscosity solvent is no higher than the outer surface of the IC carrier;

[0064] The requirements for low-viscosity solvents are: low viscosity, good permeability, and electrical insulation. Specifically, the viscosity is below 30 Pa·s (currently, the viscosity of low-viscosity solvents on the market is generally above 5 Pa·s).

[0065] This application uses NAMICS's U8443-14 model solvent as a low-viscosity solvent, and its performance parameters are shown in Table 1. The spraying pressure is 0.1 MPa ± 0.01 MPa.

[0066] Table 1 Performance parameters of low viscosity solvents

[0067]

[0068] After injecting low viscosity solvent, the product Figure 6 shown.

[0069] Step B, first baking and curing: After filling with low-viscosity solvent, bake in an oven for curing at a temperature of 130°C ± 5°C for 5 minutes;

[0070] Step C, filling with high-viscosity solvent: injecting high-viscosity solvent into the void space 203, so that the high-viscosity solvent cannot adhere to the outer surface of the IC carrier;

[0071] The requirements for high viscosity solvents are: high viscosity, poor fluidity, and electrical insulation;

[0072] This application uses NAMICS's XS8345D-47 model solvent as a high-viscosity solvent, and its performance parameters are shown in Table 2; the spraying pressure is 0.1 MPa ± 0.01 MPa.

[0073] Table 2 Performance parameters of high viscosity solvents

[0074]

[0075] After the injection of high viscosity solvent, the product Figure 7 shown.

[0076] Step D, second baking and curing: After filling, it is still necessary to use an oven to bake and cure. The baking temperature is 160℃±5℃ for 10 minutes.

[0077] The above embodiments are preferred implementation modes of the present invention and are only used to facilitate the explanation of the present invention. They are not intended to limit the present invention in any form. Any person with ordinary knowledge in the technical field can, without departing from the scope of the technical features of the present invention, make partial changes or modifications to the technical contents disclosed in the present invention and make equivalent embodiments without departing from the technical features of the present invention. Such modifications still fall within the scope of the technical features of the present invention.

Claims

1. An active crystal oscillator, characterized in that: include: A concave container and an IC carrier formed on one side; the concave container includes a side wall and a bottom; the side wall and the bottom surround a concave storage space; A plurality of metal balls are provided on the outer surface of the bottom portion, the IC carrier is fixed to the metal balls by welding, and a gap is formed between the IC carrier and the side wall portion; A low-viscosity solvent is filled between the inner surface of the IC carrier and the outer surface of the bottom; A high viscosity solvent is coated on the outer surface of the low viscosity solvent in the void space; Neither low-viscosity nor high-viscosity solvents are coated on the outer surface of the IC substrate.

2. A method for manufacturing an active crystal oscillator, characterized in that: Turn the active crystal oscillator upside down so that the opening of the concave container faces upward; Follow these steps to fill with low-viscosity solvent as well as high-viscosity solvent: Step A, filling with a low-viscosity solvent: injecting a low-viscosity solvent into the gap formed between the IC carrier and the sidewall of the concave container, so that the low-viscosity solvent fills the gap between the IC carrier and the bottom of the concave container, and the height of the low-viscosity solvent does not exceed the outer surface of the IC carrier; Step B, first baking and curing; Step C, filling with high-viscosity solvent: Injecting high-viscosity solvent into the void space makes the outer surface of the low-viscosity solvent be wrapped by the high-viscosity solvent and the inner surface of the IC substrate, and the high-viscosity solvent cannot adhere to the outer surface of the IC substrate; Step D, second baking and curing.

3. An active crystal oscillator produced using the method for manufacturing an active crystal oscillator according to claim 2.

4. An active crystal oscillator according to claim 1 or 3, characterized in that: The viscosity difference between low-viscosity solvents and high-viscosity solvents is 40 Pa.S to 85 Pa.S.

5. An active crystal oscillator according to claim 1 or 3, characterized in that: The low-viscosity and high-viscosity solvents are insulating solvents. The viscosity of the low-viscosity solvent is below 30 Pa.S at 25°C, and the viscosity of the high-viscosity solvent is 70-90 Pa.S at 25°C.

6. An active crystal oscillator according to claim 1 or 3, characterized in that: The low-viscosity solvent has a viscosity of 10 Pa.S at 25° C., and the high-viscosity solvent has a viscosity of 81 Pa.S at 25° C.

7. An active crystal oscillator according to claim 1 or 3, characterized in that: Direction-finding terminals are provided at four corners of the side wall.

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