Active crystal oscillator and manufacturing method thereof

Abstract

The invention discloses an active crystal oscillator and a manufacturing method thereof. Belongs to the technical field of components. The technical key points are as follows: the device comprises a concave container formed on one side and an IC carrier plate; the concave container comprises a side wall part and a bottom part; the side wall part and the bottom part are encircled to form a concave part storage space; a plurality of metal balls are arranged on the outer surface of the bottom part, the IC carrier plate and the metal balls are welded and fixed, and a gap space is formed between the IC carrier plate and the side wall part; a low-viscosity solvent is filled between the inner surface of the IC carrier plate and the outer surface of the bottom; the outer surface of the low-viscosity solvent in the void space is coated with a high-viscosity solvent; and the low-viscosity solvent and the high-viscosity solvent are not coated on the outer surface of the IC carrier plate. By adopting the active crystal oscillator and the manufacturing method thereof, the corrosion resistance and the impact resistance of the product can be effectively improved, and the requirements of products with high-reliability requirements such as vehicle-mounted purposes and the like can be met.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic components, and more specifically, 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: crystal resonators (Crystal) and active crystal oscillators (Oscillator).

[0003] For the active crystal oscillator 100, its typical structure is as Figure 1 shown. Upper structure: The wafer 101 of the active crystal oscillator 100 is adhesively bonded to the substrate 102 in a suspended manner through a conductive adhesive 103. Lower structure: A concave container 105 is formed on the lower side of the active crystal oscillator 100, and an IC carrier 104 (the active circuit exists in the form of an integrated circuit board) is disposed in the concave container 105.

[0004] The direct exposure of the IC carrier 104 makes it prone to corrosion, and the service life of the product cannot meet the requirements. At the same time, the bonding property between the IC carrier and the concave container is also lacking.

[0005] In view of the above problems, as Figures 2 to 3 (the active crystal oscillator 100 is flipped 180°: the active crystal oscillator is inverted when the concave container 105 is filled with a solvent) shown, the following improvement methods are adopted:

[0006] a. A plurality of metal balls (ball grid array process) protrude from the circuit disposed on the lower surface of the multi-layer ceramic substrate 102, and the IC carrier is welded and fixed to the metal balls. The gap between the IC carrier and the multi-layer ceramic substrate 102 is filled with an insulating solvent with better permeability.

[0007] b. An insulating solvent with better permeability is also coated on the outer surface of the IC carrier ( Figure 3 the glue on the IC carrier in the figure is black because this is the final product of the active crystal oscillator 100 after the baking process).

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

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

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

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

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

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

[0014] The technical solution of the present invention is as follows:

[0015] An active crystal oscillator includes: a concave container formed on one side, an IC carrier; the concave container includes: a side wall portion and a bottom; a concave storage space is formed by surrounding the side wall portion and the bottom; a plurality of metal balls are arranged on the outer surface of the bottom, the IC carrier is welded and fixed to the metal balls, and a gap space is formed between the IC carrier and the side wall 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 gap space;

[0018] Neither the low-viscosity solvent nor the high-viscosity solvent is coated on the outer surface of the IC carrier.

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

[0020] Fill the low-viscosity solvent and the high-viscosity solvent according to the following steps:

[0021] Step A, filling the low-viscosity solvent: Inject the low-viscosity solvent from the gap space formed between the IC carrier and the side wall portion of the concave container, so that the low-viscosity solvent fills between the IC carrier and the bottom of the concave container, and the height of the low-viscosity solvent is not higher than the outer surface of the IC carrier;

[0022] Step B, the first baking and curing;

[0023] Step C, filling with a high-viscosity solvent: injecting a high-viscosity solvent into the void space so that the outer surface of the low-viscosity solvent is wrapped by the high-viscosity solvent and the inner surface of the IC carrier, and the high-viscosity solvent cannot adhere to the outer surface of the IC carrier;

[0024] Step D, the second baking and curing.

[0025] An active crystal oscillator produced by using the manufacturing method of the aforementioned 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. Further, 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 arranged at the four corners of the side wall part.

[0029] The beneficial effects of the present application are as follows:

[0030] First, when the concave container of the active crystal oscillator is injected into the low-viscosity solvent, the IC carrier will be coated. This practice will cause two problems: the low-viscosity solvent is extremely easy to overflow onto the direction-finding terminals under the action of external forces (for example, the thermal effect during baking and curing); the outer surface of the IC carrier is also covered with the low-viscosity solvent, which is inconvenient for later detection.

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

[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 to hinder its permeability, the climbing of the low-viscosity solvent is prevented, thereby improving the test stability of the test terminals.

[0033] 2.2. This viscosity index is a core index for low-viscosity solvents and high-viscosity solvents (both are insulating solvents).

[0034] The low-viscosity solvent filled between the inner surface of the IC carrier and the outer surface of the bottom should not have too high a viscosity, otherwise voids will form between the inner surface of the IC carrier and the outer surface of the bottom.

[0035] 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 limit of the viscosity of the high-viscosity solvent). And to ensure it has a certain fluidity, its viscosity should not be too high either.

[0036] 2.3. After curing and drying, the high-viscosity solvent can usually form a more solid adhesive layer with good durability.

[0037] Third, the filling method of the low-viscosity solvent and the high-viscosity solvent for the active crystal oscillator of the present application: filling the low-viscosity solvent - curing - filling the high-viscosity solvent - curing. Description of the Drawings

[0038] The following further details the present invention with reference to the embodiments in the drawings, but does not constitute any limitation to the present invention.

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

[0040] Figure 2 is an X-ray diagram of the active crystal oscillator 100 after using the golden autumn planting process and filling the low-viscosity solvent (curing).

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

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

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

[0044] Figure 6 is an external view after filling the low-viscosity solvent.

[0045] Figure 7 is an external view after filling the high-viscosity solvent.

[0046] The description of the reference numerals is as follows:

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

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

[0049] Low-viscosity solvent 201, high-viscosity solvent 202, void space 203. Detailed implementation manners

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

[0051] <I. Structural Design>

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

[0053] For the structural design, there are the following 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 needs to be connected to the metal balls, and at the same time, in order to ensure the integrity of the IC carrier and the concave container, an insulating solvent needs to be poured into the gap between the outer surface 1051 of the concave storage space and the inner surface 1041 of the IC carrier.

[0055] And in order to fill the insulating solvent between the IC carrier and the outer surface of the concave storage space, a low-viscosity solvent 201 of an insulator with low viscosity and good permeability must be used.

[0056] (2) For the outer surface of the IC carrier, with the development of technology, many IC carriers (raw materials) have been provided with a silicon dioxide coating. Therefore, there is no need to coat an insulating solvent on the outer surface of the IC carrier anymore. Moreover, if an insulating solvent is coated on the outer surface of the IC carrier, after the baking is completed, the insulating solvent will instead cover the outer surface of the IC carrier, which is not conducive to detecting the outer surface of the IC carrier 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 is respectively in contact with: the inner surface of the IC carrier, the outer surface of the bottom of the concave container 105, the side wall portion of the concave container 105, and the high-viscosity solvent.

[0059] That is, in order to make the low-viscosity solvent 201 only penetrate into the parts that need to be penetrated and prevent the low-viscosity solvent 201 from penetrating into other parts, the permeability of the low-viscosity solvent is hindered by covering it with the high-viscosity solvent 202, thereby preventing the climbing of the insulating solvent and improving the test stability of the test terminals.

[0060] <II. Experimental Verification>

[0061] When this application is implemented, its basic component is: the IC carrier has been fixed together with the metal balls. The active crystal oscillator 100 is inverted, that is, the concave container 105 has an upward opening;

[0062] The production is carried out according to the following steps:

[0063] StepA, injecting the low-viscosity solvent: Inject the low-viscosity solvent from the gap space 203 so that the low-viscosity solvent fills between the IC carrier and the bottom of the concave container, and the height of the low-viscosity solvent is not higher than the outer surface of the IC carrier;

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

[0065] This application uses the U8443-14 model solvent of NAMICS company as the 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 the low-viscosity solvent

[0067]

[0068] The product after injecting the low-viscosity solvent is as Figure 6 shown.

[0069] StepB, the first baking and curing: After the low-viscosity solvent is filled, use an oven to bake and cure it. The baking temperature is 130°C ± 5°C and it lasts for 5 minutes;

[0070] Step C, filling with a high-viscosity solvent: Inject a high-viscosity solvent into the void space 203, and the high-viscosity solvent must not adhere to the outer surface of the IC carrier board;

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

[0072] This application uses the XS8345D-47 model solvent of NAMICS Corporation as the 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 Solvent

[0074]

[0075] The product after injecting the high-viscosity solvent is as Figure 7 shown.

[0076] Step D, secondary baking and curing: After filling, it is still necessary to use an oven for baking and curing, and the baking temperature is 160°C ± 5°C for 10 minutes.

[0077] The above-described embodiments are preferred embodiments of the present invention, which are only used to conveniently illustrate the present invention and do not impose any form of limitation on the present invention. Any person with ordinary knowledge in the relevant technical field, without departing from the technical features of the present invention, makes local changes or modifications to the equivalent embodiments using the technical content disclosed in the present invention, and without departing from the technical feature content of the present invention, still belongs to 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 comprises: a side wall and a bottom; the side wall and the bottom surround a concave storage space; A plurality of metal balls are disposed on the outer surface of the bottom, the IC carrier is fixed to the metal balls by welding, and a gap space is formed between the IC carrier and the side wall; 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 low-viscosity solvent: injecting low-viscosity solvent into the gap space formed between the IC carrier and the side wall of the concave container, so that the low-viscosity solvent is filled between the IC carrier and the bottom of the concave container, and the height of the low-viscosity solvent is not higher than 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 so that the outer surface of the low viscosity solvent is 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 as claimed in claim 2.

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

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

6. An active crystal oscillator as claimed in 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 as claimed in claim 1 or 3, characterized in that: Direction-measuring terminals are arranged at four corners of the side wall.

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