A photocoupler packaging structure

Abstract

The present invention relates to the field of optical coupling technology, and specifically to an optical coupler packaging structure; by setting a ceramic substrate component and a conductive metal, on the one hand, the tensile strength of the conductive metal can be improved, and the possibility of wire breakage can be greatly reduced. At the same time, the high insulation withstand voltage performance of the ceramic substrate component itself can improve the withstand voltage performance of the product to a certain extent, and the ceramic substrate component can support and protect the conductive metal, so that the withstand voltage performance can be further improved by increasing the electrical gap, and the conductive metal will not shake during the welding process, so that the welding yield can be guaranteed while meeting the withstand voltage performance. In addition, by setting an optical fiber and a reflective coating, compared with the optical coupler produced by the traditional double plastic sealing structure process, the photoelectric transmission ratio is relatively higher, and the process is simpler, thereby saving processing time and labor costs; and the problem of low yield of optical couplers produced by the traditional gold wire bonding process is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of optical coupling, and in particular to an optical coupler packaging structure. Background Art

[0002] At present, the gold wire bonding process is mainly used in the production process of optical couplers. Among them, the structure and process of traditional planar secondary plastic packaging optical couplers are as follows: Figure 1 and Figure 2 As shown in the figure, the structure of the planar single plastic encapsulation stacking package optocoupler is as follows Figure 3 As shown, during the processing of these two types of optocouplers, due to the characteristics of the gold wire itself, in some specific circumstances, such as accidentally touching it during the production process, working in a high temperature environment (above 150°C) and generating stress pulling the gold wire, resulting in failure, and the chip and the two solder joints are independent on each pin foot. When subjected to external stress, it is easy to cause a single pin foot to move, causing the gold wire to break and the product to fail. Especially in the process of welding wires of planar single-stage plastic-sealed stacked package optocouplers, while meeting the withstand voltage performance, due to the excessive height between the IR chip and the lead frame base island, the problem of gold wire breaking often occurs during welding. According to statistics, its yield rate is less than 80%. Therefore, the yield rate of optocouplers made by traditional gold wire bonding process is low, resulting in a large amount of cost loss. Summary of the invention

[0003] In view of the deficiencies in the prior art, the present invention provides an optical coupler packaging structure, which solves the problem of low yield of optical couplers manufactured by traditional gold wire bonding process.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] An optical coupler packaging structure includes a plurality of optical coupler brackets, an LED for emitting light, and a phototransistor for receiving LED light and generating current, and also includes a fixing mechanism fixed on the plurality of optical coupler brackets for mounting the LED and the phototransistor;

[0006] The fixing mechanism includes a ceramic substrate assembly fixed on a plurality of optical coupling brackets, wherein the ceramic substrate assembly is provided with a plurality of conductive metals for electrically connecting the LED and the phototransistor to the corresponding optical coupling brackets respectively, an optical fiber for guiding light is provided between the LED and the phototransistor, and a protective layer for wrapping the LED, the phototransistor, the ceramic substrate assembly and the optical fiber is provided on the plurality of optical coupling brackets.

[0007] Preferably, the ceramic substrate assembly includes a first ceramic substrate fixed on a plurality of optocoupler brackets for mounting LEDs and phototransistors, a second ceramic substrate is arranged between the LEDs and the corresponding optocoupler brackets, a third ceramic substrate is arranged between the phototransistors and the corresponding optocoupler brackets, and a plurality of conductive metals are respectively arranged in the corresponding first ceramic substrate, second ceramic substrate and third ceramic substrate.

[0008] Preferably, a reflective coating is provided on the surface of the second ceramic substrate for reflecting the light of the LED into the optical fiber.

[0009] Preferably, the conductive metal is a metal filler integrally formed in the ceramic substrate assembly.

[0010] Preferably, the conductive metal is a pluggable metal wire disposed in a ceramic substrate assembly, and a mounting groove for placing the metal wire is disposed on the ceramic substrate assembly.

[0011] Preferably, a conductive adhesive for fixing the metal wire is provided in the installation groove, and an anti-falling surface for preventing the conductive adhesive from falling off is provided in the installation groove.

[0012] Preferably, a plurality of grooves are provided on the inner wall of the through hole for placing the metal wire on the ceramic substrate assembly, and the through hole is filled with a colloid for fixing the metal wire.

[0013] Preferably, the protective layer is a carbon black silicon dioxide layer.

[0014] Compared with the prior art, the present invention provides an optical coupler packaging structure, which has the following beneficial effects:

[0015] 1. By setting up the ceramic substrate assembly and the conductive metal, on the one hand, the tensile strength of the conductive metal can be improved, and the possibility of wire breakage can be greatly reduced. At the same time, the high insulation withstand voltage performance of the ceramic substrate assembly itself can improve the withstand voltage performance of the product to a certain extent. In addition, the support and protection of the conductive metal by the ceramic substrate assembly can further improve the withstand voltage performance by increasing the minimum electrical gap between several optocoupler brackets, and prevent the conductive metal from shaking during the welding process, thereby ensuring the welding yield while meeting the withstand voltage performance. In addition, the optocoupler using this technical solution has relatively fewer processing steps, thereby saving processing time and labor costs.

[0016] 2. Through the setting of optical fiber and reflective coating, the photoelectric transmission ratio is relatively higher than that of optical couplers produced by traditional processes, which can further ensure the stability of optical signal transmission, while reducing costs and simplifying the process.

[0017] 3. The installation groove, conductive adhesive and anti-slip surface can make the conductive metal more firmly fixed, increase the strength of the ceramic substrate assembly and the optocoupler bracket to be dislocated and separated under the action of external force, thereby improving the good contact between the conductive metal and the optocoupler bracket and improving the stability of electrical signal transmission.

[0018] 4. By setting grooves and colloids in the through holes of the ceramic substrate assembly, the conductive metal can be firmly attached to the through holes of the ceramic substrate assembly through the colloid, which can increase the tensile strength of the conductive metal and further reduce the probability of the conductive metal breaking. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0020] Figure 1 This is a schematic diagram of a traditional planar secondary plastic encapsulation optocoupler;

[0021] Figure 2 This is the process flow chart of the traditional planar secondary plastic encapsulation optocoupler;

[0022] Figure 3 It is a schematic diagram of a planar one-time plastic encapsulation stacking package;

[0023] Figure 4 It is a process flow chart of the optical coupler of the present invention;

[0024] Figure 5 is a schematic diagram of an optical coupler of the present invention;

[0025] Figure 6 is a cross-sectional view of the optical coupler of the present invention;

[0026] Figure 7 is a schematic diagram of a first ceramic substrate of the present invention;

[0027] Figure 8 is a schematic diagram of a second ceramic substrate of the present invention;

[0028] Fig. 9 is a cross-sectional view of the second ceramic substrate of the present invention;

[0029] Fig.10 is a schematic diagram of the installation slot in the second embodiment of the present invention;

[0030] Fig.11 This is a schematic diagram of the groove in the third embodiment of the present invention.

[0031] In the figure: 1. optocoupler bracket; 2. LED; 3. photosensitive transistor; 4. fixing mechanism; 41. ceramic substrate assembly; 411. first ceramic substrate; 412. second ceramic substrate; 413. third ceramic substrate; 42. conductive metal; 43. optical fiber; 44. protective layer; 45. reflective coating; 46. mounting groove; 47. conductive glue; 48. anti-slip surface; 49. groove; 50. colloid. DETAILED DESCRIPTION

[0032] The following will describe the implementation methods of the present application in detail with the help of accompanying drawings and examples, so that the implementation process of how the present application uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0033] Embodiment 1

[0034] Figure 4-Figure 9 One embodiment of the present invention abandons the traditional gold wire bonding process for manufacturing optocouplers and instead adopts a wire with another structure to improve the stability of the wire, making it less likely to break during processing or when the customer receives and uses it, thereby greatly improving the product yield, reducing losses caused by product defects, and reducing the number of complaints.

[0035] An optical coupler packaging structure includes a plurality of optical coupler brackets 1, an LED 2 for emitting light, and a phototransistor 3 for receiving light from the LED 2 and generating current, and also includes a fixing mechanism 4 fixed on the plurality of optical coupler brackets 1 for mounting the LED 2 and the phototransistor 3, wherein the fixing mechanism 4 is used to achieve relative fixing and signal transmission between the optical coupler brackets 1, the LED 2 and the phototransistor 3;

[0036] The fixing mechanism 4 includes a ceramic substrate assembly 41 fixed on a plurality of optical coupling brackets 1, and a plurality of conductive metals 42 are provided in the ceramic substrate assembly 41 for electrically connecting the LED 2 and the phototransistor 3 to the corresponding optical coupling brackets 1, respectively. Therefore, the conductive metal 42 is arranged on the ceramic substrate assembly 41, and the conductive metal 42 is fixed and insulated by the ceramic substrate assembly 41. The advantages thereof are mainly as follows: 1. Compared with the optical coupling made by the traditional gold wire bonding process, the conductive metal 42 is protected by the ceramic substrate assembly 41, so that the conductive metal 42 can be prevented from being broken due to being touched by external force during the processing, thereby improving the stress resistance of the optical coupling; 2. In the process of stacking the optical coupling welding wires, in order to protect To ensure its pressure resistance, when the height difference between the IR chip, the PT chip and the welding position on the optical coupling bracket 1 is too high, the gold wire will shake during welding, making it easier to be broken. At the same time, the IR chip and the PT chip are relatively fixed to the corresponding optical coupling bracket 1 through the ceramic substrate assembly 41, which can prevent the conductive metal 42 from being broken due to excessive tension after welding. 3. Since the optical coupling bracket 1 made by the traditional gold wire bonding process has poor rigidity, it is also easily affected by external force during processing and transportation, causing the installation part on the optical coupling bracket 1 to deviate in the up and down directions, so that the corresponding gold wire is subjected to excessive tension and breaks. Therefore, here, the ceramic substrate assembly 41 is used to fix several optical coupling brackets. The fixation of the frame 1 can also prevent the subsequent optocoupler bracket 1 from being offset by external force to prevent the conductive metal 42 from breaking. 4. For stacked optocouplers, there are certain requirements for the voltage resistance of the product. The safety regulations require that the DIP4 packaged optocoupler must have a high voltage resistance of 5000V / 60s. When the height of the insulating block is 420um, the PT chip, IR chip and insulating block are stacked too high, and it is easy to shake and frequently alarm when soldering the IR gold wire. It is impossible to mass produce. It can only be reduced to 350um to ensure the welding yield. However, because the electrical distance is short at this time, its high voltage resistance cannot meet the industry standard of 5000V. Therefore, the conditions for meeting the welding yield and meeting the high voltage resistance are required. The conditions of energy are contradictory, resulting in a low pass rate of the traditional gold wire bonding process in the production of stacked optocouplers. Therefore, this solution adopts a ceramic substrate assembly 41 and a conductive metal 42. Due to the protection of the ceramic substrate assembly 41, on the one hand, the insulation performance of the ceramic substrate assembly 41 itself can be used to improve the high-voltage resistance of the product. On the other hand, when increasing the minimum electrical gap between several optocoupler brackets 1 to increase the high-voltage resistance of the product, the stability of the conductive metal 42 can be ensured by the ceramic substrate assembly 41, and the conductive metal 42 will not shake or break to affect the welding yield. 4. After adopting this solution, the process steps involved are significantly reduced, which can reduce the required labor cost and reduce the processing cycle.

[0037] An optical fiber 43 for guiding light is provided between LED2 and the phototransistor 3. Since the double-plastic sealing structure process is complicated, three more processes such as molding, degumming and rib cutting are required. In the traditional planar secondary plastic sealing optocoupler, the secondary plastic sealing conventionally uses built-in TiO2 epoxy resin for light transmission, and its light transmittance is only about 20%. After encountering the second layer of glue, it will absorb part of the light. After optical simulation verification, its light collection efficiency is less than 5%, which seriously affects the product performance photoelectric transmission ratio (CTR). In the industry, it is generally adopted to enhance the luminous intensity of the IR chip or increase the titanium dioxide reflective surface, but the above solutions will cause cost increases. Therefore, this solution adopts optical fiber 43 for light guidance, which has a lower cost, and when it is necessary to increase the insulation and withstand voltage performance of the product, it is only necessary to increase the gap between several optocoupler brackets 1, and there is no need to redesign the corresponding guide. The optical structure is not used, but light is guided through the optical fiber 43, and its light loss rate is less than 5%, and the research and development cost of the complex light-guiding structure is saved. A protective layer 44 for wrapping the LED 2, the phototransistor 3, the ceramic substrate assembly 41 and the optical fiber 43 is provided on several optical coupling brackets 1 to prevent interference and fixation of external environmental factors. Therefore, the above structure can effectively improve the yield of optical coupling production and reduce cost waste. Compared with the stacked optical coupling, the welding points at both ends of the stacked optical coupling gold wire have a large span, and the welding wire is prone to shaking when bonding. When the height of the insulating block is 400um, the stacked optical coupling frequently shakes and causes the gold wire to break, and the yield is less than 10%. By adopting the structure mentioned in this scheme, the current yield is as high as 99.8% or more. Compared with the traditional planar secondary plastic-sealed optical coupling, the welding wire yield is equivalent when this structure is adopted.

[0038] In order to further illustrate the above-mentioned improvement effect, the following experimental data are provided:

[0039] 1. The comparison of pressure resistance performance before and after improvement is as follows

[0040] Serial number The optocoupler group of this scheme Traditional stacked optocouplers 1 7500V 4000V 2 8000V 4000V 3 7500V 4000V 4 7500V 4000V 5 7500V 4000V 6 8000V 4000V 7 7500V 4000V 8 7500V 4000V 9 7500V 4000V 10 7500V 4000V 11 7500V 4000V 12 7500V 4000V 13 8000V 4000V 14 7500V 4000V 15 7500V 4000V 16 7500V 4000V 17 7500V 4000V 18 7500V 4000V 19 7500V 4000V 20 8000V 4000V 21 7500V 4000V 22 7500V 4000V 23 7500V 4000V 24 7500V 4000V 25 7500V 4000V 26 7500V 4000V 27 7500V 4000V 28 8000V 4000V 29 7500V 4000V 30 7500V 4000V 31 7500V 4000V 32 8000V 4000V

[0041] Of course, the withstand voltage of 8000V has reached the extremely high standard of the industry and meets the use requirements of the product. It is the parameter currently used in the production of stacked optocouplers, but it is not the upper limit of this solution. The withstand voltage performance can still be further improved by increasing the minimum electrical gap between several optocoupler brackets 1. However, if the withstand voltage performance of the stacked optocoupler with a traditional structure is increased by increasing the height of the insulating block, it will make the gold wire more likely to break.

[0042] 2. The comparison of the tensile force that the two ends of the wire can withstand before and after the improvement is as follows

[0043]

[0044] Therefore, the optical coupler using this solution has relatively higher stability during the production process, and the conductive metal 42 is less likely to break. The optical coupler made by the traditional gold wire bonding process has a smaller tensile strength value of the gold wire and is more likely to break during production and use.

[0045] As a preferred technical solution of this embodiment, the ceramic substrate assembly 41 includes a first ceramic substrate 411 fixed on a plurality of optical coupling brackets 1 for mounting LED 2 and phototransistor 3, a second ceramic substrate 412 is provided between LED 2 and the corresponding optical coupling bracket 1, a third ceramic substrate 413 is provided between phototransistor 3 and the corresponding optical coupling bracket 1, and a plurality of conductive metals 42 are respectively arranged in the corresponding first ceramic substrate 411, second ceramic substrate 412 and third ceramic substrate 413. According to the optical coupling mechanism, LED 2 and phototransistor 3 are generally mounted through the first ceramic substrate 411. In addition, the first ceramic substrate 411, the second ceramic substrate 412 and the third ceramic substrate 413 cooperate with the conductive metal 42 to realize the function of traditional gold wire conduction, but the first ceramic substrate 411, the second ceramic substrate 412 and the third ceramic substrate 413 can achieve the purpose of increasing the upper limit of tensile force that the conductive metal 42 can withstand and improving the product withstand voltage.

[0046] As a preferred technical solution of this embodiment, a reflective coating 45 is provided on the surface of the second ceramic substrate 412 for reflecting the light of LED2 into the optical fiber 43. The reflective coating 45 is used to further ensure that the light can enter the optical fiber 43, to improve the light guiding performance of the optical fiber 43, and to further ensure the stability of the optical signal transmission.

[0047] As a preferred technical solution of this embodiment, the conductive metal 42 is a metal filler integrally formed in the ceramic substrate assembly 41 , so that it can be fired integrally when the ceramic substrate assembly 41 is fired, which is more convenient and eliminates the assembly process of the conductive metal 42 .

[0048] As a preferred technical solution of this embodiment, the protective layer 44 is a carbon black silicon dioxide layer. The protective layer 44 can achieve the overall fixation on one hand, and can also well prevent the influence of the external environment on the internal components and prevent the interference of external light on the internal components on the other hand.

[0049] Embodiment 2

[0050] The difference between the second embodiment and the first embodiment is that the conductive metal 42 is a pluggable metal wire disposed in the ceramic substrate assembly 41, and the ceramic substrate assembly 41 is provided with a mounting groove 46 for placing the metal wire. Fig.10As shown, the conductive metal 42 can be limited in the horizontal direction of front, back, left and right in this way to prevent the ceramic substrate assembly 41 and the conductive metal 42 from being relatively misaligned and loosened during the processing, resulting in poor contact between the conductive metal 42 and the optical coupling bracket 1, thereby helping to improve the stability of the product.

[0051] As a preferred technical solution of this embodiment, a conductive glue 47 for fixing the metal wire is provided in the mounting groove 46. The conductive glue 47 can also be used in embodiment 1 to fill the gap between the conductive metal 42 and the chip and the optical coupling bracket 1 to improve the conductive effect. An anti-slip surface 48 for preventing the conductive glue 47 from falling off is provided in the mounting groove 46. The anti-slip surface 48 is a kind of inclined surface or curved surface. The upper position of the anti-slip surface 48 is closer to the central axis of the mounting groove 46 than the lower position, which can prevent the solidified conductive glue 47 from falling directly from the mounting groove 46. The conductive glue 47 cooperates with the anti-slip surface 48 to ensure the conductive effect of the conductive metal 42 on the one hand, and on the other hand, the anti-slip surface 48 can also prevent the conductive metal 42 from escaping upward from the mounting groove 46, thereby further ensuring the stability of this product.

[0052] Embodiment 3

[0053] Compared with the second embodiment, the third embodiment is more optimized in that: a plurality of grooves 49 are provided on the inner wall of the through hole for placing the metal wire on the ceramic substrate assembly 41, and the through hole is filled with a colloid 50 for fixing the metal wire. Fig.11 As shown, the pluggable metal wire can be more firmly attached to the through hole of the ceramic substrate assembly 41 after the colloid 50 solidifies, and the inner wall of the through hole and the metal wire are adhered to each other through the colloid 50, which can further enhance the tensile strength of the metal wire.

[0054] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0055] 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. An optical coupler packaging structure, comprising a plurality of optical coupler brackets (1), an LED (2) for emitting light, and a phototransistor (3) for receiving light from the LED (2) and generating current, characterized in that: It also includes a fixing mechanism (4) fixed on a plurality of optical coupling brackets (1) for mounting the LED (2) and the photosensitive triode (3); The fixing mechanism (4) comprises a ceramic substrate assembly (41) fixed on a plurality of optical coupling brackets (1); a plurality of conductive metals (42) are provided in the ceramic substrate assembly (41) for electrically connecting the LED (2) and the photosensitive transistor (3) to the corresponding optical coupling brackets (1), respectively; an optical fiber (43) for guiding light is provided between the LED (2) and the photosensitive transistor (3); and a protective layer (44) for wrapping the LED (2), the photosensitive transistor (3), the ceramic substrate assembly (41) and the optical fiber (43) is provided on the plurality of optical coupling brackets (1); The ceramic substrate assembly (41) comprises a first ceramic substrate (411) fixed on a plurality of optical coupling brackets (1) for mounting an LED (2) and a photosensitive triode (3); a second ceramic substrate (412) is provided between the LED (2) and the corresponding optical coupling bracket (1); a third ceramic substrate (413) is provided between the photosensitive triode (3) and the corresponding optical coupling bracket (1); and a plurality of conductive metals (42) are respectively provided in the corresponding first ceramic substrate (411), second ceramic substrate (412) and third ceramic substrate (413).

2. The optical coupler packaging structure according to claim 1, characterized in that: A reflective coating (45) for reflecting light from the LED (2) into the optical fiber (43) is provided on the surface of the second ceramic substrate (412).

3. The optical coupler packaging structure according to claim 1, characterized in that: The conductive metal (42) is a metal filler that is integrally formed and arranged in the ceramic substrate assembly (41).

4. The optical coupler packaging structure according to claim 1, characterized in that: The conductive metal (42) is a pluggable metal wire disposed in the ceramic substrate assembly (41); the ceramic substrate assembly (41) is provided with a mounting groove (46) for accommodating the metal wire.

5. The optical coupler packaging structure according to claim 4, characterized in that: A conductive adhesive (47) for fixing the metal wire is provided in the installation groove (46), and an anti-falling surface (48) for preventing the conductive adhesive (47) from falling off is provided in the installation groove (46).

6. The optical coupler packaging structure according to claim 4, characterized in that: A plurality of grooves (49) are provided on the inner wall of a through hole on the ceramic substrate assembly (41) for placing the metal wire, and the through hole is filled with a colloid (50) for fixing the metal wire.

7. The optical coupler packaging structure according to claim 1, characterized in that: The protective layer (44) is a carbon black silicon dioxide layer.

Images