Circuit board, packaging structure and manufacturing method of circuit board

Abstract

The invention discloses a circuit board. The circuit board comprises a dielectric layer, a circuit layer and a solder mask layer, the dielectric layer and / or the solder mask layer contains an infrared absorber, and the infrared absorber is selected from at least one of carbon black, antimony tin oxide, indium tin oxide and tungsten oxide. The invention further provides a packaging structure and a manufacturing method of the circuit board. The infrared absorber is added in the dielectric layer and / or the solder mask layer, so that the circuit board has an infrared light absorption function, and when the circuit board is connected with the light-emitting element, the circuit board replaces a part of the shell used for preventing infrared light from interfering with the light-emitting element, so that the packaging volume of the packaging structure is saved.

Description

Technical Field

[0001] The present application relates to the field of infrared light absorption, and particularly to a circuit board, a packaging structure, and a method for manufacturing a circuit board. Background Art

[0002] Infrared light has a relatively long wavelength and can be used in fields such as signal transmission and detection. An infrared coupler applied to optical signal transmission needs to be used in combination with an opaque housing to prevent external infrared light from interfering with the infrared coupler, resulting in a relatively large packaging volume of the infrared coupler, which is not conducive to the miniaturized design of the product. Summary of the Invention

[0003] In view of this, it is necessary to provide a circuit board and a packaging structure that are conducive to reducing the packaging volume to solve the above problems.

[0004] A circuit board, the circuit board includes a dielectric layer, a circuit layer, and a solder mask layer; the circuit layer is stacked with the dielectric layer; the solder mask layer is the outermost layer of the circuit board, and the solder mask layer covers the circuit layer and the surface of the dielectric layer exposed to the circuit layer; wherein, the dielectric layer and / or the solder mask layer contains an infrared absorber, and the infrared absorber is selected from at least one of carbon black, antimony tin oxide, indium tin oxide, and tungsten oxide.

[0005] In some embodiments of the present application, when the dielectric layer contains the infrared absorber, the mass fraction of the infrared absorber in the dielectric layer is 0.3%-5%; when the solder mask layer contains the infrared absorber, the mass fraction of the infrared absorber in the solder mask layer is 1%-5%.

[0006] In some embodiments of the present application, the dielectric layer further includes a resin, and the resin is at least one of a hydrocarbon resin and a polyphenylene ether resin.

[0007] In some embodiments of the present application, the circuit board further includes an adhesive layer, the adhesive layer bonds the adjacent circuit layer and the dielectric layer, and the adhesive layer contains at least one of antimony tin oxide, indium tin oxide, and tungsten oxide.

[0008] A packaging structure, including a circuit board and a light-emitting element, the light-emitting element is connected to the circuit board.

[0009] In some embodiments of the present application, the packaging structure further includes a housing, the housing is connected to the edge of the circuit board, the housing and the circuit board enclose a packaging space, and the light-emitting element is located in the packaging space.

[0010] In some embodiments of the present application, the light-emitting element includes at least one of an infrared emitting tube and a photosensitive diode.

[0011] A method for manufacturing a circuit board includes: forming a circuit layer on the surface of a dielectric layer; forming a solder mask layer on the surface of the circuit layer and the dielectric layer exposed to the circuit layer; wherein, the dielectric layer and / or the solder mask layer contains an infrared absorber, and the infrared absorber is selected from at least one of carbon black, antimony tin oxide, indium tin oxide, and tungsten oxide.

[0012] In some embodiments of the present application, when the dielectric layer contains the infrared absorber, the mass fraction of the infrared absorber in the dielectric layer is 0.3%-5%; when the solder mask layer contains the infrared absorber, the mass fraction of the infrared absorber in the solder mask layer is 1%-5%.

[0013] In some embodiments of the present application, before forming the circuit layer, the manufacturing method further includes forming an adhesive layer on the surface of the dielectric layer. After the step of forming the circuit layer, the adhesive layer bonds the circuit layer and the dielectric layer, and the adhesive layer contains at least one of antimony tin oxide, indium tin oxide, and tungsten oxide.

[0014] The circuit board provided by the embodiments of the present application adds an infrared absorber in the dielectric layer and / or the solder mask layer, so that the circuit board has an infrared light absorption function. When the circuit board is connected to a light-emitting element, the circuit board replaces a part of the housing used to prevent infrared light from interfering with the light-emitting element, thereby saving the packaging volume of the packaging structure. Description of the Drawings

[0015] Figure 1 It is a cross-sectional schematic diagram of the packaging structure provided by the embodiments of the present application.

[0016] Figure 2 It is a cross-sectional schematic diagram after bonding an adhesive layer on the surface of the dielectric layer provided by the embodiments of the present application.

[0017] Figure 3 It is for Figure 2 The cross-sectional schematic diagram after forming a bottom copper layer and a copper plating layer on the surface of the adhesive layer shown.

[0018] Figure 4 It is for Figure 3 The cross-sectional schematic diagram after performing circuit manufacturing on the bottom copper layer and the copper plating layer shown to form a circuit layer.

[0019] Figure 5 It is for Figure 4 The cross-sectional schematic diagram of the circuit board obtained after forming a solder mask layer on the surface of the circuit layer shown.

[0020] Figure 6 It is a test curve graph of the infrared transmittance of three different circuit boards manufactured according to the embodiments of the present application.

[0021] Description of Main Component Symbols

[0022] Encapsulation structure 100 Circuit board 10 Dielectric layer 11 Circuit layer 12 Bottom copper layer 122 Copper plating layer 124 Solder mask layer 13 Adhesive layer 14 Light-emitting element 20 Conductive paste 22 Housing 30 Specific Embodiments

[0023] In order to more clearly understand the above objects, features and advantages of the present application, the present application will be described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that, without conflict, the embodiments of the present application and the features in the embodiments can be combined with each other. Many specific details are set forth in the following description in order to fully understand the present application. The described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments, and are not intended to limit this application. The term "and / or" used herein includes all and any combinations of one or more of the related listed items.

[0025] In the embodiments of the present application, for the convenience of description rather than limiting the present application, the term "connection" used in the patent application specification and claims of the present application is not limited to physical or mechanical connection, whether direct or indirect. "Upper", "lower", "above", "below", "left", "right", etc. are only used to represent relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship also changes accordingly.

[0026] Please refer to Figure 1 , an embodiment of the present application provides a packaging structure 100, the packaging structure 100 includes a circuit board 10 and a light-emitting element 20, and the light-emitting element 20 is electrically connected to the circuit board 10 through a conductive paste 22. The light-emitting element 20 may be at least one of an infrared emitting diode and a photosensitive diode. When the light-emitting element 20 includes an infrared emitting diode and a photosensitive diode, the packaging structure 100 may be an optocoupler.

[0027] The circuit board 10 may include a dielectric layer 11, a circuit layer 12, and a solder mask layer 13. The dielectric layer 11 and the circuit layer 12 are stacked, and the solder mask layer 13 is the outermost layer of the circuit board 10. The solder mask layer 13 may cover the circuit layer 12 and the surface of the dielectric layer 11 exposed to the circuit layer 12.

[0028] The number of layers of the dielectric layer 11 and the circuit layer 12 can be one layer or multiple layers. When the number of layers of the circuit layer 12 is multiple layers, the multiple circuit layers 12 can be electrically connected to each other. The circuit board 10 can be one of a flexible circuit board, a rigid circuit board, or a rigid-flex circuit board.

[0029] The dielectric layer 11 includes a resin and an infrared absorber dispersed in the resin. The resin can be at least one of a hydrocarbon resin and a polyphenylene ether resin. Among them, the hydrocarbon resin is a high-molecular compound composed of carbon and hydrogen elements. Due to the high bond energy between carbon and hydrogen elements, the hydrocarbon resin can maintain good stability in a high-temperature environment, thereby improving the heat resistance of the dielectric layer 11; in addition, due to the high bond energy between carbon and hydrogen elements, the hydrocarbon resin has high strength and hardness, thereby improving the rigidity of the dielectric layer 11. The polyphenylene ether resin includes an unmodified polyphenylene ether resin and a modified polyphenylene ether resin. The polyphenylene ether resin has high heat resistance and excellent mechanical strength, and can also improve the heat resistance and rigidity of the dielectric layer 11.

[0030] In some embodiments, the mass fraction of the hydrocarbon resin or the modified polyphenylene ether resin in the dielectric layer 11 is 10%-65%.

[0031] The infrared absorber includes at least one of carbon black, antimony tin oxide, indium tin oxide, and tungsten oxide. Among them, the carbon black is a better infrared light absorbing material, and materials such as antimony tin oxide, indium tin oxide, and tungsten oxide can also be used to absorb infrared light. In some embodiments, the mass fraction of the infrared absorber in the dielectric layer 11 is 0.3%-5%.

[0032] The solder mask layer 13 can also contain an infrared absorber. The infrared absorber includes at least one of carbon black, antimony tin oxide, indium tin oxide, and tungsten oxide for absorbing infrared light. The mass fraction of the infrared absorber in the solder mask layer 13 is 1%-5%.

[0033] In some embodiments, the circuit board 10 may further include an adhesive layer 14. The adhesive layer 14 can be located between adjacent dielectric layers 11 and circuit layers 12 to bond the dielectric layer 11 and the circuit layer 12. The adhesive layer 14 includes a resin and a reinforcing material. The reinforcing material includes at least one of antimony tin oxide, indium tin oxide, and tungsten oxide, and antimony tin oxide, indium tin oxide, and tungsten oxide are used to absorb infrared light. Among them, since the adhesive layer 14 is usually made of a transparent or semi-transparent material, adding antimony tin oxide, indium tin oxide, or tungsten oxide has little effect on the color of the adhesive layer 14.

[0034] The encapsulation structure 100 may further include a housing 30. The housing 30 is semi-sealed and is connected to the edge of the circuit board 10. The housing 30 and the circuit board 10 enclose a closed encapsulation space, and the light-emitting element 20 is located in the encapsulation space. Since the circuit board 10 has an infrared light absorption function, the circuit board 10 and the housing 30 cooperate to reduce the interference of external infrared light on the light-emitting element 20. Therefore, the circuit board 10 can replace a part of the housing 30 in the related art, thereby reducing the encapsulation volume of the encapsulation structure 100.

[0035] Please refer to Figures 2 to 5 , an embodiment of the present application further provides a method for manufacturing a circuit board 10, which may include the following steps:

[0036] Step S1: Please refer to Figure 2 , provide a core board (not labeled in the figure), and paste an adhesive layer 14 on the surface of the core board.

[0037] The core board may be a single dielectric layer 11 or one or more circuit substrates. In this embodiment, the core board is a single dielectric layer 11, and the adhesive layer 14 is located on the opposite two surfaces of the dielectric layer 11.

[0038] The dielectric layer 11 includes a resin and an infrared absorber dispersed in the resin. The resin may be at least one of a hydrocarbon resin and a polyphenylene ether resin. The infrared absorber includes at least one of carbon black, antimony tin oxide, indium tin oxide, and tungsten oxide, and the mass fraction of the infrared absorber in the dielectric layer 11 is 0.3%-5%.

[0039] The adhesive layer 14 contains a resin and a reinforcing material. The reinforcing material contains at least one of antimony tin oxide, indium tin oxide, and tungsten oxide, and antimony tin oxide, indium tin oxide, and tungsten oxide are used to absorb infrared light.

[0040] Step S2: Please refer to Figure 3 and Figure 4 , form a circuit layer 12 on the surface of the adhesive layer 14.

[0041] In this embodiment, a bottom copper layer 122 is formed on the surface of the adhesive layer 14, and then a copper plating layer 124 is formed on the surface of the bottom copper layer 122. Circuit production is performed on the bottom copper layer 122 and the copper plating layer 124 to form the circuit layer 12. After the circuit layer 12 is manufactured, the adhesive layer 14 bonds the dielectric layer 11 and the circuit layer 12.

[0042] Step S3: Please refer to Figure 5, a solder mask layer 13 is formed on the surface of the circuit layer 12 facing away from the dielectric layer 11, and the solder mask layer 13 covers the circuit layer 12 and the adhesive layer 14 exposed to the circuit layer 12.

[0043] The solder mask layer 13 may also contain an infrared absorber, which includes at least one of carbon black, antimony tin oxide, indium tin oxide, and tungsten oxide, for absorbing infrared light. The mass fraction of the infrared absorber in the solder mask layer 13 is 1% - 5%. In some embodiments, the step of forming the adhesive layer 14 may be omitted, or the circuit layer 12 is directly formed on the surface of the dielectric layer 11, and the solder mask layer 13 may cover the circuit layer 12 and the dielectric layer 11 exposed to the circuit layer 12.

[0044] The surfaces of some parts of the circuit layer 12 are exposed to the solder mask layer 13 to serve as solder pads for subsequent electrical connection with the light-emitting element 20.

[0045] Please refer to Figure 6 , three circuit boards 10 fabricated according to the embodiments of the present application, and the infrared transmittance of the circuit boards 10 is tested. Among them, the lower the infrared transmittance, the better the absorption effect of the circuit board 10 on infrared light, and the smaller the influence of infrared light on the light-emitting element 20. The test wavelength range of light is 450nm - 1500nm, and the near-infrared wavelength range is 760nm - 1400nm. L1 represents the test curve of the circuit board 10 with an infrared absorber added only in the dielectric layer 11; L2 represents the test curve of the circuit board 10 with infrared absorbers added in both the dielectric layer 11 and the solder mask layer 13; L3 represents the test curve of the circuit board 10 with infrared absorbers added in the dielectric layer 11 and the solder mask layer 13, and a reinforcing material added in the adhesive layer 14. It can be seen from the test results that the circuit boards 10 represented by L1, L2, and L3 all have a certain degree of absorption of infrared light. Among them, the circuit board L3 has the lowest infrared transmittance, indicating the best infrared light absorption performance, because infrared light-absorbing substances are added in the dielectric layer 11, the solder mask layer 13, and the adhesive layer 14 of the circuit board L3; the infrared transmittance of the circuit board L2 is the second, and the infrared absorption performance of the circuit board L1 is weaker than that of the circuit boards L2 and L3, but it still has a certain degree of absorption of infrared light.

[0046] For the circuit board 10 provided by the embodiments of the present application, an infrared absorber is added in the dielectric layer 11 and / or the solder mask layer 13 to enable the circuit board 10 to have an infrared light absorption function. When the circuit board 10 is connected to the light-emitting element 20, the circuit board 10 replaces a part of the housing 30 used to prevent infrared light from interfering with the light-emitting element 20, thereby saving the packaging volume of the packaging structure 100.

[0047] The above embodiments are only used to illustrate the technical solutions of the present application and not to limit them. Although the present application has been described in detail with reference to the above preferred embodiments, those of ordinary skill in the art should understand that modifications or equivalent replacements can be made to the technical solutions of the present application without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A circuit board, characterized in that, The circuit board includes: a dielectric layer; a circuit layer, which is stacked with the dielectric layer; and a solder mask layer, which is the outermost layer of the circuit board, and the solder mask layer covers the circuit layer and the surface of the dielectric layer exposed to the circuit layer; wherein, the dielectric layer and / or the solder mask layer contains an infrared absorber, and the infrared absorber is selected from at least one of carbon black, antimony tin oxide, indium tin oxide, and tungsten oxide.

2. The circuit board according to claim 1, characterized in that, When the dielectric layer contains the infrared absorber, the mass fraction of the infrared absorber in the dielectric layer is 0.3%-5%; when the solder mask layer contains the infrared absorber, the mass fraction of the infrared absorber in the solder mask layer is 1%-5%.

3. The circuit board according to claim 1 or 2, characterized in that, The dielectric layer further includes a resin, and the resin is at least one of a hydrocarbon resin and a polyphenylene ether resin.

4. The circuit board according to claim 1, characterized in that, The circuit board further includes an adhesive layer, the adhesive layer bonds the adjacent circuit layer and the dielectric layer, and the adhesive layer contains at least one of antimony tin oxide, indium tin oxide, and tungsten oxide.

5. A packaging structure, characterized in that, Including: the circuit board according to any one of claims 1-4; and a light-emitting element, the light-emitting element being connected to the circuit board.

6. The encapsulation structure according to claim 5, wherein The packaging structure further includes a housing, the housing is connected to the edge of the circuit board, the housing and the circuit board enclose a packaging space, and the light-emitting element is located in the packaging space.

7. The encapsulation structure according to claim 5 or 6, characterized in that, The light-emitting element includes at least one of an infrared emitting tube and a photosensitive diode.

8. A method for manufacturing a circuit board, characterized in that, Including: forming a circuit layer on the surface of the dielectric layer; and forming a solder mask layer on the surface of the circuit layer and the dielectric layer exposed to the circuit layer; wherein, the dielectric layer and / or the solder mask layer contains an infrared absorber, and the infrared absorber is selected from at least one of carbon black, antimony tin oxide, indium tin oxide, and tungsten oxide.

9. The manufacturing method of the circuit board according to claim 8, characterized in that, When the dielectric layer contains the infrared absorber, the mass fraction of the infrared absorber in the dielectric layer is 0.3%-5%; when the solder mask layer contains the infrared absorber, the mass fraction of the infrared absorber in the solder mask layer is 1%-5%.

10. The manufacturing method of the circuit board according to claim 8, characterized in that, Before forming the circuit layer, the manufacturing method further includes forming an adhesive layer on the surface of the dielectric layer. After the step of forming the circuit layer, the adhesive layer bonds the circuit layer and the dielectric layer, and the adhesive layer contains at least one of antimony tin oxide, indium tin oxide, and tungsten oxide.

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