A ceramic photoelectric coupler and a method for manufacturing the same

Abstract

The present invention relates to a ceramic photoelectric coupler and a manufacturing method thereof, comprising a multi-layer ceramic substrate and a metal cap disposed on the ceramic substrate and forming a sealed cavity with the upper surface of the ceramic substrate, wherein the upper and lower surfaces of the ceramic substrate are respectively provided with a plurality of metallized areas, wherein different metallized areas on the upper surface of the multi-layer ceramic substrate are electrically connected to different metallized areas on the corresponding lower surface, and the metallized areas on the upper surface of the multi-layer ceramic substrate are provided with light-emitting diodes and photosensitive triodes electrically connected thereto. The present invention directly uses the multi-layer ceramic substrate as a packaging base through the internal wiring and precise circuit layout of the multi-layer ceramic substrate, realizes internal light path transmission through the structural design of the packaging cavity and the provision of a reflective coating in the cap, avoids the phenomenon that cracking and delamination of the light-guiding glue affect light path transmission, improves the transmission efficiency and stability of the reflective photoelectric coupler, and reduces the difficulty of process assembly.

Description

Technical Field

[0001] The invention relates to the field of optoelectronic technology, and in particular to a ceramic optoelectronic coupler and a manufacturing method thereof. Background Art

[0002] Photocouplers are generally composed of three parts: light emission, light reception and signal amplification. The principle is that the input electrical signal drives the light emitting diode (LED) to emit light of a certain wavelength, which is received by the photodetector to generate photocurrent, and then output after further amplification, thereby completing the electrical-optical-electrical conversion and playing the role of input, output and isolation. Since the input and output of the photocoupler are isolated from each other, and the electrical signal transmission has the characteristics of unidirectionality, it has good electrical insulation and anti-interference capabilities.

[0003] Most existing photocouplers are plastic-encapsulated devices. However, high-quality military-grade photocouplers need to operate within the full military temperature range of -55°C to 125°C, and epoxy plastic encapsulation materials cannot effectively control the internal water vapor content, so long-term reliability cannot be guaranteed. In addition, as weapons and equipment develop towards miniaturization, the demand for miniaturization of photocouplers is becoming more and more urgent. The photocoupler devices in the prior art have complex structures, complex production processes, and cumbersome packaging processes. Summary of the invention

[0004] The object of the present invention is to provide a ceramic photoelectric coupler and a manufacturing method thereof, which can greatly reduce the size of the device, reduce the weight and simplify the assembly process through multi-layer wiring and high-precision assembly.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A ceramic photoelectric coupler comprises a multi-layer ceramic substrate and a metal cap which is arranged on the ceramic substrate and forms a sealed cavity with the upper surface of the ceramic substrate. The upper and lower surfaces of the ceramic substrate are respectively provided with a plurality of metallized areas. The different metallized areas on the upper surface of the multi-layer ceramic substrate are electrically connected with the corresponding different metallized areas on the lower surface. The metallized areas on the upper surface of the multi-layer ceramic substrate are provided with light-emitting diodes and phototransistors which are electrically connected with them.

[0007] As a further improvement of the above technical solution:

[0008] The upper surface of the multilayer ceramic substrate is provided with a welding metallization area matched with the metal cap port.

[0009] The metal cap port is sealed and connected to the multi-layer ceramic substrate by reflow soldering.

[0010] A reflective coating is arranged inside the metal cap cavity for reflecting the light signal emitted by the light emitting device.

[0011] The electrical connection between the upper and lower surfaces of the multilayer ceramic substrate is achieved by through holes inside the substrate.

[0012] The back electrodes of the light emitting diode and the phototransistor are electrically connected to and fixed on the metallized area on the multilayer ceramic substrate through conductive glue, and the front electrodes are electrically connected to the metallized area on the multilayer ceramic substrate through gold wire bonding.

[0013] The following steps are involved:

[0014] Electroplating a reflective coating on the surface of the metal cap cavity;

[0015] Multilayer ceramic substrate and device assembly: Use LTCC or HTCC process to make multilayer ceramic substrate, and electroplate metallization areas on the upper and lower surfaces of the multilayer ceramic substrate, then bond the components to the corresponding metallization areas of the substrate and complete the bonding;

[0016] The metal cap is fixed on the welding metallization area of ​​the multilayer ceramic substrate by reflow soldering, and the welding process is carried out in a nitrogen protection atmosphere;

[0017] After assembly, electrical performance test is carried out.

[0018] The method comprises the following steps: in the steps, the thickness of the reflective coating is 2 μm.

[0019] In the steps, the melting point of the solder during the welding process is 280°C, and the process temperature is 310-330°C.

[0020] It can be seen from the above technical scheme that the present invention directly uses the multilayer ceramic substrate as the packaging base through the internal wiring and precise circuit layout of the multilayer ceramic substrate, and changes the traditional three-dimensional structure of the light-emitting component and the photosensitive component placed in an upper and lower position into a planar placement structure attached to the substrate. The internal light path transmission is realized by the structural design of the packaging cavity and the arrangement of a reflective coating on the top of the cap. This planar placement structure does not require the light-guiding colloid to be wrapped around the circuit component, thus avoiding the phenomenon of cracking and stratification of the light-guiding colloid affecting the light path transmission, the phenomenon that the light-guiding colloid may cause corrosion on the device surface when corrosive ions exist in the light-guiding colloid, and the problem of stress pulling of the bonding gold wire by the light-guiding colloid. The volume of the ceramic optocoupler of the present invention is reduced to one-fourth of the existing optocoupler of the same type, and the sealing is ≤1×10-3pa·cm3 / s. It is safe and reliable, resistant to temperature cycles, and resistant to mechanical shock. While the device size is greatly reduced, the insulation resistance can reach 10 10 Ω, isolation voltage can reach 1000V, CTR can be adjusted linearly within a certain range, up to 200%. The transmission efficiency and stability of the reflective photocoupler are improved, and the difficulty of process assembly is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the structure of the present invention;

[0022] Figure 2 is a top view of the upper surface of the multilayer ceramic substrate of the present invention;

[0023] Figure 3 It is a top view of the lower surface of the multilayer ceramic substrate of the present invention. DETAILED DESCRIPTION

[0024] The present invention will be further described below in conjunction with the accompanying drawings:

[0025] like Figure 1-3 As shown, the ceramic optocoupler of this embodiment includes a multilayer ceramic substrate 1 and a metal cap 4 disposed on the ceramic substrate 1 and forming a sealed cavity with the upper surface of the ceramic substrate 1. A metallized area 8 for welding the metal cap 4 and a metallized area 5 for connecting components are disposed on the edge of the ceramic substrate 1. The metallized area 8 is connected to the metal cap 4 by gold-tin welding to achieve integrated sealing. A light-emitting diode 3 and a phototransistor 2 are mounted on the multilayer ceramic substrate 1. Different electrodes of the light-emitting diode 3 and the phototransistor 2 are electrically connected to a specific metallized area 5 on the upper surface of the multilayer ceramic substrate 1 respectively; the metallized area 5 on the upper surface of the multilayer ceramic substrate and the metallized area 6 on the lower surface of the substrate as a device pad are electrically connected through the internal through-holes of the substrate; the lead interconnection adopts a φ25μm gold wire.

[0026] A reflective coating 7 is provided on the top of the metal cap 4 . The thickness and material of the reflective coating 7 can be set according to actual needs. In the present embodiment, the reflective coating 7 is a gold layer with a thickness of 2 μm.

[0027] like Figure 2 As shown, this embodiment uses an AlN-HTCC wiring substrate, and all metallization on the upper and lower surfaces is electroplated gold.

[0028] The specific manufacturing steps of the ultra-small ceramic optocoupler of this embodiment are as follows:

[0029] Step 1: A gold-plated reflective layer is provided in the metal cap cavity, and the thickness of the layer is 2 μm;

[0030] Step 2: Multilayer ceramic substrate and device assembly: The multilayer ceramic substrate uses the AlN-HTCC process to achieve internal wiring and through-holes, and electroplates the upper and lower surface metallization areas. The frame-type metallization area on the upper surface provides metallization positioning for the later welding cap. Multiple block metallization areas are chip bonding and bonding areas. The four block metallization areas on the lower surface serve as device pads. The components are bonded to the substrate with conductive glue and bonding is completed.

[0031] Step 3: Use a gold-tin solder sheet to place between the upper surface welding metallization area 8 and the metal cap 4 port, and complete the sealing by gold-tin welding. The welding process is carried out in a nitrogen protection atmosphere. The melting point of the solder is 280°C and the process temperature is 310-330°C.

[0032] Step 4: Complete electrical performance testing.

[0033] The embodiments described above are merely descriptions of preferred implementation modes of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A ceramic photocoupler, characterized in that: It comprises a multi-layer ceramic substrate and a metal cap disposed on the multi-layer ceramic substrate and forming a sealed cavity with the upper surface of the ceramic substrate, wherein the upper and lower surfaces of the ceramic substrate are respectively provided with a plurality of metallized areas, and the different metallized areas on the upper surface of the multi-layer ceramic substrate are electrically connected with the corresponding different metallized areas on the lower surface, and the metallized areas on the upper surface of the multi-layer ceramic substrate are provided with light-emitting diodes and phototransistors electrically connected thereto; The upper surface of the multilayer ceramic substrate is provided with a welding metallization area adapted to the metal cap port; The metal cap port is sealed and connected to the multi-layer ceramic substrate by reflow soldering; A reflective coating is provided inside the metal cap cavity for reflecting the light signal emitted by the light emitting device; The electrical connection between the upper and lower surfaces of the multilayer ceramic substrate is achieved by through holes inside the substrate; The back electrodes of the light-emitting diode and the phototransistor are electrically connected to and fixed to the metallized area on the upper surface of the multilayer ceramic substrate through conductive glue, and the front electrodes are electrically connected to the metallized area on the upper surface of the multilayer ceramic substrate through gold wire bonding; The ceramic photoelectric coupler is manufactured by the following method: (1) A reflective coating is provided on the inner wall of the metal cap cavity; (2) Multilayer ceramic substrate and device assembly: The multilayer ceramic substrate is manufactured by LTCC or HTCC process, and metallized areas are electroplated on the upper and lower surfaces of the multilayer ceramic substrate. The components are then bonded to the corresponding metallized areas of the substrate and bonding is completed; (3) The metal cap is fixed to the welding metallization area of ​​the multilayer ceramic substrate by reflow soldering, and the welding process is carried out in a nitrogen protection atmosphere; (4) Testing after assembly is completed; In step (1), the metallized layer inside the cap is made of gold with a thickness of 2 μm; In step (3), the melting point of the solder during the welding process is 280°C, and the process temperature is 310-330°C.

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