An optical module COC substrate

Abstract

The application provides an optical module COC substrate, comprising a substrate body, a gold plating layer region arranged on the substrate body, a first pre-plated solder region and a second pre-plated solder region arranged on the gold plating layer region, the first pre-plated solder region being arranged around the second pre-plated solder region, the first pre-plated solder region having a first solder transition layer and a first eutectic solder layer, the second pre-plated solder region having a second solder transition layer and a second eutectic solder layer, the upper surfaces of the first eutectic solder layer and the second eutectic solder layer being flush, and the thickness of the second eutectic solder layer being greater than that of the first eutectic solder layer. The application can effectively ensure the welding quality by designing the second pre-plated solder region and making the thickness of the second eutectic solder layer of the second pre-plated solder region greater than that of the first eutectic solder layer of the first pre-plated solder region.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of optical communication, and particularly relates to a COC substrate of an optical module. BACKGROUND

[0002] The main function of an optical module is to convert input electrical signals into optical signals and output, and convert received optical signals into electrical signals to complete signal transmission. The transmitting end of the optical module has a very important laser chip. The laser is usually soldered to an aluminum nitride substrate through gold-tin soldering, and then bonded to the shell of the optical module, and then connected to the PCB of the optical module through gold wire bonding. We usually call the finished product of soldering the laser to the aluminum nitride substrate as COC (Chip On Carrier). Since the laser used in optical communication is very small in size, usually less than 300um*300um, and the power consumption of the laser itself is relatively large, usually more than 0.1W, and the performance of the laser itself will deteriorate seriously at high temperature, therefore, the quality of soldering the laser to the aluminum nitride substrate directly affects the performance of the laser. If the laser is not well soldered to the aluminum nitride substrate, it will directly affect the heat dissipation of the laser, and also affect the connection reliability of the laser and the aluminum nitride substrate. Poor soldering will cause the laser to fall off during use, thereby causing reliability problems.

[0003] The surface plating layer of the COC aluminum nitride substrate is usually as shown in Figure 1 The plating layer on the COC substrate includes a gold plating layer area 2 (used for gold wire bonding) and a pre-plated gold-tin solder area 3. During the entire soldering process of the laser to the COC substrate, the suction nozzle will maintain contact with the laser chip, and the contact pressure is about 10g. After the gold-tin solder is melted, due to the very small size of the laser chip, there is a force acting on the top of the laser chip, and the gold-tin solder in liquid state under the laser chip will overflow, thereby causing the bottom of the laser chip to lack solder and resulting in soldering failure. SUMMARY

[0004] The purpose of the present application is to provide a COC substrate of an optical module, which can at least solve some defects in the prior art.

[0005] To achieve the above purpose, the present application adopts the following technical solutions:

[0006] An optical module COC substrate comprises a substrate body, a gold plating layer region is arranged on the substrate body, a first pre-plated solder region and a second pre-plated solder region are arranged on the gold plating layer region, the first pre-plated solder region is arranged around the second pre-plated solder region, the first pre-plated solder region has a first solder transition layer and a first eutectic solder layer, the second pre-plated solder region has a second solder transition layer and a second eutectic solder layer, the upper surfaces of the first eutectic solder layer and the second eutectic solder layer are flush, and the thickness of the second eutectic solder layer is greater than that of the first eutectic solder layer.

[0007] Further, the size of the second pre-plated solder region is slightly smaller than that of the element to be soldered.

[0008] Further, the substrate body is an aluminum nitride substrate.

[0009] Further, the plating layer structure of the gold plating layer region from bottom to top comprises a Ti plating layer, a Pt plating layer and an Au plating layer.

[0010] Further, the thickness of the Ti plating layer is 50-100 nm, the thickness of the Pt plating layer is 50-200 nm, and the thickness of the Au plating layer is 2000-4000 nm.

[0011] Further, the plating layer structure of the first solder transition layer from bottom to top comprises a Pt plating layer, an Au plating layer and a Pt plating layer.

[0012] Further, the second solder transition layer is a Pt plating layer.

[0013] Further, the first eutectic solder layer and the second eutectic solder layer adopt gold-tin solder.

[0014] Compared with the prior art, the present application has the following beneficial effects:

[0015] The optical module COC substrate provided by the present application can effectively ensure the quality of soldering by designing the second pre-plated solder region and making the thickness of the second eutectic solder layer of the second pre-plated solder region greater than that of the first eutectic solder layer of the first pre-plated solder region, so that even if the solder overflows due to the force acting on the element to be soldered after the eutectic solder melts, there is still enough solder at the bottom of the element to be soldered to complete the soldering.

[0016] The present application will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a schematic view of the surface of a prior art COC substrate;

[0018] Figure 2 is a schematic view of the surface of the optical module COC substrate of the present application;

[0019] Figure 3 is a sectional view of the optical module COC substrate of the present application;

[0020] Figure 4 is a schematic view of the plating layer structure of the gold plating layer region in the present application;

[0021] Figure 5 is a schematic view of the plating layer structure of the first pre-plated solder region in the present application;

[0022] Figure 6 is a schematic view of the plating layer structure of the second pre-plated solder region in the present application.

[0023] The reference signs are as follows: 1, substrate body; 2, gold plating layer region; 3, pre-plated gold-tin solder region; 4, first pre-plated solder region; 5, second pre-plated solder region; 6, first solder transition layer; 7, first eutectic solder layer; 8, second solder transition layer; 9, second eutectic solder layer. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of the present application.

[0025] In the description of the present application, it should be understood that the terms "center", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only intended to facilitate the description of the present application and simplify the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0026] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or abutting connection, or integrally connected; for those of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0027] The terms "first", "second", "third", etc. are used only for descriptive purposes and should not be construed as implying or suggesting relative importance or an indicated number of technical features. Thus, features defined with "first", "second", etc. can explicitly or implicitly include one or more of such features; in the description of the present application, the meaning of "a plurality" is two or more, unless otherwise stated.

[0028] As shown in Figure 2 and Figure 3 , the present embodiment provides a kind of optical module COC substrate, including substrate body 1, the gold plating layer area 2 is equipped on the substrate body 1, the first preset solder area 4 and the second preset solder area 5 are equipped on the gold plating layer area 2, the first preset solder area 4 is located around the second preset solder area 5, the first preset solder area 4 has first solder transition layer 6 and first eutectic solder layer 7, the second preset solder area 5 has second solder transition layer 8 and second eutectic solder layer 9, the upper surface of first eutectic solder layer 7 and second eutectic solder layer 9 is flush, and the thickness of second eutectic solder layer 9 is greater than that of first eutectic solder layer 7.In the present embodiment, by designing a second preset solder area 5 inside the first preset solder area 4, and making the thickness of the second eutectic solder layer 9 in the second preset solder area 5 greater than the thickness of the first eutectic solder layer 7 in the first preset solder area 4, when eutectic welding is welded, even if there is pressure above the component to be welded, the eutectic solder in liquid state overflows, because the thickness of the second eutectic solder layer 9 is greater than that of the first eutectic solder layer 7, part of the second eutectic solder layer 9 is in the groove area formed by the first solder transition layer 6 of the first preset solder area 4, so this part of the eutectic solder in the second preset solder area 5 does not overflow, thereby ensuring that there is enough solder at the bottom of the component to be welded to complete the welding, and further ensuring the quality of the welding.

[0029] In a detailed embodiment, the size of the second preset solder area 5 is slightly smaller than that of the component to be welded, and the thickness of the eutectic solder (i.e. the second eutectic solder layer 9) in the second preset solder area 5 is greater than that of the eutectic solder (i.e. the first eutectic solder layer 7) in the first preset solder area 4, for example, the thickness of the eutectic solder in the second preset solder area 5 can be designed to be 4um, and the thickness of the eutectic solder in the first preset solder area 4 can be designed to be 2um.In the present embodiment, the eutectic solder in the first preset solder area 4 and the second preset solder area 5 can be selected from, but not limited to, gold-tin solder; the substrate body 1 can be selected from, but not limited to, aluminum nitride substrate.

[0030] Specifically, as shown in Figure 4 , Figure 5 and Figure 6As shown, the plating layer structure of the gold plating layer region 2 is sequentially plated with a Ti layer, a Pt layer and an Au layer from bottom to top, wherein the thickness of the Ti layer is 50-100nm, the thickness of the Pt layer is 50-200nm, and the thickness of the Au layer is 2000-4000nm; the plating layer structure of the first solder transition layer 6 is sequentially plated with a Pt layer, an Au layer and a Pt layer from bottom to top; and the second solder transition layer 8 is a Pt layer.

[0031] The specific preparation process of the optical module COC substrate of the embodiment is as follows: first, sequentially plate a Ti layer, a Pt layer and an Au layer on the gold plating layer region 2 designed on the aluminum nitride substrate from bottom to top; then, plate a Pt layer in the designed first pre-plated solder region 4 and second pre-plated solder region 5; then, cover the second pre-plated solder region 5, and sequentially plate an Au layer and a Pt layer in the first pre-plated solder region 4 from bottom to top; finally, remove the covering of the second pre-plated solder region 5, plate an AuSn solder layer in the first pre-plated solder region 4 and second pre-plated solder region 5, and make the upper surfaces of the AuSn solder layers in the first pre-plated solder region 4 and second pre-plated solder region 5 flush. In the preparation process, the thickness of each plating layer is plated according to the designed thickness.

[0032] In summary, the optical module COC substrate provided by the application can effectively ensure the quality of soldering by designing the second pre-plated solder region and making the thickness of the second eutectic solder layer of the second pre-plated solder region greater than that of the first eutectic solder layer of the first pre-plated solder region, so that even if the solder overflows due to the force acting on the upper part of the component to be soldered after the eutectic solder melts, there is still enough solder at the bottom of the component to be soldered to complete the soldering.

[0033] The above examples are only illustrative of the application and do not constitute a limitation on the protection scope of the application. Any design identical or similar to the application falls within the protection scope of the application.

Claims

1. A COC substrate for optical modules, characterized in that: The system includes a substrate body, on which a gold-plated layer area is provided. The gold-plated layer area has a first pre-placed solder area and a second pre-placed solder area. The first pre-placed solder area is located around the second pre-placed solder area. The first pre-placed solder area has a first solder transition layer and a first eutectic solder layer. The second pre-placed solder area has a second solder transition layer and a second eutectic solder layer. The upper surfaces of the first eutectic solder layer and the second eutectic solder layer are flush, and the thickness of the second eutectic solder layer is greater than that of the first eutectic solder layer.

2. The optical module COC substrate as described in claim 1, characterized in that: The size of the second pre-placed solder area is slightly smaller than the size of the component to be soldered.

3. The optical module COC substrate as described in claim 1, characterized in that: The substrate body is an aluminum nitride substrate.

4. The optical module COC substrate as described in claim 1, characterized in that: The plating structure of the gold plating area, from bottom to top, consists of a Ti plating layer, a Pt plating layer, and an Au plating layer.

5. The optical module COC substrate as described in claim 4, characterized in that: The thickness of the Ti plating layer is 50-100nm, the thickness of the Pt plating layer is 50-200nm, and the thickness of the Au plating layer is 2000-4000nm.

6. The optical module COC substrate as described in claim 4, characterized in that: The plating structure of the first solder transition layer, from bottom to top, consists of a Pt plating layer, an Au plating layer, and another Pt plating layer.

7. The optical module COC substrate as described in claim 4, characterized in that: The second solder transition layer is a Pt-plated layer.

8. The optical module COC substrate as described in claim 1, characterized in that: The first eutectic solder layer and the second eutectic solder layer are made of gold-tin solder.

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