A copper surface protectant and its preparation method

Abstract

This invention relates to a method for preparing a copper surface protectant, comprising: adding pure water to a reaction vessel until the pure water accounts for 30% of the volume fraction of the reaction vessel, then sequentially adding a compound as shown in formula (I), acetic acid, a compound as shown in formula (II) or (III), a compound as shown in formula (IV), and a nano-directional dispersant, and adding pure water to the liquid level of the reaction vessel; stirring for 1 hour, allowing to stand for 1 hour, and filtering to obtain the copper surface protectant. The copper surface protectant of this invention can form a copper surface protective layer with resistance to alkali stripping and acid etching. This copper surface protective layer has the properties of resisting high temperatures (150°C, no discoloration of copper within 2 hours), no discoloration of copper after three reflow soldering cycles, oxidation resistance, and fluxing effect; furthermore, the surface tension of the copper surface protectant solution is 30 dyn / cm, which can perfectly cover micro-blind holes.

Description

Technical Field

[0001] This invention relates to the field of circuit board surface treatment technology, and in particular to a copper surface protectant and its preparation method. Background Technology

[0002] In the current circuit board industry, pattern electroplating is a commonly used process, which includes multiple steps, such as cleaning, copper electroplating, pure tin electroplating, film removal, alkaline etching, tin removal, and subsequent solder mask treatment. Among them, the pure tin layer exists as a protective layer, mainly used to protect the copper below the tin surface, and has the function of resisting alkaline film removal and alkaline etching.

[0003] However, there are some problems that need to be solved: First, alkaline etching is much less efficient than acid etching and is prone to side etching; second, pure tin layers are resistant to alkalis but not to acids; in addition, the surface tension of the pure tin plating solution is 70 dyn / cm, which cannot cover extremely small blind holes; finally, tin plating and stripping will result in metal waste.

[0004] Therefore, there is an urgent need for a copper surface protectant and its preparation method. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a copper surface protectant and its preparation method.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] The first aspect of the present invention is to provide a method for preparing a copper surface protectant, comprising:

[0008] After adding pure water to the reactor until the pure water accounts for 30% of the volume fraction of the reactor, the following are added sequentially: a compound as shown in formula (I) to 32% of the volume fraction of the material in the reactor; acetic acid to 35% of the volume fraction of the material in the reactor; a compound as shown in formula (II) or formula (III) to 37% of the volume fraction of the material in the reactor; a compound as shown in formula (IV) to 40% of the volume fraction of the material in the reactor; and a nano-directional dispersant to 41% of the volume fraction of the material in the reactor. Pure water is then added to the reactor level. After stirring for 1 hour, the mixture is allowed to stand for 1 hour and then filtered to obtain the copper surface protectant.

[0009]

[0010] Where n1∈[3,1000]; n2∈[100,3000000].

[0011] Preferably, the nano-directional dispersant comprises a compound as shown in formula (V);

[0012]

[0013] Preferably, R1 is selected from -H or -CH3.

[0014] Preferably, R is selected from -C n H 2n , n∈[1, 50].

[0015] Preferably, M1 and M2 are each independently selected from H + [NH4] + Or metal ions.

[0016] Preferably, x∈[1, 100].

[0017] Preferably, x1∈[1, 100].

[0018] Preferably, x2∈[0, 50].

[0019] Preferably, x3∈[1, 100].

[0020] A second aspect of the present invention is to provide a copper surface protectant, prepared by the method described above.

[0021] The present invention adopts the above technical solution and has the following technical effects compared with the prior art:

[0022] The copper surface protectant of the present invention can form a copper surface protective layer with anti-alkali film removal and anti-acid etching effects. The copper surface protective layer has the effects of resisting high temperature (150°C, copper does not change color within 2 hours), copper does not change color after three reflow soldering, anti-oxidation, and has a fluxing effect. In addition, the surface tension of the copper surface protectant solution is 30 dyn / cm, which can perfectly cover tiny blind holes.

[0023] Therefore, the copper surface protectant of the present invention can replace electroplating pure tin, thereby reducing costs and eliminating the need to strip pure tin, thus reducing the burden on water treatment. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the surface insulation resistance detection results in Embodiment 3 of the present invention. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0027] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the scope of the invention.

[0028] Example 1

[0029] This embodiment provides a method for preparing a copper surface protectant, the steps of which include:

[0030] After adding pure water to the reactor until the pure water accounts for 30% of the volume fraction of the reactor, the following are added sequentially: a compound as shown in formula (I) to 32% of the volume fraction of the material in the reactor; acetic acid to 35% of the volume fraction of the material in the reactor; a compound as shown in formula (II) or formula (III) to 37% of the volume fraction of the material in the reactor; a compound as shown in formula (IV) to 40% of the volume fraction of the material in the reactor; and a nano-directional dispersant to 41% of the volume fraction of the material in the reactor. Pure water is then added to the reactor level. After stirring for 1 hour, the mixture is allowed to stand for 1 hour and then filtered to obtain the copper surface protectant.

[0031]

[0032] Wherein, n1∈[3,1000]; n2∈[100,3000000]; the nano-directional dispersant comprises: a compound as shown in formula (V);

[0033]

[0034] R1 is selected from -H or -CH3; R is selected from -C n H 2n , n∈[1, 50]; M1 and M2 are independently selected from H + [NH4] + Or metal ions; x∈[1,100]; x1∈[1,100]; x2∈[0,50]; x3∈[1,100].

[0035] Example 2

[0036] This embodiment provides an application of the copper surface protectant as described in Embodiment 1, the steps of which include:

[0037] The process includes patterned copper plating, water washing, treatment with a copper surface protectant as described in Example 1, water washing, drying, film removal, rapid etching, water washing, and subsequent processes; wherein...

[0038] The copper surface protection agent treatment as described in Example 1 includes: immersing the copper surface protection agent at a concentration of 800 mL / L to 1000 mL / L at 30°C to 55°C for 2 to 8 minutes.

[0039] In a preferred embodiment, the copper surface protectant treatment as described in Example 1 includes: immersing the copper surface protectant at 40°C with 900 mL / L of the copper surface protectant for 5 minutes.

[0040] Example 3

[0041] This embodiment provides an acid corrosion resistance test on a copper surface after application as described in Embodiment 2, and the results are shown in the table below:

[0042] Acidic corrosion resistance conditions Corrosion resistance time Sodium persulfate 80g / L, sulfuric acid 5%, copper content 8g / L More than 16 hours Sodium persulfate 120g / L, sulfuric acid 10%, copper content 8g / L More than 16 hours Sulfuric acid 10%, hydrogen peroxide (25%) 10%, copper content 8g / L greater than 1 hour Sulfuric acid 20%, hydrogen peroxide (25%) 20%, copper content 8g / L greater than 20 minutes Rapid etching solution 5min-10min

[0043] This embodiment also provides a method for flux testing of the copper surface after application as described in Embodiment 2. The flux testing conditions include:

[0044] The thickness of the copper protective layer formed after treatment is 0.2 μm;

[0045] In infrared reflow soldering heating conditions, the temperature is 150℃-180℃ for 112 seconds, the maximum temperature is 252℃, and the processing time is 58 seconds for temperatures above 200℃.

[0046] In the humidity environment test, the temperature was 40℃, the humidity was 90%, and the time was 96 hours.

[0047] Under wetting equilibrium conditions, the solder composition was 96.5% Sn, 3.0% Ag, and 0.5% Cu; the solder temperature was 250℃; the immersion depth was 2mm; the immersion time was 4s; the immersion speed was 16mm / s; and the flux was lead-free and no-clean.

[0048] The results are shown in the table below:

[0049]

[0050] This embodiment also provides a method for surface insulation resistance testing of the copper surface after application as described in Embodiment 2. During the surface insulation resistance testing...

[0051] The testing standard is IPC 007813.1.5;

[0052] The detection board uses the IPC B-25 pattern.

[0053] The testing conditions included: temperature of 85℃, humidity of 85%, DC of 100V, and time of 1000h.

[0054] The results are as follows Figure 1 As shown, there is no electron migration on the surface of the detection plate.

[0055] In summary, the copper surface protectant of the present invention can form a copper surface protective layer with resistance to alkaline film removal and acid etching. This copper surface protective layer has the effects of resisting high temperature (150°C, copper does not discolor within 2 hours), not discoloring copper after three reflow solderings, anti-oxidation, and fluxing effect. In addition, the surface tension of the copper surface protectant solution is 30 dyn / cm, which can perfectly cover tiny blind holes.

[0056] Therefore, the copper surface protectant of the present invention can replace electroplating pure tin, thereby reducing costs and eliminating the need to strip pure tin, thus reducing the burden on water treatment.

[0057] The above description is merely a preferred embodiment of the present invention and does not limit the implementation and protection scope of the present invention. Those skilled in the art should realize that any equivalent substitutions and obvious changes made based on the description and illustrations of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a copper surface protectant, characterized in that, include: After adding pure water to the reactor until the pure water accounts for 30% of the volume fraction of the reactor, the following compounds are added sequentially: compound (I) to 32% of the volume fraction of the material in the reactor, acetic acid to 35% of the volume fraction of the material in the reactor, compound (II) or (III) to 37% of the volume fraction of the material in the reactor, compound (IV) to 40% of the volume fraction of the material in the reactor, and nano-directional dispersant (V) to 41% of the volume fraction of the material in the reactor. Pure water is then added to the reactor level. After stirring for 1 hour, the mixture is allowed to stand for 1 hour and then filtered to obtain the copper surface protectant. ； （I） ； (II) ； (III) ； (IV) ； （V） Where n1∈[3,1000]; n2∈[100,3000000]; R1 is selected from -H or -CH3; R is selected from -C n H 2n , n∈[1, 50]; M1 and M2 are independently selected from H + [NH4] + Or metal ions; x∈[1,100]; x1∈[1,100]; x2∈[0,50]; x3∈[1,100].

2. A copper surface protectant, characterized in that, It is prepared by the method described in claim 1.

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