Conductive adhesive degumming agent and degumming method

Abstract

The invention discloses a conductive adhesive degumming agent which comprises the following components: a, a soaking solution; the soaking solution is composed of 40-100 wt% of a water-soluble organic solvent and 0-60 wt% of water; and b, an acidic solution. The invention further discloses a degumming method, in the first stage, the conductive adhesive on the surface of the wiring substrate makes contact with a soaking solution, and the soaking solution is a mixture of 40-100 wt% of a water-soluble organic solvent and 0-60 wt% of water; and in the second stage, the conductive adhesive on the surface of the wiring substrate is contacted with the acid solution until the conductive adhesive is stripped. According to the method, an alkaline amine compound is not used for soaking, the neutral water-soluble organic solvent is used for infiltrating the conductive adhesive, and then the acidic solvent is used for removing the conductive adhesive, so that the used time is short, the corrosion is light, and the damage to substrate metal is greatly reduced.

Description

Technical Field

[0001] The invention belongs to the field of chemical materials, and in particular relates to a conductive adhesive degumming agent and a degumming method. Background Art

[0002] Conductive adhesive is an adhesive that has certain conductive properties after curing or drying. It usually has a base resin and conductive fillers, i.e. conductive particles, as its main components. The conductive particles are combined together by the bonding effect of the base resin to form a conductive path, thus achieving conductive connection of the bonded material on the wiring substrate. Due to the irreversible reaction performance, conductive adhesive has certain difficulties in disassembly and recycling. It generally needs to be mechanically crushed or processed by high-temperature incineration. Some processes also use the solvent swelling principle for degumming.

[0003] CN107434958 discloses a conductive adhesive and a method for using the conductive adhesive as a binder and a degumming method thereof, wherein the bound target material or the encapsulated electronic component is immersed in pure water and / or a lipid solvent, and the conductive adhesive is degummed by the swelling effect of the solvent and the monomer epoxy resin having a hydrophilic and / or lipophilic group. The average degumming time of the method is 1-2 hours.

[0004] CN201010581663 discloses a conductive adhesive degumming agent and a preparation method thereof, which contains an amine compound, sodium dodecylbenzene sulfonate, a polyoxyethylene surfactant, and an organic solvent, wherein the amine compound is at least one of 2,2′-dihydroxydipropylamine, N,N-diethyl-1,3-diaminopropane, 2-(2-aminoethoxy)ethanol, tetraethylenepentamine, diisopropanolamine, and trimethylcyclohexylamine. The average degumming time of the method is 30-40 minutes.

[0005] CN201310738079 discloses a degumming agent and a method for recovering IC from electronic devices, wherein the degumming agent comprises 70-90 parts by weight of an organic amine, 5-15 parts by weight of an ether, 1-5 parts by weight of a metal ion chelating agent, 1-5 parts by weight of an alcohol, and 1-10 parts by weight of a nonionic surfactant, wherein the organic amine is ethanolamine, the ether is ethylene glycol butyl ether, the metal ion chelating agent is ethylenediaminetetraacetic acid, the alcohol is sorbitol, and the nonionic surfactant is fatty alcohol polyoxyethylene ether. The processing temperature of the method is 100°C, and the degumming time is 40 minutes on average.

[0006] The above patents all use a mixture of organic amines (such as ethanolamine, diethanolamine, triethanolamine, etc.) and organic solvents, because these are commonly used formulas for removing organic films. Such conductive adhesive debonding agents can indeed effectively remove ACF conductive adhesives, but the ingredients of the debonding agents in these patents (such as ethanolamine, diethanolamine, triethanolamine, etc.) will produce obvious corrosion to metals such as aluminum and copper, and are not suitable for use in chips or components containing circuits or electrode pads containing aluminum and copper materials in the new generation of processes.

[0007] New conductive adhesive debonding agents are urgently needed to adapt to the new generation of processes and materials. Summary of the invention

[0008] In order to solve the shortcomings of the prior art, the present invention provides a conductive adhesive degumming agent and a degumming method. Instead of using alkaline amine compounds for soaking, the conductive adhesive is soaked with a neutral water-soluble organic solvent and then removed with an acid solvent. This method takes a short time and has light corrosion, greatly reducing damage to the metal of the wiring substrate.

[0009] In order to achieve the above technical purpose, the technical solution of the present invention is a conductive adhesive debonding agent, comprising:

[0010] a soaking solution; the soaking solution consists of 40-100wt% water-soluble organic solvent and 0-60wt% water;

[0011] b. Acid solution;

[0012] Wherein, the water-soluble organic solvent is at least one of N-methylpyrrolidone, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, ether alcohol compounds or polyol compounds and mixtures thereof.

[0013] Preferably, the ether alcohol compound is at least one of diethylene glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol propyl ether, ethylene glycol butyl ether, diethylene glycol butyl ether, dipropylene glycol methyl ether, dipropylene glycol ethyl ether, dipropylene glycol propyl ether and dipropylene glycol butyl ether.

[0014] Preferably, the water-soluble organic solvent is N-methylpyrrolidone or diethylene glycol butyl ether. More preferably, the water-soluble organic solvent is diethylene glycol butyl ether.

[0015] Preferably, the acid solution is selected from sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, metaphosphoric acid, sulfonic acid and its derivatives, hydrofluoric acid, hydrobromic acid, formic acid, acetic acid, propionic acid, n-butyric acid, isobutyric acid. More preferably, the acid solution is sulfuric acid, hydrochloric acid, nitric acid or acetic acid solution. More preferably, the acid solution is hydrochloric acid or acetic acid solution.

[0016] Preferably, the pH value of the acidic aqueous solution is less than 4.

[0017] The present invention also provides a conductive adhesive debonding method, the steps of which include:

[0018] a. First stage of immersion: the conductive adhesive on the surface of the wiring substrate is exposed to an immersion solution, wherein the immersion solution is a mixture of 40-100 wt % of a water-soluble organic solvent and 0-60 wt % of water; the water-soluble organic solvent is at least one of N-methylpyrrolidone, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, ether alcohol compounds or polyol compounds and mixtures thereof;

[0019] b. Second stage of immersion: The conductive adhesive on the surface of the wiring substrate is exposed to the acid solution until the conductive adhesive is removed.

[0020] Preferably, in step a, the temperature during which the immersion solution contacts the conductive adhesive is 60°C to 90°C, and the contact time does not exceed 15 minutes. More preferably, in step a, the temperature during which the immersion solution contacts the conductive adhesive is 60°C to 70°C, and the contact time is 10 minutes.

[0021] Preferably, in step b, the temperature of the acid solution during contact with the conductive adhesive is 20° C. to 40° C. More preferably, in step b, the temperature of the acid solution during contact with the conductive adhesive is 25° C.

[0022] Preferably, the degumming method is a. first stage immersion: immerse the conductive glue on the surface of the wiring substrate in diethylene glycol butyl ether or N-methylpyrrolidone at 60-70°C for 10 minutes; b. second stage immersion: contact the conductive glue on the surface of the wiring substrate with an acid solution, wherein, if it is a hydrochloric acid solution, the temperature during the contact period is 25°C and the time is 2-3 minutes; if it is an acetic acid solution, the temperature during the contact period is 25°C and the time is 10-12 minutes.

[0023] More preferably, the degumming method is a. first stage immersion: immerse the conductive glue on the surface of the wiring substrate in diethylene glycol butyl ether at 60-70°C for 10 minutes; b. second stage immersion: contact the conductive glue on the surface of the wiring substrate with a hydrochloric acid solution at a temperature of 25°C for 2 minutes; or, contact the conductive glue on the surface of the wiring substrate with an acetic acid solution at a temperature of 25°C for 10 minutes.

[0024] Preferably, the total degumming time of the degumming method does not exceed 25 minutes.

[0025] The method of the present invention does not use alkaline amine compounds, but uses organic compounds with a pH value close to neutral (such as pyrrolidone and ether alcohol compounds) for the first stage of soaking, so that the conductive glue is soaked, and then an acidic solvent is used for removal. The soaking time of this method is relatively short, so although the formula of the present invention will also cause corrosion, because the cleaning time is short, the conductive glue can be removed and stripped off in a short time, so the copper corrosion generated is smaller.

[0026] The experimental results show that simply using an acid solution with a proper ratio can remove the ACF conductive glue on the substrate, but it will cause severe corrosion to the metal; however, if the substrate surface is first soaked in an appropriate organic solvent and then soaked in an acid solution, better cleaning performance and lower corrosion levels can be achieved.

[0027] The present invention can effectively remove the ACF conductive glue without damaging the aluminum, copper and other metals of the substrate, and has high efficiency, can strip the conductive glue in a short time, and improve the removal efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a microscope photograph of a wiring board before the conductive adhesive is removed.

[0029] Figure 2 This is a microscope photo of Example 1 after the conductive adhesive was removed.

[0030] Figure 3 This is a microscope photo of Example 6 after the conductive adhesive was removed.

[0031] Figure 4 This is a microscope photograph of Example 10 after the conductive adhesive was removed.

[0032] Figure 5 This is an electron microscope photograph of Example 10 after the conductive adhesive was removed.

[0033] Figure 6 This is a microscope photograph of Example 12 after the conductive adhesive was removed.

[0034] Figure 7 This is an electron microscope photograph of Example 12 after the conductive adhesive was removed. DETAILED DESCRIPTION

[0035] In order to better understand the present invention, the technical solutions of the present invention are further described below in conjunction with specific embodiments, but the present invention is not limited to these embodiments.

[0036] The raw materials used in the present invention are as follows:

[0037]

[0038]

[0039] In all experiments of the present invention, after the debonding time is confirmed, the copper corrosion condition is confirmed by using a microscope and a scanning electron microscope.

[0040] Comparative Examples 1-4 used conventional ethanolamine / organic compound desizing, and the results are shown in Table 1.

[0041] Table 1

[0042] Formula (ratio by weight) Glue removal time Copper corrosion Comparative Example 1 Ethanolamine: Ethylene glycol butyl ether = 1:1 60 minutes 5 Comparative Example 2 Ethanolamine: ethylene glycol butyl ether = 3:1 40 minutes 5 Comparative Example 3 Ethanolamine: diethylene glycol butyl ether = 1:1 60 minutes 5 Comparative Example 4 Ethanolamine: diethylene glycol butyl ether = 3:1 45 minutes 5

[0043] Note: Corrosion condition 0-5 (0 means no corrosion, 5 means severe corrosion)

[0044] Microscope photo before the conductive glue is removed Figure 1 As shown, the black part is the conductive glue to be removed, and the rectangular and square bumps are copper crystal pads. Figure 2 This is a microscope photo of comparative example 1 after the conductive adhesive is removed. It can be seen that there is obvious corrosion and the crystal pad falls off in the microscope photo, indicating that the corrosion condition is 5.

[0045] Comparative Examples 5-13

[0046] Compared with the traditional ethanolamine / organic compound degumming formula, the first-stage acid solution was used to test the degumming condition at room temperature (25°C), and the results are shown in Table 2. The acid solutions used are all pure acids, such as concentrated sulfuric acid and concentrated nitric acid. It can be seen that only using acidic solution has high removal efficiency and the copper corrosion rate is lower than that of the traditional formula.

[0047] Table 2

[0048] formula Glue removal time Copper corrosion Comparative Example 5 sulfuric acid 5 minutes 3 Comparative Example 6 hydrochloric acid 5 minutes 3 Comparative Example 7 Phosphoric acid 10 minutes 3 Comparative Example 8 Nitric acid 3 minutes 5 Comparative Example 9 acetic acid 15 minutes 3 Comparative Example 10 Sulfuric acid:nitric acid=1:1 4 minutes 4 Comparative Example 11 Sulfuric acid:nitric acid=3:1 5 minutes 4 Comparative Example 12 Hydrochloric acid: nitric acid = 1:1 2 minutes 5 Comparative Example 13 Hydrochloric acid: nitric acid = 3:1 5 minutes 5

[0049] Note: Corrosion condition 0-5 (0 means no corrosion, 5 means severe corrosion)

[0050] Figure 3 This is a microscope photo of comparative example 6 after the conductive adhesive was removed. There are obvious signs of corrosion in the photo, indicating that the corrosion condition is 3.

[0051] Examples 1-12

[0052] Two-stage immersion was used: the first stage was immersion with organic solvent, and the second stage was immersion with acid solution at room temperature (25°C). After the degumming was completed, the metal condition of the substrate was tested, and the results are shown in Table 3. The hydrochloric acid used was concentrated hydrochloric acid, and the acetic acid used was concentrated acetic acid. It can be seen that the removal efficiency after two-stage immersion is higher and the copper corrosion rate is lower.

[0053] Table 3

[0054]

[0055] Note: Corrosion condition 0-5 (0 means no corrosion, 5 means severe corrosion)

[0056] Figure 4 This is a microscope photo of Example 10 after the conductive adhesive was removed. The photo shows no signs of corrosion, and the corrosion condition is 0-1. This was later confirmed using an electron microscope. Figure 5 This is an electron microscope photo of Example 10 after the conductive adhesive was removed. It can be seen that there is no sign of corrosion in the microscope photo, but there is slight corrosion in the electron microscope photo. Therefore, the corrosion status confirmed by electron microscopy is 1, not 0, which means no corrosion at all. This degree of corrosion is considered acceptable to the process end by feedback from downstream users.

[0057] Figure 6 This is a microscope photo of Example 12 after the conductive adhesive was removed. Slight signs of corrosion can be seen in the photo, indicating that the corrosion condition is 2. Subsequently, an electron microscope was used to confirm that Figure 7 This is an electron microscope photo of Example 12 after the conductive adhesive is removed. Slight corrosion is visible in the electron microscope photo. The copper part is severely corroded and the upper edge begins to collapse. The corrosion condition is confirmed to be 2. This corrosion degree is considered acceptable to the subsequent process end by some downstream users.

[0058] It can be seen from the above series of comparative examples and embodiments that, compared with the traditional degumming method using ethanolamine / organic compounds, the degumming method of the present invention takes much less time and thus causes much less corrosion to copper.

[0059] Compared with degumming with acid solution only, the method of the present invention also takes less time and has less corrosion to copper. For example, comparative example 6 uses concentrated hydrochloric acid to soak for 5 minutes, and comparative example 9 uses concentrated acetic acid to soak for 15 minutes to achieve degumming, resulting in a copper corrosion degree of 3, which is unacceptable to subsequent processes. In contrast, in Examples 1-6, degumming can be achieved by first soaking in diethylene glycol butyl ether or N-methyl pyrrolidone and then soaking in concentrated hydrochloric acid for 2-3 minutes. Due to the short acid soaking time, the copper corrosion degree is only 1 or 2. The same is true when acetic acid is used.

[0060] Therefore, the time for cleaning with an acidic solution is much shorter than that of a conventional amine solution, and when cleaning is completed, the corrosion of copper is also lighter than that of an amine solution. In the present invention, the conductive adhesive on the substrate is first contacted with and soaked in an organic solvent before the acidic solution, and then the acidic solution is used for a short soaking and cleaning. The total time for the two stages does not exceed 25 minutes, which is shorter, and the corrosion of copper is also lighter, which greatly reduces the damage to the metal of the wiring substrate, so that the wiring substrate can be put into the application of subsequent processes.

[0061] The above-described embodiments are only preferred implementations of the present invention. It should be pointed out that a person skilled in the art may make several modifications and improvements without departing from the inventive concept of the present invention, and these modifications and improvements all belong to the protection scope of the present invention.

Claims

1. A conductive adhesive debonding agent, characterized in that: The conductive adhesive debonding agent comprises: a soaking solution; the soaking solution consists of 40-100wt% water-soluble organic solvent and 0-60wt% water; b. Acid solution; Wherein, the water-soluble organic solvent is at least one of N-methylpyrrolidone, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, ether alcohol compounds or polyol compounds and mixtures thereof.

2. The conductive adhesive debonding agent according to claim 1, characterized in that: The ether alcohol compound is at least one of diethylene glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol propyl ether, ethylene glycol butyl ether, diethylene glycol butyl ether, dipropylene glycol methyl ether, dipropylene glycol ethyl ether, dipropylene glycol propyl ether and dipropylene glycol butyl ether.

3. The conductive adhesive debonding agent according to claim 1, characterized in that: The water-soluble organic solvent is N-methylpyrrolidone or diethylene glycol butyl ether.

4. The conductive adhesive debonding agent according to claim 1, characterized in that: The acid solution is selected from sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, metaphosphoric acid, sulfonic acid and its derivatives, hydrofluoric acid, hydrobromic acid, formic acid, acetic acid, propionic acid, n-butyric acid, and isobutyric acid.

5. The conductive adhesive debonding agent according to claim 1, characterized in that: The acid solution is hydrochloric acid or acetic acid solution.

6. A conductive adhesive debonding method, characterized in that: The method comprises the following steps: a. The first stage of immersion: the conductive adhesive on the surface of the wiring substrate is exposed to an immersion solution, wherein the immersion solution is a mixture of 40-100wt% water-soluble organic solvent and 0-60wt% water; the water-soluble organic solvent is at least one of N-methylpyrrolidone, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, ether alcohol compounds or polyol compounds and mixtures thereof; b. Second stage of immersion: The conductive adhesive on the surface of the wiring substrate is exposed to the acid solution until the conductive adhesive is removed.

7. The conductive adhesive debonding method according to claim 6, characterized in that: In the step a, the temperature during which the immersion solution and the conductive adhesive are in contact is 60° C. to 90° C., and the contact time does not exceed 15 minutes.

8. The conductive adhesive debonding method according to claim 6, characterized in that: In the step b, the temperature of the acid solution during contact with the conductive adhesive is 20° C. to 40° C.

9. The conductive adhesive debonding method according to claim 6, characterized in that: The degumming method is a. first stage immersion: immersing the conductive glue on the surface of the wiring substrate in diethylene glycol butyl ether or N-methyl pyrrolidone at 60-70° C. for 10 minutes; b. Second stage of immersion: the conductive adhesive on the surface of the wiring substrate is exposed to an acid solution at 25°C. If it is a hydrochloric acid solution, the contact time is 2-3 minutes; If it is an acetic acid solution, the contact period is 10-12 minutes.

10. The conductive adhesive debonding method according to any one of claims 6 to 9, characterized in that: The total degumming time of the degumming method does not exceed 25 minutes.

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