Based on the activation process before circuit board hole metallization

Abstract

The present disclosure provides an activation process before metallization of a circuit board hole, comprising the following steps: obtaining a circuit board after pretreatment, wherein a first rough scouring area is formed on the surface of the first copper foil layer of the circuit board, and a second rough scouring area is formed on the surface of the second copper foil layer of the circuit board. Placing the circuit board in a prepreg cylinder for prepreg treatment. Performing a first drop treatment on the circuit board after the prepreg treatment directly above the prepreg cylinder. Placing the circuit board after the first drop treatment in an activation cylinder for activation treatment. Performing a second drop treatment on the circuit board after the activation treatment directly above the activation cylinder. Using the prepreg liquid in the prepreg cylinder, the first rough scouring area and the second rough scouring area of ​​the circuit board after the second drop treatment are scoured directly above the prepreg cylinder, and the scouring liquid is returned to the prepreg cylinder. Placing the scouring-treated circuit board in the prepreg cylinder for re-soaking treatment. Performing a third drop treatment on the circuit board after the re-soaking treatment directly above the prepreg cylinder.

Description

Technical Field

[0001] The present disclosure relates to the field of circuit board production, and in particular to an activation process before metallization of circuit board holes. Background Art

[0002] The copper deposition process of the circuit board is also called hole metallization (PTH), which connects the wires between the layers of the double-sided or multi-layer circuit board. It uses the chemical deposition method to deposit a thin layer of chemical copper on the hole wall after drilling to provide conductivity for the subsequent electroplating copper. Copper deposition is divided into vertical line copper deposition and horizontal line copper deposition due to different production lines. The method in this article is applied to vertical copper deposition. The vertical copper deposition process is as follows: bulking → degumming → pre-neutralization → neutralization → whole hole → micro-etching → pre-dip → activation → acceleration → copper deposition. Except for the pre-dip tank and the activation tank, overflow water washing is set between the other two chemical tanks to prevent cross-contamination of the chemical tanks.

[0003] Among them, the role of pre-dip is to protect the activation tank, prevent impurities from contaminating the activation tank or bringing in water to cause hydrolysis of the activation tank; the role of activation makes the tin-palladium colloid or ionic palladium adhere to the hole wall, acting as a catalyst for the subsequent copper deposition reaction. The difference between the components of the pre-dip tank and the activation tank is that the activation tank is based on the components of the pre-dip tank, with an additional palladium compound, generally in the form of colloidal palladium or ionic palladium. Palladium is rarer than gold and is one of the rarest precious metals in the world. Its usage price can be comparable to or even higher than gold. Therefore, the activation solution containing palladium accounts for a high proportion of the material cost of copper deposition. Therefore, it is of great significance to reduce the use and consumption of palladium without changing the concentration of palladium in the activation tank and affecting the quality of copper deposition.

[0004] In the existing copper plating process, the consumption of activated palladium is as follows: on the one hand, the acidic solution without activated palladium brought into the pre-impregnation tank will dilute the activated palladium concentration in the activation tank; on the other hand, during the production of boards, the activated palladium will be taken away after adsorption in the holes or on the board surface, thereby reducing the concentration of activated palladium in the activation tank. The reduction in the activated palladium concentration in the activation tank will lead to uneven adsorption of activated palladium in the hole walls of the board, resulting in poor copper plating effect of the circuit board, reducing the yield of the circuit board and causing waste of activated palladium. To this end, the Chinese patent application number CN202211447223.3 discloses a circuit board and a copper plating activation treatment method thereof. After the activated board is activated, an activator for attaching copper foil is formed on its surface, and before copper plating, the activated board to be re-immersed is re-immersed, that is, the board to be re-immersed is re-pre-immersed. Although it can reduce the unnecessary waste of activated palladium caused by bringing excess activated palladium into the next process, the neutralization treatment and micro-etching treatment will increase the roughness of the surface of the copper foil layer of the circuit board, that is, there are uneven areas on the surface of the copper foil layer, which will increase the adsorption effect of activated palladium, and it is difficult to remove the activated palladium in the uneven area by the re-immersion immersion treatment alone, resulting in excess activated palladium still remaining on the circuit board, thereby reducing the concentration of activated palladium in the activation tank and causing waste of activated palladium. Summary of the invention

[0005] The purpose of the present disclosure is to overcome the deficiencies in the prior art and provide an activation process before metallization of circuit board holes that can reduce the consumption of activated palladium.

[0006] The purpose of this disclosure is achieved through the following technical solutions:

[0007] An activation process before metallization of circuit board holes, comprising the following steps:

[0008] Obtaining a pre-treated circuit board, wherein a first rough washed area is formed on the surface of a first copper foil layer of the circuit board, and a second rough washed area is formed on the surface of a second copper foil layer of the circuit board;

[0009] Placing the circuit board in a prepreg tank for prepreg treatment;

[0010] The circuit board after the prepreg treatment is subjected to a first liquid drop treatment just above the prepreg tank;

[0011] Placing the circuit board after the first drop of liquid treatment in an activation tank for activation treatment;

[0012] The circuit board after activation is subjected to a second liquid dripping treatment just above the activation tank;

[0013] Using the pre-soak liquid in the pre-soak tank to perform a scouring treatment on the first rough scouring area and the second rough scouring area of ​​the circuit board after the second liquid drop treatment just above the pre-soak tank, and returning the scouring liquid to the pre-soak tank;

[0014] Placing the flushed circuit board in the pre-soaking tank for re-soaking;

[0015] The circuit board after the back-immersion treatment is subjected to a third liquid dripping treatment just above the pre-immersion tank.

[0016] In one embodiment, the step of using the prepreg liquid in the prepreg tank to perform a flushing treatment on the first rough flushing area and the second rough flushing area of ​​the circuit board after the second liquid drop treatment directly above the prepreg tank comprises:

[0017] The pre-soaking liquid in the pre-soaking tank is pumped to the first pumping pipe by a first pumping pump and sprayed on the first rough flushing area of ​​the circuit board through a first nozzle on the liquid outlet end of the first pumping pipe, and the flushing liquid is returned to the pre-soaking tank;

[0018] The pre-soaking liquid in the pre-soaking tank is pumped to the second pumping pipe by a second pumping pump and sprayed to the second rough flushing area of ​​the circuit board through a second nozzle on the liquid outlet end of the second pumping pipe, and the flushing liquid is returned to the pre-soaking tank.

[0019] In one embodiment, the prepreg treatment time is 45 to 60 seconds.

[0020] In one embodiment, the first drop of liquid is treated for 30 to 50 seconds.

[0021] In one embodiment, the activation treatment time is 6 to 8 minutes.

[0022] In one embodiment, the second droplet treatment time is 30 to 50 seconds.

[0023] In one embodiment, the flushing treatment time is 15 to 30 seconds.

[0024] In one embodiment, the spray pressure of the first nozzle is 4-8 MPa, and the spray pressure of the second nozzle is 4-8 MPa.

[0025] In one embodiment, the back-immersion treatment time is 45 to 60 seconds.

[0026] In one embodiment, the third droplet treatment time is 30 to 50 seconds.

[0027] Compared with the prior art, the present invention has at least the following advantages:

[0028] 1. Pre-impregnation treatment of the circuit board in the pre-impregnation tank can prevent impurities and moisture from being brought into the activation tank. Then, the circuit board is subjected to the first drop treatment just above the pre-impregnation tank to reduce the pre-impregnation liquid brought into the activation tank by the circuit board, thereby reducing the concentration drop of activated palladium in the activation tank. When the circuit board after the first drop treatment is activated in the activation tank, the activated palladium in the hole wall of the circuit board can be evenly adsorbed, so as to improve the copper deposition effect of the circuit board.

[0029] 2. By performing a second droplet treatment on the activated circuit board just above the activation cylinder, the excess activation liquid on the circuit board is returned to the activation cylinder, and then the first rough flushing area and the second rough flushing area of ​​the circuit board are flushed with the pre-dip liquid just above the pre-dip cylinder, that is, the uneven area on the copper foil surface of the circuit board is flushed, which can not only flush the activation liquid remaining on the copper surface of the circuit board into the pre-dip cylinder, but also reduce the adsorption force of the activated palladium in the uneven area, so that the activated palladium in the uneven area can be stripped when the flushed circuit board is back-dipped in the pre-dip cylinder, thereby reducing unnecessary activated palladium residue on the circuit board, and further reducing the consumption of activated palladium. In addition, the concentration of activated palladium in the pre-dip cylinder is increased, so that the hole wall of the circuit board can be attached with activated palladium in advance during the pre-dip treatment, so that the activated palladium in the hole wall of the circuit board is more dense, thereby improving the copper deposition effect of the circuit board. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 This is a flow chart of an activation process before metallization of a circuit board hole in one embodiment;

[0032] Figure 2 It is a schematic diagram of a pre-preg tank before re-immersion treatment in the activation process before metallization of a circuit board hole disclosed in the present invention;

[0033] Figure 3 It is a schematic diagram of a prepreg tank after the back-dip treatment in the activation process before the metallization of the circuit board hole disclosed in the present invention;

[0034] Figure 4 This is the on-site equipment diagram for the palladium chloride waste liquid recovery process. DETAILED DESCRIPTION

[0035] In order to facilitate the understanding of the present disclosure, the present disclosure will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present disclosure are given in the drawings. However, the present disclosure can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present disclosure more thoroughly and comprehensively understood.

[0036] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present disclosure. The terms used herein in the specification of the present disclosure are only for the purpose of describing specific embodiments and are not intended to limit the present disclosure. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0038] The present disclosure provides an activation process before metallization of a circuit board hole, comprising the following steps: obtaining a circuit board after pretreatment, wherein a first rough scouring area is formed on the surface of the first copper foil layer of the circuit board, and a second rough scouring area is formed on the surface of the second copper foil layer of the circuit board. Placing the circuit board in a prepreg cylinder for prepreg treatment. Performing a first drop treatment on the circuit board after the prepreg treatment directly above the prepreg cylinder. Placing the circuit board after the first drop treatment in an activation cylinder for activation treatment. Performing a second drop treatment on the circuit board after the activation treatment directly above the activation cylinder. Using the prepreg liquid in the prepreg cylinder, the first rough scouring area and the second rough scouring area of ​​the circuit board after the second drop treatment are scoured directly above the prepreg cylinder, and the scouring liquid is returned to the prepreg cylinder. Placing the scouring-treated circuit board in the prepreg cylinder for re-soaking treatment. Performing a third drop treatment on the circuit board after the re-soaking treatment directly above the prepreg cylinder.

[0039] The above-mentioned activation process performs pre-impregnation treatment on the circuit board in a pre-impregnation tank to avoid impurities and moisture from being brought into the activation tank, and then performs the first drop treatment on the circuit board just above the pre-impregnation tank to reduce the pre-impregnation liquid brought into the activation tank by the circuit board, thereby reducing the decrease in the concentration of activated palladium in the activation tank, so that the activated palladium in the hole wall of the circuit board after the first drop treatment can be evenly adsorbed when the circuit board is activated in the activation tank, thereby improving the copper deposition effect of the circuit board.

[0040] Furthermore, by performing a second liquid drop treatment on the circuit board after the activation treatment just above the activation cylinder, the excess activation liquid on the circuit board is returned to the activation cylinder, and then the first rough scouring area and the second rough scouring area of ​​the circuit board are scoured with the pre-dip liquid just above the pre-dip cylinder, that is, the uneven area on the surface of the copper foil layer of the circuit board is scoured, which can not only flush the activation liquid remaining on the copper surface of the circuit board into the pre-dip cylinder, but also reduce the adsorption force of the activated palladium in the uneven area, so that the circuit board after the scouring treatment can peel off the activated palladium in the uneven area when it is back-dipped in the pre-dip cylinder, thereby reducing unnecessary activated palladium residue on the circuit board, and further reducing the consumption of activated palladium. In addition, the concentration of activated palladium in the pre-dip cylinder is increased, so that the hole wall of the circuit board can be attached with activated palladium in advance during the pre-dip treatment, so that the activated palladium in the hole wall of the circuit board is more dense, thereby improving the copper deposition effect of the circuit board.

[0041] See also Figure 1 In order to better understand the activation process before metallization of the circuit board hole disclosed in the present invention, the activation process before metallization of the circuit board hole is further explained below:

[0042] An activation process before metallization of a circuit board hole according to one embodiment includes the following steps:

[0043] S100, obtaining a pre-processed circuit board, wherein a first rough washed area is formed on the surface of a first copper foil layer of the circuit board, and a second rough washed area is formed on the surface of a second copper foil layer of the circuit board.

[0044] In this embodiment, the circuit board after drilling is sequentially subjected to the pre-treatment steps of bulking treatment, degumming treatment, pre-neutralization treatment, neutralization treatment, hole-sizing treatment and micro-etching treatment. Specifically, the residual glue on the surface of the circuit board is softened by bulking treatment, so that the residual glue can be completely removed during the degumming treatment process. At the same time, the degumming treatment will corrode the epoxy resin substrate of the circuit board, so that the epoxy resin area in the hole wall of the circuit board forms a micro-rough surface, which can enhance the adsorption effect of the substrate on activated palladium. The pre-neutralization treatment and neutralization treatment are to remove the residual degumming liquid in the degumming treatment process, and at the same time, they will corrode the copper surface of the circuit board and improve the surface roughness of the copper foil layer of the circuit board. Then, the charge state in the hole wall of the circuit board is changed by the hole-sizing treatment, and the adsorption effect of the circuit board on colloidal palladium is further enhanced. Finally, the circuit board is micro-etched to remove the oxide on the copper surface of the circuit board, but the surface roughness of the copper foil layer of the circuit board will be increased, further improving the adsorption effect of the copper foil layer surface of the circuit board on activated palladium.

[0045] S200, placing the circuit board in a prepreg tank for prepreg treatment.

[0046] In this embodiment, the circuit board after micro-etching and water washing is placed in a pre-dip tank for pre-dip treatment, so that the acid pre-dip liquid is spread all over the circuit board, avoiding impurities and moisture from being brought into the activation tank to cause pH changes and cause colloid agglomeration, thereby ensuring a stable acidic environment in the activation tank.

[0047] Furthermore, in one of the embodiments, the pre-impregnation time is 45 to 60 seconds. By controlling the pre-impregnation time between 45 and 60 seconds, the moisture and impurities remaining on the surface of the circuit board can be removed, ensuring that the surface of the circuit board is covered with acidic pre-impregnation liquid, so that the circuit board will not cause pH changes after entering the activation tank, thereby ensuring that the activated palladium in the hole wall of the circuit board has a better adsorption effect.

[0048] S300, subjecting the pre-preg-treated circuit board to a first liquid drop treatment just above the pre-preg tank.

[0049] In this embodiment, the circuit board is moved between the cylinders by a ceiling crane. The circuit board after pre-preg treatment is suspended by the ceiling crane just above the pre-preg cylinder, so that the pre-preg liquid on the surface of the circuit board drips into the pre-preg cylinder, thereby reducing the amount of pre-preg liquid residue on the circuit board and reducing the concentration of activated palladium caused by the excess pre-preg liquid being brought into the activation cylinder, ensuring that the hole wall of the circuit board can evenly absorb the activated palladium, thereby ensuring that the circuit board has a better copper deposition effect.

[0050] Furthermore, in one embodiment, the first dripping treatment time is 30 to 50 seconds. In order to remove the excess pre-dip liquid on the circuit board and avoid the circuit board surface from being oxidized, in this embodiment, the first dripping treatment time is controlled between 30 and 50 seconds, which can maximize the excess pre-dip liquid on the circuit board to drip into the pre-dip tank and avoid the circuit board surface from being oxidized.

[0051] S400, placing the circuit board treated with the first drop of liquid in an activation tank for activation treatment.

[0052] In this embodiment, the circuit board is placed in the activation tank by a ceiling crane so that the activation liquid is spread all over the circuit board, and the activated palladium can be adsorbed in the hole wall of the circuit board, so that the hole wall of the circuit board can be evenly adsorbed with the activated palladium, thereby improving the copper deposition effect of the circuit board.

[0053] Furthermore, in one embodiment, the activation treatment time is 6 to 8 minutes. It can be understood that by controlling the activation treatment time to be between 6 and 8 minutes, the hole wall of the circuit board can be fully adsorbed with activated palladium, ensuring that the hole wall of the circuit board adsorbs dense activated palladium, thereby ensuring that the circuit board has a better copper deposition effect.

[0054] S500, the activated circuit board is subjected to a second liquid drop treatment just above the activation tank.

[0055] In this embodiment, the circuit board after activation treatment is suspended in the air above the activation cylinder by a ceiling crane, so that the activation liquid on the surface of the circuit board drips into the activation cylinder, thereby reducing the residual amount of activation liquid on the circuit board and reducing the reduction in the concentration of activated palladium caused by excess activation liquid being carried out of the activation cylinder, ensuring that the hole walls of the subsequent circuit boards can uniformly absorb the activated palladium, thereby ensuring that the circuit board has a better copper deposition effect, improving the yield of the circuit board and reducing the waste of activated palladium.

[0056] Furthermore, in one embodiment, the second dripping treatment time is 30 to 50 seconds. In order to remove the excess activation liquid on the circuit board while avoiding the oxidation of the circuit board surface and the activated palladium, in this embodiment, the second dripping treatment time is controlled between 30 and 50 seconds, which can maximize the excess activation liquid on the circuit board to drop into the activation tank and avoid the oxidation of the circuit board surface and the activated palladium.

[0057] S600, using the pre-soak liquid in the pre-soak tank to perform a scouring treatment on the first rough scouring area and the second rough scouring area of ​​the circuit board after the second drop liquid treatment just above the pre-soak tank, and making the scouring liquid flow back into the pre-soak tank.

[0058] In this embodiment, the front-end pre-neutralization treatment, neutralization treatment and micro-etching treatment will form an uneven rough surface on the surface of the copper foil layer of the circuit board, namely the first rough scouring area and the second rough scouring area. At the same time, in order to make the hole wall of the circuit board have a better copper deposition effect, the activation time is controlled between 6 and 8 minutes, which will not only make the activated palladium in the hole wall adsorbed evenly, but also make the first rough scouring area and the second rough scouring area fully adsorbed with activated palladium. Therefore, the circuit board after the second drop treatment is scourred by the pre-dip liquid directly above the pre-dip cylinder, that is, the pre-dip liquid is used for the first rough scouring area and the second rough scouring area. Because the concentration of activated palladium in the pre-dip liquid is low or zero, combined with the scouring force, the activated palladium in the tiny gaps of the first rough scouring area and the second rough scouring area can be scoured out, and the scouring force can reduce the binding force between the activated palladium and the copper foil layer, so that the subsequent back-dip treatment can fully separate the activated palladium adsorbed in the first rough scouring area and the second rough scouring area, thereby minimizing the consumption of activated palladium. Furthermore, although the concentration of activated palladium in the activation cylinder will still decrease, the above-mentioned treatment can minimize the decrease in the concentration of activated palladium in the activation cylinder, and the activated palladium adsorbed in the first rough scouring area and the second rough scouring area will be flushed into the pre-impregnation cylinder, thereby increasing the concentration of activated palladium in the pre-impregnation liquid, so that the hole walls of the subsequent circuit boards can adsorb the activated palladium in advance during the pre-impregnation treatment, thereby improving the density of the activated palladium in the hole walls of the circuit boards, further improving the copper deposition effect of the circuit boards, and then improving the yield of the circuit boards and reducing the consumption of activated palladium.

[0059] Furthermore, in one of the embodiments, the flushing treatment time is 15 to 30 seconds. By controlling the flushing treatment time between 15 and 30 seconds, the activated palladium adsorbed in the first rough flushing area and the second rough flushing area can be fully flushed away. Even if it is not flushed away, the adsorption force of the activated palladium can be reduced, so that the subsequent back-immersion treatment can fully separate the activated palladium adsorbed in the first rough flushing area and the second rough flushing area. At the same time, it can avoid the oxidation of the circuit board surface and the activated palladium, thereby ensuring that the circuit board has a better copper plating effect, thereby improving the yield of the circuit board and reducing the consumption of activated palladium.

[0060] S700, placing the flushed circuit board in a pre-immersion tank for re-immersion treatment.

[0061] In this embodiment, activated palladium particles still remain in the tiny gaps of the first rough scouring area and the second rough scouring area of ​​the circuit board after the scouring treatment, but the binding force of the activated palladium is reduced after the scouring treatment, so that the residual activated palladium particles can be separated from the first rough scouring area and the second rough scouring area during the back-immersion treatment in the pre-immersion tank, reducing the excess activated palladium residue on the circuit board, thereby reducing the consumption of activated palladium. In addition, after the back-immersion treatment, the activated palladium concentration of the pre-immersion liquid in the pre-immersion tank will increase, so that the subsequent circuit board can be pre-adsorbed with activated palladium in the hole wall during the pre-immersion treatment, and a denser activated palladium layer can be formed during the subsequent activation treatment, thereby effectively improving the copper deposition effect of the circuit board, thereby improving the yield of the circuit board, and reducing the consumption of activated palladium.

[0062] Furthermore, in one of the embodiments, the time of the back-immersion treatment is 45 to 60 seconds. By controlling the back-immersion treatment time of the circuit board between 45 and 60 seconds, the activated palladium particles remaining in the tiny gaps between the first rough scouring area and the second rough scouring area of ​​the circuit board can be peeled off, thereby minimizing the amount of unnecessary activated palladium residue on the circuit board, thereby minimizing the consumption of activated palladium and saving the production cost of the circuit board.

[0063] S800, the circuit board after the re-immersion treatment is subjected to a third liquid dripping treatment just above the pre-immersion tank.

[0064] In this embodiment, the circuit board after the re-immersion treatment is suspended above the pre-immersion tank by a ceiling crane, so that the pre-immersion liquid on the surface of the circuit board drips into the pre-immersion tank, thereby reducing the amount of residual pre-immersion liquid on the circuit board.

[0065] Furthermore, in one embodiment, the third dripping treatment time is 30 to 50 seconds. In order to remove the excess pre-dip liquid on the circuit board while avoiding the oxidation of the circuit board surface and the activated palladium, in this embodiment, the third dripping treatment time is controlled between 30 and 50 seconds, which can maximize the excess pre-dip liquid on the circuit board to drip into the pre-dip tank and avoid the oxidation of the circuit board surface and the activated palladium.

[0066] In one embodiment, the step of using the prepreg liquid in the prepreg tank to perform a flushing treatment on the first rough flushing area and the second rough flushing area of ​​the circuit board after the second drop liquid treatment directly above the prepreg tank includes:

[0067] The pre-soaking liquid in the pre-soaking tank is pumped to the first pumping pipe by a first pumping pump and sprayed on the first rough flushing area of ​​the circuit board through a first nozzle on the liquid outlet end of the first pumping pipe, and the flushing liquid is returned to the pre-soaking tank;

[0068] The pre-soaking liquid in the pre-soaking tank is pumped to the second pumping pipe by the second pumping pump and sprayed on the second rough flushing area of ​​the circuit board through the second nozzle on the liquid outlet end of the second pumping pipe, and the flushing liquid is returned to the pre-soaking tank.

[0069] It should be noted that, regardless of whether the circuit board is placed flat or vertically, the spray direction of the first nozzle is adjustable and directed toward the first rough scouring area, the spray direction of the second nozzle is adjustable and directed toward the second rough scouring area, and the first rough scouring area and the second rough scouring area of ​​the circuit board are scoured with pre-dip liquid, so that the activation liquid remaining on the circuit board can be scoured in the pre-dip cylinder and the activated palladium particles in the first rough scouring area and the second rough scouring area of ​​the copper foil layer of the circuit board are stripped in the pre-dip cylinder, so as to avoid unnecessary activated palladium from being brought into the next process and causing waste of activated palladium, thereby reducing the consumption of activated palladium and saving production costs. In addition, in the present embodiment, the periphery of the pre-dip cylinder is provided with an acid-resistant annular baffle plate, which can prevent the pre-dip liquid from splashing into other cylinders during the scouring process and causing pollution. At the same time, the splashed pre-dip liquid flows back into the pre-dip cylinder through the acid-resistant annular baffle plate, so as to reduce the waste of activated palladium.

[0070] Further, in one of the embodiments, the injection pressure of the first nozzle is 4 to 8 MPa, and the injection pressure of the second nozzle is 4 to 8 MPa. It is understandable that the injection pressure of the first nozzle is controlled between 4 and 8 MPa, which can flush the residual activated palladium particles and the activation liquid in the first rough scouring area into the prepreg cylinder, and even weaken the binding force of the activated palladium particles in the tiny gaps of the first rough scouring area, so that the subsequent prepreg treatment can peel off the residual activated palladium particles in the tiny gaps of the first rough scouring area. Similarly, the injection pressure of the second nozzle is controlled between 4 and 8 MPa, which can flush the residual activated palladium particles and the activation liquid in the second rough scouring area into the prepreg cylinder, and even weaken the binding force of the activated palladium particles in the tiny gaps of the second rough scouring area, so that the subsequent prepreg treatment can peel off the residual activated palladium particles in the tiny gaps of the second rough scouring area.

[0071] It can be understood that since the circuit boards are mass-produced, and the surface roughness of the copper foil layer of each board after pre-treatment is different, the parameters of the flushing treatment are different for different roughnesses. Once the parameters of the flushing treatment are incorrect, the activated palladium content remaining on the surface of the copper foil layer of the circuit board will be too much, resulting in a waste of activated palladium. In this embodiment, the roughness of the copper surface of the circuit board after pre-treatment is detected to simultaneously obtain the flushing treatment parameters. The flushing treatment is the pressure value of the nozzle. The circuit board is flushed according to the flushing treatment parameters, which can fully peel off the activated palladium remaining on the copper foil layer of the circuit board and reduce the waste of activated palladium.

[0072] Furthermore, the step of testing the roughness of the copper surface of the circuit board after pretreatment to simultaneously obtain the flushing treatment parameters includes: firstly, establishing a database of one-to-one correspondence between the surface roughness of multiple copper foil layers and multiple flushing operation parameters; then testing the roughness of the first rough flushing area and the second rough flushing area of ​​the circuit board to be tested to obtain the actual roughness of the first rough flushing area and the actual roughness of the second rough flushing area of ​​the circuit board; then, according to the actual roughness of the first rough flushing area and the actual roughness of the second rough flushing area of ​​the circuit board, the flushing treatment target parameters corresponding to the circuit board to be tested are retrieved to improve the applicability of the flushing treatment. Furthermore, flushing the circuit board according to the target parameters of the flushing treatment can strip off the activated palladium adsorbed in the first rough flushing area and the second rough flushing area to the greatest extent, reduce the amount of unnecessary activated palladium residue on the circuit board, and thus reduce the consumption of activated palladium.

[0073] Furthermore, the step of detecting the roughness of the first rough flushing area and the second rough flushing area of ​​the circuit board to be detected is specifically as follows: measuring the roughness of the first rough flushing area and the second rough flushing area of ​​the circuit board by a roughness measuring instrument to obtain the actual roughness of the first rough flushing area and the actual roughness of the second rough flushing area of ​​the circuit board. Furthermore, measuring multiple sites of the first rough flushing area and multiple sites of the second rough flushing area of ​​the circuit board by a roughness measuring instrument respectively to obtain the actual roughness of multiple first rough flushing areas and the actual roughness of multiple second rough flushing areas; averaging the actual roughness of multiple first rough flushing areas and averaging the actual roughness of multiple second rough flushing areas to obtain the actual roughness average value of the first rough flushing area and the actual roughness average value of the second rough flushing area of ​​the circuit board. Furthermore, the step of calling the corresponding flushing treatment target parameters of the circuit board to be tested according to the actual roughness of the first rough flushing area and the actual roughness of the second rough flushing area of ​​the circuit board is specifically as follows: calling the flushing treatment target parameters of the circuit board to be tested according to the actual roughness average value of the first rough flushing area and the actual roughness average value of the second rough flushing area of ​​the circuit board to match the actual flushing requirements of the circuit board, and averaging the actual roughness of the copper foil layer surface of the circuit board to make the data accuracy of the roughness of the copper foil layer surface of the circuit board higher, so as to maximize the stripping of the activated palladium remaining in the first rough flushing area and the second rough flushing area of ​​the circuit board, thereby reducing the waste of activated palladium.

[0074] It is understandable that too high a copper ion concentration of the pre-soaking liquid in the pre-soaking tank will reduce the treatment effect of the medicine. Similarly, too high a copper ion concentration of the activation liquid in the activation tank will reduce the treatment effect of the medicine. Therefore, in one embodiment, when the copper ion concentration of the pre-soaking liquid in the pre-soaking tank is greater than or equal to 1.0 g / L, the pre-soaking liquid in the pre-soaking tank is replaced, and the pre-soaking waste liquid is transferred to the waste liquid barrel;

[0075] When the copper ion concentration of the activation liquid in the activation tank is greater than or equal to 1.5g / L, the activation liquid in the activation tank is replaced and the waste activation liquid is transferred to the waste liquid bucket. This can ensure the treatment effect of the pre-preg treatment and activation treatment, and improve the yield rate of the circuit board.

[0076] Furthermore, since the components of the pre-impregnation waste liquid and the activation waste liquid are basically the same, they can be recycled and processed uniformly. If the waste liquid in the waste liquid barrel is scrapped, it will cause a waste of activated palladium. For this reason, in one embodiment, the waste liquid in the waste liquid barrel is treated for palladium recovery, so that the recovered palladium can be reused in the preparation of the activation solution, realizing the recycling and reuse of palladium metal, and further saving the production cost of the circuit board.

[0077] Furthermore, the specific operation steps for palladium recovery treatment of the waste liquid in the waste liquid barrel are as follows:

[0078] First, the palladium chloride waste liquid is pretreated to remove impurities and other metal ions;

[0079] Secondly, the pretreated palladium chloride waste liquid is subjected to reduction treatment;

[0080] Next, the palladium chloride waste liquid after the reduction treatment is subjected to precipitation separation treatment to obtain a metal palladium precipitate;

[0081] Finally, the metallic palladium precipitate is subjected to melt electrolysis to obtain pure palladium.

[0082] It should be noted that the impurities and other metal ions in the palladium chloride waste liquid are removed by the treatment steps of precipitation or ion exchange or solvent extraction of palladium chloride waste liquid. Then, palladium chloride is reduced to metallic palladium by reacting the palladium chloride waste liquid with sodium bisulfite, and a metallic palladium precipitate is obtained by precipitation separation, but other impurities still remain in the metallic palladium precipitate. Further, pure palladium is obtained by melting electrolysis of the metallic palladium precipitate, that is, by refining and reusing the metallic palladium, the purity of palladium is improved, and pure palladium can be reused in the preparation of the activation solution, so that the activated palladium waste liquid can be recycled and reused, and the consumption of activated palladium is reduced while saving the production cost of the circuit board.

[0083] Compared with the prior art, the present invention has at least the following advantages:

[0084] 1. Pre-impregnation treatment of the circuit board in the pre-impregnation tank can prevent impurities and moisture from being brought into the activation tank. Then, the circuit board is subjected to the first drop treatment just above the pre-impregnation tank to reduce the pre-impregnation liquid brought into the activation tank by the circuit board, thereby reducing the concentration drop of activated palladium in the activation tank. When the circuit board after the first drop treatment is activated in the activation tank, the activated palladium in the hole wall of the circuit board can be evenly adsorbed, so as to improve the copper deposition effect of the circuit board.

[0085] 2. By performing a second droplet treatment on the activated circuit board just above the activation cylinder, the excess activation liquid on the circuit board is returned to the activation cylinder, and then the first rough flushing area and the second rough flushing area of ​​the circuit board are flushed with the pre-dip liquid just above the pre-dip cylinder, that is, the uneven area on the copper foil surface of the circuit board is flushed, which can not only flush the activation liquid remaining on the copper surface of the circuit board into the pre-dip cylinder, but also reduce the adsorption force of the activated palladium in the uneven area, so that the activated palladium in the uneven area can be stripped when the flushed circuit board is back-dipped in the pre-dip cylinder, thereby reducing unnecessary activated palladium residue on the circuit board, and further reducing the consumption of activated palladium. In addition, the concentration of activated palladium in the pre-dip cylinder is increased, so that the hole wall of the circuit board can be attached with activated palladium in advance during the pre-dip treatment, so that the activated palladium in the hole wall of the circuit board is more dense, thereby improving the copper deposition effect of the circuit board.

[0086] Examples are listed below, but it should be noted that the following examples do not exhaust all possible situations, and the materials used in the following examples can be obtained from commercial channels unless otherwise specified.

[0087] The above-mentioned embodiments only express several implementation methods of the present disclosure, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the disclosed patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present disclosure, and these all belong to the protection scope of the present disclosure. Therefore, the protection scope of the disclosed patent shall be subject to the attached claims.

Claims

1. An activation process before metallization of circuit board holes, characterized in that: The steps include: Obtaining a pre-treated circuit board, wherein a first rough washed area is formed on the surface of a first copper foil layer of the circuit board, and a second rough washed area is formed on the surface of a second copper foil layer of the circuit board; Placing the circuit board in a prepreg tank for prepreg treatment; The circuit board after the prepreg treatment is subjected to a first liquid drop treatment just above the prepreg tank; Placing the circuit board after the first drop of liquid treatment in an activation tank for activation treatment; The circuit board after activation is subjected to a second liquid dripping treatment just above the activation tank; Using the pre-soak liquid in the pre-soak tank to perform a scouring treatment on the first rough scouring area and the second rough scouring area of ​​the circuit board after the second liquid drop treatment just above the pre-soak tank, and returning the scouring liquid to the pre-soak tank; Placing the flushed circuit board in the pre-soaking tank for re-soaking; The circuit board after the back-immersion treatment is subjected to a third liquid dripping treatment just above the pre-immersion tank.

2. The activation process before circuit board hole metallization according to claim 1, characterized in that: The step of using the prepreg liquid in the prepreg tank to perform a flushing treatment on the first rough flushing area and the second rough flushing area of ​​the circuit board after the second liquid drop treatment directly above the prepreg tank comprises: The pre-soaking liquid in the pre-soaking tank is pumped to the first pumping pipe by a first pumping pump and sprayed to the first rough flushing area of ​​the circuit board through a first nozzle on the liquid outlet end of the first pumping pipe, and the flushing liquid is returned to the pre-soaking tank; The pre-soaking liquid in the pre-soaking tank is pumped to the second pumping pipe by a second pumping pump and sprayed to the second rough flushing area of ​​the circuit board through a second nozzle on the liquid outlet end of the second pumping pipe, and the flushing liquid is returned to the pre-soaking tank.

3. The activation process before circuit board hole metallization according to claim 1, characterized in that: The pre-preg treatment time is 45 to 60 seconds.

4. The activation process before circuit board hole metallization according to claim 1, characterized in that: The first drop of liquid treatment takes 30 to 50 seconds.

5. The activation process before circuit board hole metallization according to claim 1, characterized in that: The activation treatment time is 6 to 8 minutes.

6. The activation process before circuit board hole metallization according to claim 1, characterized in that: The treatment time of the second drop of liquid is 30 to 50 seconds.

7. The activation process before circuit board hole metallization according to claim 1, characterized in that: The flushing treatment time is 15 to 30 seconds.

8. The activation process before circuit board hole metallization according to claim 2, characterized in that: The spray pressure of the first nozzle is 4-8 MPa, and the spray pressure of the second nozzle is 4-8 MPa.

9. The activation process before circuit board hole metallization according to claim 1, characterized in that: The back-leaching treatment time is 45 to 60 seconds.

10. The activation process before circuit board hole metallization according to claim 1, characterized in that: The third droplet treatment time is 30 to 50 seconds.

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