CN113825319B - Method for removing dry film on copper layer of circuit board - Google Patents
Method for removing dry film on copper layer of circuit board Download PDFInfo
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- CN113825319B CN113825319B CN202010564873.0A CN202010564873A CN113825319B CN 113825319 B CN113825319 B CN 113825319B CN 202010564873 A CN202010564873 A CN 202010564873A CN 113825319 B CN113825319 B CN 113825319B
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- circuit board
- copper
- copper layer
- dry film
- layer
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/10—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern
- H05K3/18—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern using precipitation techniques to apply the conductive material
- H05K3/181—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern using precipitation techniques to apply the conductive material by electroless plating
- H05K3/182—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern using precipitation techniques to apply the conductive material by electroless plating characterised by the patterning method
- H05K3/184—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern using precipitation techniques to apply the conductive material by electroless plating characterised by the patterning method using masks
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
- H05K2203/05—Patterning and lithography; Masks; Details of resist
- H05K2203/0562—Details of resist
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Abstract
The invention discloses a method for removing a dry film on a copper layer of a circuit board, and relates to the field of circuit board manufacturing. The method comprises the following steps: providing a circuit board substrate, wherein a copper layer is arranged on the surface of the circuit board substrate; forming a dry film with a plurality of openings on the copper layer, wherein the copper layer area exposed in each opening is a gold-plated area; forming a metal layer in each of the gold-plated regions; soaking the circuit board in organic stripping liquid at 50-60 ℃ to remove the film, wherein the organic stripping liquid comprises sodium hydroxide, a surfactant, a copper protecting agent and a regenerant; after the soaking is completed, the oxidation rate of the copper surface of the copper layer is 0.13-1.25%.
Description
Technical Field
The invention relates to the field of circuit board manufacturing, in particular to a method for removing a dry film on a copper layer of a circuit board.
Background
The PCB (Printed Circuit Board ) is a circuit board formed by patterning the electronic wiring connecting circuit components according to the circuit design and reproducing the electronic conductors on an insulator through specific machining, processing and other processes, and mainly aims to make the electronic components arranged on the circuit board function by means of the circuits on the circuit board.
With the high performance of electronic products, gold plating or gold melting with excellent performance is selected for the surface treatment of the PCB. To protect the substrate of the PCB, a dry film is typically used to cover the surface of the substrate of the circuit board and selectively expose the copper surface to be plated or gold plated prior to plating or gold plating. After gold plating or gold plating, stripping is performed. At present, naOH (sodium hydroxide) is generally adopted as a stripping liquid for stripping the film of the immersed circuit board (generally, the immersion is carried out for 4-5 times). However, when NaOH is used for stripping, the following drawbacks exist:
NaOH reacts with copper surfaces of PCBs to produce Cu (O H) 2 The oxidation of the copper surface is caused; further, naOH requires a long total time to remove the dry film (total time of soaking 4 times is typically 680 s), and the long time of removing the film and the properties of NaOH itself increase the oxidation rate and oxidation area of the copper surface, which severely reduces the quality of the entire PCB.
Disclosure of Invention
Aiming at the defects in the prior art, the invention solves the technical problems as follows: how to avoid excessive oxidation of the copper side of the circuit board while significantly reducing the length of time required to remove the dry film.
In order to achieve the above object, the method for removing a dry film on a copper layer of a circuit board provided by the invention comprises the following steps:
s1: providing a circuit board substrate, wherein a copper layer is arranged on the surface of the circuit board substrate;
s2: forming a dry film with a plurality of openings on the copper layer, wherein the copper layer area exposed in each opening is a gold-plated area;
s3: forming a metal layer in each of the gold-plated regions;
s4: soaking the circuit board in organic film removing liquid at 50-60 ℃ for 4-5 times, wherein the soaking time is 83-102 s each time; the organic membrane removing liquid comprises sodium hydroxide with the concentration of 4.2-7 wt%, a surfactant with the concentration of 0.9-1.5 wt%, a copper-protecting agent with the concentration of 0.6-1.0 wt% and a regenerant with the concentration of 0.3-0.5 wt%, wherein the total concentration of the sodium hydroxide, the surfactant, the copper-protecting agent and the regenerant is 6-10 wt%; after the soaking is completed, the oxidation rate of the copper surface of the copper layer is 0.13-1.25%.
Based on the technical scheme, the specific flow of S2 comprises: and forming a patterned dry film by using a micro-shadow process, baking the copper layer at 135 ℃ for 30 minutes, and then pasting the dry film on the surface of the copper layer through a hot-pressing wheel.
On the basis of the technical scheme, the metal layer in the step S3 comprises a nickel-containing layer and a gold layer positioned on the nickel-containing layer.
Based on the technical scheme, the specific flow of the S4 comprises the following steps: soaking the circuit board in organic film removing liquid at 55 ℃ for 4 times; the soaking time period is 90s, 93s, 96s and 99s in sequence, the organic film removing liquid comprises 5.6wt% sodium hydroxide, 1.2wt% interfacial agent, 0.8wt% copper protection agent and 0.4wt% regenerant, and the oxidation rate of the copper surface is 0.97% after the soaking is completed.
Compared with the prior art, the invention has the advantages that:
according to the invention, through matching of the independently developed organic stripping liquid and the corresponding parameters, tests and comparison show that compared with a stripping mode in which the average stripping time is 545s and serious copper surface oxidation (the copper surface oxidation rate is 35%) occurs after soaking for 9 minutes in the prior art, the average time required for removing the dry film of the circuit board by adopting the method is 341s, and slight copper surface oxidation (the copper surface oxidation rate is 0.13%) occurs after soaking for 10 minutes.
Therefore, the dry film on the circuit board can be removed quickly, the oxidation speed of the copper layer can be reduced effectively, and the copper layer is prevented from being excessively oxidized;
drawings
FIG. 1 is a flow chart of a method for removing a dry film on a copper layer of a circuit board according to an embodiment of the invention;
FIG. 2 is a schematic cross-sectional view corresponding to S1 in an embodiment of the present invention;
FIG. 3 is a schematic cross-sectional view corresponding to S2 in an embodiment of the present invention;
FIG. 4 is a schematic cross-sectional view corresponding to S3 in an embodiment of the present invention;
FIG. 5 is a schematic cross-sectional view corresponding to S4 in an embodiment of the invention;
FIG. 6A is a photograph of a circuit board after conventional sodium hydroxide lotion soaking;
FIG. 6B is a photograph of a circuit board after being immersed in an organic stripping solution according to an embodiment of the present invention;
FIG. 7A is a photograph of the surface of a metal layer of a circuit board after conventional sodium hydroxide lotion immersion;
fig. 7B is a photograph of the surface of the metal layer of the circuit board after the organic stripping solution is immersed in the embodiment of the present invention.
In the figure: 10-circuit board substrate, 11-copper layer, 12-dry film, 13-gold-plated area and 14-metal layer.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples.
Referring to fig. 1, the method for removing a dry film on a copper layer of a circuit board according to an embodiment of the invention includes the following steps:
s1: referring to fig. 2, a circuit board substrate 10 is provided, and a copper layer 11 is disposed on a surface of the circuit board substrate 10, wherein in practical application, the copper layer 11 may be a conductive layer; may be fabricated by photolithography and etching, and may be formed using electroplating, electroless plating, or other suitable methods.
S2: referring to fig. 3, a patterned dry film 12 is formed on a copper layer 11, the patterned dry film 12 having a plurality of openings, and a copper layer area exposed in each opening is a gold-plated area 13.
Preferably, the specific flow of S2 includes: forming a patterned Dry Film 12, alternatively referred to as DFR (Dry Film Resist), using a photolithography process; after baking the copper layer 11 at 135 ℃ for 30 minutes, a dry film 12 was attached to the surface of the copper layer 11 by a hot press roller.
The design has the following advantages: the copper layer 11 is baked at the above temperature and time before the dry film 12 is applied, which improves the adhesion degree of the dry film 12 to the copper layer 11.
S3: referring to fig. 4, a metal layer 14 is formed in each gold-plated region 13, and in practice, the metal layer 14 may be formed using electroplating, electroless plating, or other suitable methods; the metal layer 14 in this embodiment includes a nickel-containing layer capable of improving corrosion resistance, and a gold layer on the nickel-containing layer.
S4: referring to FIG. 5, the circuit board is soaked in the organic stripping liquid at the temperature of 50-60 ℃ for stripping, the soaking times are 4-5 times, and the soaking time is 83-102 s each time; the organic membrane removing liquid comprises sodium hydroxide with the concentration of 4.2-7 wt%, a surfactant with the concentration of 0.9-1.5 wt%, a copper-protecting agent with the concentration of 0.6-1.0 wt% and a regenerant with the concentration of 0.3-0.5 wt%, wherein the total concentration of the sodium hydroxide, the surfactant, the copper-protecting agent and the regenerant is 6-10 wt%; after stripping, each metal layer 14 remains in the corresponding gold-plated region 13.
The sodium hydroxide, the surfactant, the copper protection agent and the regenerant are matched with each other according to the concentration parameter and the soaking parameter (soaking temperature, times and time duration of each time), so that the following effects can be achieved:
4.2 to 7 weight percent of sodium hydroxide can effectively remove the dry film;
the surfactant with the weight percent of 0.9 to 1.5 can reduce the tension of the organic stripping liquid, reduce the CA (contact angle) of the organic stripping liquid on the dry film, further quickly wet the dry film and accelerate the decomposition speed of the dry film;
0.6 to 1.0 weight percent of copper protection agent can protect the copper layer of the circuit board, reduce the oxidation speed of the copper layer and avoid excessive oxidation;
the regenerant with the weight percent of 0.3 to 0.5 percent can prevent the volume expansion of the circuit board and avoid the damage of the structure of the circuit board caused by the volume expansion.
The organic stripping solution formed by the components in the proportion can remove the dry film in a short time and can maximally reduce the oxidation speed of copper by matching with the soaking temperature and the soaking time in the S4. The oxidation rate of the copper surface is 0.13-1.25% after the soaking is completed.
Preferably, the specific flow of S4 includes: soaking the circuit board in organic film removing liquid at 55 ℃ for 4 times; the soaking time period is 90s, 93s, 96s and 99s in sequence, the organic film removing liquid comprises 5.6wt% sodium hydroxide, 1.2wt% interfacial agent, 0.8wt% copper protection agent and 0.4wt% regenerant, and the oxidation rate of the copper surface is 0.97% after the soaking is completed. Under this condition, the stripping speed is higher, and the copper surface oxidation condition is better (i.e. the oxidation rate is lower).
The effects of the present invention are described below by 1 comparative example and actual product photograph, respectively.
Comparative example:
table I, comparison of total time of stripping of conventional sodium hydroxide and organic stripping solution after soaking for 4 times
Referring to table one, the difference between the average stripping time of the conventional sodium hydroxide and the organic stripping solution of the present invention is 545-341=204 s, and the stripping speed is significantly improved.
Stripping efficacy of surface two, traditional sodium hydroxide and organic stripping solution
Referring to Table II, the circuit board is immersed in the conventional sodium hydroxide solution for 9 minutes to generate serious copper surface oxidation (the copper surface oxidation rate is 35%), while the circuit board is immersed in the organic stripping liquid for 10 minutes to generate slight copper surface oxidation (the copper surface oxidation rate is 0.13%), and the circuit board is not oxidized for 10 minutes, namely the invention can effectively avoid the copper surface oxidation, thereby obviously improving the quality of the circuit board.
Actual product photographs:
comparing fig. 6A (photograph of circuit board after soaking with conventional sodium hydroxide solution) with fig. 6B (photograph of circuit board after soaking with organic stripping solution according to the present invention), the oxidation condition of fig. 6B is far better than that of fig. 6A.
As can be seen from comparison between fig. 7A (a photograph of the surface of the metal layer of the circuit board after the conventional aqueous sodium hydroxide solution is immersed) and fig. 7B (a photograph of the surface of the metal layer of the circuit board after the organic stripping solution of the present invention is immersed), the organic stripping solution of the present invention does not excessively oxidize the surface of the metal layer.
Further, the present invention is not limited to the above-described embodiments, and it is apparent to those skilled in the art that several modifications and variations can be made without departing from the principle of the present invention, and these modifications and variations are also considered to be within the scope of the present invention. What is not described in detail in this specification is prior art known to those skilled in the art.
Claims (2)
1. A method of removing a dry film from a copper layer of a circuit board, the method comprising the steps of:
s1: providing a circuit board substrate (10), wherein a copper layer (11) is arranged on the surface of the circuit board substrate (10);
s2: forming a dry film (12) with a plurality of openings on the copper layer (11), wherein the copper layer area exposed in each opening is a gold-plated area (13);
s3: forming a metal layer (14) in each gold-plated region (13);
s4: soaking the circuit board in organic film removing liquid at 50-60 ℃ for 4-5 times, wherein the soaking time is 83-102 s each time; the organic membrane removing liquid comprises sodium hydroxide with the concentration of 4.2-7 wt%, a surfactant with the concentration of 0.9-1.5 wt%, a copper-protecting agent with the concentration of 0.6-1.0 wt% and a regenerant with the concentration of 0.3-0.5 wt%, wherein the total concentration of the sodium hydroxide, the surfactant, the copper-protecting agent and the regenerant is 6-10 wt%; after the soaking is finished, the oxidation rate of the copper surface of the copper layer (11) is 0.13-1.25%;
the specific flow of S2 comprises: forming a patterned dry film (12) by using a micro-imaging process, baking the copper layer (11) at 135 ℃ for 30 minutes, and then pasting the dry film (12) on the surface of the copper layer (11) through a hot-pressing wheel;
the metal layer (14) in S3 comprises a nickel-containing layer and a gold layer on the nickel-containing layer.
2. The method for removing a dry film on a copper layer of a circuit board according to claim 1, wherein the specific process of S4 comprises: soaking the circuit board in organic film removing liquid at 55 ℃ for 4 times; the soaking time period is 90s, 93s, 96s and 99s in sequence, the organic film removing liquid comprises 5.6wt% sodium hydroxide, 1.2wt% interfacial agent, 0.8wt% copper protection agent and 0.4wt% regenerant, and the oxidation rate of the copper surface is 0.97% after the soaking is completed.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010564873.0A CN113825319B (en) | 2020-06-19 | 2020-06-19 | Method for removing dry film on copper layer of circuit board |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202010564873.0A CN113825319B (en) | 2020-06-19 | 2020-06-19 | Method for removing dry film on copper layer of circuit board |
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| CN113825319A CN113825319A (en) | 2021-12-21 |
| CN113825319B true CN113825319B (en) | 2023-04-25 |
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1527747A (en) * | 2000-09-19 | 2004-09-08 | ϣ | Process for treating adhesion promoted metal surfaces |
| TW201509921A (en) * | 2013-09-11 | 2015-03-16 | Shikoku Chem | Surface treating agent for copper or copper alloy and its applications |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2849191B2 (en) * | 1990-09-07 | 1999-01-20 | 旭化成工業株式会社 | Manufacturing method of printed wiring board |
| TWI288187B (en) * | 2005-09-13 | 2007-10-11 | Amia Co Ltd | Method for fabricating circuit |
| CN101071278A (en) * | 2006-05-12 | 2007-11-14 | 湖南省科学技术研究开发院 | Photo resist film removing agent |
| CN107278039A (en) * | 2016-04-08 | 2017-10-20 | 东莞市斯坦得电子材料有限公司 | A kind of organic base dry film stripping technique for printed wiring board |
| CN110597026B (en) * | 2019-09-26 | 2022-11-29 | 上海富柏化工有限公司 | Dry film removing process for flexible circuit board |
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2020
- 2020-06-19 CN CN202010564873.0A patent/CN113825319B/en active Active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1527747A (en) * | 2000-09-19 | 2004-09-08 | ϣ | Process for treating adhesion promoted metal surfaces |
| TW201509921A (en) * | 2013-09-11 | 2015-03-16 | Shikoku Chem | Surface treating agent for copper or copper alloy and its applications |
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| CN113825319A (en) | 2021-12-21 |
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