CN115666008A - Method for reworking short circuit after etching with small influence on impedance value of PCB (printed circuit board) circuit - Google Patents
Method for reworking short circuit after etching with small influence on impedance value of PCB (printed circuit board) circuit Download PDFInfo
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- CN115666008A CN115666008A CN202211442722.3A CN202211442722A CN115666008A CN 115666008 A CN115666008 A CN 115666008A CN 202211442722 A CN202211442722 A CN 202211442722A CN 115666008 A CN115666008 A CN 115666008A
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Abstract
The application relates to a method for reworking a short circuit after etching, which has little influence on the impedance value of a PCB (printed circuit board), and comprises the following steps of S1, determining a short circuit position, and marking the short circuit position on a production board; s2, carrying out surface roughening treatment on the production plate; s3, sticking a dry film on the surface of the production plate; s4, placing the production plate with the film attached into an exposure machine and aligning by using a negative film; s5, exposing the production board; s6, taking down the film; s7, carrying out local shading treatment on the short circuit position on the cover film of the dry film of the production board; s8, carrying out secondary exposure on the production board; s9, developing the production plate; s10, locally etching the exposed position of the production plate at the external short circuit position; s11, inspecting the production board; the method can perform local reworking on short circuits at different positions, and reduces the influence on the impedance value of the whole board circuit; after development, only the short circuit part is exposed outside, partial etching can be carried out on the short circuit part, and the etching of circuits at other positions on the production board is avoided, so that the influence on the width and the impedance value of the circuits of the production board is reduced.
Description
Technical Field
The invention relates to the technical field of circuit board processing and preparation, in particular to a method for reworking a short circuit after etching, which has small influence on the impedance value of a PCB circuit.
Background
The heating strip circuit board has excellent insulation strength, excellent voltage resistance, excellent heat conduction efficiency and excellent resistance stability, and is widely used for heating medical instruments and low-temperature baking equipment. One side of the heating strip circuit board product is provided with dense wires and is connected with the other side of the large copper sheet circuit through holes, the product has strict requirements on the line width and the copper thickness, particularly the final resistance value, and the resistance value range is generally controlled within +/-15%.
When the short circuit that can't be repaired manually appears in the circuit board after the etching, for reducing the influence of doing over again to circuit impedance, prior art is:
1. if the short circuit of different production boards occurs at a fixed position, a set of negative film with a local pattern only at the short circuit position can be manufactured to carry out the rework of the negative process at the short circuit position, and the circuits at the rest positions of the circuit board are shielded by the corrosion resistant layer.
2. If the short circuits of different production boards occur at different positions, the method is not feasible, and only the circuit of the whole board can be subjected to rework etching by using a negative film process.
Disclosure of Invention
The invention aims to overcome the defects and provides a method for reworking the short circuit after etching, which has small influence on the impedance value of the PCB circuit.
The technical scheme adopted by the invention for solving the technical problem is to provide a method for reworking the short circuit after etching, which has small influence on the impedance value of a PCB circuit and comprises the following steps:
s1, determining a short circuit position, and marking the short circuit position on a production board;
s2, carrying out surface roughening treatment on the production plate;
s3, pasting a dry film on the surface of the production plate;
s4, placing the production plate with the film attached into an exposure machine and aligning by using a negative film;
s5, exposing the production plate;
s6, taking down the film;
s7, carrying out local shading treatment on the short circuit position on a cover film of the dry film of the production board;
s8, carrying out secondary exposure on the production plate;
s9, developing the production plate;
s10, locally etching the exposed position of the production board at the external short circuit position;
s11, inspecting the production board;
if the product is qualified, entering a subsequent production process;
if not, the process returns to step S1.
Further, the subsequent production process flow comprises the following steps:
s12, performing solder mask on the production board;
s13, carrying out surface treatment on the production plate.
Further, in step S1, the marking method is to mark a coordinate arrow on the production board process edge with an oil pen, so as to facilitate subsequent positioning.
Further, in step S1, the mark is required to be visible through the dry film after the dry film is attached.
Further, in step S2, the surface of the production board is treated by microetching, and the mark of the short-circuit position should be prevented from being removed.
Further, in step S7, the light shielding manner is to use a film pen to paint the short circuit position on the cover film of the dry film or use a light shielding tape to cover the short circuit position.
Further, in step S11, the detection may be observed by naked eyes;
or, electrical measurement, using needle measurement or general electromechanical performance to check whether there is open circuit or short circuit;
or, carrying out optical AOI line scanning, firstly carrying out rapid shooting by using a high-definition image camera, then comparing the shot picture with an original file, and checking whether an open circuit or a short circuit exists.
Further, in step S13, the surface treatment method is any one of a spray tin, an immersion gold, an OSP, an immersion tin, an immersion silver, a nickel-palladium gold, an electro-hard gold, and an electro-gold finger.
Compared with the prior art, the invention has the following beneficial effects: the short circuit at different positions can be subjected to local reworking, so that the influence on the impedance value of the whole board line is reduced; when short circuit batch production plates with different positions are processed, only the short circuit position is exposed after development, the rest positions on the production plate are covered by a corrosion resistant layer (the corrosion resistant layer is a dry film after sensitization), partial etching can be carried out on the short circuit position, the etching of circuits at the rest positions on the production plate is avoided, and therefore the influence on the circuit width and the impedance value of the production plate is reduced.
Drawings
The invention is further described with reference to the following figures.
FIG. 1 is a process flow diagram of the present method.
FIG. 2 is a process flow diagram of a subsequent production process.
Fig. 3 is a schematic diagram of the structure of embodiment 2 before exposure.
Fig. 4 is a schematic diagram of the structure of embodiment 3 after exposure.
In the figure:
1-a board base layer; 2-a printed circuit layer; 3-a film layer; 301-exposed portions; 302-unexposed parts; 4-a light-shielding layer; 5-short circuit of line; and 6-marking.
Detailed Description
The preferred embodiments of the present invention are described in more detail below, however, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Example 1:
the heating strip circuit board has excellent insulation strength, excellent voltage resistance, excellent heat conduction efficiency and excellent resistance stability, and is widely used for heating medical instruments and low-temperature baking equipment. One side of the heating strip circuit board product is distributed with dense wires and is connected with the other side of the large copper sheet circuit through a via hole, the product has strict requirements on the line width and the copper thickness, particularly the final resistance value, and the resistance value range is generally controlled within +/-15%.
When the etched circuit board has a short circuit which cannot be repaired manually, if the short circuits of different production boards occur at different positions, the circuit of the whole board can only be subjected to rework etching by using a negative film process, and the processing method can cause the circuit of the whole board to be thinner, thereby causing larger resistance value and larger impedance influence on the circuit.
Therefore, embodiment 1 provides a method for reworking a short circuit after etching, which has little influence on the impedance value of a PCB line, and can perform local rework on short circuits at different positions to reduce the influence on the impedance value of the whole board line.
As shown in fig. 1, the method comprises the steps of:
s1, determining a short-circuit position, and marking the short-circuit position on a production board, wherein the marked mark needs to be visible through a dry film after the dry film is attached;
in practical application, the marking mode is to mark a coordinate arrow on the process edge of the production plate by using an oil pen so as to facilitate subsequent positioning.
S2, carrying out surface roughening treatment on the production plate to increase the roughness of the copper surface;
in practical application, the surface rough treatment is a grinding plate, mainly solves the problems of surface cleanliness and surface roughness, removes oxidation, increases the roughness of a copper surface and facilitates the attachment of a film on the copper surface;
preferably, the surface of the production plate is treated by adopting a microetching mode, and the mark of the short-circuit position is prevented from being removed during treatment;
s3, pasting a dry film on the surface of the production board, and pressing a layer of blue dry film on the pressed circuit board, wherein the dry film is a carrier;
s4, placing the production board with the film pasted in an exposure machine and aligning by using a negative film;
the negative film is designed according to the design circuit, and the short circuit position is actually extra copper which exceeds the redundant treatment of the design circuit and does not belong to the design circuit;
s5, exposing the production plate;
the dry film fully exposes the position of the circuit film with the designed circuit (the position with the designed circuit is transparent, the position without the designed circuit is lightproof, and the short circuit position does not belong to the designed circuit) under the energy of the lamp tube of the exposure machine; after exposure, the circuit is transferred to the dry film, and the dry film is exposed at the position where the circuit is designed, and is not exposed at the position where the circuit is not designed (including a short circuit position);
s6, taking down the film;
s7, carrying out local shading treatment on the short circuit position on a cover film of the dry film of the production board;
in practical application, a film pen is used for smearing a short circuit position on a cover film of a dry film or a shading adhesive tape is used for covering the short circuit position;
s8, carrying out secondary exposure on the production plate;
after exposure, the part without shading treatment on the dry film is exposed, and the part with shading treatment (namely the short circuit position) is not exposed;
s9, developing the production board, wherein only the short circuit part is exposed after development, and the rest positions on the production board are covered by a corrosion resistant layer (the corrosion resistant layer is a dry film after sensitization);
developing the unexposed part with developer solution in the developing machine, wherein the developer solution is nonreactive to the exposed part;
s10, locally etching the exposed short circuit position of the production board, avoiding etching the circuits at other positions on the production board and reducing the influence on the width and the impedance value of the circuit of the production board;
s11, inspecting the production board;
if the quality is qualified, entering a subsequent production processing flow;
if not, returning to the step S1;
in practical application, the detection can be observed by naked eyes;
or, electrical measurement, using needle measurement or general electromechanical performance to check whether there is open circuit or short circuit;
or, carrying out optical AOI line scanning, firstly carrying out rapid shooting by using a high-definition image camera, then comparing the shot picture with an original file, and checking whether an open circuit or a short circuit exists.
As shown in fig. 2, the subsequent production process flow includes the following steps:
s12, performing solder mask on the production board;
solder resist, also called solder resist and green oil, is one of the most critical processes in the manufacture of printed boards, and is mainly characterized in that a layer of solder resist is coated on the board surface by screen printing or solder resist ink coating to prevent short circuit during welding;
s13, carrying out surface treatment on the production plate.
In practical applications, the surface treatment method includes, but is not limited to, tin spraying, gold immersion, OSP, tin immersion, silver immersion, nickel-palladium-gold, electro-hard-gold, and electro-gold finger.
The method can perform local reworking on short circuits at different positions, and reduces the influence on the impedance value of the whole board line.
When the method is used for processing short circuit batch production plates with different positions, only the short circuit part is exposed after development, the rest positions on the production plate are covered by the anti-corrosion layer (the anti-corrosion layer is a dry film after sensitization), the short circuit part can be etched, the etching of circuits at the rest positions on the production plate is avoided, and therefore the influence on the circuit width and the impedance value of the production plate is reduced.
Example 2:
As shown in fig. 3, the post-etching short circuit rework preprocessing structure includes a board base layer 1, a printed circuit layer 2, a film layer 3, and a light-shielding layer 4, which are sequentially disposed;
the film layer comprises an exposed part 301 covering the circuit area and an unexposed part 302 covering the non-circuit area, and the short circuit position is positioned in the unexposed part;
a mark 6 which is convenient to search is arranged at the short circuit position 5 of the circuit on the board base layer, and the mark can be seen by naked eyes through the film layer;
the shading layer covers the film layer and covers the short circuit position of the circuit.
When the structure is used, the board with the structure is exposed, as shown in fig. 4, the exposed short circuit positions except the short circuit position covered by the light shielding layer are exposed, and only the short circuit position is exposed after the development treatment, the short circuit position can be locally etched, so that the etching of the circuits at the other positions on the production board is avoided, and the influence on the line width and the impedance value of the production board is reduced.
The relative arrangement of the components and steps, the numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present application unless specifically stated otherwise. In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numerals and letters denote like items and, therefore, once an item is defined, further discussion thereof is not required later.
In the description of the present application, it is to be understood that the directions or positional relationships indicated by the directional terms such as "front, rear, upper, lower, left, right", "lateral, vertical, horizontal" and "top, bottom", etc., are generally based on the directions or positional relationships shown for the convenience of description and simplicity of description, and that these directional terms, unless stated to the contrary, do not indicate and imply that the device or element so referred to must have a particular orientation or be constructed and operated in a particular orientation, and therefore should not be construed as limiting the scope of this application; the terms "inner and outer" refer to the inner and outer relative to the profile of the respective component itself.
For convenience of description, spatially relative terms such as "over 8230; \8230above", "over 8230; \8230;, \8230above", "over 8230; \8230; upper surface", "above", etc., may be used herein to describe the spatial positional relationship of features. It will be understood that the spatially relative terms are intended to encompass different orientations in use or operation in addition to the orientation depicted.
It should be noted that the terms "first", "second", and the like are used to define the components, and are only used for convenience of distinguishing the corresponding components, and the terms have no special meanings unless otherwise stated, and therefore, the scope of protection of the present application is not to be construed as being limited.
If the present application discloses or refers to parts or structures that are fixedly connected to each other, the fixedly connected parts may be understood as follows, unless otherwise stated: a detachable fixed connection (for example using a bolt or screw connection) can also be understood as: non-detachable fixed connections (e.g. riveting, welding), but of course, fixed connections to each other may also be replaced by one-piece structures (e.g. manufactured integrally using a casting process) (unless it is obviously impossible to use an integral forming process).
The above-mentioned preferred embodiments, object, technical solutions and advantages of the present invention are further described in detail, it should be understood that the above-mentioned preferred embodiments are only illustrative of the present invention, and should not be construed as limiting the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (8)
1. A method for reworking a short circuit after etching with little influence on the impedance value of a PCB circuit is characterized by comprising the following steps:
s1, determining a short circuit position, and marking the short circuit position on a production board;
s2, carrying out surface roughening treatment on the production plate;
s3, sticking a dry film on the surface of the production plate;
s4, placing the production plate with the film attached into an exposure machine and aligning by using a negative film;
s5, exposing the production plate;
s6, taking down the film;
s7, carrying out local shading treatment on the short circuit position on a cover film of the dry film of the production board;
s8, carrying out secondary exposure on the production plate;
s9, developing the production plate;
s10, locally etching the exposed position of the production plate at the external short circuit position;
s11, inspecting the production board;
if the quality is qualified, entering a subsequent production processing flow;
if not, the process returns to step S1.
2. The method of reworking a short circuit after etching according to claim 1, wherein the method further comprises the steps of:
the subsequent production and processing flow comprises the following steps:
s12, performing resistance welding on the production board;
s13, carrying out surface treatment on the production plate.
3. The method of reworking a short circuit after etching according to claim 1, wherein the method further comprises the steps of: in step S1, the marking method is to mark a coordinate arrow on the process edge of the production board with an oil pen to facilitate subsequent positioning.
4. The method of rework of post etch shorts with small impact on PCB line impedance values as claimed in claim 1, characterized by: in step S1, the mark is required to be visible through the dry film after the dry film is attached.
5. The method of rework of post etch shorts with small impact on PCB line impedance values as claimed in claim 1, characterized by: in step S2, the surface of the production board is treated by microetching, and the removal of the mark of the short-circuit position should be avoided.
6. The method of rework of post etch shorts with small impact on PCB line impedance values as claimed in claim 1, characterized by: in step S7, the short circuit position is coated on the cover film of the dry film by using a film pen or covered by using a light-shielding tape.
7. The method of reworking a short circuit after etching according to claim 1, wherein the method further comprises the steps of:
in step S11, the detection may be by visual observation;
or, electrical measurement, needle measurement or universal electromechanical performance check is carried out to determine whether an open circuit or a short circuit exists;
or, performing optical AOI line scanning, firstly performing rapid shooting by using a high-definition image camera, then comparing the shot image with an original file, and checking whether an open circuit or a short circuit exists.
8. The method of rework of post etch shorts with small impact on PCB line impedance values as recited in claim 2, wherein: in step S13, the surface treatment method is any one of tin spraying, gold immersion, OSP, tin immersion, silver immersion, nickel-palladium-gold, electro-hard gold, and electro-gold finger.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211442722.3A CN115666008A (en) | 2022-11-18 | 2022-11-18 | Method for reworking short circuit after etching with small influence on impedance value of PCB (printed circuit board) circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211442722.3A CN115666008A (en) | 2022-11-18 | 2022-11-18 | Method for reworking short circuit after etching with small influence on impedance value of PCB (printed circuit board) circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115666008A true CN115666008A (en) | 2023-01-31 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202211442722.3A Pending CN115666008A (en) | 2022-11-18 | 2022-11-18 | Method for reworking short circuit after etching with small influence on impedance value of PCB (printed circuit board) circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115666008A (en) |
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2022
- 2022-11-18 CN CN202211442722.3A patent/CN115666008A/en active Pending
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