WO2022100682A1 - Processing method for high-speed photoelectric coupling module printed plug pcb - Google Patents

Abstract

A processing method for a high-speed photoelectric coupling module printed plug PCB comprises the following steps: photoelectric coupling module PCB → inner layer → lamination → edge milling → drilling → plating → outer circuit → AOI scan → wet film circuit → thick gold dry film → nickel and gold plating → film removal → film attachment → exposure → alkaline etching → AOI scan → solder resist → legend → surface finish → forming → electrical test → finished product inspection. After an inner pull wire is plated with nickel and gold, etching is performed on the wire, thereby implementing a process of covering four sides of edge connectors of the photoelectric coupling module PCB with nickel and gold, enabling a product to pass a mixed flowing gas (MFG) test and a salt spray test, and providing a processing method that improves product quality.

Description

A processing method of high-speed photoelectric coupling module printed plug PCB technical field

The invention belongs to the technical field of manufacturing a high-speed photoelectric coupling module printed circuit board, and in particular relates to a processing method for a high-speed photoelectric coupling module printed plug PCB.

Background technique

The optoelectronic coupling module is composed of optoelectronic devices, functional circuits and optical interfaces. The optoelectronic devices include two parts: transmitting and receiving. The optical module is mainly responsible for photoelectric conversion. The transmitting end converts the electrical signal into an optical signal. After transmission through the optical fiber, the receiving end converts the optical signal into an electrical signal.

technical problem

The optoelectronic module market basically adopts the gold-plated + gold-finger technology for the rate below 10Gbps. In this process, the gold fingers are electroplated first, and then the lead is drawn before etching. Only the upper layer of the copper layer of the fingers is coated with nickel and gold, and the eaves (overhanging copper) of the gold fingers are protruding, and there is a risk of collapse and falling off, which is often complained by customers. More than 10-100Gbps rate is made of immersion gold + gold finger, immersion nickel palladium gold + gold finger. The industry mainly adopts the process of front-pulling the lead, and some patents use the inner-layer lead-pulling (immersion gold + gold finger) process. After completion, the connecting line is cut off through the second drilling process. For high-density products, the wiring density is very high. There is little space for drilling, and the drilling process is the bottleneck of the PCB factory and requires customers to accept porous and exposed copper defects in the hole. All of the above are insufficient.

technical solutions

In view of this, the present invention starts from the process capability of design and process, adopts the method of pulling gold finger leads inside, and makes the copper layer of the gold finger connection part of the optoelectronic coupling module uniform through a new design of the PCB processing flow and processing method. The ground is covered with nickel layer and gold layer to meet the needs of customers for MFG mixed gas test and salt spray test. Meet the design requirements of high transfer rate of 5G optocoupler modules.

The technical scheme of the present invention is:

A method for processing a printed plug PCB of a high-speed photoelectric coupling module, which is characterized by comprising the following steps: photoelectric coupling module PCB → inner layer → pressing → edge milling → drilling → electroplating → outer layer circuit → AOI scanning → wet film Line → thick gold dry film → nickel gold plating → film removal → film sticking → exposure → alkaline etching → AOI scanning → solder mask → character → surface treatment → forming → electrical measurement → finished product inspection.

Further, in the outer layer circuit, each gold finger is made into an inner lead with a width of 5 mil. The junction area of the gold finger lead set needs to be crossed in the X and Y directions to the edge of the board, and the circuit is made according to this file.

Further, in the AOI scanning after the outer layer line, the AOI calls the outer layer engineering data scan with the lead wire to confirm the defects, and the CCD magnification of the re-inspection machine is fixed at 25-40 times when repairing the abnormal point.

Further, the products that have completed the AOI overhaul are pre-treated by super-roughening the inner layer, the spray pressure is 1.0-1.4kg/cm ² , and the speed is 2.5-2.8m/min to ensure the quality of the film.

Further, in the wet film line, the coating speed of the wet film printing is 2-7 m/min, and the plate is baked at 150 degrees for 5 minutes after printing.

Further, in the thick gold dry film, the exposed plated edge and the fingers that need to be plated with nickel and gold are exposed to the LDI equipment for laser imaging according to the parameters of the thick gold dry film, and the energy is set to 65±5mj to ensure that the gold-plated area is pulled into the board. The lead direction extends 6 mil, and the conventional opening of the solder mask is 1-2 mil.

Further, in the nickel-gold plating, the photoelectric coupling module PCB board is installed on the gold-plated wire, and the added inward lead is used to connect the power supply to nickel-plating for 15-30 minutes and then gold-plating for 400-800 seconds, and the detection nickel thickness is 150-200 U. ", the thickness of gold is between 2-4 U".

Further, during the film removal, the film removal line removes the dry film, and the conveying speed is controlled at 1.8-2.2m/min, and the quality of the gold finger position is checked without leakage plating and appearance quality problems.

Further, in applying the dry film, a thick dry film with a thickness of more than 2 mils is used to protect the non-gold finger area. Preferably, a 2mil thick dry film of DuPont 220 is used to protect the exposed leads in the non-gold finger area.

Further, during exposure, a conventional exposure machine is used to expose the leads. When there are independent gold finger pads or there is a requirement for lead residues, LDI exposure is used, and the energy is set to 65±5mj.

Further, in alkaline etching, turn off the new liquid washing and ammonia washing to etch the inner lead, and remove the film immediately after the etching is clean, and control the conveying speed at 1.8-2.2m/min. membrane. The product residence time should be less than 1 minute to prevent copper surface corrosion.

Further, after alkaline etching, remove the film, and then perform AOI scanning: use the customer's original data or lead-free line data to scan to check whether the inner lead is etched cleanly, and the residual standard of the inner lead is repaired according to the customer's requirements. No repairs are made.

It also includes engineering data design, specifically: the preferred choice of gold finger leads in the board is added to the inner pads and through-hole solder rings, and connected to the edge of the board;

The pads are added at the corners, and the via rings are added at the edges. When there are pads and vias in the same network, the vias are preferred. When the vias cannot be added due to location reasons, the pads are selected;

Independent pads are added on the inner side, and if the inner space is limited, they are added at the inner corners.

In the present invention, the principle of engineering data design is:

1. Make sure that 100% of the gold finger pads are added with leads during data production, including independent pads, and the gold fingers without leads will leak nickel-gold;

2. Each junction area of the gold finger leads needs to be crossed in the X and Y directions to the copper sheet on the edge of the board, so that the fingers can be electroplated with nickel, gold, and gold.

3. The distance between the conventional gold finger leads from the connection position and the periphery is ≥6mil, and the gold finger leads can be drawn from the center of the pad to ensure that the window and cover wire are at least 3 mils respectively when gold-plated fingers; Lead out from the inner corner of the golden finger.

4. The width of the inner lead is 5mil, and the minimum width of the window and cover line is 3mil;

5. The gold-plated area extends 6 mil in the direction of the lead inside the board;

6. The lead wire bypasses the line. If the line cannot be bypassed, choose a non-impedance line;

7. Impedance lines that cannot be avoided by the leads, differential impedance lines are added on the outside where the spacing will not be affected.

The product is designed according to the engineering data, and the inner layer circuit, lamination, drilling, electroplating, outer layer circuit, drawing tin, alkaline etching to the outer layer AOI are made according to the conventional process.

The invention effectively solves the problem that the eaves (overhanging copper) of the PCB gold fingers of the opto-coupler module are protruding, and there is a risk of collapse and falling off, ensuring product quality and meeting the rate requirements of the 10G-100Gbps PCB opto-coupler module in the optical module market.

beneficial effect

1. The present invention is used as a new technology and a new process: the conventional process is to first electroplate gold fingers and then etch the lead wire process. Only the copper layer of the fingers and the front are covered with nickel and gold, and the eaves (overhanging copper) of the gold fingers are prominent, and there are The risk of collapse and shedding is often complained by customers. The new process can realize nickel-gold on all sides of the product, and solve the quality problem of collapse and shedding of hair on the four sides of the PCB gold finger part of the optocoupler module that cannot be solved by the conventional process. breakthrough.

2. Improve the quality: The new process realizes the process technology of four-covered nickel-gold on the gold fingers of the PCB of the opto-coupler module through the technical scheme of electroplating nickel-gold on the inner lead and then etching the lead, which satisfies the product's test for MFG mixed gas. , The demand for salt spray test has improved product quality.

3. Cost reduction: The photoelectric coupling module PCB is a high value-added processing project in the 5G and subsequent markets. Mastering key manufacturing technologies can obtain more orders for the company, win the market for the company, and obtain higher processing profits.

4. Improve the delivery cycle: The new process is a technological innovation of the current process, with strong operability, which can meet the needs of printed board manufacturers for mass production and safe production, and can become a new profit increase point for enterprises.

In the present invention, the lead is etched by electroplating nickel-gold inside the lead, so as to realize the process technology of four-covered nickel-gold on the gold finger part of the PCB of the optoelectronic coupling module, and meet the requirements of the product for MFG mixed gas test and salt spray test. , Processing methods to improve product quality.

Description of drawings

Fig. 1 is the process flow chart of the processing method of the present invention.

Embodiments of the present invention

The present invention will be described in further detail below in conjunction with specific embodiments, but it should not be understood that the scope of the present invention is limited to the following examples. The raw materials used can be obtained from open commercial sources unless otherwise specified.

Example 1

A method for processing a printed plug PCB of a high-speed photoelectric coupling module, which is characterized by comprising the following steps: photoelectric coupling module PCB → inner layer → pressing → edge milling → drilling → electroplating → outer layer circuit → AOI scanning → wet film Line → thick gold dry film → nickel gold plating → film removal → film sticking → exposure → alkaline etching → AOI scanning → solder mask → character → surface treatment → forming → electrical measurement → finished product inspection.

Further, in the outer layer circuit, each gold finger is made into an inner lead with a width of 5 mil. The junction area of the gold finger lead set needs to be crossed in the X and Y directions to the edge of the board, and the circuit is made according to this file.

Further, in the AOI scanning after the outer layer line, the AOI calls the outer layer engineering data scan with the lead wire to confirm the defects, and the CCD magnification of the re-inspection machine is fixed at 32 times when repairing the abnormal point.

Further, the products that have completed the AOI maintenance are pre-treated by super-roughening the inner layer, the spray pressure is 1.2kg/cm ² , and the speed is 2.6m/min to ensure the quality of the film.

Further, in the wet film line, the coating speed of the wet film is 5 m/min, and the plate is baked at 150 degrees for 5 minutes after printing.

Further, in the thick gold dry film, the exposed plated edge and the fingers that need to be plated with nickel and gold are exposed to the LDI equipment for laser imaging according to the parameters of the thick gold dry film, and the energy is set to 65±5mj to ensure that the gold-plated area is pulled into the board. The lead direction extends 6 mil, and the conventional opening of the solder mask is 1-2 mil.

Further, in the nickel-gold plating, the photoelectric coupling module PCB board is installed on the gold-plated wire, and the added inward lead is used to connect the power supply to nickel-plating for 24 minutes and then gold-plating for 600 seconds. The detection thickness of nickel is 170 U", and the thickness of gold is 3 U".

Further, during the film removal, the film removal line removes the dry film, and the conveying speed is controlled at 2.0m/min, and the quality of the gold finger position is checked without leakage plating and appearance quality problems.

Further, in applying the dry film, a thick dry film with a thickness of more than 2 mils is used to protect the non-gold finger area. Preferably, a 2mil thick dry film of DuPont 220 is used to protect the exposed leads in the non-gold finger area.

Further, during exposure, a conventional exposure machine is used to expose the leads. When there are independent gold finger pads or there is a requirement for lead residues, LDI exposure is used, and the energy is set to 65±5mj.

Further, in the alkaline etching, turn off the new liquid washing and ammonia washing to etch the inner pulling lead, and immediately remove the film after the etching is clean, and control the conveying speed at 2.0m/min. The product residence time should be less than 1 minute to prevent copper surface corrosion.

Further, after alkaline etching, remove the film, and then perform AOI scanning: use the customer's original data or lead-free line data to scan to check whether the inner lead is etched cleanly, and the residual standard of the inner lead is repaired according to the customer's requirements. No repairs are made.

It also includes engineering data design, specifically: the preferred choice of gold finger leads in the board is added to the inner pads and through-hole solder rings, and connected to the edge of the board;

The pads are added at the corners, and the via rings are added at the edges. When there are pads and vias in the same network, the vias are preferred. When the vias cannot be added due to location reasons, the pads are selected;

Independent pads are added on the inner side, and if the inner space is limited, they are added at the inner corners.

Example 2

A method for processing a printed plug PCB of a high-speed photoelectric coupling module, which is characterized by comprising the following steps: photoelectric coupling module PCB → inner layer → pressing → edge milling → drilling → electroplating → outer layer circuit → AOI scanning → wet film Line → thick gold dry film → nickel gold plating → film removal → film sticking → exposure → alkaline etching → AOI scanning → solder mask → character → surface treatment → forming → electrical measurement → finished product inspection.

Further, in the outer layer circuit, each gold finger is made into an inner lead with a width of 5 mil. The junction area of the gold finger lead set needs to be crossed in the X and Y directions to the edge of the board, and the circuit is made according to this file.

Further, in the AOI scanning after the outer layer line, the AOI calls the outer layer engineering data scan with the lead wire to confirm the defect, and the CCD magnification of the re-inspection machine is fixed at 25 times when repairing the abnormal point.

Further, the products that have completed AOI overhaul are pre-treated by super-roughening the inner layer. The spray pressure is 1.0kg/cm2 and the speed is 2.5m/min to ensure the quality of the film.

Further, in the wet film circuit, the coating speed of the wet film is 2m/min, and the plate is baked at 150 degrees for 5 minutes after printing.

Further, in the thick gold dry film, the exposed plated edge and the fingers that need to be plated with nickel and gold are exposed to the LDI equipment for laser imaging according to the parameters of the thick gold dry film, and the energy is set to 65±5mj to ensure that the gold-plated area is pulled into the board. The lead direction extends 6 mil, and the conventional opening of the solder mask is 1-2 mil.

Further, in the nickel-gold plating, the photoelectric coupling module PCB board is installed on the gold-plated wire, and the added inward lead is used to connect the power supply to nickel-plating for 15 minutes and then gold-plating for 400 seconds. U".

Further, during the film removal, the film removal line removes the dry film, and the conveying speed is controlled at 1.8m/min to check the quality of the gold finger position without leakage plating and appearance quality problems.

Further, in applying the dry film, a thick dry film with a thickness of more than 2 mils is used to protect the non-gold finger area. Preferably, a 2mil thick dry film of DuPont 220 is used to protect the exposed leads in the non-gold finger area.

Further, during exposure, a conventional exposure machine is used to expose the leads. When there are independent gold finger pads or there is a requirement for lead residues, LDI exposure is used, and the energy is set to 65±5mj.

Further, in the alkaline etching, turn off the new liquid washing and ammonia washing to etch the inner pulling lead, and immediately remove the film after the etching is clean, and control the conveying speed at 1.8m/min. The product residence time should be less than 1 minute to prevent copper surface corrosion.

Further, after alkaline etching, remove the film, and then perform AOI scanning: use the customer's original data or wire-free line data to scan to check whether the inner lead is etched cleanly, and the residual standard of the inner lead is repaired according to the customer's requirements. No repairs are made.

It also includes engineering data design, specifically: the preferred choice of gold finger leads in the board is added to the inner pads and through-hole solder rings, and connected to the edge of the board;

The pads are added at the corners, and the via rings are added at the edges. When there are pads and vias in the same network, the vias are preferred. When the vias cannot be added due to location reasons, the pads are selected;

Independent pads are added on the inner side, and if the inner space is limited, they are added at the inner corners.

Example 3

A method for processing a printed plug PCB of a high-speed photoelectric coupling module, which is characterized by comprising the following steps: photoelectric coupling module PCB → inner layer → pressing → edge milling → drilling → electroplating → outer layer circuit → AOI scanning → wet film Line → thick gold dry film → nickel gold plating → film removal → film sticking → exposure → alkaline etching → AOI scanning → solder mask → character → surface treatment → forming → electrical measurement → finished product inspection.

Further, in the outer layer circuit, each gold finger is made into an inner lead with a width of 5 mil. The junction area of the gold finger lead set needs to be crossed in the X and Y directions to the edge of the board, and the circuit is made according to this file.

Further, in the AOI scanning after the outer layer line, the AOI calls the outer layer engineering data scan with the lead wire to confirm the defect, and the CCD magnification of the re-inspection machine is fixed at 40 times when repairing the abnormal point.

Further, the products that have completed AOI overhaul are pre-treated by super-roughening the inner layer. The spray pressure is 1.4kg/cm2 and the speed is 2.8m/min to ensure the quality of the film.

Further, in the wet film line, the coating speed of the wet film is 7 m/min, and the plate is baked at 150 degrees for 5 minutes after printing.

Further, in the thick gold dry film, the exposed plated edge and the fingers that need to be plated with nickel and gold are exposed to the LDI equipment for laser imaging according to the parameters of the thick gold dry film, and the energy is set to 65±5mj to ensure that the gold-plated area is pulled into the board. The lead direction extends 6 mil, and the conventional opening of the solder mask is 1-2 mil.

Further, in the nickel-gold plating, the photoelectric coupling module PCB board is installed on the gold-plated wire, and the added inward lead is used to connect the power supply to nickel-plating for 30 minutes and then gold-plating for 800 seconds. between 4 U".

Further, during the film removal, the film removal line removes the dry film, and the conveying speed is controlled at 2.2m/min to check the quality of the gold finger position without leakage plating and appearance quality problems.

Further, in applying the dry film, a thick dry film with a thickness of more than 2 mils is used to protect the non-gold finger area. Preferably, a 2mil thick dry film of DuPont 220 is used to protect the exposed leads in the non-gold finger area.

Further, during exposure, a conventional exposure machine is used to expose the leads. When there are independent gold finger pads or there is a requirement for lead residues, LDI exposure is used, and the energy is set to 65±5mj.

Further, in the alkaline etching, turn off the new liquid washing and ammonia washing to etch the inner lead wire, remove the film immediately after the etching is clean, and control the conveying speed at 2.2m/min, turn off the new liquid washing and ammonia washing, and remove the film immediately after etching. The product residence time should be less than 1 minute to prevent copper surface corrosion.

Further, after alkaline etching, remove the film, and then perform AOI scanning: use the customer's original data or lead-free line data to scan to check whether the inner lead is etched cleanly, and the residual standard of the inner lead is repaired according to the customer's requirements. No repairs are made.

It also includes engineering data design, specifically: the preferred choice of gold finger leads in the board is added to the inner pads and through-hole solder rings, and connected to the edge of the board;

The pads are added at the corners, and the via rings are added at the edges. When there are pads and vias in the same network, the vias are preferred. When the vias cannot be added due to location reasons, the pads are selected;

Independent pads are added on the inner side, and if the inner space is limited, they are added at the inner corners.

Processing effect test

Through the processing method of the present invention, different materials are processed according to the material properties, and the products are tested, and the results are shown in the following table.

serial number	Part No	Number of golden fingers	Leak plating	Exterior	Nickel Thickness	Jin Hou
1	M123456	5200	none	qualified	qualified	qualified
2	M234567	4800	none	qualified	qualified	qualified
3	M345678	7500	none	qualified	qualified	qualified
4	M456789	1300	none	qualified	qualified	qualified

It will be apparent to those skilled in the art that the present invention is not limited to the details of the above-described exemplary embodiments, but that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments are to be regarded in all respects as illustrative and not restrictive, and the scope of the invention is to be defined by the appended claims rather than the foregoing description, which are therefore intended to fall within the scope of the claims. All changes within the meaning and range of the equivalents of , are included in the present invention.

In addition, it should be understood that although this specification is described in terms of embodiments, not each embodiment only includes an independent technical solution, and this description in the specification is only for the sake of clarity, and those skilled in the art should take the specification as a whole , the technical solutions in each embodiment can also be appropriately combined to form other implementations that can be understood by those skilled in the art. It should be noted that the technical features not described in detail in the present invention can be realized by any prior art in the art.

Claims (10)

1. A method for processing a printed plug PCB of a high-speed photoelectric coupling module, which is characterized by comprising the following steps: photoelectric coupling module PCB → inner layer → pressing → edge milling → drilling → electroplating → outer layer circuit → AOI scanning → wet film Circuit → thick gold dry film → nickel gold plating → film stripping → film sticking → exposure → alkaline etching → AOI scanning → solder mask → character → surface treatment → forming → electrical measurement → finished product inspection.
2. The method for processing a printed plug PCB of a high-speed optocoupler module according to claim 1, wherein in the AOI scanning after the outer layer line, the AOI calls the outer layer engineering data scan with the leads to confirm the defects and detect the abnormal points. When repairing, the CCD magnification of the re-inspection machine is fixed at 25-40 times.
3. The method for processing a printed plug PCB of a high-speed optoelectronic coupling module according to claim 1, wherein the product that has completed the AOI overhaul is pre-treated by super-roughening the inner layer, and the spray pressure is 1.0-1.4 kg/cm ² , The speed is 2.5 -2.8m/min to ensure the quality of the film.
4. The processing method for printing a plug PCB of a high-speed photoelectric coupling module according to claim 1, characterized in that, in the wet film circuit, the printing wet film coating speed is 2-7 m/min, and after printing, the plate is baked at 150 degrees for 5 minutes , The product after printing the wet film is not exposed to be exposed together after the dry film is attached.
5. The method for processing a printed plug PCB of a high-speed optoelectronic coupling module according to claim 1, wherein, in the thick gold dry film, the plated edge and fingers that need to be electroplated with nickel and gold are exposed, and the laser is selected according to the thick gold dry film parameters. The imaged LDI equipment is exposed, the energy is set to 65±5mj, to ensure that the gold-plated area extends 6mil in the direction of pulling the lead in the board, and the conventional opening of the solder mask is 1-2mil.
6. The method for processing a printed plug PCB of a high-speed opto-coupler module according to claim 1, wherein in the nickel-gold plating, the opto-coupler module PCB board is mounted on the gold-plated wire, and the added inner lead is used to turn on the power first. Nickel-plating for 15-30min and gold-plating for 400-800 seconds, the nickel thickness is between 150-200 U" and the gold thickness is between 2-4 U".
7. The method for processing a printed plug PCB of a high-speed optoelectronic coupling module according to claim 1, wherein, during the film removal, the film removal line removes the dry film, the conveying speed is controlled at 1.8-2.2m/min, and the position of the golden finger is checked for Quality without leakage plating and appearance quality problems.
8. The method for processing a printed plug PCB of a high-speed optocoupler module according to claim 1, wherein in the exposure, a conventional exposure machine is used to expose the leads, and LDI is used when there are independent gold finger pads or there is a requirement for residual leads. Exposure, energy setting 65±5mj.
9. The method for processing a printed plug PCB of a high-speed photoelectric coupling module according to claim 1, characterized in that, in the alkaline etching, the new liquid washing and ammonia washing are turned off to etch the inner pulling leads, the film is removed immediately after the etching is clean, and the conveying speed is controlled At 1.8-2.2m/min, the product stay time should be less than 1 minute; after alkaline etching, remove the film, and then perform AOI scanning: use the customer's original data or lead-free line data to scan, and check whether the inner lead is etched cleanly, The residual standard of the inner lead wire shall be repaired according to the customer's requirements, and no repair shall be made if there is no requirement.
10. The method for processing a printed plug PCB of a high-speed opto-coupler module according to claim 1, further comprising engineering data design, specifically: the preferred selection of gold finger leads in the board to add pads on the inner side, through-hole soldering at the ring and connected to the edge of the board;

    The pads are added at the corners, and the via rings are added at the edges. When there are pads and vias in the same network, the vias are preferred. When the vias cannot be added due to location reasons, the pads are selected;

    Independent pads are added on the inner side, and if the inner spacing is limited, they are added at the inner corners.