Processing method for low-cost multi-stage signal finger of 1.6 T optical module

Abstract

The invention relates to a processing method of a low-cost multi-stage signal finger of a 1.6 T optical module, which comprises the following steps of: pressing an anti-gold-plating dry film on an electroplated circuit board, exposing by adopting an LDI exposure machine, and only windowing a finger contact to be gold-plated; electroplating nickel and gold on the finger contact of the windowing; removing the gold-plated dry film; pasting a film on the gold-plated finger; carrying out etching processing on the exposed circuit board, and processing an outer-layer circuit and a grading finger; carrying out AOI full-automatic optical detection on the etched circuit board, and carrying out solder mask processing; performing film pressing and exposure on the finger contact in the gold plating area; plating a layer of nickel-palladium-gold on the non-gold-plated finger and the side edge area, completing the film removing treatment, then carrying out AOI scanning detection on the circuit board, and finally carrying out the post-processing treatment. According to the processing method, a mixed surface treatment process is adopted for the multi-stage plugging contact, so that the plating area of electroplated hard gold can be reduced by about 40%, and the gold plating cost is greatly reduced.

Description

TECHNICAL FIELD

[0001] The application relates to a circuit board manufacturing technology, in particular to a processing method of a 1.6T optical module low-cost multi-stage signal finger. BACKGROUND

[0002] With the development of communication technology and the demand of AI big data processing machine data transmission, the requirements of optical module products are getting higher and higher, and the transmission rate is gradually increased from 10GHZ to 400G, 800G and 1.6T. In order to increase the transmission rate, multi-channel superposition derives multi-stage finger contact, and the quality requirement of signal contact is getting higher and higher. At present, the conventional finger gold plating combined with reverse etching process cannot meet the reliability quality requirement of gold-plated contact, and the quality requirement of corrosion resistance of optical module plug must be met.

[0003] The corrosion resistance experiment of PCB (Printed Circuit Board) is a salt spray test, that is, a sodium chloride salt spray test. Common corrosion phenomena include plug end wear corrosion, surface corrosion, end corrosion and sidewall corrosion. At the same time, based on the requirement of wear resistance of plug contact, the process of gold plating processing has brought serious cost challenge to the continuous rise of current gold price. How to meet the appearance quality and reliability of plug contact, and at the same time, greatly save the gold plating process flow and reduce the process cost is a problem to be solved at present. SUMMARY

[0004] In order to overcome the above defects, the application provides a processing method of low-cost multi-stage signal finger, which adopts a mixed surface treatment process for multi-stage plug contact, can reduce the plating area of electroplated hard gold by about 40%, thereby greatly reducing the gold plating cost.

[0005] The technical scheme adopted by the application to solve the technical problems is:

[0006] A processing method of a 1.6T optical module low-cost multi-stage signal finger, comprising the following steps:

[0007] Gold plating dry film: press an anti-gold plating dry film on the circuit board after electroplating, expose it by using an LDI exposure machine, and only open a window for the gold-plated finger contact;

[0008] Gold plating: electroplating nickel gold on the windowed finger contact;

[0009] Gold plating film removal: remove the gold plating dry film;

[0010] Second dry film: paste a film on the finger after gold plating, and use an LDI exposure machine to transfer the image of the outer layer pattern, so as to expose the circuit area that needs to be etched, and prepare for etching processing;

[0011] Etching: The process of etching the exposed circuit board to create the outer circuitry and hierarchical fingers;

[0012] AOI: Perform fully automated optical inspection on the etched circuit board to ensure that the circuit quality is up to standard and perform solder mask treatment;

[0013] Selective dry film: Press and expose the finger contact points in the gold-plated area to expose the unplated fingers and side areas;

[0014] Nickel-palladium-gold plating: A layer of nickel-palladium-gold is plated onto the unplated finger and side areas, and the coating is removed. Then, the circuit board is scanned and inspected by AOI, and finally, post-processing is carried out.

[0015] Optionally, in the gold-plating dry film, a 50±5μm thick anti-gold plating dry film is used, which is laminated by a vacuum laminator, and the exposure machine energy is set to 1400±100mj, the scanning speed is 27±5cm / min, and the alignment method is single-process 24-point partition free expansion and contraction alignment.

[0016] Optionally, the gold plating process includes micro-etching, nickel plating, and gold plating, wherein the gold plating current is 48±3V, the gold plating voltage is 2.0~2.8V, the gold plating line speed is 1.6~2.0m / min, the temperature control of the micro-etching tank is 40±5℃, the temperature control of the nickel bath solution is 53±3℃, and the temperature control of the gold bath solution is 50±2℃.

[0017] Optionally, in the gold plating process, the parameters of the micro-etching tank are as follows: sodium persulfate concentration 80±20mL / L, sulfuric acid concentration 4±1wt%, Cu... 2+ The concentration of nickel is <15g / L. The parameters of the nickel plating bath are as follows: nickel concentration 130±10g / L, pH 3.9±0.3; the parameters of the gold plating bath are as follows: gold concentration 2.0±1g / L, pH 4.6±0.3.

[0018] Optionally, in the secondary dry film process, the outer layer image transfer adopts a partitioned free expansion and contraction alignment operation to ensure that the overlap deviation of the two exposure patterns is <0.3mil.

[0019] Optionally, in the etching process, it is necessary to ensure that the gold fingers are protected by a dry film before etching, and to prohibit the use of a grinding brush after etching to avoid mechanical abrasion of the gold layer, which could lead to exposure of nickel and copper. The etching parameters are as follows: etching rate: 2.3±0.5mil / min, etching bath temperature: 50±2.1℃, etching spray pressure: 2.3±0.35kg / cm 2 Etching solution: Cu 2+ Concentration of HCl: 140±20 g / L, HCl concentration: 1.8±0.3 N, etching line speed: 4.5~4.8 m / min.

[0020] Optionally, in the dry film process, the dry film model is DuPont W265, the dry film is matched with a vacuum film pressing machine, a local partial separation alignment is adopted, a free expansion grabbing is adopted once a pattern identification point, and a pattern alignment deviation needs to be controlled within 0.3 mil.

[0021] Optionally, the process of plating nickel-palladium-gold includes: adhesive tape → adhesive tape pressing → pretreatment → oil removal → micro-etching → acid washing → pre- immersion → activation → post- immersion tank → nickel plating → palladium plating → gold plating → adhesive tape tearing → post-treatment, the pretreatment includes micro-etching and sand blasting, and the post-treatment includes hot water washing and drying.

[0022] Optionally, in the process of plating nickel-palladium-gold, the parameters of the nickel plating tank are as follows: the nickel concentration is 5±0.2 g / L, the pH is 4.5±0.2, and the sodium hypophosphite concentration is 25±5 g / L; the parameters of the palladium plating tank are as follows: the Pd 2+ concentration is 0.3±0.1 g / L, and the pH is 6.5±0.4; and the parameters of the gold plating tank are as follows: the gold concentration is 0.8±0.2 g / L, and the pH is 3.85±0.75.

[0023] Optionally, in the process of removing the film after plating nickel-palladium-gold, the parameters of removing the film are as follows: the linear speed is 1.2-1.7 m / min, the soft film tank temperature is controlled to be 45±5℃, the film removing tank temperature is controlled to be 55±3℃, the acid washing tank temperature is controlled to be 35±5℃, and the drying section temperature is controlled to be 80±5℃.

[0024] The beneficial effects of the application are as follows: in the application, a mixed surface treatment process is adopted for the multi-stage plug-in contact, the core plug-in friction area is processed by electroplated hard gold process, the remaining non-important area and the finger contact sidewall are processed by nickel-palladium-gold process, the plating area of the electroplated hard gold can be reduced by about 40%, and thus the gold plating cost is greatly reduced; the full-plate processing is designed without lead, and is once formed, which can ensure that the gold finger contact is complete without any protrusion and lead residue, can ensure the insertion loss and quality of high-speed signal transmission, and solves the problems of nickel corrosion in the segmented position and the side salt spray test, the suspended gold problem in the reverse etching process, and the high cost problem of four-side full-coating gold plating. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 FIG. 1 is a schematic diagram of a circuit board after gold plating in the application;

[0026] Figure 2 FIG. 2 is a schematic diagram of a circuit board after gold plating in the application;

[0027] Figure 3 FIG. 3 is a schematic diagram of a circuit board after removing the film after gold plating in the application;

[0028] Figure 4 FIG. 4 is a schematic diagram of a circuit board after secondary dry film in the application;

[0029] Figure 5A schematic diagram of a circuit board after etching in the present application;

[0030] Figure 6 A schematic diagram of a circuit board after dry film selection in the present application;

[0031] Figure 7 A schematic diagram of a circuit board after nickel-palladium-gold plating in the present application. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application. Obviously, the embodiments described in the present application are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0033] It should be noted that the terms "first", "second", and the like in the description, claims, and the following drawings of the present application are used to distinguish similar objects, and do not necessarily indicate a specific order or sequence. It should be understood that the objects thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or device including a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products, or devices.

[0034] For ease of description, spatial relative terms such as "over", "above", "upper surface", "upper", and the like can be used herein to describe the spatial positional relationship of one device or feature with respect to other devices or features as shown in the drawings. It should be understood that the spatial relative terms are intended to include different orientations in use or operation in addition to the orientation of the devices as described in the drawings. For example, if the devices in the drawings are inverted, the device described as "above" or "over" other devices or structures will be positioned "below" or "under" the other devices or structures. Thus, the exemplary term "above" can include both "above" and "below" orientations. The devices can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein are interpreted accordingly.

[0035] A processing method of a 1.6T optical module low-cost multi-stage signal finger, comprising the following steps:

[0036] Gold plating dry film: After electroplating, the anti-gold plating dry film is pressed on the circuit board, and the LDI exposure machine is used for exposure, only the finger contact to be plated with gold is windowed; only the gold-plated pad is windowed, and the segmented position between the fingers is covered with a gold-plated dry film;

[0037] Gold plating: electroplating nickel gold on the windowed finger contact;

[0038] Gold plating film removal: remove the gold plating dry film; that is, remove the segmented position and other dry films etched;

[0039] Secondary dry film: after the gold plating is completed, the finger film is exposed to the outer layer image using the LDI exposure machine, so that the circuit area to be etched is exposed, preparing for etching processing;

[0040] Etching: etching the exposed circuit board to process the outer layer circuit and the hierarchical finger; that is, etching the copper foil of the segmented position to form a gap, thereby forming a hierarchical finger;

[0041] AOI: AOI full-automatic optical detection is performed on the etched circuit board to ensure that the circuit quality is qualified, and the solder mask treatment is performed;

[0042] Selecting chemical dry film: the finger contact in the gold-plated area is pressed and exposed, exposing the un-gold-plated finger and side area;

[0043] Nickel-palladium-gold plating: a layer of nickel-palladium-gold is plated on the un-gold-plated finger and side area, and the film removal process is completed, then the circuit board is scanned and detected by AOI, and finally the post-processing is performed.

[0044] After electroplating in this application, the whole plate is pressed with a gold plating dry film, only the gold-plated finger is windowed for gold plating, and after gold plating, the normal dry film is made, the circuit is processed out after etching, the lead is not reserved, the solder mask is normally made after AOI inspection, the solder mask is completed, the nickel-palladium-gold is made by vacuum pressing, the finger is processed by semi-replacement and semi-reduction nickel-palladium-gold process, the gold thickness is processed to 0.07-0.13 μm, and then the normal film removal, text, and molding are completed. In this application, a mixed surface treatment process is used for the multi-hierarchical plug-in contact, the core plug-in friction area is reserved for electroplated hard gold process, the remaining non-important area and the finger contact side wall are processed by nickel-palladium-gold process, which can reduce the plated area of the electroplated hard gold by about 40%, thereby greatly reducing the gold plating cost; the whole plate is processed without lead design, one-time molding can ensure that the gold finger contact is complete without any protrusion and lead residue, can ensure the insertion loss and quality of high-speed signal transmission, and solves the problems of nickel corrosion in segmented position and side salt spray test, reverse etching process suspended gold, and high cost of four-side full-coating gold plating.

[0045] In the gold plating dry film, a special anti-gold plating dry film with a thickness of 50±5 μm is used, a vacuum film press is used for film pressing, the energy of the exposure machine is set to 1400±100 mj, the scanning speed is 27±5 cm / min, and the alignment mode is single-process 24-point partition free expansion alignment.

[0046] The gold plating process includes micro-etching, nickel plating and gold plating, wherein the gold plating current is 48±3 V, the gold plating voltage is 2.0-2.8 V, the gold plating line speed is 1.6-2.0 m / min, the micro-etching tank temperature control is 40±5℃, the nickel tank medicine water temperature control is 53±3℃, and the gold tank medicine water temperature control is 50±2℃.

[0047] In the gold plating process, the parameters of the micro-etching tank are as follows: the concentration of sodium persulfate is 80±20 mL / L, the concentration of sulfuric acid is 4±1 wt%, the concentration of Cu 2+ is <15 g / L, the parameters of the nickel plating tank are as follows: the concentration of nickel is 130±10 g / L, and pH is 3.9±0.3; and the parameters of the gold plating tank are as follows: the concentration of gold is 2.0±1 g / L, and pH is 4.6±0.3.

[0048] In the process of the second dry film, the outer layer image transfer adopts partition free expansion alignment operation to ensure that the deviation of the coincidence degree of the two exposure patterns is <0.3 mil.

[0049] In the etching process, the gold finger needs to be protected by the dry film before etching, and the gold layer is prevented from being exposed to nickel and copper due to mechanical grinding and brushing after etching. The etching processing parameters are as follows: etching rate: 2.3±0.5 mil / min, etching tank liquid temperature: 50±2.1℃, etching spray pressure: 2.3±0.35㎏ / cm 2 , etching medicine: the concentration of Cu 2+ : 140±20 g / L, the concentration of HCl: 1.8±0.3 N, and etching line speed: 4.5-4.8 m / min.

[0050] In the dry film process for chemical selection, the dry film model is DuPont W265, the dry film is matched with a vacuum film press, the film pressing and exposure are performed on the plug-in contact finger with a completed anti-welding thickness, about 70% of the area with plated gold is covered, and the side area of the plug-in contact pad is exposed, the exposure machine adopts local partition alignment, and the pattern alignment deviation needs to be controlled within 0.3 mil.

[0051] The process of nickel-palladium-gold plating includes: adhesive tape → glue pressing → pretreatment → oil removal → micro-etching → pickling → pre-impregnation → activation → post-impregnation tank → nickelization → palladiumization → goldization → adhesive tape tearing → post-treatment, the pretreatment includes micro-etching and sand blasting, and the post-treatment includes hot water washing and drying.

[0052] In the process of plating nickel-palladium-gold, the parameters of the nickel plating tank are: nickel concentration 5±0.2 g / L, pH 4.5±0.2, and sodium hypophosphite concentration 25±5 g / L; the parameters of the palladium plating tank are: Pd concentration 0.3±0.1 g / L, pH 6.5±0.4; and the parameters of the gold plating tank are: gold concentration 0.8±0.2 g / L, and pH 3.85±0.75. 2+

[0053] In the post-plating nickel-palladium-gold stripping process, the parameters of the stripping are as follows: linear speed: 1.2-1.7 m / min, soft film tank temperature control 45±5℃, stripping tank temperature control 55±3℃, pickling tank temperature control 35±5℃, and drying section temperature control 80±5℃. In order to cope with the rising gold price, the PCB contact terminal core contact (about 70%) is retained for gold plating in the present application, and the non-core area (about 30%) adopts a low-cost alternative process. ENEPIG has the best compatibility (no galvanic corrosion) with the gold surface, excellent salt spray resistance, good solderability / contact, and the cost is significantly lower than that of the pure thick gold process. In the present application, ENEPIG is selected as the alternative process, the whole gold plating is adopted to reduce the gold plating area, only the core contact area (about 70%) is retained for gold plating windowing, and then line processing is performed. After the completion of the solder mask, the ENEPIG nickel-palladium-gold process is used to deposit and cover the gold side edge and the non-core area (about 30%). Precise patterning design and strict mask making, alignment and process control are adopted. The whole process is processed by LDI (laser direct imaging) process, and the exposure alignment accuracy can be controlled to 0.012 mm. Comprehensive interface design and thorough reliability verification (emphasis on salt spray test and interface analysis).

[0054] Example 1: The simplified process of a low-cost multi-stage signal finger processing method is as follows: cutting → inner layer → pressing → brown oxidation copper reduction → laser drilling → mechanical drilling → horizontal PTH → electroplating filling → pulse electroplating → outer layer (only windowed gold pad) → gold plating → stripping → secondary dry film → etching (line + pad) → AOI → solder mask → selective chemical dry film → ENEPIG (finger side wall adopts semi-displacement + semi-reduction nickel-palladium-gold process, gold thickness processing 3-5 μ") → stripping → text → forming → electrical measurement → appearance inspection → packaging. The key process is described as follows:

[0055] Step 1: outer layer (only windowed gold pad): as shown in Figure 1 , gold plating dry film is covered at the segmented position, 50 μm anti-gold plating dry film is used, and LDI exposure machine is used after pressing film, exposure energy is set to 1400 mj, scanning speed is 27 cm / min, and the alignment method is single step 24 point partition free expansion alignment.

[0056] Step 2: gold plating: as shown in Figure 2 ​As shown, the plated gold dry film and the windowed hierarchical finger contact are electroplated with nickel gold, gold plating current: 48±3V, gold plating voltage: 2.0-2.8V, gold plating line speed: 1.6-2.0m / min, micro-etching tank temperature control: 40±5℃, nickel tank chemical temperature control: 53±3℃, gold tank chemical temperature control 50±2℃, as shown Figure 3 As shown, the gold plating dry film at the segmented position is removed after gold plating;

[0057] Step 3: Secondary dry film: as shown Figure 4 After gold plating is completed, the finger is pasted with a secondary dry film, and an LDI exposure machine is used for image transfer operation of the outer layer pattern. The outer layer image transfer uses partitioned free expansion alignment operation to ensure that the coincidence deviation of the two exposure patterns is less than 0.3 mil, so that the circuit area that needs to be etched is exposed, preparing for etching processing;

[0058] Step 4: Etching (circuit + pad): as shown Figure 5 The printed circuit board with completed secondary dry film is etched for etching processing. Gold finger needs to be protected by dry film before etching, and brushing is prohibited after etching to avoid nickel and copper exposure caused by mechanical brushing of the gold layer. Etching processing parameters are as follows: etching rate: 2.3±0.5mil / min, etching tank temperature: 50±2.1℃, etching spray pressure: 2.3±0.35㎏ / cm2, etching chemical Cu2+: 140±20g / l, etching chemical HCl: 1.8±0.3N, etching line speed: 4.5-4.8m / min;

[0059] Step 5: Selective dry film: as shown Figure 6 The completed solder mask of the plug-in contact finger is pressed with a vacuum film press and exposed using a dry film type: DuPont W265 dry film. The exposed area covers 70% of the gold-plated area and exposes the side area of the plug-in contact pad. An LDI exposure machine is used for local segmentation alignment, and a free expansion Mark point is captured once. The pattern alignment deviation needs to be controlled within 0.3 mil;

[0060] Step 6: ENEPIG: as shown Figure 7 The printed circuit board with completed selective dry film is processed with nickel, palladium and gold.

[0061] Nickel, palladium and gold processing flow: paste→pressing→pretreatment (micro-etching + sandblasting)→oil removal→micro-etching→acid pickling→pre- immersion→activation→post- immersion tank→nickel plating→palladium plating→gold plating→tearing→post-processing (hot water washing + drying);

[0062] Step 7: Film removal: the printed board after selective gold plating is subjected to film removal treatment, and the film removal parameters are as follows: linear speed: 1.2-1.7 m / min, soft film tank temperature control 45±5℃, film removal tank temperature control 55±3℃, pickling tank temperature control 35±5℃, drying section temperature control: 80±5℃.

[0063] It should be noted that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present application, which are all within the scope of protection of the present application. Therefore, the scope of protection of the patent of the present application shall be subject to the appended claims.

Claims

1. A method for processing a 1.6T optical module low-cost multi-stage signal finger, characterized in that: It comprises the following steps: Gold plating dry film: After electroplating, the anti-gold plating dry film is pressed on the circuit board, and LDI exposure machine is used for exposure, only the finger contact to be plated with gold is windowed; Gold plating: The finger contact is electroplated with nickel gold; Gold plating film removal: The gold plating dry film is removed; Secondary dry film: After the gold plating is completed, the finger film is transferred to the outer layer image by using LDI exposure machine, so that the circuit area to be etched is exposed, and preparation is made for etching processing; Etching: The circuit board after exposure is etched to process the outer layer circuit and the hierarchical finger; AOI: The circuit board after etching is subjected to AOI full-automatic optical detection to ensure that the circuit quality is qualified, and the solder mask treatment is carried out; Selective chemical dry film: The finger contact in the gold plating area is subjected to film pressing and exposure to expose the un-gold plated finger and side edge area; Nickel-palladium-gold plating: A layer of nickel-palladium-gold is plated on the un-gold plated finger and side edge area, and film removal treatment is carried out, then the circuit board is subjected to AOI scanning detection, and finally post-processing treatment is carried out.

2. The method of claim 1, wherein the 1.6T optical module low-cost multi-stage signal finger is characterized by: In the gold plating dry film, a 50±5μm thick anti-gold plating special dry film is used, the film is pressed by a vacuum film press, the exposure machine energy is set to 1400±100mj, the scanning speed is 27±5cm / min, and the alignment mode is single process 24-point partition free expansion alignment.

3. The method of claim 1, wherein the 1.6T optical module low-cost multi-stage signal finger is characterized by: The gold plating process comprises micro-etching, nickel plating and gold plating, wherein the gold plating current is 48±3V, the gold plating voltage is 2.0-2.8V, the gold plating line speed is 1.6-2.0m / min, the micro-etching tank temperature control is 40±5℃, the nickel tank chemical temperature control is 53±3℃, and the gold tank chemical temperature control is 50±2℃.

4. The method of claim 3, wherein the 1.6T optical module low-cost multi-stage signal finger is processed. In the gold plating process, the parameters of the micro-etching tank are as follows: the concentration of sodium persulfate is 80±20 mL / L, the concentration of sulfuric acid is 4±1 wt%, the concentration of Cu 2+ is <15 g / L, the parameters of the nickel plating tank are as follows: the concentration of nickel is 130±10 g / L, pH is 3.9±0.3; the parameters of the gold plating tank are as follows: the concentration of gold is 2.0±1 g / L, pH is 4.6±0.

3.

5. The method of claim 1, wherein the 1.6T optical module low-cost multi-tiered signal finger is processed. In the secondary dry film process, the outer layer image transfer adopts partition free expansion alignment operation to ensure that the deviation of the two exposure pattern coincidences is less than 0.3mil.

6. The method of claim 1, wherein the 1.6T optical module low-cost multi-tiered signal finger is processed. In the etching process, the gold fingers need to be protected by dry film before etching, and mechanical brushing is prohibited after etching to avoid exposure of nickel and copper due to mechanical brushing of the gold layer. The etching process parameters are as follows: etching rate: 2.3±0.5 mil / min, etching bath temperature: 50±2.1℃, etching spray pressure: 2.3±0.35㎏ / cm 2 , etching chemical: Cu 2+ concentration: 140±20g / L, HCl concentration: 1.8±0.3N, etching line speed: 4.5-4.8m / min.

7. The method of claim 1, wherein the 1.6T optical module low-cost multi-tiered signal finger is processed. In the selective chemical dry film process, the dry film type is Dupont W265, the dry film is matched with a vacuum film press, the exposure machine adopts local partition alignment, and the free expansion captures the pattern identification point once, and the pattern alignment deviation needs to be controlled within 0.3mil.

8. The method of claim 1, wherein the 1.6T optical module low-cost multi-tiered signal finger is processed. The nickel-palladium-gold plating process comprises: glue sticking→glue pressing→pretreatment→oil removal→micro-etching→acid washing→pre-impregnation→activation→post-impregnation tank→nickelization→palladiumization→goldization→glue tearing→post-treatment, the pretreatment comprises micro-etching and sand blasting, and the post-treatment comprises hot water washing and drying.

9. The processing method for the low-cost multi-level signal finger of the 1.6T optical module according to claim 8, characterized in that: In the process of plating nickel-palladium-gold, the parameters of the plating solution in the nickel plating tank are: nickel concentration 5±0.2 g / L, pH 4.5±0.2, and sodium hypophosphite concentration 25±5 g / L; the parameters of the plating solution in the palladium plating tank are: Pd 2+ concentration 0.3±0.1 g / L, and pH 6.5±0.4; and the parameters of the plating solution in the gold plating tank are: gold concentration 0.8±0.2 g / L, and pH 3.85±0.

75.

10. The method of claim 1, wherein the 1.6T optical module low-cost multi-tiered signal finger is characterized by: In the film removal process after nickel-palladium-gold plating, the film removal parameters are as follows: line speed: 1.2-1.7m / min, soft film tank temperature control: 45±5℃, film removal tank temperature control: 55±3℃, acid washing tank temperature control: 35±5℃, and drying section temperature control: 80±5℃.

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