CN111112842A - Gold-removing tin-coating method and application - Google Patents
Gold-removing tin-coating method and application Download PDFInfo
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- CN111112842A CN111112842A CN201911344103.9A CN201911344103A CN111112842A CN 111112842 A CN111112842 A CN 111112842A CN 201911344103 A CN201911344103 A CN 201911344103A CN 111112842 A CN111112842 A CN 111112842A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/36—Removing material
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/70—Auxiliary operations or equipment
- B23K26/702—Auxiliary equipment
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Abstract
The invention discloses a gold-removing tin-coating method and application, comprising the following steps: setting laser parameters, wherein the wavelength is 300-355 nm, the diameter of a light spot is 0.012-0.015, the average energy is 1.2-2.0W, the frequency is 32-40 KHZ, the marking speed is 200-350 mm/s, and the path interval is 0.005-0.008 mm; marking the surface of the electronic component for 1-3 times according to the laser marking path to remove the gold layer on the surface of the electronic component; marking the surface of the electronic component for 1-3 times according to the laser marking path to activate the surface of the electronic component; the method has the advantages of high processing efficiency, good consistency, thorough gold removal, simple operation, good controllability and consistency of gold removal tin plating effect, no damage and environmental pollution to a nickel layer, good surface wettability and easy operation of subsequent welding.
Description
Technical Field
The invention belongs to the technical field of welding of electronic product printing plates, and particularly relates to a gold-removing tin-coating method and application.
Background
The gold element is widely applied to the surface coating of the electrode or the bonding pad of the electronic component due to the characteristics of good chemical stability, difficult oxidation and the like. In the production of printed board assemblies for electronic products, electronic components are usually mounted on a printed board by a tin-lead eutectic alloy soldering method. In the process of welding gold-plated components, Au-Sn intermetallic compounds are formed in welding spots, the Vickers hardness of the Au-Sn intermetallic compounds is as high as 750, the Au-Sn intermetallic compounds are obviously brittle and hard, and the existence of the Au-Sn intermetallic compounds can cause the mechanical property of the welding spots to be greatly reduced, thereby seriously influencing the reliability of electrical connection. The phenomenon that a common welding spot is subjected to brittle fracture due to the existence of a compound is called 'gold brittleness', the 'gold brittleness' phenomenon seriously influences the reliability of a product during service, and in order to prevent the 'gold brittleness' phenomenon, the gold-plated components are specified in national and international military industry standards to be weldable after being subjected to gold tin-coating treatment.
At present, the main method for removing gold and tin in electronic components is a manual tin coating method. The manual tin enameling method is characterized in that manual tin enameling is carried out by using a soldering iron, the tin enameling temperature is generally 260-280 ℃ and the time is 2-3 s, then a tin enamel layer on the surface is absorbed and removed after a tin absorption rope is used for heating, the manual tin enameling method depends on the proficiency of operators, the production efficiency is low, and the phenomenon of uneven gold removal is easily caused.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the gold removal and tin enameling method and application are provided in the prior gold removal and tin enameling process of electronic components, wherein gold removal is not uniform.
The invention solves the technical problems through the following technical scheme, and the method for removing gold and tin on the electronic component comprises the following steps:
(1) removing the gold layer on the surface of the electronic component:
placing an electronic component to be subjected to gold removal on a laser processing platform, placing a surface to be subjected to gold removal in a processing focal distance plane of a laser, and marking the surface of the electronic component for 1-3 times according to a laser marking path under the condition that auxiliary gas blows the surface to be subjected to gold removal to complete removal of a gold layer on the surface of the electronic component;
the laser parameters are that the wavelength is 300-355 nm, the diameter of a light spot is 0.012-0.015 mm, the average energy is 1.2-2.0W, the frequency is 32-40 KHZ, the marking speed is 200-350 mm/s, and the path interval is 0.005-0.008 mm;
(2) activating the surface of the electronic component:
placing the electronic component subjected to gold removal on the laser processing platform, placing the gold-removed surface in a processing focal distance plane of a laser, and marking the surface of the electronic component for 1-3 times according to a laser marking path under the condition that auxiliary gas blows the gold-removed surface to complete activation of the surface of the electronic component;
the laser parameters are: the wavelength is 300-355 nm, the diameter of a light spot is 0.015mm, the average energy is 0.2-0.6W, the frequency is 40-45 KHZ, the marking speed is 280-300 mm/s, and the path interval is 0.005-0.008 mm;
(3) carrying out tin coating treatment on the surface of the electronic component:
carrying out tin coating treatment on the surface of the activated electronic component, wherein the treatment process comprises the following steps: lead-tin soldering pieces with the thickness of 25 microns are placed on the surface of the activated electronic component, the temperature of the bottom of the heating table is set to be 210 ℃, and the temperature of the bottom of the heating table is set to be the temperature of the heating table.
In the step (1), the electronic component comprises any one of a metal tube shell, a gold-plated circuit board and a ferrule pin; the laser is an ultraviolet nanosecond pulse laser; the auxiliary gas is compressed air;
in the step (2), the laser marking path is transverse scanning or longitudinal scanning.
An electronic component for removing gold and tin by using a gold and tin removing method of the electronic component;
the immersion angle of the gold-removed tin-coated surface of the electronic component is less than 40 degrees; the soldering penetration rate of the gold-removed tin-lined surface of the electronic component is not less than 90%;
an application of an electronic component in preparing a spaceflight TR component.
The invention relates to a method for removing gold and tin on an electronic component, which adopts ultraviolet laser beams to treat the surface of a nickel-gold layer of the electronic component to be welded, the ultraviolet laser beams have short wavelength and concentrated energy, and the surface to be gold-removed absorbs laser under the physical and chemical action of the laserAfter energy is applied, physical and chemical changes such as vibration, melting, combustion, gasification and the like are generated, so that the gold layer material is quickly separated from the surface of the electronic component, a nickel layer is exposed, the gold removing efficiency is high, the gold removing is uniform, and the surface treatment rate can reach 0.8mm2And/s, and has no damage to the nickel layer.
In addition, the gold-plated layer-containing base material absorbs laser energy, so that the surface coating can be melted instantly, and due to the fact that the ultraviolet laser is short in wavelength, concentrated in energy and small in heat affected zone and is cooled rapidly under the action of external cooling air flow, the cleanliness of the surface of the bonding pad after remelting is high, and the consistency is good.
Auxiliary gas is adopted for cooling in the process of laser marking the surface of the electronic component, so that the heat effect of laser processing is reduced, and meanwhile, impurity components generated by laser etching on the surface of the electronic component are extracted; after gold removing treatment is carried out on the gold-plated layer of the electronic component by adopting ultraviolet laser, surface activation treatment is carried out, so that the surface wetting angle is smaller than 40 degrees, and good wettability is achieved; tin coating treatment is carried out on the surface of the electronic component after gold removing treatment, so that the wettability of the surface is improved, and the surface is prevented from being oxidized after gold removing.
And (3) carrying out tin coating treatment on the surface of the activated electronic component, adopting a lead-tin soldering lug with the thickness of 25 mu m, setting the temperature of a hot platform at 210 ℃, and enabling the soldering lug to be compatible with the surface of the activated electronic component, thereby preventing the nickel plating layer from being oxidized and improving the wettability.
Therefore, compared with the prior art, the invention has the following advantages: the method has the advantages of high gold removing efficiency, uniform gold removing, no damage to a nickel layer, high cleanliness and good consistency after remelting the surface of the bonding pad, thorough gold removing, simple operation and strong controllability, can prevent the nickel plating layer from being oxidized after gold removing, ensures that the surface of the electronic component after gold removing and tin coating treatment has better surface wettability, is beneficial to subsequent welding operation and has no environmental pollution.
Drawings
FIG. 1 is a schematic view of the gold removal operation of the present invention,
1-laser source, 2-laser processing path, 3-tube shell to be removed of gold, 4-movable workbench;
FIG. 2 is a scanning electron microscope photograph of the surface of the electronic component after the gold removing treatment,
a-before gold removal and b-after gold removal;
fig. 3 is a spectrum of the surface of the electronic component after the gold removing treatment.
Detailed Description
The following examples are given for the detailed implementation and specific operation of the present invention, but the scope of the present invention is not limited to the following examples.
Example 1
The bottom plate of the tube shell of a certain aerospace TR component is made of carbon-silicon-aluminum materials which are subjected to surface treatment by adopting an electroplating nickel-gold process, the bottom plate is welded on a substrate by using a tin-lead eutectic alloy soldering (SnPb) method, and in order to avoid the phenomenon of gold brittleness, gold-removing tin-coating treatment needs to be carried out on a gold-plated layer of the bottom plate.
The gold removing and tin coating steps are as follows:
(1) placing the component tube shell on a laser processing platform, fixing the component tube shell by extracting vacuum, and focusing a laser spot on the surface to be processed by adjusting the height of a laser head;
(2) carrying out surface treatment on the welding disk by adopting an ultraviolet pulse laser:
the cleaning range of the gold plating layer of the bonding pad is set to be 30mm x 40mm, the laser marking path adopts a transverse filling scanning mode, and the path interval is 0.005 mm; the laser wavelength is 300nm, the diameter of a laser spot is 0.012mm, the average laser energy is set to be 1.2W, the frequency is 32KHZ, and the laser marking speed is 200 mm/s; opening auxiliary compressed air to carry out blowing cooling on the surface of the welding disc in the machining process, machining for 1 time by laser according to a set path, and finishing the gold removing treatment of the welding disc;
TABLE 1 results of energy spectrum analysis
| Element(s) | Weight percent of | Atomic percent |
| Ni K | 32.48 | 61.74 |
| Au M | 67.52 | 38.26 |
| Total amount of | 100.00 | -- |
As shown in FIG. 2, the left image in FIG. 2 is the scanning electron microscope image before gold removal and the right image is the scanning electron microscope image after gold removal, and the comparison shows that the surface has better smoothness and uniform gold removal after laser gold removal;
fig. 3 is an energy spectrum diagram of the surface to be welded after being treated by the gold removing method of the present invention, and table 1 is an energy spectrum analysis result, and it can be seen from the analysis of the results of fig. 3 and table 1 that the surface has both gold element and nickel element after laser gold removing, which indicates that the gold removing thickness has reached the bonding surface layer of the nickel-gold plating layer, so that the gold removing effect is good.
Then, changing the average energy of each pulse of the laser into 0.2W, keeping the other parameters unchanged, and reprocessing for 1 time according to a set path to complete the activation treatment on the welding disk;
(3) carrying out tin coating treatment on the surface of the electronic component:
after the gold on the surface of the bonding pad is removed and activated, hot stage welding is adopted, SnPb solder is used for soldering the tube shell and the substrate, the welding temperature is 210 ℃, the wetting visual angle of the surface subjected to gold tin coating activation treatment and the solder is 40 degrees through experiment, the penetration rate after welding is 90 percent, and the welding effect is good.
Example 2
The bottom plate of a certain FP packaging chip is a carbon-silicon-aluminum material which is subjected to surface treatment by adopting an electroplating nickel-gold process, and is welded on a substrate by using a tin-lead eutectic alloy soldering (SnPb) method, so that in order to avoid the phenomenon of gold brittleness, gold-removing tin-coating treatment needs to be carried out on a gold-plating layer.
The gold removing and tin coating steps are as follows:
(1) placing the component tube shell on a laser processing platform, fixing the component tube shell by extracting vacuum, and focusing a laser spot on the surface to be processed by adjusting the height of a laser head;
(2) carrying out surface treatment on the welding disk by adopting an ultraviolet pulse laser:
the cleaning range of the gold plating layer of the bonding pad is set to be 30mm x 40mm, the laser marking path adopts a longitudinal filling scanning mode, and the distance between the paths is 0.006 mm; the laser wavelength is 325nm, the diameter of a laser spot is 0.013mm, the average laser energy is set to be 1.5W, the frequency is 35KHZ, and the laser marking speed is 300 mm/s; opening auxiliary compressed air to carry out blowing cooling on the surface of the welding disc in the machining process, and machining for 2 times by laser according to a set path to finish the gold removing treatment of the welding disc;
then, the average energy of each pulse of the laser is changed into 0.4W, the other parameters are unchanged, and the laser is processed for 2 times according to a set path to complete the activation treatment of the welding disk;
(3) carrying out tin coating treatment on the surface of the electronic component:
after the gold on the surface of the bonding pad is removed and activated, hot stage welding is adopted, SnPb solder is used for soldering the tube shell and the substrate, the welding temperature is 210 ℃, the wetting visual angle between the surface subjected to gold tin coating activation treatment and the solder is 35 degrees through experiment, the penetration rate after welding is 92 percent, and the welding effect is good.
Example 3
The bottom plate of a QFP packaging chip is a carbon-silicon-aluminum material which is subjected to surface treatment by adopting an electroplating nickel-gold process, and is welded on a substrate by using a tin-lead eutectic alloy soldering (SnPb) method, so that in order to avoid the phenomenon of gold brittleness, gold-removing tin-coating treatment needs to be carried out on a gold-plating layer.
The gold removing and tin coating steps are as follows:
(1) placing the component tube shell on a laser processing platform, fixing the component tube shell by extracting vacuum, and focusing a laser spot on the surface to be processed by adjusting the height of a laser head;
(2) carrying out surface treatment on the welding disk by adopting an ultraviolet pulse laser:
the cleaning range of the gold plating layer of the bonding pad is set to be 30mm x 40mm, the laser marking path adopts a transverse filling scanning mode, and the path interval is 0.008 mm; the laser wavelength is 355nm, the diameter of a laser spot is 0.015mm, the average laser energy is set to be 2.0W, the frequency is 40KHZ, and the laser marking speed is 350 mm/s; opening auxiliary compressed air to carry out blowing cooling on the surface of the welding disc in the machining process, machining for 3 times by laser according to a set path, and finishing the gold removing treatment of the welding disc;
then, the average energy of each pulse of the laser is changed into 0.6W, the other parameters are unchanged, and the processing is carried out for 3 times according to the set path, so as to complete the activation treatment of the bonding pad;
(3) carrying out tin coating treatment on the surface of the electronic component:
after the gold on the surface of the bonding pad is removed and activated, hot stage welding is adopted, SnPb solder is used for soldering the tube shell and the substrate, the welding temperature is 210 ℃, the wetting visual angle of the surface subjected to gold tin coating activation treatment and the solder is 32 degrees through experiment, the penetration rate after welding is 95 percent, and the welding effect is good.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (10)
1. A method for removing gold and tin on an electronic component is characterized by comprising the following steps:
(1) removing the gold layer on the surface of the electronic component:
placing an electronic component to be subjected to gold removal on a laser processing platform, placing a surface to be subjected to gold removal in a processing focal distance plane of a laser, blowing auxiliary gas, and marking the surface of the electronic component for 1-3 times according to a laser marking path to complete removal of a gold layer on the surface of the electronic component;
the laser parameters are that the wavelength is 300-355 nm, the diameter of a light spot is 0.012-0.015 mm, the average energy is 1.2-2.0W, the frequency is 32-40 KHZ, the marking speed is 200-350 mm/s, and the path interval is 0.005-0.008 mm;
(2) activating the surface of the electronic component:
placing the electronic component subjected to gold removal on a laser processing platform, placing the gold-removed surface in a processing focal distance plane of a laser, blowing auxiliary gas, and marking the surface of the electronic component for 1-3 times according to a laser marking path to complete activation of the surface of the electronic component;
the laser parameters are: the wavelength is 300-355 nm, the diameter of a light spot is 0.015mm, the average energy is 0.2-0.6W, the frequency is 40-45 KHZ, the marking speed is 280-300 mm/s, and the path interval is 0.005-0.008 mm;
(3) carrying out tin coating treatment on the surface of the electronic component:
carrying out tin coating treatment on the surface of the activated electronic component, wherein the treatment process comprises the following steps: lead-tin soldering flakes with the thickness of 25 microns are placed on the surface of the activated electronic component, and the bottom temperature of a hot table is set to be 210 ℃.
2. The method for removing gold and coating tin on an electronic component as claimed in claim 1, wherein in the step (1), the electronic component comprises any one of a metal package, a gold-plated circuit board and a pin of a ferrule.
3. The method for removing gold and tin on the electronic component as claimed in claim 1, wherein in the step (1), the laser is an ultraviolet nanosecond pulse laser.
4. The method for removing gold and tin on an electronic component as claimed in claim 1, wherein in the step (1), the auxiliary gas is compressed air.
5. The method for removing gold and tin on an electronic component as claimed in claim 1, wherein in the step (2), the laser marking path is a transverse scanning.
6. The method for removing gold and tin on an electronic component as claimed in claim 1, wherein in the step (2), the laser marking path is a longitudinal scan.
7. An electronic component which is subjected to gold and tin removing by using the gold and tin removing method of the electronic component according to any one of claims 1 to 6.
8. The electronic component as claimed in claim 7, wherein a wetting angle of the gold-removed tin-coated surface of the electronic component is less than 40 °.
9. The electronic component as claimed in claim 7, wherein the gold-tin-removed surface soldering penetration rate of the electronic component is not less than 90%.
10. Use of an electronic component as claimed in any one of claims 7 to 9 in the manufacture of an aerospace TR assembly.
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| CN201911344103.9A CN111112842A (en) | 2019-12-24 | 2019-12-24 | Gold-removing tin-coating method and application |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113798682A (en) * | 2021-08-25 | 2021-12-17 | 南京理工大学 | Femtosecond laser thinning method for micron-sized gold plating layer in field of pad pretreatment |
| CN114654039A (en) * | 2020-12-23 | 2022-06-24 | 深圳市振华微电子有限公司 | Method for coating tin on nickel coating layer by adopting preformed soldering lug |
| CN115592223A (en) * | 2022-09-27 | 2023-01-13 | 张永忠（Cn） | Tin-coating and gold-removing device for aviation plug welding cup |
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| CN109950162A (en) * | 2019-03-22 | 2019-06-28 | 中国电子科技集团公司第三十八研究所 | Promote the laser surface treatment method of pad ultrasonic bonding quality |
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| US20060196857A1 (en) * | 2005-03-03 | 2006-09-07 | Samtec, Inc. | Methods of manufacturing electrical contacts having solder stops |
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| Publication number | Priority date | Publication date | Assignee | Title |
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Application publication date: 20200508 |