A method and apparatus for depositing a metal film on the surface of metal contacts.

Abstract

This invention discloses a method and apparatus for depositing a metal film on the surface of metal contacts, comprising the following steps: S1, covering the surface of the object to be coated with a metal foil with metal contacts; S3, melting the portion of the metal foil corresponding to the metal contacts by laser scanning, and solidifying the molten portion onto the metal contacts; S4, removing the remaining portion of the metal foil that has not solidified onto the metal contacts from the object to be coated. Because the thickness of the metal foil is fixed, this invention can achieve the welding of a metal foil of fixed thickness onto the surface of the object to be coated with metal contacts, thereby precisely controlling the thickness of the coating on the surface of the metal contacts, and easily achieving uniform metal film deposition on the surface of the metal contacts. Furthermore, it has low environmental pollution.

Description

Technical Field

[0001] This invention relates to the technical field of coating of electrical components, and in particular to a method and apparatus for coating a metal film on the surface of metal contacts. Background Technology

[0002] In some electrical components (such as circuit boards and connectors), it is often necessary to plate metal films on the "contact" surface. For example, tin plating is often required on copper pads of circuit boards, and nickel or gold plating is required on some pads or contacts. Some traditional metal plating methods usually use electroplating or chemical plating, which are often environmentally polluting, and the plating thickness is related to the time of electroplating or chemical plating, making it difficult to accurately control the plating thickness and uniformity. Summary of the Invention

[0003] The purpose of this invention is to solve the problem that traditional metal coating methods often involve precise control of coating thickness and uniformity on the surface of metal contacts and are usually environmentally polluting. The invention proposes a method and apparatus for coating metal contacts that is easy to control precisely and uniformly, and has low environmental pollution.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A method for depositing a metal film on the surface of a metal contact includes the following steps:

[0006] S1. Cover the surface of the object to be coated with a metal foil with metal contacts; S3. Melt the portion of the metal foil corresponding to the metal contacts by laser scanning, and the molten portion solidifies on the metal contacts; S4. Remove the remaining portion of the metal foil that has not solidified on the metal contacts from the object to be coated.

[0007] In some embodiments of the present invention, the following step is further included between steps S1 and S3:

[0008] S2. The metal foil is rolled or brushed flat on the object to be coated using a flexible roller or a flexible brush.

[0009] In some embodiments of the present invention, the flexible roller or the flexible brush is made of a silicon- or fluorine-containing organic material.

[0010] In some embodiments of the present invention, in step S3, the laser is selected with a blue wavelength and the laser power is 1W to 100W.

[0011] In some embodiments of the present invention, in step S3, an industrial camera is used to perform position identification to determine the melting position of the metal foil, and the laser scanning is performed based on the identification result.

[0012] In some embodiments of the present invention, in step S3, a laser focusing head is used and its movement is controlled to achieve laser focusing scanning, or a combination of a scanning galvanometer and a field lens is used to achieve laser focusing scanning, wherein the scanning galvanometer is used to control the direction of the laser beam, and the field lens is used to focus the laser beam onto the metal foil plane.

[0013] In some embodiments of the present invention, the laser focusing head is driven to move by a two-dimensional displacement stage, the diameter of the focused spot is 10μm to 100μm, and the scanning linear velocity at the melting position of the metal foil is 1mm / s to 1000mm / s.

[0014] In some embodiments of the present invention, in step S4, the remaining portion of the metal foil is scraped off from the coated object using a flexible scraper.

[0015] In some embodiments of the present invention, the translational speed of the flexible scraper is 10 mm / s to 1000 mm / s, and the pressure applied by the flexible scraper to the coating object is 0.1 N to 10 N.

[0016] The present invention also includes an apparatus for depositing a metal film on the surface of a metal contact, comprising the following components:

[0017] A controller, a flexible roller or flexible brush, controlled by the controller, is used to lay a metal foil flat on the surface of the object to be coated, having metal contacts; a laser, controlled by the controller, is used to emit a laser to melt the portion of the metal foil corresponding to the metal contacts, the molten portion solidifying on the metal contacts; a laser focusing head, or scanning galvanometer and field lens, controlled by the controller, is used to achieve focused scanning of the laser; a flexible scraper, controlled by the controller, is used to scrape off the remaining portion of the metal foil that has not solidified on the metal contacts from the object to be coated; preferably, the object to be coated is a circuit board or a connector; preferably, the contacts are solder pads or electrodes or pins; preferably, the metal foil is nickel foil, gold foil, or tin foil.

[0018] The present invention has the following beneficial effects:

[0019] This invention proposes a method and apparatus for depositing a metal film on the surface of metal contacts. The method involves covering the surface of the object with metal contacts with a metal foil, then using laser scanning to melt and solidify the portion of the metal foil corresponding to the metal contacts onto the metal contacts. The remaining portion of the metal foil that has not solidified onto the metal contacts is then removed from the object. Because the thickness of the metal foil is fixed, it is easy to fuse a metal foil of a fixed thickness onto the surface of the object with metal contacts, thereby precisely controlling the thickness of the coating on the metal contact surface and easily achieving a uniform metal film deposition on the metal contact surface. Furthermore, compared to traditional electroplating or chemical plating, this invention has less environmental pollution.

[0020] Other beneficial effects of the embodiments of the present invention will be further described below. Attached Figure Description

[0021] Figure 1 This is a process flow diagram of an embodiment of the present invention;

[0022] Figure 2 This is a schematic diagram showing the relative positions of the metal foil and the circuit board in step one of the embodiments of the present invention;

[0023] Figure 3 This is a schematic diagram of the rolling of the flexible roller in step one of the embodiments of the present invention;

[0024] Figure 4 This is a schematic diagram of step three in an embodiment of the present invention;

[0025] Figure 5 This is a schematic diagram of step four in an embodiment of the present invention.

[0026] The attached figures are labeled as follows:

[0027] 1 is a circuit board, 2 is a metal foil, 3 is a flexible roller or flexible brush, 4 is a laser beam, 5 is a camera, and 6 is a scraper. Detailed Implementation

[0028] The present invention will be further described below with reference to the accompanying drawings and preferred embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0029] It should be noted that the directional terms such as left, right, up, down, top, and bottom used in this embodiment are only relative concepts or are based on the normal use of the product, and should not be considered as restrictive.

[0030] In this embodiment of the invention, a metal foil of a specific thickness is laid on the "contact point" and energy is delivered by laser to melt the local area, thereby depositing it on the surface of the "contact point". This can achieve a non-chemical coating, and the coating thickness is the same as the thickness of the metal foil, making the coating thickness precisely controllable.

[0031] The following embodiments of the present invention provide a method for depositing a metal film on the surface of a metal contact, comprising the following steps:

[0032] S1. Cover the surface of the object to be coated with a metal foil with metal contacts; S3. Melt the portion of the metal foil corresponding to the metal contacts by laser scanning, and the molten portion solidifies on the metal contacts; S4. Remove the remaining portion of the metal foil that has not solidified on the metal contacts from the object to be coated.

[0033] Preferably, step S2 is included between steps S1 and S3: rolling or brushing the metal foil flat on the object to be coated using a flexible roller or a flexible brush.

[0034] In a preferred embodiment, for depositing a metal film on the surface of a metal contact, in step S3, an industrial camera is used to identify the position of the metal foil to determine the melting position, and the laser scanning is performed based on the identification result.

[0035] This invention also proposes an apparatus for depositing a metal film on the surface of metal contacts, comprising: a controller; a flexible roller or flexible brush, controlled by the controller, for laying a metal foil flat on the surface of the object to be coated, having metal contacts; a laser, controlled by the controller, for emitting a laser to melt the portion of the metal foil corresponding to the metal contacts, the molten portion solidifying on the metal contacts; a laser focusing head, or a scanning galvanometer and field lens, controlled by the controller, for achieving focused scanning of the laser; and a flexible scraper, controlled by the controller, for scraping off the remaining portion of the metal foil not solidified on the metal contacts from the object to be coated; preferably, the object to be coated is a circuit board or a connector; preferably, the contacts are solder pads, electrodes, or pins; preferably, the metal foil is nickel foil, gold foil, or tin foil.

[0036] Example 1

[0037] The method for depositing a metal film on the surface of metal contacts includes the following steps:

[0038] Step 1: Lay out 2 metal foils, as shown Figure 2 , Figure 3As shown, the flexible roller 3 flattens the metal foil 2 onto the circuit board 1. The flexible roller 3 is driven by a one-dimensional translational axis, which is parallel to the xy two-dimensional displacement stage plane. There is a certain normal force between the roller 3 and the circuit board 1. The roller's rolling speed is between 10mm / s and 1000mm / s, and the normal force between the roller and the circuit board is between 0.1N and 10N, ensuring that the flexible roller undergoes a certain deformation under the normal force. If the pads have a certain protrusion, the flexible roller 3 can conform to both the pad area and the non-pad area under the deformation.

[0039] Step Two: As Figure 4 As shown, the two-dimensional displacement stage drives the industrial camera 5 to move. The industrial camera 5 takes pictures of the plane of the circuit board 1 to find the position of the Mark point. By identifying multiple Mark points, the position of the Mark is compared with the circuit board model data to determine the position of the entire circuit board 1, and thus the position of the pads on the circuit board 1.

[0040] Step 3: A two-dimensional displacement stage moves the laser head. The focusing plane of the laser head is the plane of the metal foil 2. Preferably, the diameter of the focused spot of the laser head is 10μm to 100μm. The two-dimensional displacement stage moves the laser head to each pad position, and the laser emits laser 4. Preferably, the laser power is between 1W and 100W. Simultaneously, the laser scans within the area of ​​the pad, covering the entire pad area. Preferably, the scanning linear speed is between 1mm / s and 1000mm / s. After the two-dimensional displacement stage moves the laser head to scan the entire pad area, the laser stops emitting laser light. The two-dimensional displacement stage then moves the laser head to the next pad, and the above process is repeated until all pads on the circuit board 1 that require metal film plating are completed. In a specific embodiment, this process can also be completed by scanning with a galvanometer and a field lens.

[0041] Step Four: As Figure 5 As shown, the flexible scraper 6, driven by a one-dimensional translational axis, bidirectionally scrapes the circuit board 1. The portion of the metal foil 2 on the pads that is melted and adhered to the pads under the laser's action cannot be scraped off by the flexible scraper 6, while the portion not scanned by the laser 4 can be removed by the flexible scraper 6. During the translational motion of the flexible scraper 6, it also exerts a certain positive pressure on the circuit board 1. Under its flexible action, the flexible scraper 6 undergoes a certain deformation, allowing it to conform to the slight protrusions of the pads on the circuit board 1. Preferably, the scraper's translational speed 6 is between 10 mm / s and 1000 mm / s, and the positive pressure exerted by the scraper on the circuit board is preferably between 0.1 N and 10 N.

[0042] Example 2

[0043] The method for depositing a metal film on the surface of metal contacts includes the following steps:

[0044] Step 1: Cover with metal foil, and use a flexible roller or brush to roll or brush the metal foil flat.

[0045] Step 2: Locate the Mark positioning point and align it.

[0046] Step 3: Use a laser to scan the metal foil laid on the contact point above the "contact" where metal needs to be plated. The focused laser scans the contact point in a pattern, and the metal foil melts and is plated onto the "contact" under the action of laser energy. (In this embodiment, the "contact" is a solder pad on a circuit board. In a preferred embodiment, the "contact" is a contact point on a circuit that needs to contact the electrode or pin of a device.)

[0047] In specific embodiments, there are two methods for laser focusing: one is laser focusing head focusing, where the laser focusing head is driven to move by the x-axis and y-axis, thereby realizing laser focusing scanning; the other is scanning galvanometer + field lens, where the scanning galvanometer controls the direction of the laser beam, and the field lens focuses the laser beam onto the metal foil plane.

[0048] Step 4: Use a flexible scraper to scrape the surface of the circuit board in both directions to clean the metal foil that has been melted and plated around the contact pad surface.

[0049] In a specific embodiment, the apparatus for depositing a metal film on the surface of a metal contact includes:

[0050] 1. A flexible roller or flexible brush 3 for flattening the metal foil 2. Preferably, the flexible roller or flexible brush is made of a silicon- or fluorine-containing organic material. Silicon- or fluorine-containing organic materials have low surface energy and are not easily sticky to other substances. Preferably, the surface material of the roller is silicone, polytetrafluoroethylene, or similar materials, which have a certain degree of flexibility and are not easily stuck to the metal foil 2, and will not lift the metal foil 2.

[0051] 2. Laser: The laser uses blue light, which has a higher absorption rate for yellow metals such as metal foil 2, making it easier for the metal foil 2 to absorb the laser and melt, thus adhering to the metal pad; preferably, a 450nm wavelength fiber-coupled output laser is preferred, with laser power adjustable between 1W and 100W.

[0052] 3. Laser optical path and laser focusing head: In specific embodiments, a laser optical path and galvanometer + field lens can also be used.

[0053] 4. An industrial camera 5 (preferably using an imaging lens + CCD) is used to identify mark points and align the positions on the circuit board 1 with the positions in the model data.

[0054] 5. An xy two-dimensional displacement stage can drive the laser focusing head and industrial camera to translate in the xy plane; it can also be equipped with a z-axis motion axis to adjust the laser focusing plane and the industrial camera focusing surface.

[0055] 6. Flexible scraper 6 is used to scrape off the metal foil outside the pads. The reason why a certain degree of flexibility is needed is that the height of the pads may not be strictly equal to that of the non-pads. Especially after the metal foil is plated on the pads, theoretically the height of the pads will be higher than that of the non-pads. The preferred flexible scraper is polytetrafluoroethylene or other adhesive materials, which have a certain degree of flexibility. It can scrape off the metal foil that has not melted and solidified on the pads without damaging the metal plating that has already solidified on the pads.

[0056] 7. Two one-dimensional translational axes in the xy plane, one for driving the roller and the other for driving the flexible scraper.

[0057] 8. Controller, which controls and coordinates the above actions.

[0058] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, several equivalent substitutions or obvious modifications can be made without departing from the concept of the present invention, and all such modifications, achieving the same performance or purpose, should be considered within the scope of protection of the present invention.

Claims

1. A method for depositing a metal film on the surface of circuit board pads, characterized in that, Includes the following steps: S1. Cover the surface of the circuit board with circuit board pads with metal foil; S2. The metal foil is rolled or brushed flat on the surface of the circuit board using a flexible roller or a flexible brush. The flexible roller or the flexible brush is made of an organic material containing silicon or fluorine. S3. By laser scanning, the portion of the metal foil corresponding to the circuit board pad is melted, and the molten portion is solidified on the circuit board pad; S4. The remaining portion of the metal foil that has not solidified on the circuit board pads is scraped off from the circuit board using a flexible scraper. The height of the circuit board pads is higher than the height of the non-pads. When the flexible scraper moves horizontally, it applies positive pressure to the circuit board and deforms under the action of flexibility, conforming to the slight protrusion of the circuit board pads.

2. The method as described in claim 1, characterized in that, In step S3, the laser is selected with a blue wavelength and a laser power of 1W to 100W.

3. The method as described in claim 1, characterized in that, In step S3, an industrial camera is used to identify the location of the melting point of the metal foil, and the laser scanning is performed based on the identification result.

4. The method as described in claim 1, characterized in that, In step S3, a laser focusing head is used and its movement is controlled to achieve laser focusing scanning, or a combination of a scanning galvanometer and a field lens is used to achieve laser focusing scanning. The scanning galvanometer is used to control the direction of the laser beam, and the field lens is used to focus the laser beam onto the metal foil plane.

5. The method as described in claim 4, characterized in that, In step S3, the laser focusing head is moved by a two-dimensional displacement stage, the diameter of the focused spot is 10μm~100μm, and the scanning linear velocity at the melting position of the metal foil is 1mm / s~1000mm / s.

6. The method as described in claim 1, characterized in that, The translational speed of the flexible scraper is 10mm / s to 1000mm / s, and the pressure applied by the flexible scraper to the circuit board is 0.1N to 10N.

7. An apparatus for depositing a metal film on the surface of circuit board pads, characterized in that, include: Controller; A flexible roller or flexible brush, controlled by the controller, is used to lay metal foil flat on the surface of a circuit board with circuit board pads. The flexible roller or the flexible brush is made of a silicon- or fluorine-containing organic material. A laser, controlled by the controller, is used to emit a laser to melt the portion of the metal foil corresponding to the circuit board pads, the molten portion solidifying on the circuit board pads; A laser focusing head, or scanning galvanometer and field lens, is controlled by the controller to achieve focused scanning of the laser. A flexible scraper, controlled by the controller, is used to scrape off the remaining portion of the metal foil that has not solidified on the circuit board pads from the circuit board; the height of the circuit board pads is higher than the height of the non-pads, and when the flexible scraper moves horizontally, it applies positive pressure to the circuit board and deforms under the action of flexibility, conforming to the slight protrusion of the circuit board pads.

8. The apparatus as claimed in claim 7, characterized in that, The metal foil is nickel foil, gold foil, or tin foil.

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