Circuit board packaging component repairing method

Abstract

The invention discloses a circuit board packaging component repairing method, belongs to the technical field of rewelding maintenance of surface-mounted components on a circuit board, is suitable for packaging components with pins located at the bottom of packaging, and comprises the following steps: S1, disassembling repaired components on the circuit board; s2, manufacturing soldering tin sheets which are in one-to-one correspondence with the repair part bonding pads; s3, the soldering tin sheets are placed on the repair part bonding pads in a one-to-one correspondence mode, and the replacement components are placed on the soldering tin sheets; and S4, placing the circuit board on which the replacement component and the soldering tin sheet are placed into a reflow soldering furnace for welding. According to the method, the repair step is improved through the mode of manufacturing the soldering tin sheet, the production cycle and cost of the circuit board can be reduced, and the product quality can be guaranteed.

Description

Technical Field

[0001] The invention belongs to the technical field of re-welding and repairing surface mounted components on a circuit board, and in particular relates to a method for repairing circuit board packaged components. Background Art

[0002] Circuit boards often need to be repaired during production and debugging. The high density and variety of components on many circuit boards make it difficult to repair components on circuit boards.

[0003] In circuit boards, packaged components such as QFN (Quad Flat No-leads Package) and BGA (Ball Grid Array) cannot be installed by manual soldering due to their unique pin layout (i.e., the pins are located at the bottom of the package). Therefore, whether it is the installation or rework of components, reflow soldering can only be used. Unlike manual soldering, reflow soldering requires the entire circuit board with components to be placed in a reflow oven for soldering. An existing method for rework of packaged components with pins located at the bottom of the package is to customize a steel sheet (the steel sheet is engraved with holes corresponding to the position of the reworked component), use the steel sheet to brush solder paste on the circuit board, and then reflow solder the components.

[0004] This repair method has the following problems:

[0005] (1) The production cycle of steel sheets is long (requires two or three days) and the cost is high;

[0006] (2) Each different type of package (circuit board or component) requires a steel sheet, which makes the applicability of the steel sheet low;

[0007] (3) Since the steel sheet is larger than the components, the components around the repaired components need to be removed when printing solder paste;

[0008] (4) During rework, it is easy to leave excess solder paste on the board surface when brushing solder paste through the steel sheet, thus affecting the product quality of the circuit board;

[0009] Therefore, a different circuit board QFN and BGA package component rework method is needed to solve the above problems. Summary of the invention

[0010] In view of this, the present invention provides a circuit board package component rework method, which improves the rework steps by making solder sheets, which can not only reduce the production cycle and cost of the circuit board, but also ensure the quality of the product.

[0011] The present invention is achieved through the following technical solutions:

[0012] A method for repairing a circuit board packaged component, wherein the packaged component is a packaged component with a pin located at the bottom of the package;

[0013] The rework method comprises the following steps:

[0014] S1: Remove the repaired components on the circuit board;

[0015] S2: Make solder sheets corresponding to the pads of the reworked parts one by one;

[0016] S3: Place the solder sheets on the pads of the reworked parts one by one, and place the replacement components on the solder sheets;

[0017] S4: Place the circuit board with the replaced components and solder sheets into a reflow oven for soldering.

[0018] Furthermore, in step S2, making the solder sheet includes the following steps:

[0019] S201: Printing solder paste; the solder paste is printed onto the metal plate through a printing plate steel mesh; the printing plate steel mesh is a printing plate steel mesh corresponding to the circuit board;

[0020] S202: heating the solder paste printed on the metal plate to form solder beads; the formed solder beads correspond one to one with the solder pads of the reworked parts;

[0021] S203: Flatten the tin beads to form solder sheets.

[0022] Furthermore, in step S1, the replacement components are heated and removed by a circuit board rework station using infrared heating.

[0023] Furthermore, before the circuit board is placed on the circuit board rework station, components around the rework components are covered with infrared reflective materials.

[0024] Furthermore, after removing and replacing the components, the remaining solder on the pads of the repaired parts is cleaned.

[0025] Furthermore, when printing solder paste in step S201, the printed board steel mesh is pressed to the board surface of the metal plate.

[0026] Furthermore, in step S203, after the solder sheet is made, the solder sheet is cleaned.

[0027] Furthermore, in step S3, flux is coated between the solder sheet and the pad of the reworked part, and flux is coated between the solder sheet and the replacement component.

[0028] Beneficial effects:

[0029] (1) The present invention provides a method for rework of circuit board package components, comprising the steps of making solder sheets corresponding to the pads of the reworked component, and then placing the circuit board with the solder sheets and the replacement components placed thereon into a reflow oven for soldering. Compared with the conventional rework method using a steel sheet, this method only requires placing the solder sheet on the pads of the reworked component, thereby eliminating the step of printing solder paste through the steel sheet. During rework, there is no need to remove components around the reworked component, thereby reducing the production cycle and the production cost. At the same time, the solder sheet can be stably placed on the pads of the reworked component, thereby preliminarily preventing the placed solder sheet from moving during the process of moving the circuit board.

[0030] (2) In a circuit board package component rework method of the present invention, solder paste is printed onto a metal plate through a printed board steel mesh. Since the steel mesh holes of the printed board steel mesh correspond to the solder pad positions of all components on the circuit board, there is no need to customize steel sheets, which can further reduce the production cycle and reduce production costs.

[0031] (3) In a circuit board package component repair method of the present invention, components surrounding the repaired component are covered with infrared reflective material; the infrared reflective material can prevent components surrounding the repaired component from absorbing infrared rays and increasing in temperature, thereby being affected.

[0032] (4) A circuit board package component rework method of the present invention can clean the remaining solder on the pad of the reworked part to ensure that the pad surface is smooth and easy to weld.

[0033] (5) A circuit board package component rework method of the present invention presses the printed circuit board steel mesh to the board surface of the metal plate. The method can make the printed circuit board steel mesh and the board surface of the metal plate fit tightly, which can improve printing accuracy and prevent solder paste overflow.

[0034] (6) The circuit board package component rework method of the present invention can clean the solder sheet and remove the flux residue and dirt in the solder paste, further ensuring the welding quality and thus ensuring the reliability of the circuit board.

[0035] (7) In the present invention, a circuit board package component rework method is provided, wherein flux is coated between the solder sheet and the rework pad, and flux is coated between the solder sheet and the replacement component. The solder sheet and the rework pad, and the solder sheet and the replacement component can be adhered together by the viscosity of the flux, thereby preventing the components from moving before soldering is completed, thereby ensuring the reliability of the circuit board. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a flow chart of the present invention;

[0037] Figure 2 It is a production flow chart of the solder sheet of the present invention. DETAILED DESCRIPTION

[0038] The present invention is described in detail below in conjunction with embodiments.

[0039] This embodiment provides a circuit board package component repair method, such as Figure 1 As shown, this is achieved through the following steps:

[0040] S1: Remove the repaired components on the circuit board;

[0041] S2: Make solder sheets corresponding to the pads of the reworked parts one by one;

[0042] S3: Place the solder sheets one by one on the pads of the reworked part (the pads are metal areas on the circuit board for soldering components, and the pads correspond one by one to the pins of the components), and place the replacement components on the solder sheets;

[0043] S4: Place the circuit board with the replaced components and solder sheets into a reflow oven for soldering.

[0044] Specifically, in step S1, the method for disassembling the repaired components is as follows:

[0045] S101: Baking circuit boards and replacing components

[0046] Before rework, place the circuit board and replacement components (the components are replacement parts for the repaired components) in a baking oven for baking, so as to remove moisture from the circuit board and replacement components, to prevent short circuits, poor welding and other problems during the rework process, and to ensure the improvement of repair quality and safety. The baking time and temperature of the circuit board and replacement components are selected according to the storage time of the circuit board and replacement components, and the models of the circuit board and replacement components. When the circuit board and replacement components are baked at the same time, the baking temperature shall not exceed the maximum baking temperature of the circuit board and replacement components, and the baking time shall not be less than the shortest baking time of the circuit board and replacement components at this temperature. In this embodiment, the baking temperature of the circuit board is 90°C and the baking time is 24 hours, and the baking temperature of the replacement components is 125 degrees and the baking time is 12 hours. In this embodiment, the models of the replacement components are ADP2118ACPZ-1.0-R7 and ADP2118ACPZ-3.3-R7.

[0047] S102: Disassembly and repair components

[0048] The rework components are heated and removed by an infrared-heated circuit board rework station.

[0049] Before disassembly, first cover the components around the repaired components with infrared reflective material (hereinafter described as surrounding components), and then place the covered circuit board correctly on the circuit board repair station for heating. The infrared reflective material is a high temperature resistant material with a mirror surface. During heating, the circuit board repair station heats the circuit board using preset heating parameters (usually directly calling the heating process curve parameters in the circuit board repair station software). When the heating temperature is greater than the melting point of solder (183°C in this embodiment), and the solder of the pin of the repaired component begins to melt, remove the repaired components on the pad (the pad is the metal area on the circuit board for soldering components, and the pad corresponds to the pin of the component one by one, and is described as the repair pad below) and cool the circuit board. In this embodiment, the infrared reflective material is preferably aluminum foil tape, which can reflect infrared light while preventing the surrounding components from overheating. In this embodiment, the maximum heating area of ​​the circuit board repair station is 60mm×60mm.

[0050] S103: Clean the solder pads of the reworked parts

[0051] After the repaired components are disassembled, the remaining solder in the pad of the repaired component is cleaned to make the surface of the pad of the repaired component smooth and convenient for welding. In this embodiment, the remaining solder is cleaned by an electric soldering iron and a tin-absorbing belt.

[0052] S104: Clean the pads of replacement components and reworked parts

[0053] Clean and wipe the surfaces of the replacement components and the reworked parts pads to ensure that the surfaces of the replacement components and the reworked parts pads are clean and free of foreign matter, thereby further ensuring the welding quality and further ensuring the reliability of the circuit board. In this embodiment, the replacement components and the reworked parts pads are wiped with alcohol cotton balls.

[0054] like Figure 2 As shown, in step S2, the method for making the solder sheet is as follows:

[0055] S201: Printing solder paste

[0056] The solder paste is printed on the metal plate through a printed circuit board steel mesh (i.e., the printed circuit board steel mesh when the circuit board is produced, and the steel mesh holes of the printed circuit board steel mesh correspond to the pad positions of all components on the circuit board). The metal plate has a flat surface, has a solder resist effect, and can withstand high temperatures above 200°C. In this embodiment, the metal plate is preferably a stainless steel sheet.

[0057] The steps for printing solder paste are as follows:

[0058] S2011: Place the metal plate on the table, then place the printed board stencil on the surface of the metal plate, press the printed board stencil to make the printed board stencil fit closely with the surface of the metal plate, thereby improving the printing accuracy and preventing solder paste from overflowing;

[0059] S2012: Place the prepared solder paste on the printed circuit board steel mesh and use a scraper to print the solder paste onto the metal plate;

[0060] S2013: After printing the solder paste, slowly lift the PCB stencil to complete the printing and check whether the printing quality meets the requirements.

[0061] S202: Heating the solder paste printed on the metal plate to form solder beads

[0062] The solder paste is heated to form solder beads; the formed solder beads correspond one-to-one with the solder pads of the repaired parts, that is, one-to-one with the pins of the replaced components. In this embodiment, the solder paste is heated by a hot air gun, and the brand model of the solder paste used is Alpha Sn63Pb37-120.

[0063] S203: Flatten the solder ball to form a solder sheet

[0064] S2031: Use a hard tool (such as a flat-blade screwdriver) to flatten the solder ball to form a solder sheet. Compared with the solder ball, the flattened solder sheet can be stably placed on the rework pad, which can initially prevent the placed solder sheet from moving during the process of moving the circuit board.

[0065] S2032: Clean the solder sheet to remove flux residue and dirt (the flux and dirt are from the solder paste used to make the solder sheet). In this embodiment, the solder sheet is cleaned with anhydrous ethanol.

[0066] In step S3, the steps of placing solder sheets and replacing components are as follows:

[0067] S301: Apply flux;

[0068] Before placing the solder sheet and the replacement components, apply flux to the rework pad and the solder sheet. The stickiness of the flux can further prevent the solder sheet and the replacement components from moving during the process of moving the circuit board. In this embodiment, the flux is a rosin pen.

[0069] S302: placing solder sheet;

[0070] When placing the solder sheet, the solder sheet is placed at the center of the corresponding rework pad. This placement method can prevent the solder sheet from connecting to other pads and causing a short circuit, thereby ensuring the welding quality and improving the reliability of the circuit board. The solder sheet adheres to the rework pad through the viscosity of the flux. In this embodiment, the solder sheet is placed on the rework pad of the circuit board by pointed tweezers. After all the solder sheets are placed, check whether the placement position of the solder sheet deviates from the pad or adheres to other pads. The whole process requires delicate operation and can be completed under a magnifying glass.

[0071] S303: Place replacement components

[0072] The pins of the replacement components are adhered to the solder sheet by the viscosity of the flux. The pins of the replacement components correspond to the solder sheet one by one. After all the replacement components are placed, check whether the replacement components are placed correctly and accurately.

[0073] Due to the poor stability of the flux, the circuit board still needs to be handled with care to prevent the components from moving.

[0074] In step S4, the aluminum foil tape on the circuit board is removed before the circuit board with the replacement components and solder sheets is placed into a reflow oven.

[0075] Place the circuit board with the replacement components mounted on it into a reflow oven for reflow soldering.

[0076] When performing reflow soldering, the reflow oven uses the temperature curve of the circuit board during soldering. The temperature curve of the circuit board during soldering depends on the type of components and the type of solder paste.

[0077] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A circuit board package component rework method, characterized in that: The packaged component is a packaged component with pins located at the bottom of the package; The rework method comprises the following steps: S1: Remove the repaired components on the circuit board; S2: Make solder sheets corresponding to the pads of the reworked parts one by one; S3: Place the solder sheets on the pads of the reworked parts one by one, and place the replacement components on the solder sheets; S4: Place the circuit board with the replaced components and solder sheets into a reflow oven for soldering.

2. A circuit board package component rework method as claimed in claim 1, characterized in that: In step S2, making the solder sheet includes the following steps: S201: Printing solder paste; the solder paste is printed onto the metal plate through a printing plate steel mesh; the printing plate steel mesh is a printing plate steel mesh corresponding to the circuit board; S202: heating the solder paste printed on the metal plate to form solder beads; the formed solder beads correspond one to one with the solder pads of the reworked parts; S203: Flatten the tin beads to form solder sheets.

3. A circuit board package component rework method as claimed in claim 1, characterized in that: In step S1, the replacement components are heated and removed by an infrared heated circuit board rework station.

4. A circuit board package component rework method as claimed in claim 3, characterized in that: Before the circuit board is placed on the circuit board rework station, the components around the rework components are covered with infrared reflective materials.

5. A circuit board package component rework method as claimed in claim 1 or 3, characterized in that: After removing and replacing components, clean the remaining solder on the pads of the reworked parts.

6. A circuit board package component rework method as claimed in claim 2, characterized in that: When printing solder paste in step S201, the printed board stencil is pressed onto the board surface of the metal board.

7. A circuit board package component rework method as claimed in claim 2, characterized in that: In step S203, after the solder sheet is made, the solder sheet is cleaned.

8. A circuit board package component rework method as claimed in any one of claims 1 to 7, characterized in that: In step S3, soldering flux is applied between the solder sheet and the pad of the reworked component, and soldering flux is applied between the solder sheet and the replacement component.

Images