Method for reliably repairing and welding surface-mounted memory bank socket

Abstract

The invention discloses a method for reliably repairing and welding a surface-mounted memory bank socket, which specifically comprises the following steps of: quantitatively tinning pins of the surface-mounted memory bank socket on a PCB (Printed Circuit Board) by adopting a designed solder paste transfer tinning method in advance, coating a layer of flux paste on a bonding pad of the surface-mounted memory bank socket on the PCB during repairing, and after welding and heating, carrying out soldering on the pins of the surface-mounted memory bank socket on the PCB by adopting the flux paste transfer tinning method; and the tin material attached to each pin of the socket is re-melted to form a welding spot meeting the requirement with the bonding pad. According to the invention, the pre-tinning tin amount of each pin of the surface-mounted socket is uniform and consistent, and the tin amount is controllable; the shape of the repaired surface-mounted memory bank socket pin welding spot is consistent with that of a qualified welding spot before repair, and the welding quality is reliable.

Description

Technical Field

[0001] The invention relates to the technical field of rework welding of a surface mounted memory stick socket, and more particularly to a method for reliably rework welding of a surface mounted memory stick socket. Background Art

[0002] As people's requirements for miniaturization and multi-function of electronic products become higher and higher, the assembly density of PCBA is also getting higher and higher, and the spacing between components is getting smaller and smaller. Figure 1 In particular, electronic information and communication products, such as computer motherboards, have higher and higher CPU main frequencies and more and more line cores. The surface mount memory sockets on the PCB are arranged around the CPU chip, and the spacing between the surface mount memory sockets is basically less than 1mm.

[0003] If the surface mount memory socket on the PCB board has poor welding or subsequent damage, the rework welding of the surface mount memory socket is very difficult, and the welding quality and reliability cannot be guaranteed, resulting in the scrapping of the entire PCB board. The main reasons are: ① There is no welding space during traditional manual welding rework; ② When using the SMT process for rework, it is difficult and almost impossible to print solder paste on the solder pad of the PCB surface mount memory socket; the commonly used method is to use a soldering iron to tin the pins of the surface mount memory socket, and then install the surface mount memory socket into the welding position, and use a hot air soldering station to heat and melt the tin on the socket pins to form a solder joint with the pad. Due to the small amount of tin on the pins and the uneven consistency, the solder joint quality is poor, the reliability cannot be guaranteed, and even the direct rework fails. Summary of the invention

[0004] The purpose of the present invention is to provide a method for reliably repairing and soldering a surface mount memory stick socket, which is convenient for printing solder paste on a tooling bottom plate. The shape of the solder joints of the pins of the surface mount memory stick socket after repair is consistent with the qualified solder joints before repair, and the welding quality is reliable.

[0005] The technical solution to achieve the purpose of the present invention is:

[0006] A reliable method for rework soldering a surface mount memory stick socket. Pins of a new surface mount memory stick socket on a PCB are pre-tinned quantitatively using a designed solder paste transfer tinning method. During rework, a layer of flux paste is coated on the soldering pad of the surface mount memory stick socket on the PCB. After soldering heating, the tin material attached to each pin of the socket is re-melted to form a solder joint that meets the requirements with the soldering pad.

[0007] Further, the steps include:

[0008] Step 2-1, using a solder paste transfer tinning tool, printing solder paste on the tool base, inserting a new surface mount memory module socket, heating to melt the solder paste, melting the solder paste printed on the tool base, and attaching it to each pin of the surface mount memory module socket;

[0009] Step 2-2, during rework, clean the pads of the surface mount memory module socket on the PCB board to be reworked, evenly apply a layer of flux paste, install the pre-tinned surface mount memory module socket, use a hot air nozzle, and heat and solder on the BGA rework station.

[0010] Furthermore, the solder paste transfer tinning tooling includes a solder paste printing steel sheet, a steel sheet mesh frame, positioning pins and a tooling base plate; the solder paste printing steel sheet has a solder paste pattern, the steel sheet mesh frame is placed on the solder paste printing steel sheet, both are provided with positioning holes, and are fixed by positioning pins to form a solder paste printing tooling, and the solder paste printing tooling is installed on the tooling base plate; when using the solder paste transfer tinning tooling, all the pins of the surface mount memory stick socket are placed on the solder paste pattern printed by the solder paste printing tooling.

[0011] Furthermore, the opening size and thickness of the solder paste printed steel sheet are determined according to the pin spacing of the surface mount memory stick socket and the pad size of the socket pin on the PCB, and all the pads of the surface mount memory stick socket to be removed on the PCB are evenly heated.

[0012] Furthermore, the tooling bottom plate is provided with solder paste printing tooling positioning holes and surface mount memory stick socket placement positioning holes.

[0013] Furthermore, the size of the hot air nozzle is determined according to the size of the surface mount memory module socket.

[0014] Furthermore, the hot air nozzle includes an upper nozzle and a lower nozzle, which heat the upper and lower surfaces of the surface mount memory module socket respectively, and the upper part of the upper nozzle and the bottom of the lower nozzle are consistent with the size of the original nozzle of the rework station.

[0015] Furthermore, the size of the hot air outlet of the upper air nozzle is consistent with the length and width of the surface mount memory module socket.

[0016] Furthermore, the size and length of the hot air outlet of the lower air nozzle are consistent with the length of the surface mount memory stick socket, and the width is 1.5-2 times the width of the surface mount memory stick socket.

[0017] Furthermore, the diameters of the air guide holes of the air guide plates in the upper air nozzle and the lower air nozzle gradually increase from the middle to both ends.

[0018] Compared with the prior art, the present invention has the following advantages: the pins of the surface mount memory stick socket are pre-tinned in a quantitative manner using the "solder paste transfer tinning method" involved, which facilitates the printing of solder paste onto the tooling base plate, and there is no need to consider the difficulty of local solder paste printing on the surface mount socket caused by the high assembly density of the PCB board; the amount of pre-tinning on each pin of the surface mount socket is uniform and consistent, and the amount of tin is controllable; the morphology of the solder joints of the pins of the surface mount memory stick socket after rework is consistent with the qualified solder joints before rework, and the welding quality is reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of high-density printed circuit board.

[0020] Figure 2 Schematic diagram of solder paste printing on steel sheet.

[0021] Figure 3 Schematic diagram of steel mesh frame.

[0022] Figure 4 This is a schematic diagram of solder paste printing tooling.

[0023] Figure 5 This is a schematic diagram of the tooling base.

[0024] Figure 6 This is a schematic diagram of the solder paste distribution on the tooling base plate after solder paste printing.

[0025] Figure 7 Schematic diagram of the air nozzle on the customized BGA rework station.

[0026] Figure 8 Schematic diagram of the customized BGA rework station under-nozzle. DETAILED DESCRIPTION

[0027] The present invention aims at the existing technical problems, simulates the SMT process, and adopts the "tin paste transfer tinning method" to pre-weld the pins of the new surface mount memory stick socket. The required appropriate amount (controllable) of tin material is first melted and attached to each pin of the socket. When rework, there is no need to print tin paste on the pad of the surface mount memory stick socket on the PCB board, only a layer of flux paste needs to be applied. After welding and heating, the appropriate amount of tin material attached to each pin of the socket is re-melted to form a qualified solder joint with the pad. The method for reliably reworking the surface mount memory stick socket provided in this embodiment specifically includes the following steps:

[0028] 1. According to the size of the surface mount memory socket, a special hot air nozzle is customized to heat all the pads of the surface mount memory socket to be removed on the PCB evenly. After heating, the temperature is basically the same, and the temperature difference is generally less than 3°C. In this way, when removing the faulty surface mount memory socket, all the solder joints of the surface mount memory socket pins can be melted at the same time, which is convenient for removal, and will not cause damage to the pin pads on the PCB.

[0029] When rework and solder a new surface mount memory socket, the heating is uniform, and the PCB board and the surface mount memory socket are less deformed by heat, which is beneficial to ensure the welding quality.

[0030] 2. Design the "solder paste transfer tinning method" tooling, which includes the surface mount memory socket solder paste printing steel sheet, steel sheet mesh frame, positioning pins and tooling base plate;

[0031] The opening size and thickness of the solder paste printed steel sheet are determined according to the surface mount memory module socket pin spacing and the pad size of the socket pin on the PCB, so that the amount of tin missing is appropriate. The thickness of the solder paste printed steel sheet is 0.15mm.

[0032] Combining 2 and 3, positioning holes are designed on the solder paste printing steel sheet and the steel sheet mesh frame. The solder paste printing steel sheet and the steel sheet mesh frame are composed of solder paste printing tooling with positioning pins. The steel sheet mesh frame is made of aluminum and has a thickness of 3mm.

[0033] like Figure 5 The tooling base is designed with solder paste printing tooling positioning holes and surface mount memory module socket placement positioning holes to ensure that when the surface mount memory module socket is installed into the tooling base, all the socket pins are placed on the solder paste pattern printed by the solder paste printing tooling, such as Figure 6 As shown, the mounting base plate is made of FR4 material with a thickness of 2 mm.

[0034] 3. Use the "solder paste transfer tinning method" tooling, print solder paste on the tooling base, install the new surface mount memory stick socket, heat it through the BGA rework station (or hot air soldering station) to melt the solder paste, and melt the solder paste printed on the tooling base and attach it to the pins of the surface mount memory stick socket.

[0035] 4. Rework the surface mount memory socket, remove the residual tin on the PCB pads, clean the pads of the surface mount memory socket to be reworked on the PCB board, evenly apply a layer of flux paste, install the pre-tinned surface mount memory socket, use a customized hot air nozzle, and heat and weld on the BGA rework station.

[0036] The hot air nozzle includes an upper nozzle and a lower nozzle. Figure 7 and Figure 8 As shown, Figure 7 (a), (b), and (c) are the top view, front view, and left view, respectively, and Figure 8 (a), (b), and (c) are the main view, left view, and top view, respectively, and the size customization requirements include: 1. The upper part of the upper nozzle and the bottom of the lower nozzle are consistent with the original nozzle size of the rework station to facilitate installation: 2. The size of the hot air outlet at the bottom of the upper nozzle is basically consistent with the length and width of the surface mount memory module socket, which can be slightly larger by 1-2mm; 3. The size of the upper hot air outlet of the lower nozzle is basically consistent with the length of the surface mount memory module socket, which can be slightly larger by 1-2mm, and the width can be 1.5-2 times the width of the surface mount memory module socket.

[0037] The diameter and number of the air guide holes of the air guide plates of the upper and lower air nozzles gradually increase from the middle to the two ends, and the temperature difference of the heating part of the printed circuit board is measured to be no more than 3°C. For the hot air nozzles (upper and lower nozzles), the focus of this application is on the customization requirements of the size, and its structure is well known in the art and will not be described here.

[0038] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are exhaustively listed. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0039] For those skilled in the art, several modifications and improvements may be made without departing from the concept of the present invention, all of which belong to the protection scope of the present invention. The protection scope of the present invention shall be based on the attached claims.

Claims

1. A method for reliably repairing a soldered surface mount memory socket, characterized in that: The pins of the new surface mount memory stick socket on the PCB board are pre-tinned using the designed solder paste transfer tinning method. During rework, a layer of flux is applied to the pads of the surface mount memory stick socket on the PCB board. After welding and heating, the tin attached to the pins of the socket is re-melted to form solder joints that meet the requirements with the pads.

2. A method for reliably repairing a surface mount memory socket according to claim 1, characterized in that: Includes steps: Step 2-1, using a solder paste transfer tinning tool, printing solder paste on the tool base, inserting a new surface mount memory module socket, heating to melt the solder paste, melting the solder paste printed on the tool base, and attaching it to each pin of the surface mount memory module socket; Step 2-2, during rework, clean the pads of the surface mount memory module socket on the PCB board to be reworked, evenly apply a layer of flux paste, install the pre-tinned surface mount memory module socket, use a hot air nozzle, and heat and solder on the BGA rework station.

3. A method for reliably repairing a surface mount memory socket according to claim 2, characterized in that: The solder paste transfer tinning tooling includes a solder paste printing steel sheet, a steel sheet mesh frame, positioning pins and a tooling base plate; the solder paste printing steel sheet has a solder paste pattern, the steel sheet mesh frame is placed on the solder paste printing steel sheet, both are provided with positioning holes, and are fixed by positioning pins to form a solder paste printing tooling, and the solder paste printing tooling is installed on the tooling base plate; when using the solder paste transfer tinning tooling, all the pins of the surface mount memory stick socket are placed on the solder paste pattern printed by the solder paste printing tooling.

4. A method for reliably repairing a surface mount memory socket according to claim 3, characterized in that: The opening size and thickness of the solder paste printed steel sheet are determined according to the pin spacing of the surface mount memory module socket and the pad size of the socket pin on the PCB.

5. The method for reliably repairing a surface mount memory socket according to claim 3, characterized in that: The tooling bottom plate is provided with a solder paste printing tooling positioning hole and a surface mount memory stick socket placement position positioning hole.

6. The method for reliably repairing a surface mount memory socket according to claim 1, characterized in that: The size of the hot air nozzle is determined according to the size of the surface mount memory stick socket, and all the pads of the surface mount memory stick socket to be removed on the PCB are evenly heated.

7. A method for reliably repairing a surface mount memory socket according to claim 6, characterized in that: The hot air nozzle comprises an upper nozzle and a lower nozzle, which heat the upper and lower surfaces of the surface mounted memory module socket respectively. The upper part of the upper nozzle and the bottom of the lower nozzle are consistent with the size of the original nozzle of the rework station.

8. The method for reliably repairing a surface mount memory socket according to claim 7, characterized in that: The size of the hot air outlet of the upper air nozzle is consistent with the length and width of the surface mount memory module socket.

9. The method for reliably repairing a surface mount memory socket according to claim 7, characterized in that: The size and length of the hot air outlet of the lower air nozzle are consistent with the length of the surface mount memory module socket, and the width is 1.5-2 times the width of the surface mount memory module socket.

10. The method for reliably repairing a surface mount memory socket according to claim 1, characterized in that: The diameters of the air guide holes of the air guide plates in the upper air nozzle and the lower air nozzle gradually increase from the middle to the two ends.

Images