Lead frame production and processing technology

Abstract

The present invention discloses a lead frame production and processing process, including a copper plate pretreatment process and a frame punching process. The copper plate pretreatment process steps are as follows: S1: the copper blank is subjected to a primary cold rolling to a thickness of 2.5 mm; S2: the copper blank after the primary rolling is subjected to a primary annealing treatment; S3: secondary cold rolling; S4: secondary annealing treatment; S5: grooving; S6: milling; S7: degreasing and pickling; and the frame punching process steps are as follows: Step 1: placing the pretreated copper plate in a continuous punching machine; Step 2: performing continuous high-speed punching, with the punch and die punching along the wire grooves. In the copper plate pretreatment stage, the present invention performs double-sided grooving on the copper plate surface, with the grooving depth being greater than the milling feed depth, so that the copper plate surface retains the grooving after the copper plate pretreatment. The grooving can reduce the contact between the punch and die during punching and the lead frame, thereby reducing the problem of passivation of the punch and die after long-term punching and the collapse of the lead frame edge.

Description

Technical Field

[0001] The present invention relates to the technical field of lead frame processing, in particular to a lead frame production and processing technology. Background Art

[0002] As the chip carrier of integrated circuits, the lead frame is a key structural component that uses bonding materials to achieve electrical connection between the internal circuit leads of the chip and the external leads to form an electrical circuit. It acts as a bridge connecting to external wires. Lead frames are required in most semiconductor integrated blocks and are an important basic material in the electronic information industry.

[0003] After extensive searching, the prior art was found, with publication number: CN108389803B, which discloses a high-reliability lead frame processing technology for small plastic-encapsulated integrated circuits, belonging to the field of integrated circuit packaging technology. The high-reliability lead frame processing technology of the present invention is to first subject the lead frame to conventional degreasing, activation, neutralization, copper plating, pre-silver plating, silver plating and silver stripping processes, and then subject the lead frame after silver stripping to micro-etching, re-activation, copper surface treatment, anode cleaning, silver surface treatment, and silver protection processes in sequence. The processing technology of the present invention increases the bonding force between the plastic encapsulation material and the substrate during the packaging process by treating the copper surface and the silver surface on the lead frame, and the integrated circuit is not easy to delaminate after packaging, thereby improving the reliability of the integrated circuit after packaging; after multiple production line verifications, the integrated circuit after packaging can pass the first-level reliability test 100%, and can meet the production requirements of high-reliability integrated circuits.

[0004] In summary, in the lead frame production process, the pre-treated copper plate needs to be continuously stamped on the surface of the copper plate using a punching equipment to obtain the lead frame. After a long period of stamping, the edges of the punch and die of the punching machine will become blunt, which will greatly reduce the punching effect, causing the accuracy of the punched lead frame to be unable to be guaranteed and the edge of the lead frame to collapse. Summary of the Invention

[0005] The object of the present invention is to provide a lead frame production process to solve the problems raised in the above background technology.

[0006] To achieve the above-mentioned object, the present invention provides the following technical solution: a lead frame production and processing process, including a copper plate pretreatment process and a frame stamping process, wherein the copper plate pretreatment process comprises the following steps:

[0007] S1: The copper billet is cold rolled once to a thickness of 2.5 mm;

[0008] S2: The copper billet after the first rolling is subjected to an annealing treatment at an annealing temperature of 630°C for 7 hours;

[0009] S3: Perform secondary cold rolling to reduce the copper billet thickness to 1.5 mm;

[0010] S4: secondary annealing treatment, annealing temperature is 760℃, annealing time is 5h;

[0011] S5: Grooving: Use a drill bit with a diameter of 0.5 mm to groove the copper billet on both sides. The depth of the grooves on both sides is 0.5 mm.

[0012] S6: Milling: Mill the copper billet on both sides after the groove is cut. The thickness of the copper billet after milling is 0.8 mm.

[0013] S7: Degreasing and pickling: remove oil stains on the surface of the copper plate and pickling to remove burrs;

[0014] The frame punching process steps are as follows:

[0015] Step 1: Place the pre-treated copper plate in a continuous punching machine and align both sides of the copper plate with the punch and die respectively;

[0016] The second step: continuous high-speed punching is performed, and the punch and die are punched along the wire groove respectively to separate the waste from the copper plate frame.

[0017] Preferably, in S5 based on the copper plate pretreatment process:

[0018] The drill bit grooves the surface of the copper plate, and the grooves match the lead frame of the lead frame. The grooves create a gap between the lead frame and the copper plate waste. The edges of the grooves are flush with the edges of the lead frame, that is, the grooves open along the outside of the lead frame, which can show the specific structure of the lead frame.

[0019] Preferably, in S6 based on the copper plate pretreatment process:

[0020] The copper plate surface is milled, and the milling cutter is fed 0.35mm on the copper plate surface. After double-sided milling, the copper plate surface still retains the grooves. The milling surface is used to level the copper plate surface.

[0021] Preferably, in S7 based on the copper plate pretreatment process:

[0022] After the copper plate is milled, it is placed in a cleaning solution and soaked for 30 minutes to clean the oil and debris on the surface of the copper plate. The copper plate is then dried and placed in a weak acid liquid to remove burrs on the edge of the copper plate and the inner wall of the groove.

[0023] Preferably, in the frame-based blanking process:

[0024] The surfaces on both sides of the copper plate are aligned with the punch and die respectively, the punch and die are respectively fitted with the edges of the groove, the edges of the punch and die are respectively adapted to the edges of the lead frame, and the punch and die are engaged to achieve blanking of the copper plate.

[0025] Preferably, in the frame-based blanking process:

[0026] During the blanking process, the impact speed between the punch and the die is 200 times / minute. Through continuous blanking, blanking reliability is achieved. The opening of the groove can reduce the contact pressure between the punch, the die and the lead frame, which is used to reduce the wear of the punch and die edges and the collapse of the lead frame edges. It can extend the service life of the punch and die and improve the accuracy of the lead frame.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows: during the pretreatment of the copper plate, the present invention adopts a double-sided grooving process on the surface of the copper plate, so that the shape of the lead frame is respectively engraved on the surfaces of both sides of the copper plate and the lead frame is separated from the copper plate waste. In the subsequent punching process, the edges of the punch and the die are placed in the grooves, and the outer walls of the punch and the die are fitted with the edge of the lead frame, reducing the impact of the punch and the die on the lead frame and reducing the contact with the lead frame, so that during the punching process, the edges of the punch and the die are subjected to less pressure, so that the edges of the punch and the die will not be passivated after long-term use, thereby ensuring the service life of the punch and the die, and reducing the problem of the punch and the die causing the edge of the lead frame to collapse, further ensuring the accuracy and quality of the punching, and providing quality assurance for the production of lead frames. DETAILED DESCRIPTION

[0028] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0029] In the description of the present invention, it should be noted that terms such as "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," and "the other end" to indicate positions or relationships are used solely to facilitate description and simplify the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0030] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "provided with," "connected," etc., should be understood in a broad sense. For example, "connected" may refer to a fixed connection, a detachable connection, or an integral connection; it may refer to a mechanical connection or an electrical connection; it may refer to a direct connection or an indirect connection through an intermediate medium; it may refer to internal communication between two components. Those skilled in the art will be able to understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0031] The present invention provides four embodiments: a lead frame production and processing process, including a copper plate pretreatment process and a frame stamping process.

[0032] Example 1:

[0033] The copper plate pretreatment process steps are as follows:

[0034] S1: The copper billet is cold rolled once to a thickness of 2.5 mm;

[0035] S2: The copper billet after the first rolling is subjected to an annealing treatment at an annealing temperature of 630°C for 7 hours;

[0036] S3: Perform secondary cold rolling to reduce the copper billet thickness to 1.5 mm;

[0037] S4: secondary annealing treatment, annealing temperature is 760℃, annealing time is 5h;

[0038] S5: Grooving: Use a drill bit with a diameter of 0.5 mm to groove the copper billet on both sides. The depth of the grooves on both sides is 0.5 mm.

[0039] S6: Milling: Mill the copper billet on both sides after the groove is cut. The thickness of the copper billet after milling is 0.8 mm.

[0040] S7: Degreasing and pickling: Remove oil stains on the surface of the copper plate and remove burrs by pickling.

[0041] During the pretreatment of the copper plate, a double-sided grooving process is used on the surface of the copper plate, so that the shape of the lead frame is engraved on the surfaces of both sides of the copper plate and the lead frame is separated from the copper plate waste. In the subsequent punching process, the edges of the punch and the die are placed in the grooves, and the outer walls of the punch and the die are fitted with the edge of the lead frame, reducing the impact of the punch and the die on the lead frame and reducing the contact with the lead frame. In the punching process, the edges of the punch and the die are subjected to less pressure, so that the edges of the punch and the die will not be passivated after long-term use, thereby ensuring the service life of the punch and the die, and reducing the problem of the punch and the die causing the edge of the lead frame to collapse, further ensuring the accuracy and quality of the punching, and providing quality assurance for the production of lead frames.

[0042] Example 2:

[0043] In S5 based on copper plate pretreatment process:

[0044] The drill bit grooves the surface of the copper plate, and the grooves match the lead frame of the lead frame. The grooves create a gap between the lead frame and the copper plate waste. The edges of the grooves are flush with the edges of the lead frame, that is, the grooves open along the outside of the lead frame, which can show the specific structure of the lead frame.

[0045] In S6 based on copper plate pretreatment process:

[0046] The copper plate surface is milled, and the milling cutter is fed 0.35mm on the copper plate surface. After double-sided milling, the copper plate surface still retains the grooves. The milling surface is used to level the copper plate surface.

[0047] In S7 based on copper plate pretreatment process:

[0048] After the copper plate is milled, it is placed in a cleaning solution and soaked for 30 minutes to clean the oil and debris on the surface of the copper plate. The copper plate is then dried and placed in a weak acid liquid to remove burrs on the edge of the copper plate and the inner wall of the groove.

[0049] Example 3:

[0050] The frame punching process steps are as follows:

[0051] Step 1: Place the pre-treated copper plate in a continuous punching machine and align both sides of the copper plate with the punch and die respectively;

[0052] The second step: continuous high-speed punching is performed, and the punch and die are punched along the wire groove respectively to separate the waste from the copper plate frame.

[0053] In the subsequent punching process, the edges of the punch and die are placed in the grooves, and the outer walls of the punch and die fit the edge of the lead frame, reducing the impact of the punch and die on the lead frame and reducing the contact with the lead frame. In this way, the edges of the punch and die are subjected to less pressure during the punching process, so that the edges of the punch and die will not become blunt after long-term use, thereby ensuring the service life of the punch and die, and reducing the problem of the punch and die causing the edge of the lead frame to collapse, further ensuring the accuracy and quality of the punching, and providing quality assurance for the production of lead frames.

[0054] Example 4:

[0055] In the frame-based blanking process:

[0056] The surfaces on both sides of the copper plate are aligned with the punch and die respectively, the punch and die are respectively fitted with the edges of the groove, the edges of the punch and die are respectively adapted to the edges of the lead frame, and the punch and die are engaged to achieve blanking of the copper plate.

[0057] In the frame-based blanking process:

[0058] During the blanking process, the impact speed between the punch and the die is 200 times / minute. Through continuous blanking, blanking reliability is achieved. The opening of the groove can reduce the contact pressure between the punch, the die and the lead frame, which is used to reduce the wear of the punch and die edges and the collapse of the lead frame edges. It can extend the service life of the punch and die and improve the accuracy of the lead frame.

[0059] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

Claims

1. A lead frame production process, characterized by: The process includes a copper plate pretreatment process and a frame stamping process. The steps of the copper plate pretreatment process are as follows: S1: The copper billet is cold rolled once to a thickness of 2.5 mm; S2: The copper billet after the first rolling is subjected to an annealing treatment at an annealing temperature of 630°C for 7 hours; S3: Perform secondary cold rolling to reduce the copper billet thickness to 1.5 mm; S4: secondary annealing treatment, annealing temperature is 760℃, annealing time is 5h; S5: Grooving: Use a drill bit with a diameter of 0.5 mm to groove the copper billet on both sides. The depth of the grooves on both sides is 0.5 mm. S6: Milling: Mill the copper billet on both sides after the groove is cut. The thickness of the copper billet after milling is 0.8 mm. S7: Degreasing and pickling: remove oil stains on the surface of the copper plate and pickling to remove burrs; The frame punching process steps are as follows: Step 1: Place the pre-treated copper plate in a continuous punching machine and align both sides of the copper plate with the punch and die respectively; The second step: continuous high-speed punching is performed, and the punch and die are punched along the wire groove respectively to separate the waste from the copper plate frame.

2. The lead frame production process according to claim 1, characterized in that: In S5 based on copper plate pretreatment process: The drill bit grooves the surface of the copper plate, and the grooves match the lead frame of the lead frame. The grooves create a gap between the lead frame and the copper plate waste. The edges of the grooves are flush with the edges of the lead frame, that is, the grooves open along the outside of the lead frame, which can show the specific structure of the lead frame.

3. The lead frame production process according to claim 1, wherein: In S6 based on copper plate pretreatment process: The copper plate surface is milled, and the milling cutter is fed 0.35mm on the copper plate surface. After double-sided milling, the copper plate surface still retains the grooves. The milling surface is used to level the copper plate surface.

4. The lead frame production process according to claim 1, wherein: In S7 based on copper plate pretreatment process: After the copper plate is milled, it is placed in a cleaning solution and soaked for 30 minutes to clean the oil and debris on the surface of the copper plate. The copper plate is then dried and placed in a weak acid liquid to remove burrs on the edge of the copper plate and the inner wall of the groove.

5. The lead frame production process according to claim 1, characterized in that: In the frame-based blanking process: The surfaces on both sides of the copper plate are aligned with the punch and die respectively, the punch and die are respectively fitted with the edges of the groove, the edges of the punch and die are respectively adapted to the edges of the lead frame, and the punch and die are engaged to achieve blanking of the copper plate.

6. The lead frame production process according to claim 1, characterized in that: In the frame-based blanking process: During the blanking process, the impact speed between the punch and the die is 200 times / minute. Through continuous blanking, blanking reliability is achieved. The opening of the groove can reduce the contact pressure between the punch, the die and the lead frame, which is used to reduce the wear of the punch and die edges and the collapse of the lead frame edges. It can extend the service life of the punch and die and improve the accuracy of the lead frame.