Lead frame repeated film pasting prevention structure and film pasting machine

Abstract

This utility model relates to a structure and a film-applying machine for preventing repeated film application to lead frames. The structure includes a backlight source, a backlight assembly, and a vision detection element. The backlight source is configured to emit white light. The backlight assembly is positioned above the backlight source and includes a filter plate configured to transmit blue light. The vision detection element is positioned above the backlight assembly, and a channel for the lead frame to pass through is provided between the vision detection element and the backlight assembly. This utility model can solve the technical problems of low detection accuracy, easy misjudgment, and repeated film application in the prior art due to the inability to effectively overcome the high light transmittance of high-temperature films.

Description

Technical Field

[0001] This utility model belongs to the field of semiconductor packaging technology, specifically relating to a structure for preventing repeated film application to lead frames and a film application machine. Background Technology

[0002] With the rapid development of modern communication technologies and portable small digital electronic products (such as smartphones, wearable devices, and IoT terminals), higher requirements have been placed on integrated circuit packaging, including high frequency, wide bandwidth, low noise, high thermal conductivity, small size, high integration, and high-speed signal transmission capabilities. Against this backdrop, new surface mount packaging technologies such as QFN (Quad Flat No-Leader) and DFN (Double Flat No-Leader) have emerged and are widely used in small- and medium-scale integrated circuits.

[0003] In the manufacturing process of QFN / DFN packages, to prevent epoxy molding compound from overflowing into the leadframe pad area during subsequent injection molding, affecting the reliability of subsequent soldering and electrical performance, a high-temperature resistant and chemically resistant thin film material is usually pre-applied to the back of the leadframe (i.e., the area corresponding to the pads) to physically block the molding resin. In actual production, the leadframe needs to be precisely coated with a high-temperature film using automated coating equipment. To prevent repeated coating of the same leadframe, which could lead to film layer overlap, excessive thickness, or positioning deviations, the coating equipment is usually equipped with a vision inspection system to inspect the leadframe before it enters the coating station to determine if it has been coated. Currently, the mainstream detection method is based on differences in light transmittance, using a fixed threshold for the area of ​​the light-transmitting region to distinguish between uncoated and coated states. However, because the high-temperature films used are typically thin and have high light transmittance, the difference in light transmittance between the filmed and unfilmed areas is small in the visual inspection system. This weak optical contrast makes it difficult for the inspection system to accurately identify the lead frame with film, resulting in a high risk of misjudgment. Consequently, the equipment may re-film the already filmed products. Re-filming not only wastes materials and increases production costs, but may also lead to reliability issues such as uneven encapsulation, weld voids, or increased thermal resistance due to film layer overlap, seriously affecting product yield and packaging quality. Utility Model Content

[0004] In view of the shortcomings of existing technologies, a structure and a film-applying machine for preventing repeated film application to lead frames are proposed to solve the technical problems of low detection and identification accuracy, easy misjudgment, and repeated film application caused by the inability of existing technologies to effectively overcome the high light transmittance of high-temperature films.

[0005] To achieve the above objectives, this utility model provides the following technical solution: In a first aspect, this utility model provides a structure for preventing repeated film application to a lead frame, comprising: The backlight source is configured to emit white light; A backlight assembly is disposed above the backlight source, the backlight assembly includes a filter plate configured to transmit blue light; And a vision detection element, which is disposed above the backlight assembly, with a channel between the vision detection element and the backlight assembly for the lead frame to pass through.

[0006] The technical solution is further configured such that the backlight source is a planar light source.

[0007] The technical solution is further configured such that the backlight assembly includes a support frame, the surface of the support frame is provided with light-transmitting holes, and the filter plate is disposed on the support frame and covers the light-transmitting holes.

[0008] The technical solution is further configured such that the backlight assembly also includes a diffuser plate, the diffuser plate and the filter plate are stacked together, and the filter plate is located between the diffuser plate and the backlight source.

[0009] The technical solution is further configured such that the filter plate is a blue acrylic plate and the diffuser plate is a white glass plate.

[0010] Secondly, this utility model provides a film applicator, including a conveyor track and the aforementioned structure for preventing repeated film application to the lead frame. The conveyor track is used to convey the lead frame, and the structure for preventing repeated film application to the lead frame is installed on the conveyor track.

[0011] The technical solution is further configured such that the support frame is located below the conveying track, the conveying track and the filter plate are respectively set as a hollow area, and the visual inspection element is located above the hollow area.

[0012] The technical solution is further configured such that a support frame is provided on the side of the carrier frame, and the support frame is connected to the bracket of the conveying track through a fixing member. The beneficial effects of this utility model are: 1. By using a filter plate to transmit blue light, the blue light is largely absorbed by the yellow high-temperature film, resulting in a significant reduction in the intensity of transmitted light. Meanwhile, the unfilmed areas allow more light to pass through. This setup significantly enhances the optical contrast between the filmed and unfilmed lead frames, improves the recognition accuracy of the visual inspection system, and thus greatly reduces the risk of repeated film application.

[0013] 2. The diffuser plate can eliminate local bright spots of blue light after filtering, ensuring that the light penetrates the lead frame evenly. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure for preventing repeated film application to the lead frame in an embodiment of this utility model; Figure 2 This is an assembly diagram of the structure for preventing repeated film application to the lead frame and the lead frame without film application in an embodiment of this utility model. Figure 3 This is an assembly diagram of the structure for preventing repeated film application to the lead frame and the already film-applied lead frame in an embodiment of this utility model. Figure 4 This is an assembly diagram of the support frame, diffuser plate, and filter plate in an embodiment of this utility model.

[0015] In the attached diagram: 1. Backlight source; 2. Filter plate; 3. Diffuser plate; 4. Support frame; 5. Vision inspection element; 6. Support frame; 7. Lead wire frame; 8. High-temperature film; 9. Conveyor track; 10. Light-transmitting hole. Detailed Implementation

[0016] To enable those skilled in the art to better understand the technical solution of this utility model, the technical solution of this utility model will be clearly and completely described below with reference to the accompanying drawings. Based on the embodiments in this application, other similar embodiments obtained by those skilled in the art without creative effort should all fall within the scope of protection of this application. Furthermore, directional terms mentioned in the following embodiments, such as "up," "down," "left," and "right," are only for reference to the directions in the accompanying drawings; therefore, the directional terms used are for illustrative purposes and not for limiting the invention.

[0017] The present invention will be further described below with reference to the accompanying drawings and preferred embodiments.

[0018] Example 1: According to an embodiment of this utility model, a structure for preventing repeated film application to lead frames is provided. Please refer to [link / reference needed]. Figures 1 to 4 ,include: Backlight source 1, configured to emit white light; A backlight assembly is disposed above the backlight source 1. The backlight assembly includes a filter plate 2, which is configured to transmit blue light. And a visual inspection element 5, which is disposed above the backlight assembly, with a channel between the visual inspection element 5 and the backlight assembly for the lead frame 7 to pass through.

[0019] Understandably, the backlight source 1 and backlight assembly are located below the lead frame 7, the vision inspection element 5 is located above the lead frame 7, and the filter plate 2 is used to filter white light, allowing only blue light to pass through. Based on the principle of three primary colors: the yellow high-temperature film 8 absorbs blue light, resulting in a significant reduction in the intensity of transmitted light, while the uncoated area allows more light to pass through. This setup significantly enhances the optical contrast between the coated and uncoated lead frames, improves the recognition accuracy of the vision inspection system, and thus greatly reduces the risk of repeated coating.

[0020] In one embodiment of the structure for preventing repeated film application to the lead frame, please refer to... Figures 1 to 4 The backlight source 1 is a planar light source, which can emit white light with a large area and high uniformity. This uniformity is a prerequisite for achieving reliable visual detection. It ensures that the blue light intensity distribution of the entire detection area is consistent under the action of the backlight component, avoiding local over-brightness or dark areas caused by point light sources or strip light sources.

[0021] Optionally, the backlight source 1 can be an LED flat panel or an integrated flat light box.

[0022] In one embodiment of the structure for preventing repeated film application to the lead frame, please refer to... Figures 1 to 4 The backlight assembly includes a support frame 4, the surface of which is provided with light-transmitting holes 10, and the filter plate 2 is disposed on the support frame 4 and covers the light-transmitting holes 10.

[0023] Understandably, the support frame 4 provides rigid support and a fixed reference for the filter plate 2, ensuring the integrity and consistency of the optical path. The light-transmitting aperture 10, as a key channel in the optical path from the backlight source 1 → filter plate 2 → lead frame 7 → vision inspection element 5, has a position and size that precisely correspond to the area to be inspected on the lead frame 7. After the filter plate 2 covers the light-transmitting aperture 10, all light used for inspection must first pass through the filter plate 2, thereby forcibly achieving blue light filtering. This ensures that the light entering the vision inspection element 5 is selected blue light, maximizing the absorption effect of the yellow high-temperature film 8 on blue light and improving the light transmission contrast.

[0024] In one embodiment of the structure for preventing repeated film application to the lead frame, please refer to... Figures 1 to 4 The backlight assembly also includes a diffuser plate 3, which is stacked with the filter plate 2, and the filter plate 2 is located between the diffuser plate 3 and the backlight source 1.

[0025] It is understandable that the backlight source 1 works synergistically with the filter plate 2 and the diffuser plate 3 above it: the filter plate 2 selectively transmits blue light, the diffuser plate 3 can further homogenize the blue light, eliminate local bright spots of the blue light after filtering, and ensure that the light penetrates the lead frame 7 evenly. The backlight source 1, as the initial light source, ensures that the blue light field after filtering and diffusion remains highly uniform.

[0026] Optionally, both the filter plate 2 and the diffuser plate 3 are provided with mounting holes, and the support frame 4 is provided with threaded holes. Screws pass through the mounting holes and threaded holes and are then locked with nuts to form a rigid mechanical connection. This connection method can effectively prevent the filter plate 2 and the diffuser plate 3 from shifting, loosening, or falling off during the operation of the laminating machine due to vibration, airflow, or thermal expansion and contraction, ensuring long-term stable operation.

[0027] Optionally, the support frame 4 has an inner cavity in which both the filter plate 2 and the diffuser plate 3 are inserted. This design greatly simplifies the replacement process of the filter plate 2 and the diffuser plate 3, allowing for quick removal of the old plate and insertion of the new plate without removing screws, significantly shortening equipment maintenance time and improving production line uptime. The inner cavity physically surrounds the filter plate 2 and the diffuser plate 3, providing some protection against dust, impacts, and displacement. Furthermore, guide rails can be installed on the cavity walls to guide the pulling motion of the filter plate 2 and the diffuser plate 3, preventing jamming, scratches, or improper installation due to misalignment, thus improving operational convenience and safety.

[0028] Optionally, the filter plate 2 is a blue acrylic plate, and the diffuser plate 3 is a white glass plate.

[0029] Example 2: According to an embodiment of this utility model, a film applicator is provided. Please refer to [link / reference]. Figures 1 to 4 It includes a conveying track 9 and the aforementioned structure for preventing repeated film application to the lead frame. The conveying track 9 is used to convey the lead frame 7, and the structure for preventing repeated film application to the lead frame is installed on the conveying track 9.

[0030] Understandably, the lead frame 7 is transported to the laminating station of the laminating machine via the conveyor track 9. During this transport process, blue light is transmitted through the filter plate 2. The blue light is largely absorbed by the yellow high-temperature film 8, resulting in a significant reduction in the intensity of transmitted light. Meanwhile, the unlaminated area allows more light to pass through. This setup significantly enhances the optical contrast between the laminated and unlaminated lead frames, thereby detecting and identifying the laminated lead frames and avoiding repeated lamination.

[0031] Optionally, the support frame 4 is located below the conveying track 9, the conveying track 9 is configured as a hollow area corresponding to the filter plate 2, and the visual inspection element 5 is located above the hollow area.

[0032] During operation, when the lead frame 7 moves on the conveyor track 9 and passes through the cutout area, its inspection area is located between the filter plate 2 and the vision inspection element 5. The blue light transmitted through the filter plate 2 can illuminate the back of the lead frame 7 without obstruction, while allowing the transmitted light to smoothly enter the vision inspection element 5 above. The vision inspection element 5 is preferably a camera.

[0033] In one embodiment of the film applicator, please refer to Figures 1 to 4 The side of the carrier frame 4 is provided with a support frame 6, which is connected to the bracket of the conveying track 9 through a fixing member, so that the entire backlight assembly obtains rigid mechanical support.

[0034] Optionally, the support frame 6 is set perpendicular to the carrier frame 4. The carrier frame 4 passes through the support of the conveying track 9 and extends to the bottom of the conveying track 9. The support frame 6 is connected to and locked to the support by screws.

[0035] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0036] Optionally, specific examples in this embodiment can refer to the examples described in the above embodiments, and will not be repeated here.

[0037] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0038] In the above embodiments of this application, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0039] The above description is only a preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A structure for preventing repeated film application to a lead frame, characterized in that, include: The backlight source is configured to emit white light; A backlight assembly is disposed above the backlight source, the backlight assembly includes a filter plate configured to transmit blue light; And a vision detection element, which is disposed above the backlight assembly, with a channel between the vision detection element and the backlight assembly for the lead frame to pass through.

2. The structure for preventing repeated film application to the lead frame according to claim 1, characterized in that, The backlight source is a planar light source.

3. The structure for preventing repeated film application to the lead frame according to claim 1 or 2, characterized in that, The backlight assembly includes a support frame with light-transmitting holes on its surface. The filter plate is disposed on the support frame and covers the light-transmitting holes.

4. The structure for preventing repeated film application to the lead frame according to claim 3, characterized in that, The backlight assembly also includes a diffuser plate, which is stacked with the filter plate, and the filter plate is located between the diffuser plate and the backlight source.

5. The structure for preventing repeated film application to the lead frame according to claim 4, characterized in that, The filter plate is a blue acrylic plate, and the diffuser plate is a white glass plate.

6. A film applicator, characterized in that, The device includes a conveyor track and a structure for preventing repeated film application to the lead frame as described in any one of claims 3-5, wherein the conveyor track is used to convey the lead frame and the structure for preventing repeated film application to the lead frame is installed on the conveyor track.

7. The film applicator according to claim 6, characterized in that, The support frame is located below the conveying track, and the area corresponding to the filter plate on the conveying track is set as a hollow area, with the visual inspection element located above the hollow area.

8. The film applicator according to claim 7, characterized in that, The side of the carrier frame is provided with a support frame, which is connected to the support of the conveying track by a fixing member.

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