Movable mold core supporting glue injection structure for plastic package mold, mold and method

Abstract

The invention discloses a movable mold core supporting glue injection structure for a plastic package mold. The structure comprises a mold cavity, a movable mold core and a core pulling driving mechanism, wherein the movable mold core is arranged in the mold cavity and used for supporting cooling fins in the plastic package process, and the core pulling driving mechanism is connected with the movable mold core. The movable mold core is located at the supporting position in the initial stage of glue injection so as to support the cooling fins, and the cooling fins are prevented from being bent and deformed in the resin injection process. Through the cooperation of the structure and the glue injection process, the problem that glue cannot be injected locally due to fixed supporting is avoided while the structural stability of the cooling fin is guaranteed, the cooling fin is completely wrapped by resin and is isolated from air, and a plastic-packaged product can meet the high-voltage test requirement without secondary glue injection; and the plastic package forming quality and the production efficiency are improved.

Description

Technical Field

[0001] This invention relates to the field of molds, and more specifically to a movable core support injection structure, mold, and method for molding encapsulation. Background Technology

[0002] In the packaging process of semiconductor and power devices, molding dies are widely used to encapsulate chips, lead frames, and heat sinks within resin materials to achieve mechanical protection and electrical insulation. Among these components, the heat sink, as a crucial heat-conducting element, is typically located inside the mold cavity, and its positional stability during the molding process directly affects the product's molding quality and reliability.

[0003] Since heat sinks are typically suspended or semi-suspended within the mold cavity, the molten resin exerts a significant fluid impact force on them during resin injection, easily causing bending or displacement deformation and affecting the structural accuracy of the molded product. To address this issue, existing technologies typically employ a fixing core 6 beneath the heat sink to support it and prevent bending deformation during resin injection. A schematic diagram of this structure is shown below. Figure 1 As shown.

[0004] However, while the aforementioned fixed core support method solves the bending problem of the heat sink to some extent during the initial molding process, it also introduces new technical defects. Because the fixed core supports and occupies a localized space beneath the heat sink throughout the molding process, resin cannot penetrate the area supported by the fixed core after molding, resulting in resin gaps in that area and causing localized exposed points on the heat sink (situation 7). A typical structural defect is as follows: Figure 2 and Figure 3 As shown.

[0005] Exposed heatsinks not only compromise the integrity of the molded structure but also pose a risk of arcing during subsequent high-voltage testing, causing the product to fail high-voltage reliability testing and be deemed a defective product. To compensate for this deficiency, current manufacturing processes typically require an additional secondary potting process after molding to re-encapsulate the exposed areas of the heatsink, ensuring complete coverage. However, this secondary potting process not only increases the complexity of the production process but also significantly reduces production efficiency and increases manufacturing costs, hindering large-scale continuous production.

[0006] Therefore, how to effectively prevent the heat sink from bending and deforming due to resin impact in the early stage of the molding process, and how to avoid the problem of insufficient resin filling and partial exposure of the heat sink due to the long-term occupation of the fixed support structure, has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0007] To address the aforementioned problems, this invention provides a movable core support injection structure, mold, and method for molding, which effectively overcomes the shortcomings of the prior art.

[0008] This invention is achieved through the following technical solution: a movable core support injection structure for molding dies, comprising: Mold cavity; A movable core disposed within the mold cavity for supporting the heat sink during the molding process; And a core-pulling drive mechanism connected to the movable core; in, The movable core is positioned in a support position during the initial resin injection stage to support the heat sink and prevent the heat sink from bending or deforming during resin injection. After the glue injection reaches the predetermined stage, the core-pulling drive mechanism drives the movable core to disengage from the support position, allowing the resin to flow into the area originally supported by the movable core, thereby achieving overall encapsulation of the heat sink.

[0009] As a preferred technical solution, the movable core is movable in the vertical direction and reciprocates linearly between the supported position and the disengaged position.

[0010] As a preferred technical solution, the core-pulling drive mechanism includes a hydraulic cylinder and a core-pulling assembly connected to the hydraulic cylinder. The hydraulic cylinder is used to drive the core-pulling assembly to move the movable core upward to the support position.

[0011] As a preferred technical solution, the core-pulling assembly is provided with an elastic reset member. After the oil cylinder stops supplying oil, the elastic reset member drives the movable core to move downward to the disengaged position.

[0012] As a preferred technical solution, the disengagement position is the position where the movable core completely exits the heat sink support area, so as to ensure that the resin can fill the original support area and completely seal the heat sink.

[0013] As a preferred technical solution, the predetermined stage is the stage in which resin sufficient to form impact-resistant and bending-resistant support for the heat sink has been injected into the mold cavity.

[0014] As a preferred technical solution, the heat sink is completely encapsulated by resin and isolated from air by the switching of the movable core from the supporting position to the detached position during the glue injection process.

[0015] The present invention provides a molding die, comprising a movable core support and a core-pulling and injection structure.

[0016] The present invention provides a method for encapsulating heat sinks using a molding die, comprising: Step 1: In the initial stage of glue injection, support the heat sink with a movable core; Step 2: After the glue injection has reached the predetermined stage, remove the movable core from the support position; Step 3: Continue applying resin to fill the original support area, completing the overall encapsulation of the heat sink.

[0017] The beneficial effects of this invention are as follows: By incorporating a movable core within the molding die that can change position during the resin injection process, and cooperating with a core-pulling mechanism to achieve timing control of the movable core, the invention allows the movable core to effectively support the heat sink in the initial stage of resin injection and automatically detach from its supporting position in the middle and later stages. This prevents the heat sink from bending or deforming due to resin impact while ensuring that the resin fully fills the area originally supported by the core, achieving complete encapsulation of the heat sink. This structure fundamentally solves the problem of traditional fixed cores causing localized resin inaccessibility and heat sink exposure when supporting the heat sink, preventing arcing during high-pressure testing and improving product reliability and safety.

[0018] This invention uses a "support first, glue later" glue injection process control method to keep the heat sink under control throughout the entire molding process. This method can effectively resist the impact of resin flow in the early stage of glue injection and can be fully exposed to the resin flow environment in the later stage. This avoids encapsulation defects caused by the long-term occupation of the support structure and improves the consistency and stability of the molding process.

[0019] Because the movable core can automatically detach from the heat sink support area during the glue injection process, the resin can fully cover the heat sink in the same molding process. This invention effectively eliminates the secondary glue injection process required for the exposed area of ​​the heat sink in the existing process, simplifies the production process, shortens the production cycle, significantly improves production efficiency, and reduces labor and manufacturing costs.

[0020] This invention achieves automatic reset of the movable core through the cooperation of the core-pulling mechanism and the elastic reset component. It can complete the switching between the support position and the release position of the core without the need for additional complex control structure. The structure is simple and the operation is reliable. It is conducive to the modification or direct application on the basis of existing plastic sealing mold structure, and has good engineering practicality and promotion value. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of a structure in the prior art; Figure 2 Schematic diagram of the exposed heat sink structure in the prior art Figure 1 ; Figure 3 Schematic diagram of the exposed heat sink structure in the prior art Figure 2 ; Figure 4 This is a schematic diagram of the improved structure of the present invention; Explanation of reference numerals in the attached figures: 2. Mold cavity; 3. Movable core; 5. Hydraulic cylinder; 4. Core pulling assembly; 1. Heat sink. Detailed Implementation

[0023] All features disclosed in this specification, or all steps in all disclosed methods or processes, may be combined in any way, except for mutually exclusive features and / or steps.

[0024] Any feature disclosed in this specification (including any appended claims, abstract, and drawings) may be replaced by other equivalent or similar features for a similar purpose, unless specifically stated otherwise. That is, unless specifically stated otherwise, each feature is merely one example of a series of equivalent or similar features.

[0025] like Figure 4 As shown, in this embodiment, a movable core 3 supporting the injection molding structure for a molding die is provided. This structure is mainly used in the molding encapsulation process containing a heat sink 1, and is used to achieve overall encapsulation of the heat sink 1 while ensuring that it does not bend or deform during the injection molding process. The structure includes a mold cavity 2, which defines the flow space of the resin during the molding process and accommodates the heat sink 1 and related mold components. The heat sink 1 is disposed inside the mold cavity 2 and is molded as a heat-conducting component by resin encapsulation during the molding process.

[0026] A movable core 3 is provided within the mold cavity 2, positioned below the heat sink 1, to support the heat sink 1 during the molding process. This movable core 3 is not fixed but can change position during molding, being vertically movable within the mold cavity 2. The movable core 3 has at least two working positions: a supporting position and a disengaged position. In the supporting position, the upper end of the movable core 3 abuts against the heat sink 1, providing upward support. This effectively resists the impact of resin flow on the heat sink 1 during the initial resin injection into the mold cavity 2, preventing the heat sink 1 from bending or shifting downwards during the injection process.

[0027] The movable core 3 is connected to the mold structure via a core-pulling drive mechanism, which drives the movable core 3 to switch between a supported position and a disengaged position. In this embodiment, the core-pulling drive mechanism includes a hydraulic cylinder 5 and a core-pulling assembly 4 connected to the hydraulic cylinder 5. The hydraulic cylinder 5 is fixedly installed at an appropriate position outside the mold or inside the mold structure, and its output end is connected to the core-pulling assembly 4, which is further connected to the movable core 3. When the hydraulic cylinder 5 is in the oil supply state, the hydraulic cylinder 5 outputs thrust, which drives the movable core 3 to move upward in the vertical direction through the core-pulling assembly 4, causing the movable core 3 to enter the supported position, thereby supporting the heat sink 1.

[0028] An elastic reset component is also provided on the core-pulling assembly 4. This elastic reset component is under pressure when the oil cylinder 5 supplies oil, and releases its elastic force after the oil cylinder 5 stops supplying oil, which is used to drive the core-pulling assembly 4 and the movable core 3 to move downward. During the molding and injection process, after the initial injection is completed, a sufficient amount of resin has been injected into the mold cavity 2. The resin forms a certain coating structure in the cavity, which can provide anti-bending support for the heat sink 1. At this time, the oil cylinder 5 stops supplying oil, and the elastic reset component drives the movable core 3 to move downward under its elastic action, so that the movable core 3 retracts from the supported position to the disengaged position.

[0029] The disengagement position is where the movable core 3 completely exits the support area below the heat sink 1. At this position, the movable core 3 no longer contacts the heat sink 1, nor does it occupy the space below the heat sink 1, allowing the resin to flow smoothly into the area originally supported by the movable core 3. As the injection process continues, the resin further flows within the mold cavity 2 and fills this area, thereby achieving complete encapsulation of the bottom and surrounding area of ​​the heat sink 1, ensuring that the heat sink 1 is completely covered by resin and isolated from the air.

[0030] Through the combination of the above structure and the injection process, the movable core 3 provides support in the early stages of injection, preventing the heat sink 1 from deforming due to resin impact. In the later stages of injection, it withdraws from the support area, allowing the resin to completely fill and encapsulate the heat sink 1. This avoids the problems of resin incomplete filling and partial exposure of the heat sink 1 caused by the long-term support of a traditional fixed core. In the encapsulated product, the heat sink 1 is completely encapsulated by resin, meeting the requirements of subsequent high-voltage testing, eliminating the need for secondary potting of the exposed area of ​​the heat sink 1.

[0031] Based on this, this embodiment also provides a molding die, which includes the aforementioned movable core 3 support and core-pulling injection structure. By integrating this structure into the molding die, the mold can achieve automatic switching between supporting and detaching the heat sink 1 without adding additional complex control, which is applicable to existing molding production lines.

[0032] This embodiment also provides a method for encapsulating a heat sink 1 using the aforementioned encapsulation mold. This method includes supporting the heat sink 1 with a movable core 3 during the initial resin injection stage. After resin injection reaches a predetermined stage, the movable core 3 is removed from its supporting position, and resin injection continues to fill the original supporting area, completing the overall encapsulation of the heat sink 1. This method ensures that the heat sink 1 remains under control throughout the encapsulation process, guaranteeing structural stability while improving the quality of the encapsulation process and increasing production efficiency.

[0033] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions conceived without inventive effort should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A movable core support glue injection structure for a plastic encapsulation mold, characterized in that, The application relates to a structure for supporting and stripping a movable core during injection of a heat dissipation fin. The structure comprises: a mold cavity (2); a movable core (3) arranged in the mold cavity (2) and used for supporting the heat dissipation fin (1) during the injection process; and a stripping driving mechanism connected with the movable core (3). The movable core (3) is located at a supporting position in the early stage of the injection process to support the heat dissipation fin (1) and prevent the heat dissipation fin (1) from being deformed by impact bending during the resin injection process. After the injection process proceeds to a predetermined stage, the stripping driving mechanism drives the movable core (3) to move away from the supporting position, so that the resin can flow into the area originally supported by the movable core (3), thereby realizing overall encapsulation of the heat dissipation fin (1).

2. The movable core support glue injection structure for a plastic package mold according to claim 1, wherein: The movable core (3) is arranged to be movable along the vertical direction and reciprocates linearly between the supporting position and a moving-away position.

3. The movable core support glue injection structure for a plastic package mold according to claim 1, wherein: The stripping driving mechanism comprises an oil cylinder (5) and a stripping assembly (4) connected with the oil cylinder (5), and the oil cylinder (5) is used for driving the stripping assembly (4) to drive the movable core (3) to move upwards to the supporting position.

4. The movable core support glue injection structure for a plastic package mold according to claim 3, wherein: The stripping assembly (4) is provided with an elastic reset member, and after the oil cylinder (5) stops supplying oil, the elastic reset member drives the movable core (3) to move downwards to the moving-away position.

5. The movable core support glue injection structure for a plastic package mold according to claim 4, wherein: The moving-away position is a position for making the movable core (3) completely exit the supporting area of the heat dissipation fin (1), so as to ensure that the resin can fill the original supporting area and completely encapsulate the heat dissipation fin (1).

6. The movable core support glue injection structure for a plastic package mold according to claim 1, wherein: The predetermined stage is a stage at which the mold cavity (2) has been injected with enough resin to form an impact-bending-resistant support for the heat dissipation fin (1).

7. The movable core support glue injection structure for a plastic package mold according to claim 1, wherein: Through switching of the movable core (3) from the supporting position to the moving-away position during the injection process, the heat dissipation fin (1) is completely encapsulated by the resin and is isolated from air.

8. A plastic packaging mold characterized by comprising: The application further discloses a structure for supporting and stripping a movable core (3) during injection of a heat dissipation fin.

9. A method of overmolding a heat sink (1) using the overmolding mold (10) according to claim 8, characterized by, The structure comprises: Step one, supporting the heat dissipation fin (1) by the movable core (3) in the early stage of the injection process; Step two, making the movable core (3) move away from the supporting position after the injection process proceeds to a predetermined stage; Step three, continuing the injection process to make the resin fill the original supporting area and complete overall encapsulation of the heat dissipation fin (1). The application further discloses a method for supporting and stripping a movable core (3) during injection of a heat dissipation fin. The method comprises the following steps: Step one, supporting the heat dissipation fin (1) by the movable core (3) in the early stage of the injection process; Step two, making the movable core (3) move away from the supporting position after the injection process proceeds to a predetermined stage; Step three, continuing the injection process to make the resin fill the original supporting area and complete overall encapsulation of the heat dissipation fin (1).

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