A packaging structure and packaging method based on a retaining wall

Abstract

The application discloses a packaging structure and a packaging method based on a retaining wall. The packaging structure comprises a lead frame, a chip, a solder wire, a first retaining wall and / or a second retaining wall. The first retaining wall is used for supporting the solder wire above it. The second retaining wall is located between two adjacent solder wires and is used for isolating the adjacent solder wires. The application provides reliable support and isolation for the lead wire by setting a physical retaining wall structure at a key position, thereby effectively preventing the lead wire from collapsing and colliding, resisting subsequent process stress, improving product yield and operation window. Meanwhile, the retaining wall can be adjusted at any time according to the wire layout, and the process is simple and suitable for various products.

Description

Technical Field

[0001] This invention relates to the field of semiconductor packaging technology, and in particular to a barrier-based packaging structure and packaging method. Background Technology

[0002] As semiconductor packaging technology advances towards higher integration and miniaturization, the number of pins requiring connection within the package is increasing, leading to denser lead arrangements. Simultaneously, for larger packages (such as QFN and BGA), the arc length of the connecting lines (gold wires, copper wires, etc.) from the chip pads to external pins also increases. This "long arc" and "dense" wiring environment presents significant process challenges in packaging manufacturing, including lead sagging and lead shortening. Lead sagging refers to the tendency of long arcs to sag under the influence of gravity and stress from subsequent processes (such as the impact of molding compound flow). When a sagging lead contacts the underlying die pad or other structures, it can cause an electrical short circuit, leading to product failure. Lead shortening occurs in densely wired areas where the spacing between adjacent leads is extremely small. During the molding process, the high-pressure, high-speed molding compound flow exerts lateral thrust on the leads, potentially causing adjacent leads to contact and resulting in a short circuit.

[0003] The above issues directly reduce the first-pass yield of packaging operations, increase rework and scrap costs, and affect overall production efficiency and product reliability. Traditional improvement methods mainly rely on optimizing wire bonder parameters (such as wire arc shape control) or using low-loop wire bonding technology. However, these methods have limited improvement effects in extreme long wire arcs or ultra-high density wiring conditions, and may sacrifice bonding strength or increase the difficulty of process debugging.

[0004] CN115101500A discloses a semiconductor chip packaging assembly and its packaging method. Metal lead lines are pre-formed inside a flexible high-temperature resistant insulating board, with both ends of the metal lead lines connected to a semiconductor chip or PCB board. Finally, the semiconductor chip and the flexible high-temperature resistant insulating board are encapsulated. While this method avoids short circuits between the leads, the pre-designed lead lines within the flexible high-temperature resistant insulating board are fixed, meaning the number of leads, wiring method, and output method cannot be changed, limiting its application to only one type of chip product. When other wiring or connection methods are required, the flexible board must be remanufactured, resulting in high manufacturing difficulty and cost. Summary of the Invention

[0005] Purpose of the invention: The purpose of this invention is to provide a barrier-based packaging structure and packaging method to solve problems such as lead collapse and lead short circuit (wire contact) in wire bonding packaging products with long arc or dense wiring characteristics.

[0006] Technical solution: The encapsulation structure based on a retaining wall according to the present invention includes:

[0007] The lead frame includes a base island for mounting the chip and pins for electrical connections;

[0008] The chip is mounted on the base island;

[0009] Wire bonding is used for electrical connection between the chip and the pin;

[0010] A first retaining wall is disposed on the base island to support the bonding wires above it; and / or a second retaining wall is disposed on the base island and located between two adjacent bonding wires to isolate adjacent bonding wires.

[0011] Furthermore, both the first and second retaining walls are made of metal.

[0012] Furthermore, when the welding wire above the first retaining wall is a grounding wire, the first retaining wall is fixed to the base island by conductive adhesive;

[0013] When the welding wire above the first retaining wall is a non-grounded wire, the first retaining wall is fixed to the base island by insulating adhesive, and the surface of the first retaining wall is coated with insulating adhesive.

[0014] Furthermore, the second retaining wall is fixed to the base island by insulating adhesive, and the surface of the second retaining wall is coated with insulating adhesive.

[0015] Furthermore, the first and second retaining walls are disposed on a linear arc platform, which is the area between the chip edge and the base island edge on the base island surface.

[0016] Furthermore, the height of the first retaining wall does not exceed the weld line above it.

[0017] Furthermore, the height of the second retaining wall is slightly higher than the weld lines on both sides, and the width of the second retaining wall is not greater than the gap width between the weld lines on both sides.

[0018] The encapsulation method based on a barrier-wall encapsulation structure according to the present invention includes the following steps:

[0019] Step 1: Mount the chip onto the surface of the base island;

[0020] Step 2: Form bonding wires between the chip and the pins;

[0021] Step 3: Bake and seal the product to complete the packaging.

[0022] Before step 2, the method further includes setting a first barrier on the base island to support the bonding wires between the chip and the pins; and / or, after step 2, the method further includes setting a second barrier on the base island, the second barrier being located between two adjacent bonding wires to isolate the adjacent bonding wires.

[0023] Furthermore, after forming a row of bonding wires between the chip and the pins, a second barrier is set on the base island before forming the next row of bonding wires.

[0024] Another barrier-based encapsulation structure according to the present invention includes:

[0025] The lead frame includes a base island for mounting the chip and pins for electrical connections;

[0026] The chip is mounted on the base island;

[0027] Wire bonding is used for electrical connection between the chip and the pin;

[0028] The third retaining wall, located on the base island, includes a support section and an isolation section. The support section supports the welding wires above it, and the isolation section is located between two adjacent welding wires to isolate the adjacent welding wires.

[0029] Furthermore, the third retaining wall is fixed to the base island by insulating adhesive, and the surface of the third retaining wall is coated with insulating adhesive; the height of the supporting part does not exceed the weld line above it, the height of the isolation part is slightly higher than the weld lines on both sides, and the width of the isolation part is not greater than the gap width between the weld lines on both sides.

[0030] Another encapsulation method based on a barrier-wall encapsulation structure according to the present invention includes the following steps:

[0031] Step 1: Mount the chip onto the surface of the base island;

[0032] Step 2: Install a third retaining wall on the base island; the third retaining wall includes a support part and an isolation part. The support part is used to support the welding wire above it, and the isolation part is located between two adjacent welding wires to isolate adjacent welding wires.

[0033] Step 3: Form bonding wires between the chip and the pins;

[0034] Step 4: Bake and seal the product to complete the packaging.

[0035] Beneficial effects: Compared with the prior art, the advantages of this invention are as follows: By setting up a physical barrier structure at key locations, this invention provides reliable support and isolation for the lead wires, thereby effectively preventing lead wire collapse and collision, resisting stress from subsequent processes, improving product yield and operating window; at the same time, the barrier can be adjusted at any time according to the wiring situation, the process is simple, and it is adaptable to various products. Specifically, it can be divided into the following aspects:

[0036] (1) Active physical protection: By adding retaining walls, the passive "control of the arc" is transformed into the active "providing support and isolation", which fundamentally solves the problems of long arc collapse and dense lines being easy to collide.

[0037] (2) High design flexibility: Select the glue and insulation scheme of the first retaining wall according to different welding wire properties (grounded / ungrounded) to maximize process convenience while ensuring electrical safety; at the same time, the position and number of retaining walls can be adjusted at any time according to the wiring situation to flexibly adapt to a variety of products.

[0038] (3) Resisting stress from subsequent processes: Baking enhances the structural strength and adhesion of the barrier, resists the impact of the molding flow, and improves the reliability of the product in the complete packaging process.

[0039] (4) Good compatibility and simple process: The materials used (metal blocks, conductive / insulating adhesives) are all commonly used materials in semiconductor packaging. The operation method can be seamlessly embedded into the existing packaging process (before / after wire bonding), without major equipment modification and with low implementation cost.

[0040] (5) Significantly improve yield: Effectively reduces product short circuit failures caused by lead wire collapse and wire contact, which can directly improve the production yield and efficiency of packaging operations. Attached Figure Description

[0041] Figure 1 This is a perspective view of the barrier-based encapsulation structure of Embodiments 1 and 3 of the present invention.

[0042] Figure 2 This is a side view of the barrier-based encapsulation structure of Embodiment 1 of the present invention.

[0043] Figure 3 This is a perspective view of the barrier-based encapsulation structure of Embodiment 5 of the present invention.

[0044] Figure 4 This is a side view of the barrier-based encapsulation structure of Embodiment 5 of the present invention.

[0045] Figure 5 This is a perspective view of another encapsulation structure based on a retaining wall according to Embodiment 5 of the present invention.

[0046] Figure 6 This is a side view of another encapsulation structure based on a retaining wall according to Embodiment 5 of the present invention. Detailed Implementation

[0047] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0048] Example 1

[0049] The present invention discloses a barrier-based packaging structure, including a lead frame, a base island for mounting a chip and pins for electrical connection; a chip mounted on the base island; bonding wires for electrical connection between the chip and the pins; and a first barrier wall disposed on the base island for supporting the bonding wires thereon.

[0050] Specifically, the first barrier is set on a linear arc platform, which is the area between the chip edge and the base island edge on the base island surface.

[0051] Specifically, the first barrier is placed on the lead frame island supporting the chip, in the area where long lead arcs are expected to sag. It is typically placed in the "lead arc platform" area between the chip edge and the base island edge. For example... Figure 1 As shown, the height of the first retaining wall shall not exceed the weld line above it. The length and width of the first retaining wall shall be determined according to its support requirements and the range of easily collapsed wires. It shall cover the range of easily collapsed wires between two points on the arc and the number of weld lines that need to be supported.

[0052] Specifically, the first retaining wall is made of metal, such as the same alloy as the lead frame. Depending on the properties of the bonding wires above the retaining wall, and combined with the assembly and insulation treatment using conductive or non-conductive adhesive, the first retaining wall provides both mechanical support and ensures electrical safety. Specifically, it can be divided into the following two cases:

[0053] (a) When the welding wire above the first retaining wall is a grounding wire.

[0054] When the welding wire above the first retaining wall is a grounding wire (GND), the first retaining wall is fixed to the base island with conductive or non-conductive adhesive, and no additional insulation layer is required after fixing, allowing the welding wire to touch the retaining wall. Since the welding wire above the first retaining wall is a grounding wire, when the first retaining wall is fixed with conductive adhesive, the first retaining wall is electrically connected to the grounded base island through the conductive adhesive. Even if the welding wire droops and touches the retaining wall, it is still a grounded connection and will not cause a short circuit fault.

[0055] (b) The welding wire above the first retaining wall is a non-grounded wire.

[0056] When the welding wire above the first retaining wall is a non-grounded wire (such as a power line or signal line), use non-conductive adhesive (insulating adhesive) to fix the first retaining wall to the base island. After the first retaining wall is installed, a layer of insulating adhesive (such as polyimide liquid adhesive) must be brushed onto its surface. After curing, the first retaining wall becomes an insulating support. When the welding wire droops and touches the first retaining wall, it receives physical support and will not continue to collapse and contact the base island. At the same time, because the retaining wall is insulating, it will not cause a short circuit to ground in the signal line.

[0057] Furthermore, when the properties of the welding wires above the first retaining wall are different, non-conductive adhesive is still used to fix the first retaining wall to the base island, and an insulating adhesive is brushed onto its surface.

[0058] Figure 2 The image shows the insulating adhesive coating on the first retaining wall.

[0059] Example 2

[0060] The encapsulation method based on a barrier-wall encapsulation structure described in Example 1 includes the following steps.

[0061] Step 1: Die attach the chip to the surface of the base island;

[0062] Step 2: Set up the first barrier wall on the base island to support the bonding wires between the chip and the pins;

[0063] Step 3: Wire bonding is formed between the chip and the pins.

[0064] Step 4 involves baking and molding to complete the encapsulation process. This step not only cures the bonding points but also fully cures the adhesive (conductive or non-conductive) used to fix the retaining wall and the insulating adhesive applied to the surface, thereby significantly enhancing the structural strength and adhesion of the retaining wall.

[0065] Example 3

[0066] like Figure 1 As shown, another barrier-based packaging structure of the present invention includes a lead frame, including a base island for mounting a chip and pins for electrical connection; a chip, mounted on the base island; bonding wires for electrical connection between the chip and the pins; and a second barrier wall disposed on the base island and located between two adjacent bonding wires for isolating adjacent bonding wires.

[0067] Specifically, the second retaining wall is set on the arc platform, which is the area between the chip edge and the base island edge on the base island surface.

[0068] Specifically, the second barrier is placed between adjacent leads where wiring is dense and the spacing between leads is extremely small, such as... Figure 1 As shown, the height of the second retaining wall is slightly higher than the weld lines on both sides. The width s of the second retaining wall is not greater than the gap width between the weld lines on both sides. The length of the second retaining wall is determined based on the risk situation, specifying which position of the arc to which point is the area of ​​the easily touched line. The length of the second retaining wall is required to cover the area of ​​the easily touched line.

[0069] Specifically, the second retaining wall is made of metal, such as the same alloy as the lead frame. The assembly and insulation of the second retaining wall are as follows: Since the leads on both sides of the second retaining wall typically have different properties (not uniformly grounded), the retaining wall must be fixed using non-conductive adhesive. After the second retaining wall is installed, insulating adhesive must be applied to its surface (especially the sides that may come into contact with the leads) to insulate it completely. After curing, the second retaining wall forms a physical barrier between adjacent leads.

[0070] Example 4

[0071] The encapsulation method based on a barrier-wall encapsulation structure described in Example 3 includes the following steps.

[0072] Step 1: Die attach the chip to the surface of the base island;

[0073] Step 2: Wire bonding is formed between the chip and the pins.

[0074] Step 3: Install a second retaining wall on the base island to isolate adjacent welding lines;

[0075] Step 4: Bake and seal to complete the encapsulation; the baking process cures the colloid and strengthens the barrier structure.

[0076] Furthermore, as a preferred embodiment, for a large number of rows and a high density of bonding wires, the packaging method of this embodiment can be implemented in steps. For example, the first row of bonding wires is completed first, and then a "second barrier 1" is set at a predetermined position between the first and second rows of bonding wires; then the second row of bonding wires is performed, and then a "second barrier 2" is set between the second and third rows, and so on. This step-by-step operation method improves process feasibility and accuracy.

[0077] Example 5

[0078] Another barrier-based packaging structure of the present invention includes: a lead frame including a base island for mounting a chip and pins for electrical connection; a chip mounted on the base island; bonding wires for electrical connection between the chip and the pins; and a third barrier wall disposed on the base island, including a support portion and an isolation portion, the support portion for supporting the bonding wires above it, and the isolation portion located between two adjacent bonding wires for isolating adjacent bonding wires.

[0079] Specifically, the support and isolation components can be integrally molded to form the third barrier. The third barrier is made of metal, such as the same alloy as the lead frame. The assembly and insulation treatment of the third barrier are as follows: Since the leads on both sides of the isolation component of the third barrier usually have different properties (not uniformly grounded), the assembly of the third barrier must be fixed using non-conductive adhesive. After the third barrier is installed, insulating adhesive must be applied to its surface (especially the side that may come into contact with the leads) to make it completely insulated. After curing, the third barrier forms a physical barrier between adjacent leads.

[0080] As a preferred embodiment, such as Figure 3 and Figure 4 As shown, the support is fixed on the base island to support the bonding wires above it, and several isolation sections are located on top of the support, each isolation section isolating the bonding wires on its two sides. Figure 4 This is a side view of the third retaining wall. The isolation section is shown above the support section. The overall height of the third retaining wall is slightly higher than the weld lines on both sides. The width of the isolation section is not greater than the gap width between the weld lines on both sides. The overall length d of the third retaining wall is determined according to the risk situation, specifying which position of the arc is the area of ​​the line that is likely to be touched. The height of the support section does not exceed the weld line above it.

[0081] As a preferred embodiment, such as Figure 5 and Figure 6 As shown, the support is fixed on the base island to support the welding wire above it, and several isolation parts are located on the side of the support, each isolation part isolating the welding wire on both sides of it. Figure 6 This is a side view of the third retaining wall. The isolation section is located on the side of the support section. The height of the isolation section is slightly higher than the weld lines on both sides. The width of the isolation section retaining wall is not greater than the gap width between the weld lines on both sides. The overall length of the third retaining wall is determined based on the risk situation, specifying which position of the arc is prone to collapse. The height of the support section does not exceed the weld line above it.

[0082] Example 6

[0083] The encapsulation method based on a barrier-wall encapsulation structure described in Example 5 includes the following steps.

[0084] Step 1: Mount the chip onto the surface of the base island;

[0085] Step 2: Install a third retaining wall on the base island; the third retaining wall includes a support part and an isolation part. The support part is used to support the welding wire above it, and the isolation part is located between two adjacent welding wires to isolate adjacent welding wires.

[0086] Step 3: Form bonding wires between the chip and the pins;

[0087] Step 4: Bake and seal to complete the encapsulation; the baking process cures the colloid and strengthens the barrier structure.

[0088] The packaging structures in Embodiments 1 and 3 described above can be used individually or in combination depending on the product design (e.g., wire arc length, wiring density, solder wire properties). The packaging structure in Embodiment 5 described above can be used alone or in combination with the packaging structures of Embodiments 1 and / or 3. For example, in... Figure 4 and Figure 6 Both examples demonstrate the use of a combination of the first and third retaining walls.

Claims

1. A barrier-based encapsulation structure, characterized in that, include: The lead frame includes a base island for mounting the chip and pins for electrical connections; The chip is mounted on the base island; Wire bonding is used for electrical connection between the chip and the pin; A first retaining wall is disposed on the base island to support the bonding wires above it; and / or a second retaining wall is disposed on the base island and located between two adjacent bonding wires to isolate adjacent bonding wires.

2. The encapsulation structure based on the retaining wall as described in claim 1, characterized in that, Both the first and second retaining walls are made of metal.

3. The encapsulation structure based on the retaining wall as described in claim 1, characterized in that, When the welding wire above the first retaining wall is a grounding wire, the first retaining wall is fixed to the base island by conductive adhesive; When the welding wire above the first retaining wall is a non-grounded wire, the first retaining wall is fixed to the base island by insulating adhesive, and the surface of the first retaining wall is coated with insulating adhesive.

4. The encapsulation structure based on the retaining wall as described in claim 1, characterized in that, The second retaining wall is fixed to the base island by insulating adhesive, and the surface of the second retaining wall is coated with insulating adhesive.

5. The encapsulation structure based on the retaining wall as described in claim 1, characterized in that, The first and second retaining walls are disposed on the arc-shaped platform, which is the area between the chip edge and the base island edge on the base island surface.

6. The encapsulation structure based on the retaining wall as described in claim 1, characterized in that, The height of the first retaining wall does not exceed the weld line above it.

7. The encapsulation structure based on the retaining wall as described in claim 1, characterized in that, The height of the second retaining wall is slightly higher than the weld lines on both sides, and the width of the second retaining wall is not greater than the gap width between the weld lines on both sides.

8. A packaging method for a barrier-based packaging structure according to any one of claims 1-7, characterized in that, Includes the following steps: Step 1: Mount the chip onto the surface of the base island; Step 2: Form bonding wires between the chip and the pins; Step 3: Bake and seal the product to complete the packaging. Before step 2, the method further includes setting a first barrier on the base island to support the bonding wires between the chip and the pins; and / or, after step 2, the method further includes setting a second barrier on the base island, the second barrier being located between two adjacent bonding wires to isolate the adjacent bonding wires.

9. The encapsulation method based on the barrier-wall encapsulation structure according to claim 8, characterized in that, After forming a row of bonding wires between the chip and the pins, a second barrier is set on the base island before forming the next row of bonding wires.

10. A barrier-based encapsulation structure, characterized in that, include: The lead frame includes a base island for mounting the chip and pins for electrical connections; The chip is mounted on the base island; Wire bonding is used for electrical connection between the chip and the pin; The third retaining wall, located on the base island, includes a support section and an isolation section. The support section supports the welding wires above it, and the isolation section is located between two adjacent welding wires to isolate the adjacent welding wires.

11. The encapsulation structure based on a retaining wall according to claim 10, characterized in that, The third retaining wall is fixed to the base island by insulating adhesive, and the surface of the third retaining wall is coated with insulating adhesive; the height of the support part does not exceed the weld line above it, the height of the isolation part is slightly higher than the weld lines on both sides, and the width of the isolation part is not greater than the gap width between the weld lines on both sides.

12. A packaging method for a barrier-based packaging structure according to any one of claims 10-11, characterized in that, Includes the following steps: Step 1: Mount the chip onto the surface of the base island; Step 2: Install a third retaining wall on the base island; the third retaining wall includes a support part and an isolation part. The support part is used to support the welding wire above it, and the isolation part is located between two adjacent welding wires to isolate adjacent welding wires. Step 3: Form bonding wires between the chip and the pins; Step 4: Bake and seal the product to complete the packaging.

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