Packaging process for enhancing stability of SOP (Small Outline Package) multiple base islands

Abstract

The invention relates to the technical field of semiconductors, in particular to a packaging process for enhancing SOP multi-base-island stability. Comprising the following steps of S1, performing half-etching on a waste area on the front surface of the lead frame to form a half-etching area; s2, mounting a chip on the front surface of the lead frame; s3, carrying out first plastic package on the front surface of the lead frame, and filling a half-etched region in the waste region with a plastic package material; s4, etching the back surface of the lead frame until the plastic package material filled in the half-etching area is exposed, and separating and separating the base island and the pins; and S5, carrying out plastic packaging for the second time. Compared with the prior art, the lead frame is subjected to chip and external object pasting and wire welding operation after half etching, connecting ribs are not needed, and the problem that the planes of a plurality of base islands are unstable and uneven due to the fact that the supporting force of the connecting ribs is not strong after full etching of the SOP lead frame is solved. And the Dummy Lead does not need to be cut after plastic packaging is completed, so that the reliability is improved.

Description

Technical Field

[0001] The invention relates to the field of semiconductor technology, in particular to a packaging process for enhancing the stability of SOP multi-base islands. Background Art

[0002] like Figure 10 to Figure 11 As shown, the existing SOP is a multi-island design. Each island 12 of the SOP has only 1 to 3 connecting ribs 10, including Dummy Lead 11, which are supported on the same side. After the lead frame process is fully etched, the connecting ribs are impacted by the concave mold, causing the island to be easily warped. In the packaging process, multiple chips and foreign objects need to be placed on multiple islands. Because the supporting force of the connecting ribs themselves is not strong, the problems of uneven planes and warping of multiple islands are aggravated. When the chip is soldered on the island, the warping is unstable, resulting in poor welding performance, affecting product reliability. At the same time, when the Dummy Lead is cut after the plastic encapsulation is completed, it is torn forcefully, resulting in colloid stratification, which also affects product reliability. Summary of the invention

[0003] In order to overcome the deficiencies of the prior art, the present invention provides a packaging process for enhancing the stability of SOP multi-island.

[0004] To achieve the above purpose, a packaging process is designed to enhance the stability of SOP multi-base islands, including the following steps: S1, half-etching the waste area on the front side of the lead frame to form a half-etched area; S2, mounting the chip on the front side of the lead frame; S3, performing the first plastic encapsulation on the front side of the lead frame, and the half-etched area in the waste area is also filled with plastic encapsulation material; S4, etching the back side of the lead frame until the plastic encapsulation material filled in the half-etched area is exposed, so as to separate and isolate the base island and the pin; S5, second plastic sealing.

[0005] The specific method of step S2 is as follows: S21, setting a metal coating on the front side of the lead frame; S22, mounting a chip on the base island on the front side of the lead frame; S23, bonding the chip to the metal coating through wire bonding.

[0006] In the second plastic sealing of step S5, the front and back sides of the lead frame are plastic sealed simultaneously.

[0007] The process also includes step S6, removing the connecting ribs, electroplating the outer pins, bending the outer pins, cutting the individual chips, and completing the packaging.

[0008] In the step S4, the entire back side of the lead frame is etched, and the effective copper area finally formed is the area excluding the half-etched area in the step S1.

[0009] Compared with the prior art, the present invention can paste chips and foreign objects and weld wires after the lead frame is half-etched, without the need for connecting ribs, thus overcoming the problem of unstable and uneven planes of multiple base islands caused by weak supporting force of connecting ribs after full etching of the SOP lead frame. After plastic encapsulation, it is not necessary to cut Dummy Lead, thus improving reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a schematic diagram of step S1 of the present invention.

[0011] Figure 2 It is a schematic diagram of the half-etching area in step S1 of the present invention.

[0012] Figure 3 Schematic diagram of step S2 of the present invention Figure 1 .

[0013] Figure 4 Schematic diagram of step S2 of the present invention Figure 2 .

[0014] Figure 5 It is a schematic diagram of step S3 of the present invention.

[0015] Figure 6 It is a schematic diagram of step S4 of the present invention.

[0016] Figure 7 It is the effective copper area finally formed after the second etching in step S4 of the present invention.

[0017] Figure 8 It is a schematic diagram of step S5 of the present invention.

[0018] Fig. 9 It is a schematic diagram of step S6 of the present invention.

[0019] Fig.10 It is a schematic structural diagram of an existing lead frame before improvement by the present invention.

[0020] Fig.11 It is a schematic structural diagram of the existing lead frame after connection before improvement by the present invention. DETAILED DESCRIPTION

[0021] The present invention will be further described below with reference to the accompanying drawings.

[0022] like Figures 1 to 9 As shown, the packaging process for enhancing the stability of SOP multi-island in this embodiment includes the following steps: S1, half-etching the waste area on the front side of the lead frame 1 to form a half-etched area 2; S2, mounting chip 3 on the front side of lead frame 1; S3, performing the first plastic encapsulation on the front side of the lead frame 1, and also filling the half-etched area 2 in the waste area with the plastic encapsulation material 4; S4, etching the back side of the lead frame 1 until the plastic encapsulation material 4 filled in the half-etched area is exposed, and the base island 12 and the lead 13 are separated and isolated; S5, the second plastic encapsulation, plastic encapsulating the front and back sides of the lead frame 1 at the same time; the second plastic encapsulation completely covers the first plastic encapsulation body and the base island 12 and the pins 13 exposed on the back side of the lead frame in the plastic encapsulation body, thereby enhancing the bonding between the upper and lower colloids.

[0023] S6, remove the connecting ribs, electroplate the outer pins, bend the outer pins, cut into individual pieces, and complete the packaging.

[0024] The specific method of step S2 is as follows: S21, setting a metal coating 5 on the front side of the lead frame 1; S22, mounting a chip 3 on the base island on the front side of the lead frame 1; S23, bonding the chip 3 to the metal coating 5 via wires 6.

[0025] The area etched in step S4 is the entire back side of the lead frame, and the effective copper area finally formed is the area excluding the half-etched area 2 in step S1.

[0026] The invention uses secondary etching to separate the base island from the pins. The back of the lead frame is fully etched, and when the waste area colloid is exposed, it means that the base island and the pins are separated and separated. Then, through two plastic encapsulations, the base island and the pins are tightly connected through the plastic encapsulation body without connecting ribs, thus overcoming the problem of multiple base island planes being unstable and uneven due to the weak supporting force of the connecting ribs after the SOP lead frame is fully etched.

Claims

1. A packaging process for enhancing the stability of SOP multi-island, characterized by: The steps include: S1, half-etching the waste area on the front side of the lead frame (1) to form a half-etched area (2); S2, mounting a chip (3) on the front side of the lead frame (1); S3, performing a first plastic encapsulation on the front side of the lead frame (1), and also filling the half-etched area (2) in the waste area with a plastic encapsulation material (4); S4, etching the entire back side of the lead frame (1) until the plastic encapsulation material (4) filled in the half-etched area is exposed, so as to separate and isolate the base island and the pins; S5, second plastic sealing.

2. A packaging process for enhancing the stability of SOP multi-island according to claim 1, characterized in that: The specific method of step S2 is as follows: S21, providing a metal coating (5) on the front side of the lead frame (1); S22, mounting a chip (3) on the base island on the front side of the lead frame (1); S23, bonding the chip (3) to the metal coating (5) via wires (6).

3. A packaging process for enhancing the stability of SOP multi-island according to claim 1, characterized in that: In the second plastic sealing of step S5, the front and back sides of the lead frame (1) are plastic sealed simultaneously.

4. A packaging process for enhancing the stability of SOP multi-island according to claim 1, characterized in that: The process also includes step S6, removing the connecting ribs, electroplating the outer pins, bending the outer pins, cutting the individual chips, and completing the packaging.

5. A packaging process for enhancing the stability of SOP multi-island according to claim 1, characterized in that: In the step S4, the entire back side of the lead frame (1) is etched, and the effective copper area (14) finally formed is the area excluding the half-etched area (2) in step S1.

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