A qfn packaging method for a power conversion module

Abstract

The application relates to the technical field of QFN packaging, and discloses a QFN packaging method of a power conversion module, which solves the problems of poor internal heat conduction effect, short circuit and unstable connection of the existing QFN packaging structure, and comprises a power conversion module PCB and a plurality of QFN packaging bodies, wherein the QFN packaging body is composed of a packaging base, a chip seat, a chip and a plastic packaging body, a plurality of first pins are arranged on the top side of the packaging base, a plurality of second pins are arranged on the top side of the chip, and the first pins and the second pins are connected through metal wires; the power conversion module of the QFN packaging structure can improve the internal heat conduction effect, make the heat on the chip quickly dissipate, improve the connection stability between the internal pins and the stability of the connection between the QFN packaging body and the power conversion module PCB, and can avoid tin climbing and short circuit.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of QFN packaging, and particularly relates to a QFN packaging method of a power conversion module. BACKGROUND

[0002] QFN is a kind of leadless packaging, which is square or rectangular. Since the QFN packaging does not have gull-wing leads like traditional SOIC and TSOP packaging, the conductive path between the internal pins and pads is short, the self-inductance coefficient and the wiring resistance in the packaging body are very low, so it can provide excellent electrical performance. In addition, it also provides excellent heat dissipation performance through the exposed lead frame pad, which has a direct heat dissipation channel for releasing heat in the package. Usually, the heat dissipation pad is directly soldered on the circuit board, and the heat dissipation via in the PCB helps to diffuse the excess power consumption into the copper ground plate to absorb excess heat.

[0003] However, the current QFN packaging structure is still connected by a filamentous lead between the internal chip pins and the pins on the packaging base, and the connection is a single soldering point, which is prone to poor contact, and the heat conduction effect is not good, which cannot quickly transfer the heat on the chip to the pins on the packaging base, thereby affecting the heat dissipation performance. In addition, when the current QFN packaging structure is connected with the PCB, if the tin amount is too much, the tin climbing phenomenon may occur, thereby easily causing short circuit, and if the tin amount is too little, it will lead to the defects of poor connection stability and low connection strength, which is easy to cause the falling off of the connection. SUMMARY

[0004] In view of the above problems, in order to overcome the defects of the prior art, the application provides a QFN packaging method of a power conversion module, which effectively solves the problems of poor internal heat conduction effect of the existing QFN packaging structure and easy short circuit and unstable connection when connected with the PCB.

[0005] To achieve the above purpose, the application provides the following technical scheme: a QFN packaging method of a power conversion module, comprising a power conversion module PCB and a plurality of QFN packaging bodies, the QFN packaging bodies are connected to the top end of the power conversion module PCB, the QFN packaging body is composed of a packaging base, a chip seat, a chip and a plastic packaging body, the chip seat is connected to the top end of the packaging base, the chip is connected to the top end of the chip seat, the plastic packaging body is connected to the top end of the packaging base and the chip, the side of the top end of the packaging base is provided with a plurality of first pins inserted into the packaging base, the side of the top end of the chip is provided with a plurality of second pins matched with the first pins, and the first pins and the second pins are connected by metal wires.

[0006] Preferably, the QFN package is connected to the top end of the power conversion module PCB board by soldering, and the top end of the power conversion module PCB board is provided with a plurality of printed pins matched with the first pins.

[0007] Preferably, the first pin is composed of a penetrating section and an exposed section, the penetrating section is fixedly connected to the top end of the exposed section, and the penetrating section penetrates into the packaging base, and the exposed section is located at the bottom end of the side edge of the packaging base.

[0008] Preferably, the bottom end of the exposed section is provided with a solder filling groove in an arc shape, and the bottom surface of the solder filling groove is provided with an etching layer in an irregular etching surface structure.

[0009] Preferably, the top end of the packaging base is provided with a placing groove one matched with the chip seat, the top end of the chip seat is provided with a placing groove two matched with the chip, and the four corners of the top end of the packaging base are fixedly provided with T-shaped limiting connection arms matched with the plastic package.

[0010] Preferably, the top end of the first pin is provided with a connecting slot one matched with the metal wire, and the top end of the second pin is provided with a connecting slot two matched with the metal wire.

[0011] Preferably, the metal wire is composed of a first connecting contact piece, a second connecting contact piece and a connecting section, the first connecting contact piece is fixedly connected to the bottom end of the connecting section and matched with the connecting slot one, the second connecting contact piece is fixedly connected to the top end of the connecting section and matched with the connecting slot two, and the first connecting contact piece, the second connecting contact piece and the connecting section are all made of copper material.

[0012] Preferably, the QFN packaging method of the power conversion module comprises the following steps:

[0013] Step one, a solder filling groove is formed at the bottom end of the first pin, and an etching layer in an irregular etching surface structure is formed at the bottom end of the solder filling groove by etching;

[0014] Step two, a placing groove one is formed at the top end of the packaging base, a plurality of through holes are formed at the top side edge of the packaging base, the inner diameter of the through hole is the same as the outer diameter of the first pin, and the first pin is inserted into the inner part of the through hole;

[0015] Step three, T-shaped limiting connection arms are fixedly installed at the four corners of the top end of the packaging base, and the T-shaped limiting connection arms are made of aluminum alloy material;

[0016] Step four, a placing groove two is formed at the top end of the chip seat, the chip seat is connected to the inner part of the placing groove one, and the chip is placed in the inner part of the placing groove two, so that the second pin on the chip is located at the top end;

[0017] Step five, the plurality of metal wires are clamped and fixed through the auxiliary clamping plate, and the metal wires are arranged equidistantly, the width between the metal wires is same as the width between the first pin and the second pin, the first connecting contact is attached to the first pin and located in the inside of the connecting card slot one, and the second connecting contact is attached to the second pin and located in the inside of the connecting card slot two;

[0018] Step six, the metal wires are respectively soldered with the first pin and the second pin, and the auxiliary clamping plate is removed after being connected and fixed;

[0019] Step seven, the packaging die is installed and fixed at the top end of the packaging base, and the hot-melt plastic package body is poured in the inside of the packaging die, so that the overall packaging of the chip seat and the chip is realized;

[0020] Step eight, the QFN package body is connected with the printed pin on the power conversion module PCB through soldering, so that the solder filling groove is filled with solder.

[0021] Preferably, in step two, when the first pin is installed, the flared end of the solder filling groove is located on the outside of the packaging base and is exposed.

[0022] Preferably, in steps two and four, the first pin and the through hole, the chip seat and the placing groove one, and the chip and the placing groove two are all glue connection structures.

[0023] Compared with the prior art, the QFN packaging structure has the following beneficial effects:

[0024] (1), in the work, the power conversion module of the QFN packaging structure can improve the internal heat conduction effect, so that the heat on the chip is quickly dissipated, and the connection stability between the internal pins and the stability of the connection between the QFN package body and the power conversion module PCB can be improved, and the tin climbing phenomenon can be avoided, thereby avoiding the short circuit. BRIEF DESCRIPTION OF DRAWINGS

[0025] The accompanying drawings are used to provide a further understanding of the present application, and constitute a part of the specification, and are used to explain the present application together with embodiments of the present application, and do not constitute a limitation on the present application.

[0026] In the drawings:

[0027] Figure 1 It is a partial structure schematic view of the power conversion module of the present application;

[0028] Figure 2 It is a connection structure schematic view of the chip, the chip seat and the packaging base of the present application;

[0029] Figure 3 It is a structure schematic view of the packaging base of the present application;

[0030] Figure 4 Figure 1 is a schematic diagram of the chip and the chip seat connection structure of the present application;

[0031] Figure 5 Figure 2 is a sectional view of the QFN package of the present application;

[0032] Figure 6 Figure 3 is a schematic diagram of the first pin and the printed pin connection structure of the present application; Figure 5

[0033] Figure 7 Figure 4 is a schematic diagram of the first pin structure of the present application;

[0034] Figure 8 Figure 5 is a schematic diagram of the solder filling groove structure of the present application;

[0035] Figure 9 Figure 6 is a schematic diagram of the metal wire structure of the present application;

[0036] Figure 10 Figure 7 is a schematic diagram of the metal wire structure of the present application;

[0037] In the figure: 1, power conversion module PCB board; 2, QFN package; 3, package base; 4, chip seat; 5, chip; 6, plastic package; 7, first pin; 8, second pin; 9, metal wire; 10, solder; 11, printed pin; 12, insertion section; 13, exposed section; 14, solder filling groove; 15, etching layer; 16, placement groove one; 17, placement groove two; 18, T-shaped limiting connection arm; 19, connection clamping groove one; 20, connection clamping groove two; 21, first connection contact; 22, second connection contact; 23, connection section. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0039] Embodiment one, by Figures 1 to 10 ​The application discloses a QFN packaging method of a power conversion module, which comprises a power conversion module PCB board 1 and a plurality of QFN packaging bodies 2. The QFN packaging bodies 2 are connected to the top end of the power conversion module PCB board 1. The QFN packaging body 2 is composed of a packaging base 3, a chip seat 4, a chip 5 and a plastic packaging body 6. The chip seat 4 is connected to the top end of the packaging base 3. The chip 5 is connected to the top end of the chip seat 4. The plastic packaging body 6 is connected to the top end of the packaging base 3 and the chip 5. A plurality of first pins 7 are arranged on the side of the top end of the packaging base 3 and penetrate the packaging base 3. A plurality of second pins 8 matched with the first pins 7 are arranged on the side of the top end of the chip 5. The first pins 7 and the second pins 8 are connected through metal wires 9.

[0040] In the embodiment two, Figures 1 to 10 The QFN packaging body 2 is connected to the top end of the power conversion module PCB board 1 through soldering tin 10. The top end of the power conversion module PCB board 1 is provided with a plurality of printed pins 11 matched with the first pins 7. The first pin 7 is composed of a penetrating segment 12 and a bare segment 13. The penetrating segment 12 is fixedly connected to the top end of the bare segment 13 and penetrates the packaging base 3. The bare segment 13 is located at the bottom end of the side of the packaging base 3. The bottom end of the bare segment 13 is provided with a soldering tin filling groove 14 in an arc shape. The bottom surface of the soldering tin filling groove 14 is provided with an etching layer 15 in an irregular etching surface structure. The top end of the packaging base 3 is provided with a placing groove I 16 matched with the chip seat 4. The top end of the chip seat 4 is provided with a placing groove II 17 matched with the chip 5. The four corners of the top end of the packaging base 3 are fixedly provided with T-shaped limiting connection arms 18 matched with the plastic packaging body 6. The top end of the first pin 7 is provided with a connecting clamping groove I 19 matched with the metal wire 9. The top end of the second pin 8 is provided with a connecting clamping groove II 20 matched with the metal wire 9. The metal wire 9 is composed of a first connecting contact piece 21, a second connecting contact piece 22 and a connecting segment 23. The first connecting contact piece 21 is fixedly connected to the bottom end of the connecting segment 23 and matched with the connecting clamping groove I 19. The second connecting contact piece 22 is fixedly connected to the top end of the connecting segment 23 and matched with the connecting clamping groove II 20. The first connecting contact piece 21, the second connecting contact piece 22 and the connecting segment 23 are all made of copper.

[0041] The metal wire 9 in the strip structure can improve the heat conduction efficiency, increase the contact area of the metal wire 9 with the first pin 7 and the second pin 8, ensure the stability of the connection between the metal wire 9 and the first pin 7 and the second pin 8 during the soldering connection, avoid unstable connection, and transfer the heat generated during the operation of the chip 5 to the second pin 8, then to the first pin 7, and finally to the power conversion module PCB board 1, realizing rapid heat transfer and effectively improving the heat dissipation effect. When the plastic package 6 is used to integrally package the packaging base 3, the chip seat 4 and the chip 5, the T-shaped limiting connection arm 18 can improve the connection strength between the packaging base 3 and the plastic package 6, limit the plastic package 6, avoid the separation or loosening of the plastic package 6 from the packaging base 3 during the later use process, and make the solder 10 fill the inside of the solder filling groove 14 when the QFN package 2 is connected with the power conversion module PCB board 1, which can ensure the connection strength and stability, and will not cause short circuit due to excessive solder. The etching layer 15 with irregular etching surface structure can prevent the solder 10 from separating from the first pin 7.

[0042] In the third embodiment, Figures 1 to 10 A QFN packaging method of a power conversion module is given, which comprises the following steps:

[0043] Step one: a solder filling groove 14 is formed at the bottom end of the first pin 7, and an etching layer 15 with irregular etching surface structure is formed by etching at the bottom end of the solder filling groove 14;

[0044] Step two: a placing groove one 16 is formed at the top end of the packaging base 3, a plurality of through holes are formed at the top side of the packaging base 3, the inner diameter of the through holes is the same as the outer diameter of the first pin 7, and the first pin 7 is inserted into the inside of the through hole;

[0045] Step three: a T-shaped limiting connection arm 18 is fixedly installed at the top end of the packaging base 3 at four corners, and the T-shaped limiting connection arm 18 is made of aluminum alloy;

[0046] Step four: a placing groove two 17 is formed at the top end of the chip seat 4, the chip seat 4 is connected to the inside of the placing groove one 16, and the chip 5 is placed in the inside of the placing groove two 17, so that the second pin 8 on the chip 5 is located at the top end;

[0047] Step five: a plurality of metal wires 9 are clamped and fixed by an auxiliary clamping plate, and the metal wires 9 are arranged equidistantly, the width between the metal wires 9 is the same as the width between the first pin 7 and the second pin 8, the first connecting contact 21 is attached to the first pin 7 and located in the inside of the connecting card slot one 19, and the second connecting contact 22 is attached to the second pin 8 and located in the inside of the connecting card slot two 20;

[0048] Step six, the metal wire 9 is respectively connected with the first pin 7 and the second pin 8 by soldering, after connection fixation, the auxiliary clamping plate is removed;

[0049] Step seven, the packaging die sleeve is installed on the top of the packaging base 3 and fixed, the plastic package 6 is poured in the inside of the packaging die sleeve after hot melting, the overall packaging of the chip seat 4 and the chip 5 is realized;

[0050] Step eight, the QFN package 2 is connected with the printed pin 11 on the power conversion module PCB board 1 through the soldering 10, so that the soldering 10 is filled in the soldering filling groove 14.

[0051] In the fourth embodiment, the QFN package 2 is connected with the printed pin 11 on the power conversion module PCB board 1 through the soldering 10, so that the soldering 10 is filled in the soldering filling groove 14. Figures 1 to 10 It is given that when the first pin 7 is installed, the flared end of the soldering filling groove 14 is kept outside the packaging base 3 and exposed, the first pin 7 is connected with the through hole, the chip seat 4 is connected with the placing groove one 16, and the chip 5 is connected with the placing groove two 17, which are all glue connection structures.

[0052] In work, the power conversion module with the QFN packaging structure can improve the internal heat conduction effect, make the heat on the chip quickly dissipate, improve the connection stability between the internal pins and the stability of the connection between the QFN package and the power conversion module PCB board, and avoid the occurrence of solder climbing phenomenon, thereby avoiding the short circuit.

Claims

1. A power conversion module, comprising a power conversion module PCB board (1) and a plurality of QFN packages (2), characterized in that: The QFN package (2) is connected to the top of the power conversion module PCB board (1). The QFN package (2) consists of a package base (3), a chip socket (4), a chip (5) and a molding compound (6). The chip socket (4) is connected to the top of the package base (3). The chip (5) is connected to the top of the chip socket (4). The molding compound (6) is connected to the top of the package base (3) and the top of the chip (5). The top of the package base (3) has several first pins (7) inserted through the package base (3). The top of the chip (5) has several second pins (8) that match the first pins (7). The first pins (7) and the second pins (8) are connected by metal wires (9). The top of the first pin (7) is provided with a first connecting slot (19) that matches the metal wire (9), and the top of the second pin (8) is provided with a second connecting slot (20) that matches the metal wire (9). The metal wire (9) is composed of a first connecting contact piece (21), a second connecting contact piece (22) and a connecting section (23). The first connecting contact piece (21) is fixedly connected to the bottom end of the connecting section (23) and matches the first connecting slot (19). The second connecting contact piece (22) is fixedly connected to the top end of the connecting section (23) and matches the second connecting slot (20). The first connecting contact piece (21), the second connecting contact piece (22) and the connecting section (23) are all made of copper.

2. The power conversion module according to claim 1, characterized in that: The QFN package (2) is connected to the top of the power conversion module PCB board (1) by solder (10). The top of the power conversion module PCB board (1) is provided with several printed pins (11) that match the first pin (7).

3. A power conversion module according to claim 1, characterized in that: The first pin (7) is composed of an interpenetrating section (12) and an exposed section (13). The interpenetrating section (12) is fixedly connected to the top of the exposed section (13). The interpenetrating section (12) is inserted into the package base (3). The exposed section (13) is located at the bottom of the side of the package base (3).

4. A power conversion module according to claim 3, characterized in that: The exposed section (13) has a solder filling groove (14) at its bottom end. The solder filling groove (14) has an arc-shaped structure. An etching layer (15) is provided on the bottom surface of the solder filling groove (14). The etching layer (15) has an irregular etching surface structure.

5. A power conversion module according to claim 1, characterized in that: The top of the encapsulation base (3) is provided with a placement groove 1 (16) that matches the chip holder (4), and the top of the chip holder (4) is provided with a placement groove 2 (17) that matches the chip (5). T-shaped limiting connecting arms (18) that match the molding compound (6) are fixedly provided at the four corners of the top of the encapsulation base (3).

6. A QFN packaging method for a power conversion module according to any one of claims 1-5, comprising the following steps: Step 1: A solder filling groove (14) is opened at the bottom end of the first pin (7), and an etching layer (15) with an irregular etching surface structure is formed at the bottom end of the solder filling groove (14). Step 2: A placement groove 1 (16) is opened at the middle position of the top of the encapsulation base (3). Several through holes are opened on the top side of the encapsulation base (3). The inner diameter of the through holes is the same as the outer diameter of the first pin (7). The first pin (7) is inserted into the inside of the through holes. Step 3: T-shaped limiting connecting arms (18) are fixedly installed at the four corners of the top of the packaging base (3). The T-shaped limiting connecting arms (18) are made of aluminum alloy. Step 4: Open a second placement groove (17) at the top of the chip holder (4), connect the chip holder (4) to the inside of the first placement groove (16), and place the chip (5) inside the second placement groove (17) so that the second pin (8) on the chip (5) is located at the top. Step 5: Clamp and fix multiple metal wires (9) with auxiliary clamping plates, and arrange the metal wires (9) at equal intervals. The width between the metal wires (9) is the same as the width between the first pin (7) and the second pin (8), so that the first connecting contact piece (21) is attached to the first pin (7) and located inside the first connecting slot (19), and the second connecting contact piece (22) is attached to the second pin (8) and located inside the second connecting slot (20). Step 6: Solder the metal wire (9) to the first pin (7) and the second pin (8) respectively. After the connection is fixed, remove the auxiliary clamping plate. Step 7: Install and fix the encapsulation mold on the top of the encapsulation base (3), and pour the hot-melted plastic encapsulation body (6) into the encapsulation mold to achieve overall encapsulation of the chip socket (4) and the chip (5); Step 8: Connect the QFN package (2) to the printed pins (11) on the power conversion module PCB board (1) with solder (10) so that the solder (10) fills the solder filling groove (14).

7. The QFN packaging method for a power conversion module according to claim 6, characterized in that: In step two, when installing the first pin (7), the flared end of the solder filling groove (14) is kept on the outer side of the package base (3) and exposed.

8. The QFN packaging method for a power conversion module according to claim 6, characterized in that: In steps two and four, the connection between the first pin (7) and the through hole, the connection between the chip holder (4) and the first placement groove (16), and the connection between the chip (5) and the second placement groove (17) are all glued together.

Images