CN115274592A

CN115274592A - Power module and power module manufacturing method

Info

Publication number: CN115274592A
Application number: CN202210767515.9A
Authority: CN
Inventors: 郑楠楠; 陈峤; 刘谦
Original assignee: Shenzhen STS Microelectronics Co Ltd
Current assignee: Shenzhen STS Microelectronics Co Ltd
Priority date: 2022-07-01
Filing date: 2022-07-01
Publication date: 2022-11-01

Abstract

The invention discloses a power module and a preparation method thereof, wherein the power module comprises a lead frame, a first chip, a second chip and a first connecting assembly, the first chip and the second chip are connected with the lead frame, the first connecting assembly comprises a first insulating part and a first conductive part, the first conductive part is respectively and electrically connected with the first chip and the second chip, and the outer side of the first conductive part is coated with the first insulating part. The outside cladding of first electrically conductive piece has first insulating part, and first insulating part can increase first connecting element's bulk strength, reduces first connecting element because of the cracked probability of impact or vibrations, and in addition, first insulating part can also realize the insulation of first electrically conductive piece, even take place the contact between the first connecting element, first electrically conductive piece also can be through first insulating part isolation and avoid the short circuit.

Description

Power module and power module manufacturing method

Technical Field

The invention relates to the technical field of semiconductor packaging, in particular to a power module and a preparation method of the power module.

Background

The intelligent power module comprises a plurality of chips, such as a control chip and a power chip, wherein the control chip is conducted with the power chip through a lead, in the traditional intelligent power module preparation process, two ends of the lead are required to be welded and fixed with the control chip and the power chip respectively, and then the lead is packaged integrally, however, the intelligent power module is limited by the area of a bonding pad on the chip, the wire diameter of the lead is usually smaller, the strength of the lead is lower, direct contact between the leads is easily caused by vibration in a transfer process or impact of packaging materials in a packaging process, and therefore short-circuit faults are caused, and when the vibration or the impact is too large, the problems of lead fracture and the like can be caused.

Disclosure of Invention

The present invention is directed to solving at least one of the problems of the prior art. Therefore, the invention provides a power module which can solve the problems of lead fracture and short circuit.

The invention also provides a preparation method of the power module.

A power module according to a first embodiment of the present invention includes:

a lead frame;

a first chip connected to the lead frame;

a second chip connected to the lead frame;

the first connecting assembly comprises a first insulating piece and a first conductive piece, the first conductive piece is electrically connected with the first chip and the second chip respectively, and the first insulating piece is wrapped outside the first conductive piece.

The power module provided by the embodiment of the invention at least has the following beneficial effects:

the outside cladding of first electrically conductive piece has first insulating piece, and first insulating piece can increase first connecting assembly's bulk strength, reduces first connecting assembly because of strikeing or the cracked probability of vibrations, and in addition, first insulating piece can also realize the insulation of first electrically conductive piece, even take place the contact between the first connecting assembly, first electrically conductive piece also can be kept apart and avoid the short circuit through first insulating piece.

In other embodiments of the present invention, the power module further includes a rigid circuit board connected to the lead frame, the rigid circuit board includes an insulating layer and a conductive layer, a portion of the conductive layer is located in the insulating layer and electrically connected to the first chip, and another portion of the conductive layer extends out of the insulating layer to form the first conductive member.

In other embodiments of the present invention, the lead frame has a pin, the power module further includes a second connecting assembly, the second connecting assembly includes a second insulating member and a second conductive member, two ends of the second conductive member are respectively electrically connected to the first chip and the pin, and the second insulating member is wrapped outside the second conductive member.

In other embodiments of the present invention, the power module further includes a rigid circuit board connected to the lead frame, the rigid circuit board includes an insulating layer and a conductive layer, a portion of the conductive layer is located in the insulating layer and electrically connected to the first chip, and another portion of the conductive layer extends out of the insulating layer to form the second conductive member.

In another embodiment of the present invention, the power chip includes a lead, one end of the lead is electrically connected to the first chip, the other end of the lead is electrically connected to the lead frame, one end of the first conductive member is electrically connected to the second chip, and the other end of the first conductive member is electrically connected to the lead frame.

In other embodiments of the present invention, the first conductive member is a thin sheet structure, and the first conductive member is covered with the first insulating member at least along two sides in a thickness direction.

In other embodiments of the present invention, the first connecting assemblies are provided in plurality, and the plurality of first connecting assemblies are arranged at intervals along a width direction of the first conductive member;

or, the first connecting assembly includes a plurality of first conductive members, the plurality of first conductive members are wrapped in the same first insulating member, and the first conductive members are arranged at intervals in the width direction.

In another embodiment of the present invention, the second chip has a pad, the first conductive member includes a main body portion and a connecting portion, the main body portion is electrically connected to the first chip, the connecting portion is electrically connected to the pad, the first insulating member includes a first insulating portion and a second insulating portion, the first insulating portion is coated outside the main body portion, the second insulating portion is coated outside the connecting portion, and a width of the first insulating portion is smaller than a width of the second insulating portion.

In other embodiments of the present invention, the length of the second insulating portion is smaller than the length of the pad, and/or the width of the second insulating portion is smaller than the width of the pad.

In other embodiments of the invention, the parameters of the first connection component satisfy at least one of the following:

the width of the first insulating part is 0.2mm to 0.5mm;

the length of the second insulating part is 0.4mm to 1.0mm, the width of the second insulating part is 0.3mm to 0.8mm, the length of the bonding pad is 0.3mm to 0.9mm, and the width of the bonding pad is 0.2mm to 0.7mm;

the thickness of the first conductive piece is 0.035mm to 0.07mm, and the thickness of one side of the first insulating piece is 0.03mm to 0.07mm.

In another embodiment of the present invention, the second insulating portion has a third window, a portion of the connecting portion exposed from the third window is electrically connected to the pad, a length of the third window is smaller than a length of the pad, a width of the third window is smaller than a width of the pad, and a distance from each side edge of the third window to a corresponding side edge of the pad is greater than or equal to 0.2mm.

In other embodiments of the present invention, the power module further includes a heat dissipation assembly, the heat dissipation assembly is connected to the lead frame and sinks relative to the lead frame, and the second chip is connected to the heat dissipation assembly.

The method for manufacturing a power module according to the first embodiment of the present invention includes the steps of:

preparing a lead frame, a first chip, a second chip and a first connecting assembly, wherein the first chip and the second chip are both connected to the lead frame, the first connecting assembly comprises a first insulating part and a first conductive part, and the first insulating part is coated outside the first conductive part;

so that the first chip is electrically connected with the second chip through the first conductive member.

In another embodiment of the present invention, a hard circuit board is prepared, the hard circuit board including an insulating layer and a conductive layer, a portion of the conductive layer being located within the insulating layer, another portion of the conductive layer extending out of the insulating layer to form the first conductive member, the hard circuit board is connected to the lead frame, the first chip is electrically connected to the conductive layer located within the insulating layer, and the second chip is electrically connected to the first conductive member.

In other embodiments of the present invention, after the first connection assembly is moved to the welding position by the welding member having the negative pressure adsorption hole, the first conductive member is welded by the welding member in an ultrasonic welding manner.

In another embodiment of the present invention, a first reference is recognized on the second chip, a second reference is recognized on the first insulating member, a distance between the first reference and the second reference is determined, and if the distance is within a set range, it is determined to be qualified.

In another embodiment of the present invention, the second chip has a pad, the first conductive member includes a main body portion and a connecting portion, the main body portion is electrically connected to the first chip, the connecting portion is electrically connected to the pad, the first insulating member includes a first insulating portion and a second insulating portion, the first insulating portion is coated on an outer side of the main body portion, and the second insulating portion is coated on an outer side of the connecting portion;

the size of the second insulating part is smaller than that of the bonding pad along the length direction of the bonding pad, so that at least one end of the bonding pad along the length direction is exposed, a first side edge of the exposed end of the bonding pad is taken as the first standard, a third side edge corresponding to the second insulating part is taken as the second standard, the distance between the first side edge and the third side edge is detected, and if the distance is within a set range, the bonding pad is judged to be qualified;

and/or the size of the second insulating part is smaller than the size of the pad along the length direction of the pad, so that at least one end of the pad along the width direction is exposed, the second side edge of the exposed end of the pad is taken as the first reference, the fourth side edge corresponding to the second insulating part is taken as the second reference, the distance between the second side edge and the fourth side edge is detected, and if the distance is within a set range, the qualification is judged.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The invention is further described with reference to the following figures and examples, in which:

fig. 1 is a perspective view of a power module in the related art before packaging;

FIG. 2 is an enlarged view of area A of FIG. 1;

fig. 3 is a schematic perspective view of a power module before being packaged in an embodiment of the invention;

FIG. 4 is a cross-sectional view of FIG. 3;

FIG. 5 is an enlarged view of the area B in FIG. 3;

FIG. 6 is an enlarged view of area C of FIG. 4;

fig. 7 is a perspective view of a rigid circuit board of the power module of fig. 3;

FIG. 8 is an exploded view of FIG. 7;

FIG. 9 is an enlarged view of area D in FIG. 3;

FIG. 10 is an enlarged view of area E in FIG. 4;

fig. 11 is a front view of another embodiment of the power module of the present invention before packaging;

FIG. 12 is a perspective view of a first connection assembly of the power module of FIG. 3;

FIG. 13 is a perspective view of the first connector assembly of FIG. 12 in another orientation;

FIG. 14 is an exploded view of the first connector assembly of FIG. 12;

fig. 15 is a schematic diagram illustrating connection between the second insulating part of the power module in fig. 3 and a bonding pad of the second chip.

Reference numerals are as follows:

a first chip 100;

a second chip 200, a pad 210, a first side 211, and a second side 212;

a lead frame 300, a lead 310;

the first connecting assembly 400, the first insulating member 410, the first insulating portion 411, the second insulating portion 412, the third side 4121, the fourth side 4122, the third window 4123, the first conductive member 420, the main body 421, and the connecting portion 422;

the hard circuit board 500, the insulating layer 510, the insulating coating 511, the insulating plate 512, the first window 513, the second window 514, the conductive layer 520 and the conductive sheet 521;

a second connecting component 600, a second insulating component 610, a second conductive component 620,

Heat dissipation assembly 700, first metal layer 710, ceramic layer 720, second metal layer 730;

a first lead 800;

a fifth lead 900.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention and are not to be construed as limiting the present invention.

In the description of the present invention, it should be understood that the orientation or positional relationship referred to in the description of the orientation, such as the upper, lower, front, rear, left, right, etc., is based on the orientation or positional relationship shown in the drawings, and is only for convenience of description and simplification of description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.

In the description of the present invention, the meaning of a plurality is one or more, the meaning of a plurality is two or more, and the above, below, exceeding, etc. are understood as excluding the present numbers, and the above, below, within, etc. are understood as including the present numbers. If the first and second are described for the purpose of distinguishing technical features, they are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated.

In the description of the present invention, unless otherwise explicitly limited, terms such as arrangement, installation, connection and the like should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific contents of the technical solutions.

In the description of the present invention, reference to the description of "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples", etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Referring to fig. 1 and 2, which respectively illustrate a perspective view and a partially enlarged view before a conventional power module is packaged, as shown in the figure, the power module includes a first chip 100, a second chip 200 and a lead frame 300, the first chip 100 and the second chip 200 are both connected to the lead frame 300, the first chip 100 may be a control chip, the second chip 200 may be a power chip, and the first chip 100 and the second chip 200 are electrically connected through a conductive member.

As can be seen from fig. 2, the size of the first chip 100 is relatively small, and a plurality of conductive members need to be connected to a single first chip 100, so the pad area allocated to each conductive member is correspondingly small, and thus the conventional power module generally uses the first lead 800 as a conductive member to realize the electrical connection between the first chip 100 and the second chip 200. The common first leads 800 are classified into two types, one is a gold wire or a copper wire, which typically has a diameter of not more than 50.8 micrometers, and the other is an aluminum wire, which typically has a diameter of not more than 177.8 micrometers, and the following problems exist in connecting the first chip 100 and the second chip 200 by the first leads 800: in the illustrated embodiment, the lead frame 300 with the first chip 100 and the second chip 200 needs to be molded to form a complete power module, during the packaging process, a molten packaging material (e.g., epoxy resin) may impact the first lead 800, and in addition, during the transportation process before molding, the lead frame 300 with the first chip 100 and the second chip 200 may also vibrate, especially for the second chip 200, because the temperature during operation is high, the second chip 200 is usually mounted on a heat dissipation device such as a copper-clad ceramic substrate, and then a single side of the copper-clad ceramic substrate is connected to the lead frame 300 to form an overhanging structure, such a structure may cause the vibration amplitude of the second chip 200 to be much larger than that of the lead frame 300, while the diameter of the first lead 800 is small and the strength is low, so the second chip is easily deformed due to the above-mentioned impact or vibration, and it is difficult to automatically recover to the original shape after deformation, and the deformation of the first lead 800 may cause the following problems: 1. in order to avoid the first leads 800 from being in contact with the chip or the lead frame to cause short circuit, the first leads 800 need to have a certain radian so that a certain safety distance is formed between each first lead 800 and the chip or the lead frame, if the first leads 800 are deformed, the risk of short circuit caused by the first leads 800 being in contact with the chip or the lead frame exists, and in addition, the risk of short circuit caused by mutual contact exists between the first leads 800; 2. when the amount of deformation of the first lead 800 exceeds the limit, breakage of the first lead 800 may also be caused.

In view of the above problems, the present invention provides a power module, which connects a first chip 100 and a second chip 200 through an electrical connection assembly with an insulating member instead of a first lead 800, so as to improve the short circuit and breakage of the first lead 800, and is described in detail below with reference to the accompanying drawings.

Referring to fig. 3 to 5, the power module in an embodiment of the invention includes a first chip 100, a second chip 200, a lead frame 300, and a first connection assembly 400. The first chip 100 may be a control chip, the second chip 200 may be a power chip, the first chip 100 and the second chip 200 are both connected to the lead frame 300, and the first chip 100 and the second chip 200 are electrically connected through the first connection assembly 400, where it should be noted that the electrical connection means that the first chip 100 and the second chip 200 can form a conductive relationship through the first connection assembly 400, and does not limit that the first connection assembly 400 is necessarily directly connected to the chips.

The first connection assembly 400 includes a first insulating member 410 and a first conductive member 420, and the first conductive member 420 is electrically connected to the first chip 100 and the second chip 200, respectively, so as to achieve conduction between the first chip 100 and the second chip 200. The first conductive member 420 is coated with a first insulating member 410, the first insulating member 410 may be made of a material having both mechanical protection, good electrical insulation, and heat resistance (capable of withstanding the highest temperature in the power module packaging process, such as plastic encapsulation, reflow soldering, etc.), such as Polyimide (PI), polyester (PET), and Polytetrafluoroethylene (PTFE), which can increase the overall mechanical strength of the first connecting assembly 400, reduce the probability of the first connecting assembly 400 breaking due to impact or shock, and at the same time, the first insulating member 410 has good resilience, and the first connecting assembly 400 can recover its original shape after shock or shock stops, and in addition, the first insulating member 410 can also achieve insulation of the first conductive member 420, so that even if the first connecting assembly 400, and the chip or the first connecting assembly 400 and the lead frame 300 are in contact, the first insulating member 410 can also isolate and avoid short circuit. It should be noted that, single intelligent power module cost is higher, it has practical meaning to reduce the cost of enterprises to reduce the defective rate of intelligent power module, the quantity of the inside lead wire of traditional intelligent power module is more, and the risk that quality defect appears in the lead bonding mode is higher, and as long as one of them lead wire became invalid, whole module all can become invalid, consequently, promote the reliability of single lead wire and help promoting whole power module's yields, this embodiment replaces traditional first lead wire through first connecting assembly 400, can show improvement reliability, thereby improve the product yield, and the production cost is reduced.

It should be noted that, when it is described that the first conductive member 420 is coated with the first insulating member 410, the first insulating member 410 is not required to completely coat the first conductive member 420, and only the first conductive members 420 are required not to contact with each other, for example, as shown in fig. 5 and 6, two opposite sides (for example, upper and lower sides in the drawing) in the thickness direction of the first conductive member 420 are coated with the first insulating member 410, and the width of the first insulating member 410 is greater than that of the first conductive member 420, so that the first conductive member 420 can be hidden between the first insulating members 410 on the two sides.

It should be noted that, when the chip is described as being connected to the lead frame 300, the chip and the lead frame may be directly connected to each other or connected through an intermediate member, for example, the second chip 200 may generate a large amount of heat during operation, so the power module may further include a heat dissipation assembly 700, the heat dissipation assembly 700 may be a Direct Bonding Coater (DBC) or an Active Metal Bonding (AMB), the second chip 200 is connected to the lead frame 300 through the heat dissipation assembly 700, taking fig. 6 as an example, the heat dissipation assembly 700 includes a first Metal layer 710, a ceramic layer 720 and a second Metal layer 730, the first Metal layer 710, the ceramic layer 720 and the second Metal layer 730 are sequentially stacked, the first Metal layer 710 and the ceramic layer 720 are both located in the package after packaging, the second chip 200 and the lead frame 300 are both directly connected to the first Metal layer 710, an outer side surface of the second Metal layer 730 is exposed from the package, and heat generated during operation of the second chip 200 may be transferred to the second Metal layer 720 through the first Metal layer 710 and the ceramic layer 720 and the ceramic layer 730 and then dissipated to the outside 730.

For another example, referring to fig. 3, fig. 7 and fig. 8, the first chip 100 may also be connected to the lead frame 300 through a rigid circuit board 500, where the rigid circuit board 500 includes an insulating layer 510 and a conductive layer 520, a portion of the conductive layer 520 is located in the insulating layer 510, and another portion of the conductive layer 520 extends out of the insulating layer 510 to form the first conductive member 420, that is, the first conductive member 420 in this embodiment is not an independent component, but is a portion of the conductive layer 520 in the rigid circuit board 500. As shown in fig. 1, in the conventional power module packaging process, one end of a first lead 800 is soldered to a first chip 100, and the other end is soldered to a second chip 200, that is, both ends of the first lead 800 need to be soldered, but in this embodiment, only one end of a first conductive member 420 needs to be connected to the second chip 200, which can save processing steps, and in addition, because the first conductive member 420 is a part of a conductive layer 520, compared with the conventional soldering method of wire bonding, quality defects related to the conventional lead soldering, such as solder joint falling, etc., are not generated, and the reliability of soldering is greatly improved. On the other hand, if both ends of the first conductive member 420 are fixed by welding or sintering, each first conductive member 420 may generate two connection points, and each connection point has a possibility of generating a quality defect.

The insulating layer 510 has a substantially rectangular structure, and is made of a hard material that is not electrically conductive so as to be able to support the first chip 100, and as shown in fig. 8 for example, the insulating layer 510 includes an insulating coating 511 and an insulating plate 512, and a part of the conductive layer 520 is located between the insulating coating 511 and the insulating plate 512, and another part thereof protrudes from between the insulating coating 511 and the insulating plate 512. The conductive layer 520 includes a plurality of conductive sheets 521, and a portion of the conductive sheets 521 can protrude out of the insulating layer 510 to form the first conductive member 420.

The first chip 100 and the hard circuit board 500 may be connected by a second lead, not shown, the insulating layer 510 is correspondingly provided with a first window 513, one end of the second lead is electrically connected to a pad on the first chip 100, and the other end of the second lead is electrically connected to the conductive layer 520 through the first window 513, so that the first chip 100 and the second chip 200 are electrically connected to the conductive layer 520 through the second lead. In the embodiment shown in fig. 7 and 8 in particular, the first window 513 is disposed on the insulating coating 511.

The second lead may be a gold wire or a copper wire, and it should be noted that the first window 513 is disposed near the first chip 100, and the second lead is short in length and is not prone to breaking when impacted or vibrated.

In some embodiments, referring to fig. 3, the lead frame 300 has a lead 310, the lead 310 protrudes outside the package after being packaged to serve as a connection terminal for electrically connecting the power module to an external device, in order to electrically connect the first chip 100 and the lead 310, referring to fig. 3 and fig. 7 to 10, the power module further includes a second connection assembly 600, the second connection assembly 600 includes a second insulating member 610 and a second conductive member 620, two ends of the second conductive member 620 are respectively electrically connected to the first chip 100 and the lead 310, an outer side of the second conductive member 620 is covered with the second insulating member 610, similar to the first insulating member 410, the second insulating member 610 is also made of a material which is electrically non-conductive and has certain strength, such as the above-mentioned Polyimide (PI), polyester (PET), polytetrafluoroethylene (PTFE), and the like, and can increase the overall strength of the second connection assembly 600. Referring to fig. 1 and 2, in the conventional power module, the first chip 100 and the lead 310 are also electrically connected by the first lead 800, so that there is a possibility of wire breaking or solder failure due to impact or vibration, and the like, and in the embodiment, the second connection assembly 600 including the second insulating member 610 connects the first chip 100 and the lead 310, so that the probability of wire breaking or solder failure can be reduced.

In some further embodiments, the first chip 100 is connected to the lead frame 300 through the rigid circuit board 500, the rigid circuit board 500 of this embodiment also includes an insulating layer 510 and a conductive layer 520, a portion of the conductive layer 520 is located in the insulating layer 510 and electrically connected to the first chip 100, and another portion extends out of the insulating layer 510 to form the second conductive member 620, that is, the second conductive member 620 in this embodiment is not a separate component but a portion of the conductive layer 520 in the rigid circuit board 500, so that this embodiment only needs to connect one end of the second conductive member 620 to the lead 310, which can save processing steps, and in addition, since the second conductive member 620 is a portion of the conductive layer 520, compared with a conventional soldering method of wire bonding, quality defects related to conventional wire bonding, such as solder joint falling, etc., are not generated, and the reliability of soldering is greatly improved.

In this embodiment, the first chip 100 and the hard circuit board 500 may be connected by a third lead not shown, the insulating layer 510 is correspondingly provided with a second window 514, one end of the third lead is electrically connected to a pad on the first chip 100, and the other end of the third lead is electrically connected to the conductive layer 520 through the second window 514, so that the first chip 100 and the lead 310 are electrically connected to the conductive layer 520 through the third lead.

The third lead may be a gold wire or a copper wire, and it should be noted that the second window 514 is disposed near the first chip 100, and the third lead is short in length and is not prone to quality defects such as disconnection or solder joint falling off when being impacted or vibrated.

In other embodiments, the power module is provided with the first connection assembly 400 and the second connection assembly 600 at the same time, so as to respectively have the effects of the above embodiments. In addition, the power module may further include a hard circuit board 500, where the hard circuit board 500 includes an insulating layer 510 and a conductive layer 520, a first portion of the conductive layer 520 is located in the insulating layer 510 and is electrically connected to the first chip 100 through, for example, the aforementioned second lead and the third lead, respectively, a second portion of the conductive layer 520 extends out of the insulating layer 510 to form a first conductive member 420, and a second portion of the conductive layer 520 extends out of the insulating layer 510 to form a second conductive member 620, and when the power module is manufactured, only one end of the first conductive member 420 needs to be electrically connected to the second chip 200, and one end of the second conductive member 620 needs to be electrically connected to the pin 310.

In other embodiments, the first chip 100 may also be directly connected to the lead frame 300 by sintering or soldering, so as to omit the rigid circuit board 500, and accordingly, the first connection assembly 400 is a separate component electrically connected to the first chip 100 and the second chip 200 respectively. Generally, the first chip 100 has a small volume, the pads are densely distributed, and the size of each pad is small, so that the first connection assembly 400 is difficult to directly connect with the first chip 100 due to the excessively large width, and therefore, the power module further includes a fifth lead 900, one end of the fifth lead 900 is electrically connected with the pad of the first chip 100, and the other end of the fifth lead is electrically connected with the lead frame 300, so that the first chip 100 and the second chip 200 are electrically connected with the first connection assembly 400 through the fifth lead 900 and the lead frame 300.

In the above embodiments, when the lead is described as being electrically connected to another element, the lead is generally fixed by ultrasonic welding, and when the conductive member is described as being electrically connected to another element, the conductive member is generally fixed by laser welding, ultrasonic welding, solder paste welding, sintering, or the like, for example, in the case of the electrical connection between the first conductive member 420 and the second chip 200, the solder paste may be first provided on the first conductive member 420, or the solder paste may be provided on the pad of the second chip 200, and then the first conductive member 420 and the second chip 200 may be welded.

Referring to fig. 12 to 14, the first conductive member 420 has a thin-sheet structure, such as a copper sheet or other conductive metal sheets, so as to have certain flexibility, and facilitate bending of the first connection assembly 400 during the assembly process, compared with a common lead, the thin-sheet first conductive member 420 can improve strength and is not easy to break, and in addition, welding or sintering areas of the first conductive member 420 and elements such as the second chip 200 and the lead frame 300 can be increased, so as to improve connection strength, and compared with a welding point of the lead, the thin-sheet first conductive member 420 is not easy to fall off and has high reliability. When the first conductive member 420 is configured in a sheet structure, at least two sides of the first conductive member 420 in the thickness direction are coated with the first insulating member 410, thereby realizing insulation protection of the first conductive member 420. The first insulating member 410 may be an insulating film, and the first conductive member 420 is bonded between two insulating films such that the first connection member 400 is integrally formed in a flexible board structure.

Based on the above embodiment, referring to fig. 3, a plurality of first connection assemblies 400 may be provided, and the plurality of first connection assemblies 400 are spaced apart along the width direction of the first conductive member 420, so that when a subsequent molding step is performed, a molding material may flow between adjacent first connection assemblies 400, and the blocking of the flow of the packaging material by the first connection assemblies 400 is reduced. Specifically, in the present embodiment, a first connecting assembly 400 includes a first insulating member 410 and first conductive members 420, that is, each first conductive member 420 is insulated by the corresponding first insulating member 410.

Based on the above embodiments, the first connection assembly 400 includes a plurality of first conductive members 420, the plurality of first conductive members 420 are wrapped in the same first insulating member 410, and the first conductive members 420 are spaced apart to avoid contact short circuit. In this embodiment, the plurality of first conductive members 420 are located in the same first insulating member 410, so that the overall strength of the first connecting assembly 400 is higher, which can further reduce wire breakage or insufficient soldering, and improve the reliability of solder joints.

In some embodiments, referring to fig. 5, the top of the second chip 200 has a pad 210, and referring to fig. 12 to 14, the first conductive member 420 includes a main body portion 421 and a connecting portion 422, the width of the main body portion 421 is smaller than that of the connecting portion 422, and the main body portion 421 and the connecting portion 422 are connected into an integral structure, wherein the main body portion 421 is electrically connected to the first chip 100, the connecting portion 421 and the first chip 100 are electrically connected to the pad 210 by the connection methods in the above embodiments, and the connection methods may be laser welding, ultrasonic welding, solder paste welding, sintering, and the like.

Accordingly, the first insulating member 410 includes a first insulating portion 411 and a second insulating portion 412, an outer side of the main body portion 421 is coated with the first insulating portion 411, an outer side of the connecting portion 422 is coated with the second insulating portion 412, a width of the first insulating portion 411 is smaller than a width of the second insulating portion 412, and in the illustrated embodiment, the second insulating portion 412 has a rectangular structure adapted to a shape of the pad 210.

In this embodiment, the width of the main body 421 is smaller than the connecting portion 422, the width of the first insulating portion 411 is correspondingly smaller than the width of the second insulating portion 412, and since the main body 421 (the first insulating portion 411) is located in the region between the first chip 100 and the second chip 200, which may cause a certain obstruction to the flow of the encapsulating material, on the basis that the strength of the main body 421 meets the requirement, reducing the width of the main body 421 is helpful to reduce the adverse effect on the flow of the encapsulating material, and can save material at the same time, and the connecting portion 422 (the insulating plate 512) is located above the second chip 200, which may not affect the flow of the encapsulating material, so the width may be correspondingly increased, which may increase the effective connection area between the connecting portion 422 and the pad 210, and improve the soldering reliability; in addition, while the bonding area of the insulating plate 512 and the packaging material is increased, the bonding quality of the insulating plate 512 and the resin is greatly higher than that of the metal lead and the resin, the layering risk is well reduced, and the reliability of mold sealing is improved. Meanwhile, the width of the first insulating portion 411 is smaller than that of the second insulating portion 412, and a connecting portion of the first insulating portion and the second insulating portion can form a step structure, so that the step structure can be abutted against the cured packaging material, the bonding strength between the step structure and the cured packaging material is enhanced, and the risk of delamination is reduced. In addition, the step structure between the first insulating portion 411 and the second insulating portion 412 can also serve as a positioning reference for the connection portion 422 to be connected to the pad 210, and ensure the connection position of the connection portion 422 on the second chip 200.

Based on the above structure, referring to fig. 15, in some embodiments, the size of the second insulating portion 412 is smaller than that of the pad 210 along the length direction of the pad 210, when the connecting portion 422 is connected to the pad 210, the first side 211 of the pad 210 can be exposed from below the second insulating portion 412, the offset amount of the second insulating portion 412 relative to the pad 210 in the length direction can be determined by detecting the distance between the first side 211 of the pad 210 and the corresponding third side 4121 on the second insulating portion 412, and since the position between the second insulating portion 412 and the connecting portion 422 is fixed, the offset amount of the connecting portion 422 relative to the pad 210 can be finally calculated, thereby determining the accuracy of the welding position.

In addition, the size of the second insulating portion 412 is smaller than that of the pad 210 in the width direction of the pad 210, and when the connection portion 422 is connected to the pad 210, the second side 212 of the pad 210 can be exposed from below the second insulating portion 412, and the offset amount of the second insulating portion 412 with respect to the pad 210 in the longitudinal direction can be determined by detecting the distance between the second side 212 of the pad 210 and the corresponding fourth side 4122 of the second insulating portion 412, and since the positions between the second insulating portion 412 and the connection portion 422 are fixed, the offset amount of the connection portion 422 with respect to the pad 210 can be finally calculated, thereby determining the accuracy of the bonding position.

Of course, the second insulating portion 412 may have a size smaller than that of the pad 210 in both the longitudinal direction and the width direction of the pad 210, so that the amount of displacement of the connecting portion 422 with respect to the pad 210 can be determined from the longitudinal direction and the width direction.

In some embodiments, the width of the first insulating portion 411 is 0.2mm to 0.5mm, which can provide enough strength to the first connection assembly 400 and not excessively obstruct the flow of the encapsulation material.

In some embodiments, the length of the second insulating portion 412 is 0.4mm to 1.0mm, the width is 0.3mm to 0.8mm, the length of the pad 210 is 0.3mm to 0.9mm, and the width is 0.2mm to 0.7mm, and from the above dimensions, on the basis of ensuring that the length and the width of the second insulating portion 412 are all smaller than the length and the width of the pad 210, so as to be able to recognize the offset of the second insulating portion 412, the length and the width of the second insulating portion 412 can be set larger, so that the connecting portion 422 covered by the second insulating portion 412 can also be set larger, thereby increasing the connecting area between the connecting portion 422 and the pad 210. Further, in combination with the width of the first insulating portion 411 described above, it can be ensured that the second insulating portion 412 can be wider than the first insulating portion 411.

In some embodiments, the thickness of the first conductive member 420 is 0.035mm to 0.07mm, and the single-sided thickness of the first insulating member 410 is 0.03mm to 0.07mm, so that the first connection member 400 has a total thickness of 0.095mm to 0.21mm, which is not significantly increased as compared to the diameter of the first lead 800, and is less obstructed when the potting material flows in a direction parallel to the first conductive member 420. In combination with the width dimension of the first insulating portion 411, the first conductive member 420 may form a sheet structure.

In some embodiments, referring to fig. 13, the second insulating portion 412 has a third window 4123, the area of the connecting portion 422 is greater than or equal to the area of the third window 4123, the connecting portion 422 can be exposed from the third window 4123, and the exposed portion is electrically connected to the connecting portion 422, so that the connecting portion (e.g., solder or frit) between the connecting portion 422 and the pad 210 is spaced from the side edge of the pad 210 by a certain distance to prevent the connecting portion from contacting the portion outside the pad 210.

Based on the above-described embodiment, the minimum distance of each side edge of the third window 4123 from the corresponding side edge of the pad 210 is equal to or greater than 0.2mm, and the distance value satisfies the requirement of the interval between the connection portion and the side edge of the pad 210, and the third window 4123 can be set large, so that the connection area of the connection portion 422 and the pad 210 is increased, and the welding strength and the welding reliability are improved.

The invention also provides a preparation method of the power module, which comprises the following steps:

s100, a lead frame 300, a first chip 100, a second chip 200 and a first connection assembly 400 are prepared, and the first chip 100 and the second chip 200 are all connected to the lead frame 300, wherein the first chip 100 may be directly connected to the lead frame 300 by soldering or sintering, or may be connected to the lead frame 300 by the above-mentioned elements such as the rigid circuit board 500, the second chip 200 may be connected to the lead frame 300 by soldering or sintering, or the second chip 200 may be soldered or sintered to the heat dissipation assembly 700, and the heat dissipation assembly 700 is connected to the lead frame 300.

The first connecting assembly 400 may be the first connecting assembly 400 of the above embodiments, and includes a first insulating member 410 and a first conductive member 420, and the first insulating member 410 is covered outside the first conductive member 420.

S200, the first conductive member 420 is used to electrically connect the first chip 100 and the second chip 200, wherein one end of the first conductive member 420 may be directly connected to the second chip 200, and the other end is indirectly connected to the first chip 100 through a wire or the like.

The first insulating member 410 is wrapped outside the first conductive member 420, so that the overall strength of the first connection assembly 400 can be increased, the probability that the first connection assembly 400 is broken due to impact or vibration is reduced, and in addition, the first insulating member 410 can also realize insulation of the first conductive member 420, so that even if contact occurs between the first connection assemblies 400, short circuit can be avoided by isolation of the first insulating member 410.

Based on the above embodiment, in step S100, a hard circuit board 500 is also prepared, and the hard circuit board 500 may adopt the hard circuit board 500 in the above embodiment, including an insulating layer 510 and a conductive layer 520, where a part of the conductive layer 520 is located in the insulating layer 510, and another part of the conductive layer extends out of the insulating layer 510 to form the first conductive member 420. Thus, after the hard circuit board 500 is connected to the lead frame 300, the first chip 100 is electrically connected to the conductive layer 520 located in the insulating layer 510, and the second chip 200 is electrically connected to the first conductive member 420, so that the first chip 100 and the second chip 200 can be electrically connected. Compared with the mode of welding two ends, the embodiment only needs to connect one end of the first conductive member 420 with the second chip 200, which can save processing steps, and in addition, because the first conductive member 420 is a part of the conductive layer 520, compared with the mode of welding and fixing the first conductive member 420, the problem of welding point falling is not generated.

In some embodiments, the first connecting assembly 400 may be moved to the welding position by a welding member (e.g., a welding head) having a negative pressure suction hole, and the first conductive member 240 may be welded by the welding head in an ultrasonic welding manner, if the first connecting assembly 400 is transferred by the transferring member and then the first conductive member 240 is welded by the welding head, two driving means are required, and the welding head may be moved to the welding position only after the transferring member releases the first connecting assembly 400. The embodiment can complete the actions only by one welding head and one set of driving device, thereby simplifying the structure; meanwhile, the step of releasing the first connecting assembly 400 by the material moving part and the time for waiting for the material moving part to move by the welding head can be saved, and the processing efficiency can be improved. In addition, the embodiment can prevent the first connecting assembly 400 from shifting during the releasing process, and ensure the connecting position of the first conductive member 240.

Specifically, the soldered connection has the working face of the first connecting assembly 400 of contact, this working face is located the bottom of soldered connection, the inside air flue that has of soldered connection, the air flue forms a plurality of absorption holes on the working face, when the air flue communicates with outside negative pressure source, can produce the negative pressure in the absorption hole to adsorb first connecting assembly 400 on the soldered connection, afterwards, welding set's ultrasonic vibration part starts, drive soldered connection along axial high-frequency vibration, can weld first electrically conductive piece 240 to second chip 200 or lead frame 300.

In some embodiments, the power module manufacturing method further includes a detecting step for detecting whether the connection position of the first conductive member 420 is in the design position, which includes the steps of: the first reference is recognized on the second chip 200, the second reference is recognized on the first insulating member 410, the distance between the first reference and the second reference is judged, and if the distance is within the set range, the judgment is qualified, and if the distance exceeds the set range, the judgment is unqualified.

In some implementations, when the first connection assembly 400 adopts the structure shown in fig. 12 to 14, that is, the first conductive member 420 includes a main body portion 421 and a connection portion 422, the main body portion 421 is electrically connected to the first chip 100, the connection portion 422 is electrically connected to the pad 210, the first insulating member 410 includes a first insulating portion 411 and a second insulating portion 412, the main body portion 421 is coated with the first insulating portion 411, the connection portion 422 is coated with the second insulating portion 412, the width of the first insulating portion 411 is smaller than the width of the second insulating portion 412, and a reference can be selected on the pad 210 and the second insulating portion 412.

For example, the dimension of the second insulating portion 412 is smaller than the dimension of the pad 210 along the length direction of the pad 210, and when the connecting portion 422 is connected to the pad 210, at least one end of the pad 210 along the length direction is exposed and can be exposed from the lower side of the second insulating portion 412, so that the first side 211 of the exposed end of the pad 210 is selected as the first reference, the corresponding third side 4121 on the second insulating portion 412 is used as the second reference, the distance between the first side 211 of the pad 210 and the corresponding third side 4121 on the second insulating portion 412 is detected, and if the distance is within the set range, the pad is determined to be qualified.

For another example, the dimension of the second insulating portion 412 is smaller than the dimension of the pad 210 along the width direction of the pad 210, and when the connecting portion 422 is connected to the pad 210, at least one end of the pad 210 in the width direction is exposed and can be exposed from below the second insulating portion 412, so that the second side 212 of the exposed end of the pad 210 is selected as the first reference, the corresponding fourth side 4122 of the second insulating portion 412 is used as the second reference, and the distance between the second side 212 of the pad 210 and the corresponding fourth side 4122 of the second insulating portion 412 is detected, and if the distance is within the set range, the determination is passed.

Wherein, the distance in the setting range means the value: when the set range is smaller than a certain maximum value and larger than a certain minimum value, the interval between the minimum value and the maximum value is qualified.

It should be noted that the length and width of the second insulating portion 412 may also be greater than the length and width of the pad 210, that is, when the connecting portion 422 is connected to the pad 210, the pad 210 is not exposed, and in this case, other portions on the second chip 200 may be used as the first reference, and taking the outer side 220 of the second chip 200 as the first reference as shown in fig. 15 as an example.

The embodiments of the present invention have been described in detail with reference to the drawings, but the present invention is not limited to the embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present invention. Furthermore, the embodiments of the present invention and features of the embodiments may be combined with each other without conflict.

Claims

1. A power module, comprising:

a lead frame;

a first chip connected to the lead frame;

a second chip connected to the lead frame;

the first connecting assembly comprises a first insulating part and a first conducting part, the first conducting part is electrically connected with the first chip and the second chip respectively, and the first insulating part is coated on the outer side of the first conducting part.

2. The power module of claim 1, further comprising a rigid circuit board attached to the lead frame, the rigid circuit board including an insulating layer and a conductive layer, a portion of the conductive layer being located within the insulating layer and electrically connected to the first chip, and another portion extending beyond the insulating layer to form the first conductive member.

3. The power module of claim 1, wherein the lead frame has a pin, and the power module further comprises a second connecting assembly, the second connecting assembly comprises a second insulating member and a second conductive member, two ends of the second conductive member are electrically connected to the first chip and the pin, respectively, and the second insulating member is wrapped outside the second conductive member.

4. The power module according to claim 1, wherein the first conductive member is a sheet structure, and the first conductive member is covered with the first insulating member at least on both sides in a thickness direction.

5. The power module according to claim 4, wherein the first connecting assembly is provided in plurality, and the plurality of first connecting assemblies are arranged at intervals in a width direction of the first conductive member;

6. The power module of claim 1, wherein the second chip has a pad, the first conductive member includes a main body portion and a connecting portion, the main body portion is electrically connected to the first chip, the connecting portion is electrically connected to the pad, the first insulating member includes a first insulating portion and a second insulating portion, an outer side of the main body portion is coated with the first insulating portion, an outer side of the connecting portion is coated with the second insulating portion, and a width of the first insulating portion is smaller than a width of the second insulating portion.

7. The power module of claim 6, wherein the parameters of the first connection component satisfy at least one of:

the width of the first insulating part is 0.2mm to 0.5mm;

the thickness of the first conductive piece is 0.035mm to 0.07mm, and the thickness of one side of the first insulating piece is 0.03mm to 0.07mm;

the second insulating part is provided with a third window, the part of the connecting part exposed from the third window is electrically connected with the bonding pad, the length of the third window is smaller than that of the bonding pad, the width of the third window is smaller than that of the bonding pad, and the distance between each side edge of the third window and the corresponding side edge of the bonding pad is greater than or equal to 0.2mm.

8. The preparation method of the power module is characterized by comprising the following steps of:

preparing a lead frame, a first chip, a second chip and a first connecting assembly, wherein the first chip and the second chip are both connected to the lead frame, the first connecting assembly comprises a first insulating part and a first conductive part, and the first insulating part is wrapped outside the first conductive part;

9. The method according to claim 8, wherein a hard circuit board is prepared, the hard circuit board including an insulating layer and a conductive layer, a part of the conductive layer being located in the insulating layer, another part of the conductive layer protruding out of the insulating layer to form the first conductive member, the hard circuit board is connected to the lead frame, and the first chip is electrically connected to the conductive layer located in the insulating layer, and the second chip is electrically connected to the first conductive member.

10. The method of manufacturing a power module according to claim 8, wherein the first conductive member is ultrasonically welded by a welding member having a negative pressure suction hole after the first connection member is moved to the welding position.

11. The power module production method according to claim 8, wherein a first reference is identified on the second chip, a second reference is identified on the first insulating member, a distance between the first reference and the second reference is judged, and if the distance is within a set range, the determination is passed.

12. The method for manufacturing a power module according to claim 11, wherein the second chip has a pad, the first conductive member includes a main body portion and a connecting portion, the main body portion is electrically connected to the first chip, the connecting portion is electrically connected to the pad, the first insulating member includes a first insulating portion and a second insulating portion, an outer side of the main body portion is covered with the first insulating portion, and an outer side of the connecting portion is covered with the second insulating portion;

the size of the second insulating part is smaller than that of the pad along the length direction of the pad, so that at least one end of the pad along the length direction is exposed, a first side edge of the exposed end of the pad is taken as the first reference, a third side edge corresponding to the second insulating part is taken as the second reference, the distance between the first side edge and the third side edge is detected, and if the distance is within a set range, the pad is judged to be qualified;