CN114093837B - QFN/LGA package structure with exposed lead led out from top and manufacturing method thereof - Google Patents
QFN/LGA package structure with exposed lead led out from top and manufacturing method thereof Download PDFInfo
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- CN114093837B CN114093837B CN202111199466.5A CN202111199466A CN114093837B CN 114093837 B CN114093837 B CN 114093837B CN 202111199466 A CN202111199466 A CN 202111199466A CN 114093837 B CN114093837 B CN 114093837B
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- 238000004519 manufacturing process Methods 0.000 title claims abstract description 18
- 229910052802 copper Inorganic materials 0.000 claims abstract description 124
- 239000010949 copper Substances 0.000 claims abstract description 124
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 122
- 238000004806 packaging method and process Methods 0.000 claims abstract description 35
- 238000005498 polishing Methods 0.000 claims abstract description 12
- 238000003466 welding Methods 0.000 claims description 25
- 238000000034 method Methods 0.000 claims description 20
- 230000008569 process Effects 0.000 claims description 15
- 239000010410 layer Substances 0.000 claims description 10
- 239000004033 plastic Substances 0.000 claims description 10
- 239000003822 epoxy resin Substances 0.000 claims description 7
- 229920000647 polyepoxide Polymers 0.000 claims description 7
- 239000005022 packaging material Substances 0.000 claims description 6
- 239000002344 surface layer Substances 0.000 claims description 5
- 239000004593 Epoxy Substances 0.000 claims description 3
- 238000001816 cooling Methods 0.000 claims description 3
- 238000005538 encapsulation Methods 0.000 claims description 2
- 238000010438 heat treatment Methods 0.000 claims description 2
- 238000007747 plating Methods 0.000 claims description 2
- 230000010354 integration Effects 0.000 abstract description 3
- 230000009286 beneficial effect Effects 0.000 description 10
- 230000017525 heat dissipation Effects 0.000 description 5
- 229910000679 solder Inorganic materials 0.000 description 4
- 238000004140 cleaning Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 230000035515 penetration Effects 0.000 description 2
- 230000001737 promoting effect Effects 0.000 description 2
- 241000784732 Lycaena phlaeas Species 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000009713 electroplating Methods 0.000 description 1
- 230000013011 mating Effects 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L23/00—Details of semiconductor or other solid state devices
- H01L23/48—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor
- H01L23/488—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor consisting of soldered or bonded constructions
- H01L23/495—Lead-frames or other flat leads
- H01L23/49568—Lead-frames or other flat leads specifically adapted to facilitate heat dissipation
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/50—Assembly of semiconductor devices using processes or apparatus not provided for in a single one of the subgroups H01L21/06 - H01L21/326, e.g. sealing of a cap to a base of a container
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/50—Assembly of semiconductor devices using processes or apparatus not provided for in a single one of the subgroups H01L21/06 - H01L21/326, e.g. sealing of a cap to a base of a container
- H01L21/56—Encapsulations, e.g. encapsulation layers, coatings
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L23/00—Details of semiconductor or other solid state devices
- H01L23/28—Encapsulations, e.g. encapsulating layers, coatings, e.g. for protection
- H01L23/31—Encapsulations, e.g. encapsulating layers, coatings, e.g. for protection characterised by the arrangement or shape
- H01L23/3107—Encapsulations, e.g. encapsulating layers, coatings, e.g. for protection characterised by the arrangement or shape the device being completely enclosed
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L23/00—Details of semiconductor or other solid state devices
- H01L23/34—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements
- H01L23/36—Selection of materials, or shaping, to facilitate cooling or heating, e.g. heatsinks
- H01L23/367—Cooling facilitated by shape of device
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L23/00—Details of semiconductor or other solid state devices
- H01L23/48—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor
- H01L23/488—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor consisting of soldered or bonded constructions
- H01L23/495—Lead-frames or other flat leads
- H01L23/49541—Geometry of the lead-frame
- H01L23/49548—Cross section geometry
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L23/00—Details of semiconductor or other solid state devices
- H01L23/48—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor
- H01L23/488—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor consisting of soldered or bonded constructions
- H01L23/495—Lead-frames or other flat leads
- H01L23/49541—Geometry of the lead-frame
- H01L23/49548—Cross section geometry
- H01L23/49551—Cross section geometry characterised by bent parts
- H01L23/49555—Cross section geometry characterised by bent parts the bent parts being the outer leads
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
- H01L24/80—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected
- H01L24/85—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected using a wire connector
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
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- Geometry (AREA)
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- Materials Engineering (AREA)
- Cooling Or The Like Of Semiconductors Or Solid State Devices (AREA)
Abstract
The invention provides a QFN/LGA packaging structure led out from the top by an exposed lead and a manufacturing method thereof, wherein the packaging structure comprises a core, a radiating fin and a copper column, the copper column is electrically connected with the core, the radiating fin is positioned at the bottom of the QFN/LGA after packaging and is attached to the core, and the copper column extends from the position electrically connected with the core to the top of the QFN/LGA after packaging. The manufacturing method comprises the following steps: copper columns are arranged at intervals on the periphery of the radiating fin of the QFN/LGA, and extend to a first distance in the opposite direction of the exposed surface of the outer side of the radiating fin; attaching the inner core to the inner side of the radiating fin; electrically connecting the inner core with the copper column; packaging the radiating fin, the inner core and the copper column into a whole; polishing is performed so that the heat spreader and copper pillars are exposed at the bottom and top, respectively, of the QFN/LGA package. The radiating fins and the exposed lead are not on the same surface, so that the radiating fin area of the PCB can be saved, the miniaturization and integration degree of the PCB are higher, and more functions of the PCB are realized under the condition of unchanged size.
Description
Technical Field
The invention relates to the technical field of QFN packaging or LGA packaging, in particular to a QFN/LGA packaging structure led out from the top by an exposed lead and a manufacturing method thereof.
Background
QFN (Quad Flat No-leads Package), one of the surface mount packages, belongs to a leadless Package, has a square or rectangular shape, has a large-area bare pad at the center of the bottom for conducting heat, and has conductive pads for electrical connection around the periphery of the large pad. LGA (Land Grid Array) is a land grid array package, and replaces the conventional pin-shaped pins with metal contact packages.
In the prior art, the exposed lead and the heat sink of the QFN/LGA are designed on the same surface, i.e. the exposed lead and the heat sink are designed on the bottom of the package. The design requires that the PCB of the client must be provided with both the radiating fins and the exposed lead to be welded on the upper board, and the radiating fin area on the PCB cannot be wired, so that the area of the PCB is large, and the miniaturization and integration of the PCB are not facilitated.
Disclosure of Invention
In order to solve the technical problems, the invention provides a QFN/LGA packaging structure led out from the top by an exposed lead, which comprises a core, a radiating fin and a copper column, wherein the core, the radiating fin and the copper column are packaged into a whole by plastic packaging materials, the copper column is electrically connected with the core, the radiating fin is positioned at the bottom of the packaged QFN/LGA and is attached to the core, and the copper column extends to the top of the packaged QFN/LGA from the position electrically connected with the core.
Optionally, the radiating fin is bonded with the inner core by epoxy resin.
Optionally, the copper pillar is electrically connected with the inner core by adopting a gold wire bonding mode.
Optionally, the exposed portion of the copper pillar on the top of the package rear of the QFN/LGA is provided with an electroplated layer.
Optionally, the copper column is provided with an axial through hole.
The invention also provides a manufacturing method of the QFN/LGA packaging structure led out from the top by the exposed lead, which comprises the following steps:
s10, copper columns are arranged at intervals on the periphery of a radiating fin of the QFN/LGA, and extend to a first distance in the opposite direction of the exposed surface of the outer side of the radiating fin;
s20, attaching the inner core to the inner side of the radiating fin;
s30, electrically connecting the inner core with the copper column;
s40, packaging the radiating fin, the inner core and the copper column into a whole;
s50, polishing treatment is carried out, so that the radiating fin and the copper column are respectively exposed at the bottom and the top after QFN/LGA packaging.
Optionally, in step S20, the core is attached to the heat sink using epoxy.
Optionally, in step S30, the core is electrically connected to the copper pillar by using a gold wire bonding method.
Optionally, in step S50, after polishing, the exposed copper pillars on top of the package of QFN/LGA are electroplated to form an electroplated layer.
Optionally, in step S10, the copper pillar is provided with an axial through hole; when the copper column is arranged, a positioning needle of a positioning die is inserted into an axial through hole of the copper column for positioning; in step S40, after packaging, the positioning needle of the positioning mold is pulled out.
In order to save the area of the radiating fin, the invention saves the area of the radiating fin, leads the miniaturization and integration degree of the PCB to be higher, leads the position of the PCB to be fully utilized, adopts a novel QFN/LGA packaging structure, leads the exposed lead out of the top of the QFN/LGA packaging structure through a copper column, and then leads the product to be inversely adhered to the PCB, so that the radiating fin is positioned at the top of the packaging product, namely the radiating fin and the exposed lead are not positioned on the same surface, thereby not only meeting the radiating requirement of the product, but also saving the wiring position on the PCB, leading the PCB to have more signals with space design, and realizing more functions under the condition that the size of the PCB is unchanged. During manufacturing, copper columns are arranged at intervals on the periphery of the radiating fin of the QFN/LGA, and extend to the opposite direction of the exposed surface of the outer side of the radiating fin for a first distance, and the first distance can ensure that the copper columns are exposed out of the top of the packaged QFN/LGA, so that the radiating fin and the exposed lead are not on the same surface.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims thereof as well as the appended drawings.
The technical scheme of the invention is further described in detail through the drawings and the embodiments.
Drawings
The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate the invention and together with the embodiments of the invention, serve to explain the invention. In the drawings:
fig. 1 is a schematic cross-sectional view of a package structure of a QFN of an embodiment of the present invention, where the QFN is extracted from the top;
FIG. 2 is a schematic cross-sectional view of an LGA with an exposed lead from the top in an embodiment of the present invention;
FIG. 3 is a flow chart of a method for manufacturing a QFN/LGA package with exposed lead from the top according to an embodiment of the present invention;
FIG. 4 is a cross-sectional view showing the effect of each step in the flow of an embodiment of a method of manufacturing a QFN/LGA package using an exposed lead from the top;
fig. 5 is a schematic plan view showing a layout of a mating portion of a package structure employing a PCB board and QFN/LGA according to the present invention.
In the figure: 1-inner core, 2-radiating fin, 3-copper column, 4-lead surface layer, 5-epoxy resin, 6-gold wire, 7-plastic package material, 8-electroplated layer and 9-copper column welding spot.
Detailed Description
The preferred embodiments of the present invention will be described below with reference to the accompanying drawings, it being understood that the preferred embodiments described herein are for illustration and explanation of the present invention only, and are not intended to limit the present invention.
As shown in fig. 1 and 2, the embodiment of the invention provides a packaging structure of a QFN/LGA led out from the top by an exposed lead, which comprises a core 1, a heat sink 2 and a copper pillar 3, wherein the core 1, the heat sink 2 and the copper pillar 3 are packaged into a whole by a plastic package 7, the copper pillar 3 is electrically connected with the core 1, the heat sink 2 is positioned at the bottom of the packaged QFN/LGA and is attached to the core 1, and the copper pillar 3 extends from the position of the electrical connection with the core to the top of the packaged QFN/LGA.
The working principle and beneficial effects of the technical scheme are as follows: according to the scheme, a novel QFN/LGA packaging structure is adopted, an exposed lead is led out of the top of the QFN/LGA packaging structure through a copper column, then a product is flip-chip attached to a PCB, so that a radiating fin is positioned at the top of a packaging product, namely the radiating fin and the exposed lead are not on the same plane, the area of the radiating fin is saved, and the position of the PCB can be fully utilized; therefore, the heat dissipation requirement of the product is met, the wiring position on the PCB is saved, the PCB has more signals with space design, and more functions can be realized under the condition that the size of the PCB is unchanged; wherein, the electric connection part of the copper column by the inner core is the lead surface layer 4.
In one embodiment, the heat sink 2 is attached to the core 1 with an epoxy resin 5; the copper column 3 is electrically connected with the inner core 1 by adopting a gold wire 6 bonding mode; the exposed portion of the copper pillars 3 at the top of the package rear of the QFN/LGA is provided with a plating layer 8.
The working principle and beneficial effects of the technical scheme are as follows: in the scheme, the inner core is attached to the inner side of the radiating fin by epoxy resin, so that the inner core and the radiating fin are attached more tightly and firmly, and the reliability and the durability of heat dissipation of the inner core and the radiating fin are improved; the copper column is electrically connected with the inner core by adopting a gold wire bonding mode, and the process technology of the gold wire bonding mode is mature, so that the process quality is guaranteed; the electroplated layer is arranged on the exposed part of the copper column, which is positioned at the top of the packaged QFN/LGA, so that the surface of the packaged electric connection point can be protected from oxidation, the Printed Circuit Board (PCB) is reliably connected after being welded, and the performance of the printed circuit board is better ensured.
In one embodiment, the copper pillar 3 is provided with an axial through hole.
The working principle and beneficial effects of the technical scheme are as follows: according to the scheme, the copper column is provided with the axial through hole, firstly, the copper column is used for accurately positioning during manufacturing, so that the position of the packaged copper column is guaranteed, deviation between the copper column and a welded connection point on a PCB is avoided, and the process quality and the yield of products are improved; secondly, the existence of the axial through hole reduces the penetration depth of the solder and ensures the fullness and reliability of the solder filling in the welding surface; thirdly, during welding, the existence of the axial through holes can be used for exhausting gas generated by welding, so that the gas is prevented from being sealed in a welding surface to influence the welding quality; and fourthly, the existence of the axial through holes is beneficial to promoting heat dissipation in the process, reducing the possibility of deformation and improving the yield of products.
In one embodiment, the copper column 3 is coaxial with the axial through hole, and the section of the copper column 3 is in a circular ring shape or a polygonal ring shape; the height of the copper pillar 3 is equal to the thickness after encapsulation, and the relation between the wall thickness and the height of the copper pillar 3 accords with the following equation:
in the above formula, d represents the wall thickness of the circular copper column in section; gamma represents the thermal expansion coefficient of the copper column; h represents the height of the copper pillar; Δt represents the temperature rise of the copper column during welding or heating, and is determined according to the process; delta represents the maximum deformation allowed by the copper column, and is selected and determined according to the needs during design.
The working principle and beneficial effects of the technical scheme are as follows: according to the scheme, the copper column and the axial through hole are coaxial, so that the section of the copper column is in a circular ring shape or a polygonal ring shape; and according to the equation, the relation between the wall thickness and the height of the copper column is determined so as to ensure the strength of the copper column, so that the copper column can keep the original shape when the temperature of the copper column changes in the process, and the reliability of electric connection and the quality of products are prevented from being influenced by the deformation of the copper column; the equation fully considers the change possibly brought to the temperature of the copper column in the welding or other working procedures in the manufacturing process and the temperature characteristic condition of the copper column material, thereby improving the process precision and ensuring the consistency of the product quality.
As shown in fig. 3 and 4, an embodiment of the present invention provides a method for manufacturing a QFN/LGA package structure with an exposed lead led out from the top, including the steps of:
s10, copper columns 3 are arranged at intervals on the periphery of a radiating fin 2 of the QFN/LGA, and the copper columns 3 extend a first distance in the opposite direction of the exposed surface of the outer side of the radiating fin 2;
s20, bonding the inner core 1 on the inner side of the radiating fin 2;
s30, electrically connecting the inner core 1 with the copper column 3;
s40, packaging the radiating fin 2, the inner core 1 and the copper column 3 into a whole by adopting a plastic packaging material 7;
s50, polishing is performed so that the heat spreader 2 and the copper pillars 3 are exposed at the bottom and top of the QFN/LGA package, respectively.
The working principle and beneficial effects of the technical scheme are as follows: in the scheme, copper columns are arranged at intervals on the periphery of a radiating fin of the QFN/LGA, and extend to the opposite direction of the exposed surface of the outer side of the radiating fin by a first distance, and the first distance can ensure that the copper columns are exposed out of the top of the packaged QFN/LGA, so that the radiating fin and an exposed lead are not on the same surface; the novel QFN/LGA packaging structure is formed, the exposed lead is led out from the top of the QFN/LGA packaging through the copper column, and then the product is flip-chip attached to the PCB, so that the radiating fin is positioned at the top of the packaging product, namely, the radiating fin and the exposed lead are not on the same plane, thereby not only meeting the radiating requirement of the product, but also saving the wiring position on the PCB, enabling the PCB to have more signals with more space designs, and realizing more functions under the condition that the size of the PCB is unchanged; in the scheme, copper columns are arranged on lead to be led out and welded on the position where the lead is increased by using an SMT process, wherein SMT is a surface mounting technology (Surface Mounted Technology abbreviation), SMT refers to a series of process flows for processing on the basis of a PCB, and PCB (Printed Circuit Board) refers to a printed circuit board; cleaning a copper pillar welded lead surface Layer (LF) by Plasma (Plasma) before attaching the inner core to the radiating fin; and polishing the plastic package material to a height of 0-0.05 mm exposed by the exposed lead during polishing so as to realize welding with the PCB.
In one embodiment, as shown in fig. 4, in step S20, the core 1 is attached to the heat sink 2 with epoxy 5; in step S30, the core 1 is electrically connected to the copper pillar 3 by bonding with the gold wire 6.
The working principle and beneficial effects of the technical scheme are as follows: in the scheme, the inner core is attached to the inner side of the radiating fin by epoxy resin, so that the inner core and the radiating fin are attached more tightly and firmly, and the reliability and the durability of heat dissipation of the inner core and the radiating fin are improved; the copper column is electrically connected with the inner core by adopting a gold wire bonding mode, and the technology of the gold wire bonding mode is mature, so that the technology quality is guaranteed.
In one embodiment, as shown in FIG. 4, after polishing, the exposed top of the copper pillars 3 on the package back of the QFN/LGA is electroplated to form electroplated layer 8 in step S50.
The working principle and beneficial effects of the technical scheme are as follows: the scheme is characterized in that the electroplated layer is arranged on the exposed part of the copper pillar, which is positioned at the top of the packaged QFN/LGA, so that the surface of the packaged electric connection point can be protected from oxidation, the Printed Circuit Board (PCB) is reliably electrically connected after being welded, and the performance of the printed circuit board is better ensured.
In one embodiment, in step S10, the copper pillar 3 is provided with an axial through hole; when the copper column 3 is arranged, a positioning needle of a positioning die is inserted into an axial through hole of the copper column 3 for positioning; in step S40, after packaging, the positioning needle of the positioning mold is pulled out.
The working principle and beneficial effects of the technical scheme are as follows: according to the scheme, the copper column is provided with the axial through hole, firstly, the positioning pin of the positioning die is conveniently used for being inserted into the axial through hole for accurate positioning during manufacturing, so that the position of the packaged copper column is guaranteed, deviation from a welded connection point on a PCB is avoided, and the process quality and the yield of products are improved; secondly, the existence of the axial through hole reduces the penetration depth of the solder and ensures the fullness and reliability of the solder filling in the welding surface; thirdly, during welding, the existence of the axial through holes can be used for exhausting gas generated by welding, so that the gas is prevented from being sealed in a welding surface to influence the welding quality; and fourthly, the existence of the axial through holes is beneficial to promoting heat dissipation in the process, reducing the possibility of deformation and improving the yield of products.
The following is a further explanation of a six-pin QFN/LGA package, as shown in FIGS. 4 and 5, which is implemented by the following steps:
a. copper post pasting: respectively welding six copper columns 3 on six lead to be led out at positions where the lead is increased by using an SMT process;
b. cleaning: cleaning a lead surface Layer (LF) welded by a copper column by adopting Plasma (Plasma);
c. and (3) loading: the inner core 1 is attached to the inner side of the radiating fin 2 by epoxy resin 5;
d. bonding: electrically connecting the inner core 1 with the copper column 3 by adopting a gold wire bonding mode;
e. and (3) plastic packaging: packaging the radiating fin 2, the inner core 1 and the copper column 3 into a whole by adopting a plastic packaging material 7;
f. polishing: the plastic packaging material is polished to the exposed lead with the height of 0-0.05 mm, so that the cooling fin 2 and the copper column 3 are respectively exposed at the bottom and the top after QFN/LGA packaging, and the welding with the PCB is realized;
g. electroplating: after polishing, the copper pillars 3 are electroplated to form an electroplated layer 8 on exposed top of the package of QFN/LGA.
Through the packaging structure of the six-pin QFN/LGA manufactured in the mode, the radiating fin and the exposed lead are not on the same plane, so that the radiating requirement of a product is met, and the wiring position on the PCB is saved, as shown in FIG. 5, the copper column welding spots 9 on the PCB are used for being respectively welded with the six pins of the packaged QFN/LGA to realize mutual electric connection, the middle position of the six copper column welding spots 9 on the PCB is not needed to be used for avoiding the radiating fin, and therefore, the radiating fin is arranged on the end face, far away from the PCB, of the packaged QFN/LGA, and therefore, the position space on the PCB can be used for designing more signals, and more functions can be realized under the condition that the size of the PCB is unchanged.
It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
Claims (4)
1. The manufacturing method of the packaging structure of the QFN/LGA, which is led out from the top by the exposed lead, is characterized in that the packaging structure comprises a core, a radiating fin and a copper column, wherein the core, the radiating fin and the copper column are packaged into a whole by plastic packaging materials, the copper column is electrically connected with the core, the radiating fin is positioned at the bottom of the packaged QFN/LGA and is attached to the core, and the copper column extends to the top of the packaged QFN/LGA from the position electrically connected with the core; the exposed lead is led out from the top of the QFN/LGA package through a copper column, and the product is flip-chip attached to a PCB board, so that the radiating fin is positioned at the top of the package, namely, the radiating fin and the exposed lead are not positioned on the same plane;
the copper column is provided with an axial through hole; the copper column is coaxial with the axial through hole, and the section of the copper column is in a circular ring shape or a polygonal ring shape; the height of the copper column is equal to the thickness after encapsulation, and the relation between the wall thickness and the height of the copper column accords with the following equation:
in the above formula, d represents the wall thickness of the circular copper column in section; gamma represents the thermal expansion coefficient of the copper column; h represents the height of the copper pillar; Δt represents the temperature rise of the copper column during welding or heating, and is determined according to the process; delta represents the maximum deformation allowed by the copper column, and is selected and determined according to the needs during design;
the radiating fin is bonded with the inner core by adopting epoxy resin;
the copper column is electrically connected with the inner core in a gold wire bonding mode;
the exposed part of the copper column, which is positioned at the top of the packaged QFN/LGA, is provided with an electroplated layer;
copper columns are arranged at intervals on the periphery of the radiating fin of the QFN/LGA, and extend to a first distance in the opposite direction of the exposed surface of the outer side of the radiating fin, so that the radiating fin and the exposed lead are not on the same surface; arranging copper columns, namely welding the copper columns on positions where lead is added by adopting an SMT (surface mount technology) process on lead to be led out;
the manufacturing method of the packaging structure comprises the following steps:
firstly, copper columns are arranged at intervals on the periphery of a radiating fin of a QFN/LGA, and extend to a first distance in the opposite direction of the exposed surface of the outer side of the radiating fin, the first distance ensures that the copper columns are exposed out of the top of the QFN/LGA after packaging, and the fact that the radiating fin and an exposed lead are not on the same surface is achieved, and the method comprises the following steps:
s10, copper columns are arranged at intervals on the periphery of a radiating fin of the QFN/LGA, and extend to a first distance in the opposite direction of the exposed surface of the outer side of the radiating fin;
s20, attaching the inner core to the inner side of the radiating fin;
s30, electrically connecting the inner core with the copper column;
s40, packaging the radiating fin, the inner core and the copper column into a whole;
s50, polishing treatment is carried out, so that the radiating fin and the copper column are respectively exposed at the bottom and the top of the QFN/LGA package;
arranging copper columns, namely welding the copper columns on a lead increased position by adopting an SMT (surface mounting technology), wherein SMT is a surface mounting technology, SMT paster refers to short for a series of process flows of processing on the basis of a PCB (printed circuit board); before the inner core is attached to the radiating fin, plasma is adopted to clean the lead surface layer welded by the copper column; during polishing, the plastic packaging material is polished to a height of 0-0.05 mm exposed by the exposed lead so as to realize welding with the PCB; the copper column welding spots on the PCB are used for respectively welding with six pins of the packaged QFN/LGA to realize mutual electric connection, the positions in the middle of the six copper column welding spots on the PCB are not needed to be used for avoiding cooling fins, the cooling fins are arranged on the end face, far away from the PCB, of the packaged QFN/LGA, the position space on the PCB is used for designing more signals, and more functions are realized under the condition that the size of the PCB is unchanged;
in the step S10, the copper column is provided with an axial through hole; when the copper column is arranged, a positioning needle of a positioning die is inserted into an axial through hole of the copper column for positioning; in step S40, after packaging, the positioning needle of the positioning mold is pulled out.
2. The method of manufacturing a QFN/LGA package structure with exposed lead from the top according to claim 1, wherein in step S20, the core is bonded to the heat sink using epoxy.
3. The method of manufacturing a QFN/LGA package structure with exposed lead from the top according to claim 1, wherein in step S30, the core is electrically connected to the copper pillar by gold wire bonding.
4. The method of manufacturing a QFN/LGA package structure with exposed lead from the top according to claim 1, wherein in step S50, after polishing, the exposed copper pillars on the top of the QFN/LGA package are plated to form a plating layer.
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| CN208971845U (en) * | 2018-08-24 | 2019-06-11 | 广州晨越电子有限公司 | A kind of PCB pad that the thermal conduction effect of QFN encapsulation chip welding is good |
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| JP2001358442A (en) * | 2000-06-14 | 2001-12-26 | Nec Corp | Mount structure of semiconductor package |
| US20050093181A1 (en) * | 2003-11-04 | 2005-05-05 | Brandenburg Scott D. | Heat sinkable package |
| CN102832139B (en) * | 2012-08-10 | 2015-05-06 | 华为技术有限公司 | Flat packaging body without pins around, and packaging method of flat packaging body |
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