CN109166828B - High-density integrated circuit packaging structure for reducing warping amplitude based on thermal stress - Google Patents
High-density integrated circuit packaging structure for reducing warping amplitude based on thermal stress Download PDFInfo
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- CN109166828B CN109166828B CN201811002737.1A CN201811002737A CN109166828B CN 109166828 B CN109166828 B CN 109166828B CN 201811002737 A CN201811002737 A CN 201811002737A CN 109166828 B CN109166828 B CN 109166828B
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Abstract
The invention discloses a high-density integrated circuit packaging structure for reducing warpage amplitude based on thermal stress, which comprises a second substrate, a second solder ball, an outer return pipe, a first substrate, a first chip and an inner return pipe, wherein the second substrate is stacked on the upper side of the first substrate, and the second solder ball is arranged between the second substrate and the first substrate so that the second substrate is not contacted with the first substrate; the first chip is arranged between the second substrate and the first substrate and is reversely mounted on the upper surface of the first substrate, and the upper surface of the first chip is not in contact with the lower surface of the second substrate; the inner return pipe and the outer return pipe are both closed pipelines; the inner return pipe is arranged on the upper surface of the first chip; the outer return pipe is disposed on the upper surface of the first substrate. Based on the characteristic that CTE of materials in the package is different, the heat source in the middle and the heat sources around the middle are respectively formed through the outer return pipe and the inner return pipe, the thermal stress of the middle and the edge of the package, which is warped, is changed, and the final warping amplitude in the package is reduced.
Description
Technical Field
The invention relates to the field of semiconductor packaging, in particular to a high-density integrated circuit packaging structure for reducing the warping amplitude based on thermal stress.
Background
Modern portable electronic products put higher demands on microelectronic packaging, and continuous pursuit of lighter, thinner, smaller, high reliability and low power consumption thereof pushes microelectronic packaging to develop towards a three-dimensional packaging mode with higher density. The chip lamination packaging is to stack a plurality of chips in a vertical direction and then package the chips, and due to the particularity of the structure, the interconnection between the chips and the substrate and between the chips is the key of the lamination packaging. In order to avoid great change of the existing process, the total packaging thickness is generally ensured to be unchanged by thinning the thickness of the chip in the laminated packaging, but the rigidity of the chip is reduced due to the reduction of the thickness of the chip, the chip is easy to deform and warp, and stress concentration points in the chip even can cause the damage of the chip in the heat treatment process. Warpage is a common problem in electronic packaging, and the warpage is caused by mismatch of Coefficient of Thermal Expansion (CTE) of multiple materials, and in the prior art, adjustment is performed by matching the CTE of the materials with the process, but the effect is not good.
Disclosure of Invention
The present invention is directed to solving the above-mentioned problems and providing a high-density integrated circuit package structure based on thermal stress to reduce the warpage.
The invention is realized by the following technical scheme:
the high-density integrated circuit packaging structure for reducing the warping amplitude based on the thermal stress comprises a second substrate, a second welding ball, an outer return pipe, a first substrate, a first chip and an inner return pipe, wherein the second substrate is stacked on the upper side of the first substrate, and the second welding ball is arranged between the second substrate and the first substrate so that the second substrate is not in contact with the first substrate; the first chip is arranged between the second substrate and the first substrate and is reversely mounted on the upper surface of the first substrate, and the upper surface of the first chip is not in contact with the lower surface of the second substrate; the inner return pipe and the outer return pipe are both closed pipelines; the inner return pipe is arranged on the upper surface of the first chip; the outer return pipe is disposed on the upper surface of the first substrate.
The laminated packaging has become a typical solution for processor and memory components in smart phone manufacturing, but due to the dimensional characteristics of the packaging object, not only the requirement for lamination precision is higher, but also the space of the stacked structure is narrower, in which various materials with different physical and chemical properties are concentrated, and the difference between the thermal expansion coefficients of the various materials in the packaging system makes the device equivalent to a thin plate more prone to warp deformation. The warp deformation destroys the coplanarity of the solder balls, resulting in an increased level of soldering defects. When the whole package is subjected to temperature change, due to different thermal expansion coefficients of various materials, the expansion and contraction are inconsistent, so that the package is warped; in the packaging process, the temperature rise process is recorded from room temperature to high temperature, the temperature reduction process is recorded from high temperature to room temperature, the temperature rise process and the temperature reduction process can be considered as a pair of inverse processes to a certain extent, however, due to the fact that thermal expansion coefficients of materials are different, deformation in the temperature rise process cannot be inversely reversed through the temperature reduction process, and therefore the final packaging warpage phenomenon occurs. Based on the principle, the invention arranges the outer return pipe and the inner return pipe between the first substrate and the second substrate, changes the temperature delay time and the temperature concentration degree of partial area in the packaging process, thereby changing the thermal stress and the residual stress of the first substrate, the second substrate and the first chip and reducing the warping degree of the first substrate and the second substrate. The laminated package is soldered by reflow soldering, which is soldering for mechanically and electrically connecting the soldering terminal or pin of the surface-mounted component and the pad of the printed board by re-melting the paste-mounted soft solder pre-distributed on the pad of the printed board. The reflow soldering equipment blows heated nitrogen or other stable gas to the package to enable the solder to be re-melted to realize electrical connection, when hot gas flow blows to the package, the temperature around the package is rapidly increased, the re-melting time of the solder at high temperature is short, and the package has poor heat conducting performance and poor heat dissipation performance due to the characteristics of materials, so that the temperature of the package is slightly increased in the hot gas flow and is slowly reduced after the temperature is separated from the hot gas flow to a certain extent; the inner return pipe and the outer return pipe are made of materials with strong heat conduction capability, such as metal materials copper, the heat conduction of copper is fast, but the heat dissipation is slow, the temperature of the inner return pipe and the outer return pipe can be increased through hot air flow, the heat conduction performance of the inner return pipe and the outer return pipe is good, the temperature of the inner return pipe and the outer return pipe can reach the temperature of the hot air flow when the temperature is highest, after the package is separated from the hot air flow, the temperature of the first substrate, the second substrate and the first chip on the package starts to be reduced, but the temperature reduction speed is slow, therefore, after the package is separated from the hot air flow, the temperature of the first substrate, the temperature of the second substrate and the temperature of the first chip on the package are gradually recovered to normal temperature, in the process, the temperature of the inner return pipe and the temperature of the outer return pipe are always higher than the temperature of the package, at the moment, the inner, thus, the thermal stress of the first substrate, the second substrate and the first chip is changed. When the CTE of the first substrate is larger, the CTE of the second substrate is smaller, and when the outer return pipe and the inner return pipe are not used, the CTE of the first substrate is larger, so that the whole package presents positive value warping and larger amplitude, and when the normal temperature is recovered, the amplitude of the positive value warping is reduced, but the amplitude of the positive value warping can be the warping amplitude which is always kept after the package is molded, but the warping amplitude is larger, and the requirement of a high-density integrated circuit is not met; when the CTE of the first substrate is larger, the CTE of the second substrate is smaller, when the outer return pipe and the inner return pipe are used, the CTE of the first substrate is larger, so that the whole package is warped in a positive value and has larger amplitude, when the normal temperature is recovered, the amplitude of the positive value warping is reduced, but the reduction trend is insufficient, at the moment, the residual temperature of the inner return pipe and the outer return pipe can assist in enhancing the trend of the amplitude reduction, the amplitude reduction of the positive value warping is further realized on the basis of the original amplitude reduction, and thus, the amplitude of the positive value warping of the molded package is smaller, and the molded package is more suitable for the current and later high-density integrated circuit packages. When the CTE of the first substrate is smaller, the CTE of the second substrate is larger, and when the outer return pipe and the inner return pipe are not used, the CTE of the second substrate is larger, so that the whole package presents negative value warping and larger amplitude, and when the normal temperature is recovered, the amplitude of the negative value warping is reduced, but the amplitude of the negative value warping can be the warping amplitude which is always kept after the package is molded, but the warping amplitude is larger, and the requirement of a high-density integrated circuit is not met; when the CTE of the first substrate is smaller, the CTE of the second substrate is larger, when the outer return pipe and the inner return pipe are used, the second substrate causes the whole package to present negative value warpage and larger amplitude due to the larger CTE, when the normal temperature is recovered, the negative value warpage amplitude is reduced, but the reduction trend is insufficient, at the moment, the residual temperature of the inner return pipe and the outer return pipe can assist in enhancing the trend of amplitude reduction, so that the negative value warpage is further reduced on the basis of the original amplitude reduction, the amplitude of the negative value warpage of the molded package is smaller, and the molded package is more suitable for the current and later high-density integrated circuit packages.
Further, the contact between the inner return pipe and the outer return pipe allows heat transfer between the inner return pipe and the outer return pipe.
The inner return pipe is concentrated between the first chip and the first substrate, the space of the inner return pipe is more sealed relative to the outer return pipe, the heat dissipation speed of the inner return pipe is slower than that of the outer return pipe, namely, the thermal stress between the second substrate and the first chip is larger, the inner return pipe is positioned in the middle of the whole package, the thermal stress is overlarge, the middle of the second substrate and the warpage of the first chip are more serious, in order to avoid the thermal stress near the inner return pipe to be more concentrated, the heat exchange is realized between the inner return pipe and the outer return pipe, the outer return pipe is used for assisting the inner return pipe to evacuate heat, the residual heat on the inner return pipe and the outer return pipe is more uniformly dispersed in the whole package, and the warpage amplitude in the molded package is reduced.
Further, the inner return pipe comprises a plurality of straight pipes, a plurality of bent pipes, two adapters and a return pipe, the number of the straight pipes is N +1, the number of the bent pipes is N, and N is an even number greater than 0; a plurality of straight pipes are arranged in parallel, and one ends of two adjacent straight pipes at the same side are connected by adopting a bent pipe; a space is formed between two adjacent straight pipes, and two adjacent bent pipes at intervals are respectively positioned at two sides of the straight pipes; two adapters are respectively arranged at one end, which is not connected with the bent pipe, of the two straight pipes on the outer side, and a return pipe is arranged between the two adapters, so that the return pipe is positioned on the lower side of the plane of the straight pipes.
The inner return pipe is arranged to be an S-shaped closed loop, the inner return pipe is uniformly distributed between the first chip and the second substrate through the straight pipes, and the absorbed heat of the inner return pipe can be uniformly dispersed on the second substrate and the first chip, so that the package can reduce the amplitude of the warping deformation of the second substrate and the first chip in the cooling process.
Further, the outer return pipe comprises two heat release pipes, four corner joints, N outer side bent pipes and N-2 linear joints, the heat release pipes are U-shaped pipes, and the two heat release pipes are arranged on the upper surface of the first substrate and positioned on two sides of the first chip; every two corner joints are connected with two ends of a heat release pipe; the outer bent pipes correspond to the bent pipes one by one, the outer bent pipes are arranged on the outer sides of the bent pipes, and two adjacent outer bent pipes are connected through a linear joint; one end of the outside bent pipe at two sides, which is not connected with the linear joint, is connected with one end of the corner joint, which is not connected with the heat release pipe.
The outer return pipe is used for dissipating heat to the periphery of the first substrate, so the heat release pipe is arranged on the periphery of the first substrate, a main part for heat transfer is arranged between the outer bent pipe and the bent pipe, the outer bent pipe is in contact with the bent pipe, namely the outer bent pipe is positioned on a plane where the upper surface of the first chip is positioned, the heat release pipe is positioned on a plane where the first substrate is positioned, and the outer return pipe is closed by adopting a corner joint for connecting the heat release pipe and the outer bent pipe.
Furthermore, the cross section of the elbow is circular, the cross section of the outer elbow is C-shaped, and the outer elbow covers the outer surface of the elbow.
The heat transfer in heat transfer is determined by the size of the contact surface and the size of the temperature difference, the temperature difference is not easy to control, but the size of the contact surface can be easily changed. In order to increase the contact surface between the bent pipe and the outer bent pipe, the outer bent pipe is bent by a flat-plate-type water pipe to form a special bent pipe with a C-shaped section, and the outer bent pipe covers the surface of the bent pipe, so that the contact area can be maximized, more heat can be transferred, and the excessive concentration of thermal stress between the second substrate and the first chip can be avoided.
Further, the heat release pipe is flat. The heat release pipe is arranged to be of a flat structure, so that heat is released to the maximum extent, more heat is transferred, and excessive concentration of thermal stress between the second substrate and the first chip is avoided.
Furthermore, the contact part of the straight pipe and the first chip is a plane. So that heat can be more easily transferred to the first chip. The contact part between the straight pipe and the second substrate is a plane. So that heat can be more easily transferred to the second substrate.
Further, the inner return pipe and the outer return pipe are both copper pipes. The copper tube belongs to metal with stable property, can realize quick heat transfer, can bear various operations with high temperature in the lamination packaging process, has poor heat dissipation performance, is equivalent to a temporary heat source, and is used for changing residual thermal stress of the first substrate, the second substrate, the first chip and accessory parts thereof and assisting in reducing the amplitude of warping deformation.
Further, liquid is provided in the inner return pipe and the outer return pipe. The liquid arranged in the inner return pipe and the outer return pipe can assist in absorbing more heat, and the heat in the liquid is equivalent to a heat storage device of the inner return pipe and the outer return pipe, so that the time of the thermal stress effect of the inner return pipe and the outer return pipe is prolonged.
Furthermore, a plurality of springs are arranged between the first substrate and the second substrate and are uniformly distributed on two sides of the first chip; the central axis of the spring is intersected with the plane where the first substrate is located, the extension lines of the central axes of the springs on the two sides are intersected at one point, and the point is recorded as an X point; the X point is positioned on the middle vertical line of the lower side of the plane of the first substrate or the X point is positioned on the middle vertical line of the upper side of the plane of the first substrate.
The package has a large warpage deformation (hereinafter, the warpage deformation is referred to as an early-stage warpage) in the temperature rising process due to the difference of CTE of materials, the early-stage warpage can greatly influence the warpage deformation after the package molding although the early-stage warpage does not completely appear in the warpage deformation after the package molding, and in order to avoid the excessive amplitude of the early-stage warpage, a plurality of springs are adopted in the first substrate and the second substrate, and the distance between the first substrate and the second substrate is buffered and resisted through the springs. When the CTE of the first substrate is larger than that of the second substrate, negative warpage is generated, namely the distance between the middle part of the first substrate and the middle part of the second substrate is increased, and the distance between the edges is reduced, at the moment, the arrangement of the spring is to enable the X point to be positioned on a perpendicular bisector of the upper side of the plane of the first substrate, so that the elastic force of the spring is distributed at the edges, a force for repelling the first substrate and the second substrate exists between the first substrate and the second substrate, and the amplitude of the early warpage between the first substrate and the second substrate is reduced; when the CTE of the first substrate is smaller than that of the second substrate, positive warpage is generated, namely the distance between the middle part of the first substrate and the middle part of the second substrate is increased, the distance between the edges is reduced, at the moment, the arrangement of the spring is to enable the X point to be positioned on a perpendicular bisector of the lower side of the plane of the first substrate, and therefore the elastic force of the spring is distributed at the edges, so that a force for repelling the first substrate and the second substrate exists between the first substrate and the second substrate, and the amplitude of the early warpage between the first substrate and the second substrate is reduced. In order to make the force of the springs more uniform and more stable in a centralized manner, the springs are arranged so that the extension lines of the central axes of the springs can be converged at an X point, the X point is used as a vertex, and the springs on two sides are connected with the connection point of the second substrate to form a multi-pyramid structure, each cross section is triangular, and the stability of the multi-pyramid structure is guaranteed.
Compared with the prior art, the invention has the following advantages and beneficial effects:
1. based on the characteristic that CTE of materials in the package is different, a heat source in the middle and a heat source around the middle are respectively formed through an outer return pipe and an inner return pipe, so that the thermal stress of the middle and the edge of the package, which is warped, is changed, and the final warping amplitude in the package is reduced;
2. in order to avoid overlarge thermal stress around the inner return pipe, the thermal stress around the inner return pipe is reduced by adopting a heat transfer mode of the outer return pipe and the inner return pipe, and partial heat of the inner return pipe is transferred to the outer return pipe for reapplication, so that the utilization rate of residual heat of the inner return pipe and the outer return pipe is improved, and the warping amplitude of packaging is greatly improved;
3. in order to reduce the amplitude of early-stage warping, the spring is arranged between the first substrate and the second substrate, so that the amplitude of early-stage warping of the package is reduced, and therefore the thermal stress change of the inner return pipe and the outer return pipe relative to the first substrate and the second substrate is better applied.
Drawings
The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention. In the drawings:
FIG. 1 is a schematic structural diagram of the present invention applied to embodiment 1;
FIG. 2 is a schematic top view of a first substrate according to embodiment 1 of the present invention;
FIG. 3 is a schematic side view showing the structure of the inner return pipe according to embodiment 1 of the present invention;
fig. 4 is a schematic side view of an adapter in an inner return pipe according to embodiment 1 of the present invention;
fig. 5 is a schematic side view of the outer return pipe in embodiment 1 of the present invention.
Reference numbers and corresponding part names in the drawings:
1-pouring sealant, 2-third chip, 3-second chip, 4-lead, 6-second substrate, 7-second solder ball, 8-outer return pipe, 9-first substrate, 10-first solder ball, 11-first chip, 12-inner return pipe, 15-spring, 121-straight pipe, 122-bent pipe, 123-adapter, 124-return pipe, 81-heat release pipe, 82-corner joint, 83-outer bent pipe and 84-linear joint.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to examples and accompanying drawings, and the exemplary embodiments and descriptions thereof are only used for explaining the present invention and are not meant to limit the present invention.
Example 1
As shown in fig. 1 to 5, in the high-density integrated circuit package structure based on the thermal stress to reduce the warpage amplitude, the present embodiment employs three layers of chip stacking, including a second substrate 6, a second solder ball 7, an outer return tube 8, a first substrate 9, a first chip 11, and an inner return tube 12, where the second substrate 6 is stacked on the upper side of the first substrate 9, and the second solder ball 7 is disposed between the second substrate 6 and the first substrate 9 so that the second substrate 6 is not in contact with the first substrate 9; the first chip 11 is arranged between the second substrate 6 and the first substrate 9 and is flipped on the upper surface of the first substrate 9, and the upper surface of the first chip 11 is not in contact with the lower surface of the second substrate 6; the inner return pipe 12 and the outer return pipe 8 are both closed pipes; the inner return pipe 12 is arranged on the upper surface of the first chip 11; the outer return pipe 8 is provided on the upper surface of the first substrate 9. A second chip 3 and a third chip 2 are arranged on the upper surface of the second substrate 6, the second chip 3 and the third chip 2 are stacked in a bare mounting mode, and are bonded through a lead 4; in order to fix the second chip 3 and the third chip 2, the potting adhesive 1 is used to fix them together. In this embodiment, the height of the first solder ball 10 is about 0.23mm, the thickness of the first substrate 9 is about 0.3mm, the thickness of the second substrate 6 is about 0.2mm, the height of the second solder ball 7 is about 0.3mm, the distance between the solder balls is about 0.4mm to 0.8mm, the thickness of the potting adhesive 1 is about 0.4mm, and the transverse length of the first substrate 9 is about 10mm to 15mm, so the longitudinal height of the inner return pipe 12 is about 0.1mm, and the maximum value of the longitudinal height of the outer return pipe 8 is 0.2 mm. Such inner return pipe 12 and outer return pipe 13 have a small diameter and are therefore more sensitive to external heat, and the heat transfer is more effective.
The laminated packaging has become a typical solution for processor and memory components in smart phone manufacturing, but due to the dimensional characteristics of the packaging object, not only the requirement for lamination precision is higher, but also the space of the stacked structure is narrower, in which various materials with different physical and chemical properties are concentrated, and the difference between the thermal expansion coefficients of the various materials in the packaging system makes the device equivalent to a thin plate more prone to warp deformation. The warp deformation destroys the coplanarity of the solder balls, resulting in an increased level of soldering defects. When the whole package is subjected to temperature change, due to different thermal expansion coefficients of various materials, the expansion and contraction are inconsistent, so that the package is warped; in the packaging process, the temperature rise process is recorded from room temperature to high temperature, the temperature reduction process is recorded from high temperature to room temperature, the temperature rise process and the temperature reduction process can be considered as a pair of inverse processes to a certain extent, however, due to the fact that thermal expansion coefficients of materials are different, deformation in the temperature rise process cannot be inversely reversed through the temperature reduction process, and therefore the final packaging warpage phenomenon occurs. The present invention is based on the above principle, and provides the outer return pipe 8 and the inner return pipe 12 between the first substrate 9 and the second substrate 6, and changes the temperature delay time and the temperature concentration degree of the partial region in the packaging process, thereby changing the thermal stress and the residual stress of the first substrate 9, the second substrate 6 and the first chip 11, and reducing the warpage degree of the first substrate 9 and the second substrate 6. The laminated package is soldered by reflow soldering, which is soldering for mechanically and electrically connecting the soldering terminal or pin of the surface-mounted component and the pad of the printed board by re-melting the paste-mounted soft solder pre-distributed on the pad of the printed board. The reflow soldering equipment blows heated nitrogen or other stable gas to the package to enable the solder to be re-melted to realize electrical connection, when hot gas flow blows to the package, the temperature around the package is rapidly increased, the re-melting time of the solder at high temperature is short, and the package has poor heat conducting performance and poor heat dissipation performance due to the characteristics of materials, so that the temperature of the package is slightly increased in the hot gas flow and is slowly reduced after the temperature is separated from the hot gas flow to a certain extent; the inner return pipe 12 and the outer return pipe 8 are made of materials with strong heat conduction capability, such as metal materials copper, the heat conduction of copper is fast, but the heat dissipation is slow, the temperature of the inner return pipe 12 and the outer return pipe 8 can be raised through hot air flow, because the heat conduction performance of the inner return pipe 12 and the outer return pipe 8 is good, the temperature of the inner return pipe can reach the temperature of the hot air flow when the temperature is highest, after the package is separated from the hot air flow, the temperature of the inner return pipe 12 and the outer return pipe 8 starts to be lowered, but the temperature is lowered slowly, therefore, after the package is separated from the hot air flow, the temperature of the first substrate 9, the second substrate 6 and the first chip 11 on the package is gradually restored to normal temperature, in the process, the temperature of the inner return pipe 12 and the temperature of the outer return pipe 8 are always higher than the temperature of the package, at the moment, the inner return pipe 12 and the outer return, the heat of the outer return pipe 8 is radiated to the periphery of the first substrate 9, and thus the thermal stress of the first substrate 9, the second substrate 6, and the first chip 11 is changed. When the CTE of the first substrate 9 is large, the CTE of the second substrate 6 is small, and when the outer return pipe 8 and the inner return pipe 12 are not used, the CTE of the first substrate 9 is large, so that the whole package presents positive value warpage and large amplitude, and when the normal temperature is recovered, the positive value warpage amplitude is reduced, but the positive value warpage amplitude can be the warpage amplitude which is always kept after the package is molded, but the warpage amplitude is large, and the requirement of a high-density integrated circuit is not met; when the CTE of the first substrate 9 is relatively large, the CTE of the second substrate 6 is relatively small, and when the outer return pipe 8 and the inner return pipe 12 are used, the CTE of the first substrate 9 is relatively large, so that the whole package is warped in a positive value and relatively large in amplitude, the positive warping amplitude is reduced when the normal temperature is recovered, but the reduction trend is insufficient, at the moment, the residual temperature of the inner return pipe 12 and the outer return pipe 8 can assist in enhancing the trend of amplitude reduction, the amplitude reduction of positive warping is further realized on the basis of original amplitude reduction, and thus the amplitude of positive warping of the molded package is relatively small, and the molded package is more suitable for the current and later high-density integrated circuit packages. When the CTE of the first substrate 9 is small, the CTE of the second substrate 6 is large, and when the outer return pipe 8 and the inner return pipe 12 are not used, the CTE of the second substrate 6 is large, so that the whole package presents negative value warpage and large amplitude, and when the normal temperature is recovered, the negative value warpage amplitude is reduced, but the negative value warpage amplitude can be the warpage amplitude which is always kept after the package is molded, but the warpage amplitude is large, and the requirement of a high-density integrated circuit is not met; when the CTE of the first substrate 9 is small, the CTE of the second substrate 6 is large, and when the outer return pipe 8 and the inner return pipe 12 are used, the CTE of the second substrate 6 is large, so that the whole package presents negative value warpage and large amplitude, when the normal temperature is recovered, the negative value warpage amplitude is reduced, but the reduction trend is insufficient, at the moment, the residual temperature of the inner return pipe 12 and the outer return pipe 8 can assist in enhancing the trend of amplitude reduction, so that the negative value warpage is further reduced on the basis of the original amplitude reduction, and the amplitude of the negative value warpage of the molded package is small, and the molded package is more suitable for the current and later high-density integrated circuit packages.
Example 2
This embodiment differs from embodiment 1 in that the contact between the inner return pipe 12 and the outer return pipe 8 allows heat transfer between the inner return pipe 12 and the outer return pipe 8.
The inner return pipe 12 is concentrated between the first chip 11 and the first substrate 9, the space of the inner return pipe is more sealed relative to the outer return pipe, the heat dissipation speed of the inner return pipe is slower than that of the outer return pipe 8, namely, the thermal stress between the second substrate 6 and the first chip 11 is larger, the inner return pipe 12 is positioned in the middle of the whole package, the thermal stress is overlarge, the warpage of the middle of the second substrate 6 and the first chip 11 is more serious, in order to avoid the thermal stress near the inner return pipe 12 to be more concentrated, the heat exchange between the inner return pipe 12 and the outer return pipe 8 is realized, the outer return pipe 8 assists the inner return pipe 12 to dissipate heat, the residual heat on the inner return pipe 12 and the outer return pipe 8 is more uniformly dispersed in the whole package, and the warpage amplitude in the molded package is reduced.
The inner return pipe 12 comprises a plurality of straight pipes 121, a plurality of bent pipes 122, two adapters 123 and a return pipe 124, the number of the straight pipes 121 is N +1, the number of the bent pipes 122 is N, wherein N is an even number greater than 0; a plurality of straight pipes 121 are arranged in parallel, and one ends of two adjacent straight pipes 121 at the same side are connected by adopting a bent pipe 122; a space is formed between two adjacent straight pipes 121, and two adjacent spaced bent pipes 122 are respectively positioned at two sides of the straight pipes 121; two adapters 123 are respectively arranged at one ends, which are not connected with the elbow 122, of the two straight pipes 121 on the outer side, and a return pipe 124 is arranged between the two adapters 123, so that the return pipe 124 is positioned on the lower side of the plane where the straight pipes 121 are positioned.
The inner return pipe 12 is set to be an S-shaped closed loop, the inner return pipe 12 is uniformly distributed between the first chip 11 and the second substrate 6 through the straight pipes, and the heat absorbed by the inner return pipe 12 can be uniformly dispersed on the second substrate 6 and the first chip 11, so that the package can reduce the warpage deformation amplitude of the second substrate 6 and the first chip 11 in the cooling process.
The outer return pipe 88 comprises two heat releasing pipes 81, four corner joints 82, N outer bent pipes 83, and N-2 linear joints 84, the heat releasing pipes 81 are U-shaped pipes, and the two heat releasing pipes 81 are disposed on the upper surface of the first substrate 9 and on two sides of the first chip 1111; every two corner joints 82 are connected to two ends of a heat release pipe 81; the outer bent pipes 83 correspond to the bent pipes 122 one by one, the outer bent pipes 83 are arranged on the outer sides of the bent pipes 122, and two adjacent outer bent pipes 83 are connected through a linear joint 84; one end of the unconnected straight joints 84 of the outside bent pipes 83 on both sides is connected to one end of the unconnected heat releasing pipes 81 of the corner joints 82.
The outer return pipe 8 is for dissipating heat to the periphery of the first substrate 9, so the heat releasing pipe 81 is disposed on the periphery of the first substrate 9, the outer bent pipe 83 and the bent pipe 122 are the main components for heat transfer, the outer bent pipe 83 and the bent pipe 122 are in contact, that is, the outer bent pipe 83 is on the plane of the upper surface of the first chip 11, the heat releasing pipe 81 is on the plane of the first substrate 9, and the outer return pipe 8 is closed by using the corner joint 82 for connecting the heat releasing pipe 81 and the outer bent pipe 83.
Example 3
The present embodiment is different from embodiment 2 in that the cross section of the elbow 122 is circular, the cross section of the outer elbow 83 is C-shaped, and the outer elbow 83 covers the outer surface of the elbow 122.
The heat transfer in heat transfer is determined by the size of the contact surface and the size of the temperature difference, the temperature difference is not easy to control, but the size of the contact surface can be easily changed. In order to increase the contact surface between the bent tube 122 and the outer bent tube 83, the outer bent tube 83 is formed by bending a flat-plate-shaped water tube to form a special bent tube with a C-shaped cross section, and the outer bent tube 83 covers the surface of the bent tube 122, so that the contact area can be maximized, more heat can be transferred, and the thermal stress between the second substrate 6 and the first chip 11 can be prevented from being excessively concentrated.
The heat releasing pipe 81 is flat. The heat release pipe 81 is configured to be flat, so that heat can be released to the maximum extent, more heat can be transferred, and the thermal stress between the second substrate 6 and the first chip 11 can be prevented from being excessively concentrated.
The portion of the straight tube 121 in contact with the first chip 11 is a flat surface. Heat is more easily transferred to the first chip 11. The portion of contact between the straight tube 121 and the second substrate 6 is a flat surface. So that heat is more easily transferred to the second substrate 6.
The inner return pipe 12 and the outer return pipe 8 are both copper pipes. The copper tube is a metal with stable property, can realize rapid heat transfer, can bear various operations with high temperature in the lamination packaging process, has poor heat dissipation performance, and is equivalent to a temporary heat source for changing residual thermal stress of the first substrate 9, the second substrate 6, the first chip 11 and accessory parts thereof and assisting in reducing the amplitude of warping deformation.
Liquid is provided in the inner return pipe 12 and the outer return pipe 8. The arrangement of liquid in the inner return pipe 12 and the outer return pipe 8 can assist in absorbing more heat, which is equivalent to the heat storage of the inner return pipe 12 and the outer return pipe 8, so that the time of the thermal stress effect of the inner return pipe 12 and the outer return pipe 8 is prolonged.
Example 4
The present embodiment is different from embodiment 1 in that a plurality of springs 15 are disposed between the first substrate 9 and the second substrate 6, and the plurality of springs 15 are uniformly distributed on both sides of the first chip 11; the central axis of the spring 15 intersects with the plane where the first substrate 9 is located, and the extension lines of the central axes of the springs 15 on the two sides intersect at one point, which is recorded as point X; the point X is on the midperpendicular of the lower side of the plane where the first substrate 9 is located or the point X is on the midperpendicular of the upper side of the plane where the first substrate 9 is located.
The typical warpage phenomena in the warpage phenomena include two types, one type is positive warpage (convex), and the other type is negative warpage (concave), during the temperature rising process of the package, due to the difference of CTE of the materials, a large warpage deformation (hereinafter, this warpage deformation is referred to as "early warpage") occurs in the temperature rising process of the package, although this early warpage does not completely appear in the warpage deformation after the package molding, this early warpage greatly affects the warpage deformation after the package molding, in order to avoid the amplitude of the early warpage from being too large, a plurality of springs 15 are adopted in the first substrate 9 and the second substrate 6, and the distance between the first substrate 9 and the second substrate 6 is buffered and resisted through the springs 15. When the CTE of the first substrate 9 is greater than that of the second substrate 6, negative warpage occurs, that is, the distance between the middle of the first substrate 9 and the middle of the second substrate 6 increases and the distance between the edges decreases, and at this time, the spring 15 is disposed such that the point X is on the perpendicular bisector of the upper side of the plane of the first substrate 9, so that the elastic force of the spring 15 is distributed at the edges, so that a force repelling the first substrate 9 and the second substrate 6 exists between the first substrate 9 and the second substrate 6, and the amplitude of the previous warpage between the first substrate 9 and the second substrate 6 decreases; when the CTE of the first substrate 9 is smaller than that of the second substrate 6, positive warpage occurs, that is, the distance between the middle of the first substrate 9 and the middle of the second substrate 6 increases and the distance between the edges decreases, and at this time, the spring 15 is disposed such that the point X is on the perpendicular bisector of the lower side of the plane of the first substrate 9, so that the elastic force of the spring 15 is distributed at the edges, so that a force repelling the first substrate 9 and the second substrate 6 exists between them, and the amplitude of the previous warpage between the first substrate 9 and the second substrate 6 decreases. In order to make the force of the springs 15 more uniform, concentrated and stable, the springs 15 are arranged such that the extension lines of the central axes thereof can be converged at the point X, the point X is taken as a vertex, and the springs 15 at the two sides are connected to the connection point of the second substrate 6 to form a polygonal pyramid structure, each cross section is triangular, and the stability thereof is ensured.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are merely exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (7)
1. The high-density integrated circuit packaging structure for reducing the warpage amplitude based on thermal stress is characterized by comprising a second substrate (6), second solder balls (7), an outer return pipe (8), a first substrate (9), a first chip (11) and an inner return pipe (12), wherein the second substrate (6) is stacked on the upper side of the first substrate (9), and the second solder balls (7) are arranged between the second substrate (6) and the first substrate (9) so that the second substrate (6) is not in contact with the first substrate (9); the first chip (11) is arranged between the second substrate (6) and the first substrate (9) and is flipped on the upper surface of the first substrate (9), and the upper surface of the first chip (11) is not in contact with the lower surface of the second substrate (6); the inner return pipe (12) and the outer return pipe (8) are both closed pipelines; the inner return pipe (12) is arranged on the upper surface of the first chip (11); the outer return pipe (8) is arranged on the upper surface of the first substrate (9);
the inner return pipe (12) comprises a plurality of straight pipes (121), a plurality of bent pipes (122), two adapters (123) and a return pipe (124), the number of the straight pipes (121) is N +1, the number of the bent pipes (122) is N, and N is an even number greater than 0; a plurality of straight pipes (121) are arranged in parallel, and one ends of two adjacent straight pipes (121) at the same side are connected by adopting a bent pipe (122); a space is formed between two adjacent straight pipes (121), and two adjacent spaced bent pipes (122) are respectively positioned at two sides of the straight pipes (121); the two adapters (123) are respectively arranged at one ends, which are not connected with the elbow (122), of the two straight pipes (121) on the outer sides, and the return pipe (124) is arranged between the two adapters (123), so that the return pipe (124) is positioned on the lower side of the plane where the straight pipes (121) are positioned;
the outer return pipe (8) comprises two heat release pipes (81), four corner joints (82), N outer bent pipes (83) and N-2 linear joints (84), the heat release pipes (81) are U-shaped pipes, and the two heat release pipes (81) are arranged on the upper surface of the first substrate (9) and positioned on two sides of the first chip (11); every two corner joints (82) are connected with two ends of a heat release pipe (81); the outer bent pipes (83) correspond to the bent pipes (122) one by one, the outer bent pipes (83) are arranged on the outer sides of the bent pipes (122), and two adjacent outer bent pipes (83) are connected through a linear joint (84); one end of the outer bent pipe (83) on both sides, which is not connected with the straight joint (84), is connected with one end of the corner joint (82), which is not connected with the heat release pipe (81).
2. The thermal stress-reduced warpage amplitude-based high-density integrated circuit package structure according to claim 1, wherein the cross section of the bent tube (122) is circular, the cross section of the outer bent tube (83) is C-shaped, and the outer bent tube (83) covers the outer surface of the bent tube (122).
3. The thermal stress-based warpage magnitude mitigating high density integrated circuit package structure of claim 1, wherein the heat releasing pipe (81) is flat.
4. The thermal stress-based warpage magnitude alleviating structure for high density integrated circuit package according to claim 1, wherein the portion of the straight tube (121) contacting the first chip (11) is a plane.
5. The thermal stress-based warpage magnitude mitigation high density integrated circuit package structure of claim 1, wherein the inner return pipe (12) and the outer return pipe (8) are both copper pipes.
6. The thermal stress-based warpage magnitude mitigation high density integrated circuit package structure of claim 1 or 5, wherein the inner return pipe (12) and the outer return pipe (8) are provided with liquid therein.
7. The thermal stress-based warpage magnitude alleviating high density integrated circuit package structure of claim 1, wherein a plurality of springs (15) are disposed between the first substrate (9) and the second substrate (6), the plurality of springs (15) are uniformly distributed on two sides of the first chip (11); the central axis of the spring (15) is intersected with the plane where the first substrate (9) is located, the extension lines of the central axes of the springs (15) on the two sides are intersected at one point, and the point is marked as an X point; the X point is positioned on the midperpendicular of the lower side of the plane of the first substrate (9) or the X point is positioned on the midperpendicular of the upper side of the plane of the first substrate.
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| CN201811002737.1A CN109166828B (en) | 2018-08-30 | 2018-08-30 | High-density integrated circuit packaging structure for reducing warping amplitude based on thermal stress |
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| CN201811002737.1A CN109166828B (en) | 2018-08-30 | 2018-08-30 | High-density integrated circuit packaging structure for reducing warping amplitude based on thermal stress |
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| TW571374B (en) * | 2002-10-24 | 2004-01-11 | Advanced Semiconductor Eng | System in package structures |
| US7230334B2 (en) * | 2004-11-12 | 2007-06-12 | International Business Machines Corporation | Semiconductor integrated circuit chip packages having integrated microchannel cooling modules |
| US7557438B2 (en) * | 2006-04-27 | 2009-07-07 | Intel Corporation | Cooling mechanism for stacked die package, and method of manufacturing stacked die package containing same |
| US7400033B1 (en) * | 2006-12-29 | 2008-07-15 | Intel Corporation | Package on package design to improve functionality and efficiency |
| CN102522380B (en) * | 2011-12-21 | 2014-12-03 | 华为技术有限公司 | PoP packaging structure |
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