Package structure
By setting up a decimation space and through-hole exhaust passages between the solder pads, the problem of low yield of the packaging structure is solved, appropriate range control of the solder volume is achieved, and the yield and solid crystal accuracy of the packaging structure are improved.
Patent Information
- Application Number
- CN202421587232.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-05
- Publication Date
- 2025-07-11
- Estimated Expiration
- 2034-07-05
AI Technical Summary
The packaging structures in the prior art have low yields, mainly due to the strict solder volume requirements, which leads to weakening of self-alignment or frequent air welding.
Set up a decimation space between the solder pads, so that the solder is preferred to adhere to the surface of the solder pad during the reflow process, reduce the air contact area, and discharge excess solder through the through holes and exhaust channels, ensuring that the solder fills the accommodating space without accumulation, and increasing the upper limit of the solder volume.
The yield of the package structure is improved, the strict requirements on solder volume is reduced, the effect of self-alignment is enhanced, the chip offset and rotation are avoided, and the cost is reduced.
Smart Images
Figure CN223092879U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the technical field of wafer packaging, and more particularly, to a packaging structure. Background Art
[0002] In the related art, a packaging structure is provided, in which a wafer is soldered to a substrate by reflow soldering.
[0003] However, the yield of the packaging structure in the related art is relatively low. Summary of the Utility Model
[0004] This application provides a packaging structure to solve the problem of how to improve the yield of the packaging structure.
[0005] This application provides a packaging structure, including a wafer, a substrate, a pad assembly, and solder. The substrate and the wafer are spaced apart along a first direction. The pad assembly includes two pads, one of which is disposed on the side of the wafer facing the substrate, and the other of which is disposed on the side of the substrate facing the wafer. The two pads are opposite and spaced apart along the first direction to form a receiving space therebetween; at least one of the two pads is provided with a removed space, and the removed space communicates with the receiving space. A part of the solder fills the receiving space, and another part of the solder is located in the removed space.
[0006] In the above packaging structure, by providing the removed space, during the reflow soldering process, when the solder melts, due to the difference in the attraction of the removed space and the pads to the liquid solder, the solder will preferentially adhere to the surfaces of the two pads, thereby reducing the contact area between the two pads and the air and reducing the risk of open solder caused by too little solder. When the solder fills the space between the surfaces of the two pads, the solder fills the removed space to prevent the excess solder from accumulating between the surfaces of the two pads, resulting in the wafer being prone to shift, rotate, or tilt relative to the substrate, etc., which weakens the self-alignment phenomenon. Therefore, the risk of low die bonding accuracy caused by too much solder is reduced. In this way, the packaging structure can increase the upper limit of the solder volume, reduce the strict requirements for the solder volume in the process, and thus is beneficial to improving the yield.
[0007] In one embodiment, the removed space includes a through hole and an exhaust channel, and both the through hole and the exhaust channel penetrate the pad along the first direction. The exhaust channel extends in a plane perpendicular to the first direction, one end of the exhaust channel along its extending direction communicates with the through hole, and the other end of the exhaust channel along its extending direction penetrates one side of the pad along a second direction; the second direction is perpendicular to the first direction. The exposed part of the wafer and / or the substrate in the removed space is made of a non-metallic material.
[0008] In one embodiment, there are a plurality of exhaust channels, and the plurality of exhaust channels are spaced apart from each other along the circumferential direction of the through hole.
[0009] In one embodiment, there are multiple through-holes, and in a plane perpendicular to the first direction, the multiple through-holes are spaced apart from each other; at least one through-hole communicates with the exhaust passage. The excavation space further includes at least one communication passage that extends in a plane perpendicular to the first direction, and the communication passage penetrates through the pad along the first direction; the multiple through-holes are communicated through the communication passage.
[0010] In one embodiment, the radial dimension of the through-hole is greater than or equal to 10 microns and less than or equal to 100 microns.
[0011] In one embodiment, in a cross-section perpendicular to the extending direction of the exhaust passage, the size of the exhaust passage is greater than or equal to 1 micron and less than or equal to 30 microns.
[0012] In one embodiment, in a plane perpendicular to the first direction, the exhaust passage extends in a straight line or an arc.
[0013] In one embodiment, there are multiple pad assemblies, and the multiple pad assemblies are spaced apart from each other around the perimeter of the wafer. There are multiple excavation spaces, and the multiple excavation spaces correspond to the multiple pad assemblies one by one.
[0014] In one embodiment, the material of the pad is one of copper, gold, or aluminum.
[0015] In one embodiment, the material of the solder is one of tin, tin-silver, tin-lead, or tin-bismuth. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the accompanying drawings in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application, and thus should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.
[0017] Figure 1 It is a cross-sectional view of a packaging structure in the related art.
[0018] Figure 2 It is a schematic diagram of the first state of the wafer and the solder during the reflow soldering process in the related art.
[0019] Figure 3 It is a schematic diagram of the second state of the wafer and the solder during the reflow soldering process in the related art.
[0020] Figure 4 It is a schematic diagram of the third state of the wafer and the solder during the reflow soldering process in the related art.
[0021] Figure 5This is a cross-sectional view of the encapsulation structure in a plane parallel to the first direction in an embodiment of the present application.
[0022] Figure 6 This is a cross-sectional view of the encapsulation structure in a plane parallel to the first direction in another embodiment of the present application.
[0023] Figure 7 This is a schematic structural diagram of a solder pad in an embodiment of the present application.
[0024] Figure 8 is Figure 7 The top view of the solder pad in the illustrated embodiment.
[0025] Figure 9 The top view of the solder pad in another embodiment of the present application.
[0026] Figure 10 The top view of the solder pad in yet another embodiment of the present application.
[0027] Main element symbol description:
[0028] Encapsulation structure 1, 100
[0029] Wafer 2, 10
[0030] Substrate 3, 20
[0031] Solder pad assembly 30
[0032] Accommodating space 30a
[0033] Solder pad 31
[0034] Excavated space 31a
[0035] Through hole 31a1
[0036] Exhaust channel 31a2
[0037] Communication channel 31a3
[0038] Solder 4, 40
[0039] First direction A
[0040] Second direction B Detailed implementation manners
[0041] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments.
[0042] It should be noted that when an element is referred to as "fixed to" another element, it can be directly on the other element or there can also be an intermediate element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intermediate element at the same time. When an element is considered to be "disposed on" another element, it can be directly disposed on the other element or there may be an intermediate element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are only for the purpose of illustration.
[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "or / and" used herein includes any and all combinations of one or more of the related listed items.
[0044] Some embodiments of this application will be described in detail. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.
[0045] Embodiment
[0046] Figure 1 is a cross-sectional view of the packaging structure 1 in the related art; Figure 2 is a schematic diagram of the first state of the wafer 2 and the solder 4 during the reflow soldering process in the related art; Figure 3 is a schematic diagram of the second state of the wafer 2 and the solder 4 during the reflow soldering process in the related art; Figure 4 is a schematic diagram of the third state of the wafer 2 and the solder 4 during the reflow soldering process in the related art.
[0047] See Figure 1 , in the related art, a packaging structure 1 is provided. The packaging structure 1 is applied to flip chip (flip chip technology) or SMT (Surface Mount Technology). After melting the solder 4 through reflow soldering, the solder 4 solidifies again and bonds the wafer 2 to the substrate 3.
[0048] However, the yield of the packaging structure 1 in the related art is relatively low.
[0049] The inventors of this application have found through research that the reason for the above problems is that during the manufacturing process of flip chip technology or surface mount technology, when melting the solder 4 through reflow soldering, self-alignment phenomena will occur between the wafer 2 and the substrate 3. However, the packaging structure 1 in the related art is prone to weakening of the self-alignment phenomenon or open soldering, resulting in a reduction in the yield of the packaging structure 1.
[0050] Specifically, seeFigures 2 to 4 Among them, the self-alignment phenomenon refers to that during the welding process, when the solder 4 melts, the wafer 2 may automatically adjust its position under the influence of factors such as thermal expansion and surface tension, so that the wafer 2 can achieve better alignment around the solder joints when the solder 4 re-solidifies, thus helping to correct the alignment deviation caused by inaccurate position of the wafer 2 or small displacements during the welding process in certain cases. For example, Figure 2 shows the position of the wafer 2 when it is aligned at the solder joint, as Figure 3 shown. If the wafer 2 has a deflection relative to the solder joint, during the re-solidification of the solder 4, the self-alignment phenomenon may cause the wafer 2 to rotate in the opposite direction, thus offsetting a certain amount of alignment deviation, as Figure 4 shown. If the wafer 2 has a displacement relative to the solder joint, during the re-solidification of the solder 4, the self-alignment phenomenon may cause the wafer 2 to move in the opposite direction, thus offsetting a certain amount of alignment deviation. During the reflow soldering process, the wafer 2 floats on the molten solder 4. Therefore, the volume of the solder 4 between the wafer 2 and the substrate 3 has a greater impact on the effect of the self-alignment phenomenon of the wafer 2.
[0051] As Figure 1 shown, in the packaging structure 1 in the related art, when the volume of the solder 4 is too large, the excess solder 4 is likely to squeeze the wafer 2 out of the solder joint, making the wafer 2 prone to displacement, rotation or tilting, etc., resulting in the weakening of the self-alignment phenomenon of the wafer 2, thus affecting the alignment of the wafer 2 relative to the substrate 3 after the solder 4 re-solidifies, and leading to a reduction in the yield of the packaging structure 1. When the volume of the solder 4 between the wafer 2 and the substrate 3 is too small, it is prone to open circuit soldering. Therefore, the packaging structure 1 in the related art has relatively strict requirements for the volume of the solder 4, resulting in a low yield of the packaging structure 1.
[0052] This embodiment provides a packaging structure 100, which can solve the above problems and improve the yield of the packaging structure 100. The following will be exemplarily described in conjunction with the drawings.
[0053] Figure 5 is a cross-sectional view of the packaging structure 100 in a plane parallel to the first direction A in an embodiment of the present application; Figure 6 is a cross-sectional view of the packaging structure 100 in a plane parallel to the first direction A in another embodiment of the present application; Figure 7 is a schematic structural diagram of the solder pad 31 in an embodiment of the present application; Figure 8 is Figure 7 a top view of the solder pad 31 in the shown embodiment.
[0054] Referring to Figure 5 and Figure 6 , an embodiment of the present application provides a packaging structure 100, including a wafer 10, a substrate 20, a solder pad assembly 30 and a solder 40.
[0055] The substrate 20 and the wafer 10 are arranged at an interval along the first direction A. The pad assembly 30 includes two pads 31, one of the pads 31 is disposed on the side of the wafer 10 facing the substrate 20, and the other pad 31 is disposed on the side of the substrate 20 facing the wafer 10. The two pads 31 are opposite and spaced apart along the first direction A to form a receiving space 30a between the two pads 31. As Figure 7 and Figure 8 shown, at least one of the two pads 31 is provided with a dug-out space 31a, and the dug-out space 31a communicates with the receiving space 30a. A part of the solder 40 is filled in the receiving space 30a, and the other part of the solder 40 is located in the dug-out space 31a.
[0056] In the above packaging structure 100, by providing the dug-out space 31a, during the reflow soldering process, when the solder 40 melts, due to the difference in the attraction of the dug-out space 31a and the pad 31 to the liquid solder 40, the solder 40 will preferentially adhere to the surfaces of the two pads 31, thereby reducing the contact area between the two pads 31 and the air and reducing the risk of dry joints caused by too little solder 40. When the solder 40 fills the receiving space 30a, the solder 40 fills the dug-out space 31a to prevent the excess solder 40 from accumulating between the opposite surfaces of the two pads 31, resulting in the wafer 10 being prone to shift, rotate or tilt relative to the substrate 20, weakening the self-alignment phenomenon. Therefore, the risk of reduced die bonding accuracy caused by too much solder 40 can be reduced. In this way, the packaging structure 100 can prevent the solder 40 from accumulating after filling the receiving space 30a, that is, it increases the upper limit of the volume of the solder 40, reduces the strict requirements for the volume of the solder 40 in the flip-chip technology or surface mount technology process, which is beneficial to improving the yield of the packaging structure 100 and further reducing the cost.
[0057] It can be understood that, as Figure 5 shown, the solder 40 can fill a part of the dug-out space 31a, as Figure 6 shown, the solder 40 can also fill the entire dug-out space 31a, and both can prevent the solder 40 from accumulating too much between the two pads 31. Therefore, the above packaging structure 100 can expand the preset range of the volume of the solder 40 in the process. When the volume of the solder 40 is within the preset range, during the reflow soldering process, the volume of the solder 40 in the receiving space 30a is appropriate. Therefore, the wafer 10 is more likely to be attracted to the accurate position under the action of the surface tension of the molten solder 40, that is, it is beneficial to enhance the effect of the self-alignment phenomenon.
[0058] During actual use, the first direction A can be the gravity direction.
[0059] In some embodiments, as Figure 7As shown, the excavation space 31a includes a through-hole 31a1 and an exhaust passage 31a2. Both the through-hole 31a1 and the exhaust passage 31a2 penetrate through the pad 31 along the first direction A. The exhaust passage 31a2 extends on a plane perpendicular to the first direction A. One end of the exhaust passage 31a2 along its extending direction communicates with the through-hole 31a1, and the other end of the exhaust passage 31a2 along its extending direction penetrates through one side of the pad 31 along the second direction B, and the second direction B is perpendicular to the first direction A. Combining Figure 6 As shown, the exposed portions of the wafer 10 and / or the substrate 20 in the excavation space 31a are made of non-metallic materials. Thus, by providing the exhaust passage 31a2, it is convenient to discharge air through the exhaust passage 31a2 from the pad 31, avoiding the formation of sealed air bubbles in the through-hole 31a1. The through-hole 31a1 and the exhaust passage 31a2 are both arranged to penetrate through the pad 31 along the first direction A, and the exposed portions of the wafer 10 and / or the substrate 20 in the excavation space 31a are made of non-metallic materials, so that the molten solder 40 can easily fill gradually in the direction from the accommodation space 30a to the excavation space 31a, rather than being preferentially absorbed by the metallic material to the side of the excavation space 31a far from the accommodation space 30a, thereby causing insufficient solder 40 in the accommodation space 30a. And by arranging the through-hole 31a1 and the exhaust passage 31a2 to penetrate through the pad 31 along the first direction A, there is no need to add non-metallic structures on the metallic pad 31, thus making the manufacturing process of the packaging structure 100 simpler.
[0060] Figure 9 This is a top view of the pad 31 in another embodiment of the present application.
[0061] In some embodiments, as Figure 9 As shown, there are multiple exhaust passages 31a2. The multiple exhaust passages 31a2 are arranged at intervals along the circumferential direction of the through-hole 31a1 to further facilitate the discharge of air through the exhaust passage 31a2 from the pad 31.
[0062] Figure 10 This is a top view of the pad 31 in yet another embodiment of the present application.
[0063] In some embodiments, as Figure 10 As shown, there are multiple through-holes 31a1. In a plane perpendicular to the first direction A, the multiple through-holes 31a1 are arranged at intervals, and at least one through-hole 31a1 communicates with the exhaust passage 31a2. The excavation space 31a further includes at least one communication passage 31a3. The communication passage 31a3 extends on a plane perpendicular to the first direction A. The communication passage 31a3 penetrates through the pad 31 along the first direction A, and the multiple through-holes 31a1 are connected through the communication passage 31a3. Thus, through the multiple through-holes 31a1 respectively communicating with the accommodation space 30a (see Figure 6) in different regions to facilitate the solder 40 at different regions in the accommodation space 30a to be filled into different through holes 31a1 respectively, so that the thickness distribution of the solder 40 in the accommodation space 30a at different regions is more uniform.
[0064] In some embodiments, the radial dimension of the through hole 31a1 is greater than or equal to 10 microns and less than or equal to 100 microns.
[0065] In some embodiments, in a cross-section perpendicular to the extending direction of the exhaust passage 31a2, the dimension of the exhaust passage 31a2 is greater than or equal to 1 micron and less than or equal to 30 microns.
[0066] Optionally, in a plane perpendicular to the first direction A, the exhaust passage 31a2 extends along a straight line or an arc.
[0067] In some embodiments, the pad assembly 30 includes a plurality of them, and the plurality of pad assemblies 30 are arranged at intervals around the periphery of the wafer 10. The excavation space 31a includes a plurality of them, and the plurality of excavation spaces 31a correspond to the plurality of pad assemblies 30 one by one. When a plurality of pad assemblies 30 are required to be connected between the wafer 10 and the substrate 20, good self-alignment effects can be achieved at the plurality of pad assemblies 30, which is beneficial to improving the die bonding accuracy of the wafer 10 and avoiding open soldering.
[0068] In some embodiments, the material of the pad 31 is one of copper, gold or aluminum.
[0069] In some embodiments, the material of the solder 40 is one of tin, tin-silver, tin-lead or tin-bismuth.
[0070] The above embodiments are only used to illustrate the technical solutions of the present application rather than to limit them. Although the present application has been described in detail with reference to the above preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present application can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present application.
Claims
1. An encapsulation structure, characterized in that, Comprising: A wafer; A substrate, disposed at an interval from the wafer in a first direction; A pad assembly, including two pads, one of the pads being disposed on a side of the wafer facing the substrate, and the other pad being disposed on a side of the substrate facing the wafer, the two pads being opposite and spaced apart from each other in the first direction to form an accommodation space therebetween; At least one of the two pads is provided with a removed space, and the removed space communicates with the accommodation space; Solder, a part of the solder filling the accommodation space, and another part of the solder being located in the removed space.
2. The encapsulation structure according to claim 1, wherein The removed space includes a through hole and an exhaust channel, and both the through hole and the exhaust channel penetrate the pad in the first direction; The exhaust channel extends in a plane perpendicular to the first direction, one end of the exhaust channel in its extending direction communicates with the through hole, and the other end of the exhaust channel in its extending direction penetrates a side of the pad in a second direction; the second direction is perpendicular to the first direction; The part of the wafer and / or the substrate exposed in the removed space is made of a non-metallic material.
3. The encapsulation structure according to claim 2, characterized in that There are a plurality of the exhaust channels, and the plurality of exhaust channels are spaced apart from each other along the circumferential direction of the through hole.
4. The encapsulation structure according to claim 2, wherein, There are a plurality of the through holes, and in a plane perpendicular to the first direction, the plurality of through holes are spaced apart from each other; at least one of the through holes communicates with the exhaust channel; The removed space further includes at least one communication channel, the communication channel extends in a plane perpendicular to the first direction, and the communication channel penetrates the pad in the first direction; the plurality of through holes are communicated through the communication channel.
5. The encapsulation structure according to claim 2, wherein The radial dimension of the through hole is greater than or equal to 10 microns and less than or equal to 100 microns.
6. The encapsulation structure according to claim 2, wherein In a cross-section perpendicular to the extending direction of the exhaust channel, the dimension of the exhaust channel is greater than or equal to 1 micron and less than or equal to 30 microns.
7. The encapsulation structure according to claim 2, wherein, In a plane perpendicular to the first direction, the exhaust channel extends in a straight line or an arc.
8. The encapsulation structure according to claim 1, wherein There are a plurality of the pad assemblies, and the plurality of pad assemblies are spaced apart from each other around the periphery of the wafer; There are a plurality of the removed spaces, and the plurality of removed spaces correspond to the plurality of pad assemblies one by one.
9. The encapsulation structure according to claim 1, wherein The material of the pad is one of copper, gold or aluminum.
10. The encapsulation structure according to claim 1, wherein The material of the solder is one of tin, tin-silver, tin-lead or tin-bismuth.