CN114220896B - Flip chip packaging process and flip chip packaging structure - Google Patents
Flip chip packaging process and flip chip packaging structure Download PDFInfo
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- CN114220896B CN114220896B CN202111319650.9A CN202111319650A CN114220896B CN 114220896 B CN114220896 B CN 114220896B CN 202111319650 A CN202111319650 A CN 202111319650A CN 114220896 B CN114220896 B CN 114220896B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/48—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
- H01L33/52—Encapsulations
- H01L33/54—Encapsulations having a particular shape
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/44—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the coatings, e.g. passivation layer or anti-reflective coating
- H01L33/46—Reflective coating, e.g. dielectric Bragg reflector
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/48—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
- H01L33/50—Wavelength conversion elements
- H01L33/505—Wavelength conversion elements characterised by the shape, e.g. plate or foil
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/48—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
- H01L33/62—Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2933/00—Details relating to devices covered by the group H01L33/00 but not provided for in its subgroups
- H01L2933/0008—Processes
- H01L2933/0033—Processes relating to semiconductor body packages
- H01L2933/005—Processes relating to semiconductor body packages relating to encapsulations
Abstract
The application provides a flip chip packaging process, which comprises the following steps: respectively pasting a plurality of flip chips on a substrate, and performing light guide glue dispensing and heating curing among the flip chips; cutting the light guide glue in a waterless cutting mode to form a plurality of chips with the light guide glue; fixing the chip with the light guide glue in the packaging cup; filling white reflective glue on the periphery of the wafer with the light guide glue to form a reflective layer; fluorescent glue is filled above the wafer with the light guide glue and the white reflective glue to form a fluorescent layer. A flip chip package structure is manufactured by the packaging process. This application leads optical cement and cuts through anhydrous cutting's mode through the thermal cure and leads optical cement for the leaded light of flip chip periphery is glued and is roughly trapezoidal, and the side of leading optical cement has the straight face of vertical rule, thereby can reduce when the flip chip side direction is got light and glue the internal consumption that the inside multiple refraction that produces or reflection produced of leaded light, improves flip chip's side direction rate of getting light.
Description
Technical Field
The present disclosure relates to chip manufacturing technologies, and in particular, to a flip chip packaging process and a flip chip packaging structure.
Background
With the development of the LED chip manufacturing process, the flip chip has been brought to the market due to its excellent thermal conductivity. At present, due to the difference between the design structure of the flip chip and the front-mounted chip, the lateral light emitting rate of the flip chip reaches 20%, and the forward light emitting rate is about 80%.
Along with the development of society, people are more and more conscious of energy conservation. Therefore, the improvement of the luminous efficiency after the flip chip packaging structure is packaged is a common pursuit of people in the LED industry. How to effectively improve the utilization rate of the light emitted from the side direction of the flip chip becomes a key research and development direction in the flip chip package structure design.
In the conventional scheme, a layer of anti-vulcanization liquid or a layer of white reflective glue is coated in the bottom of the packaging cup. However, when the processes are carried out, the light on the side surface of the flip chip can be blocked regardless of the anti-vulcanization liquid or the white reflective glue, so that the light has multiple refraction and reflection internal losses in the lateral light taking process, the light taking of the flip chip is influenced, the anti-vulcanization effect cannot be achieved, and the light-emitting efficiency of the flip chip is considered.
Disclosure of Invention
The application provides a flip chip packaging process and a flip chip packaging structure, which aim to solve the technical problem of low light-emitting utilization rate of the side face of a flip chip in the prior art.
In order to solve the above problem, in a first aspect, an embodiment of the present application provides a technical solution that: a flip chip packaging process comprises the following steps:
dispensing: respectively pasting a plurality of flip chips on a substrate, and performing light guide glue dispensing and heating curing among the flip chips;
cutting: cutting the light guide glue in a waterless cutting mode to form a plurality of light guide glue containing wafers;
die bonding: fixing the wafer with the light guide glue in a packaging cup;
forming a reflecting layer: filling white reflective glue on the peripheral side surface of the chip with the light guide glue to form a reflecting layer;
forming a fluorescent layer: and filling fluorescent glue above the chip with the light guide glue and the white reflective glue to form a fluorescent layer.
According to the flip chip packaging process provided by the embodiment of the application, light guide glue is dispensed between flip chips and is heated and cured, so that the cured light guide glue presents a shape that two ends are high and the middle is arc-shaped and concave between the adjacent flip chips, and then the light guide glue is cut at the position of the light guide glue in a waterless cutting mode, so that the light guide glue at the periphery of each flip chip is roughly trapezoidal, the side surface of the light guide glue is provided with a vertical and regular straight surface, the internal loss caused by multiple refraction or reflection generated inside the light guide glue during lateral light taking of the flip chips can be reduced, and the lateral light taking rate of the flip chips is improved; in addition, the arrangement of the reflecting layer can reflect lateral light with high lateral light extraction rate, further improve the lateral light extraction rate of the flip chip and reduce the energy consumption of lateral light.
In one possible design, the dispensing step includes:
uniformly distributing a plurality of flip chips on the substrate;
performing a dam on the periphery of a plurality of flip chips;
and carrying out light guide glue dispensing and heating curing between the dam and the flip chips.
In one possible design, in the dispensing step, the distance between two adjacent flip chips is greater than or equal to half of the length of the flip chips.
In one possible design, the flip chip includes a chip body and an electrode disposed on one side of the chip body;
in the dispensing step, the flip chip is pasted on the substrate in a mode that the electrodes face upwards, and the dispensing height is smaller than or equal to the height of the chip body.
In one possible design, in the dicing step, dicing is performed at an intermediate position between two adjacent flip chips.
In one possible design, in the dispensing step, a pasting film is further arranged on the substrate, the pasting film comprises a base layer, and a first adhesive tape and a second adhesive tape which are arranged on two opposite sides of the base layer, the first adhesive tape is pasted on the substrate, and the flip chips are respectively pasted on the second adhesive tape;
triangular diffuse reflection structures with different heights are printed on the surface of the second adhesive tape;
in the cutting step, the surface of the wafer with the light guide glue after cutting is provided with a diffuse reflection layer formed by rubbing a triangular diffuse reflection structure.
In one possible design, the diffuse reflective structure has roughness parameters Ra > 1.5 and Rz > 6.
In one possible design, the cutting step cuts to a depth extending at least half the thickness of the base layer.
In one possible design, the following steps are further included between the cutting step and the die bonding step:
a reverse mold, wherein the light guide adhesive wafer is reversed on the base film in a mode that the diffuse reflection layer faces upwards;
and transferring, namely transferring the light guide adhesive wafer onto the packaging cup through a transfer device.
In one possible design, in the step of forming the reflective layer: the top surface of the white reflecting glue is lower than the diffuse reflection layer of the wafer with the light guide glue.
In one possible design, the step of forming the phosphor layer includes:
uniformly stirring the fluorescent glue;
filling the fluorescent glue on the reflecting layer and the diffuse reflecting layer in a dispensing manner;
precipitating the fluorescent glue in a centrifugal mode;
and heating and curing the precipitated fluorescent glue.
In a second aspect, the present application further provides a flip chip package structure fabricated using the above flip chip packaging process;
the flip chip package structure includes:
packaging the cup;
the chip with the light guide glue is arranged in the packaging cup; the chip with the light guide glue comprises a flip chip and light guide glue arranged around the peripheral side surface of the flip chip; the longitudinal section of the light guide glue is in a right trapezoid shape, the longer bottom edge of the right trapezoid is attached to the side face of the flip chip, the shorter bottom edge of the right trapezoid is away from the flip chip, and the right-angle waist of the right trapezoid is flush with the top side of the flip chip;
the reflecting layer is filled between the inner wall of the packaging cup, the light guide glue and the flip chip;
and the fluorescent layer is filled above the reflecting layer, the light guide glue and the flip chip.
The flip chip packaging structure provided by the embodiment of the application makes a week side of the flip chip have the light guide glue with the longitudinal section in the shape of a right trapezoid through the flip chip packaging process, so that internal consumption caused by multiple refraction or reflection generated inside the light guide glue during lateral light taking of the flip chip can be reduced, and the lateral light taking rate of the flip chip is improved.
In one possible design, the flip chip includes a chip body and an electrode disposed on one side of the chip body; the flip chip is fixed in the packaging cup in a mode that the electrode faces downwards, and the bottom end of the right trapezoid is flush with the lower side of the chip body or higher than the lower side of the chip body.
In one possible design, the top side of the wafer with light guiding glue is provided with a diffuse reflective layer.
In one possible design, the diffuse reflective layer has roughness parameters Ra > 1.5 and Rz > 6.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive exercise.
Fig. 1 is a schematic process flow diagram of a flip chip packaging process provided in an embodiment of the present application;
FIG. 2 is a schematic structural diagram of a substrate and a bonding film according to an embodiment of the present disclosure;
FIG. 3 is an enlarged schematic view of portion A of FIG. 2;
FIG. 4 is a schematic view of a process for mounting a flip chip on a substrate;
FIG. 5 is a schematic view of the dispensing process of FIG. 1;
FIG. 6 is a schematic view of the post-dispensing heating process of FIG. 5;
FIG. 7 is a schematic view of the cutting process of FIG. 6 after heating;
FIG. 8 is a schematic view of the reverse mold process of FIG. 7 after cutting;
FIG. 9 is a schematic view of the light guiding wafer of FIG. 8;
FIG. 10 is a schematic view of the die attach process of FIG. 1;
FIG. 11 is a schematic view of the process of FIG. 1 for forming a reflective layer;
FIG. 12 is a schematic view of the process of forming a phosphor layer of FIG. 1;
fig. 13 is a schematic structural diagram of a flip chip tooling structure according to an embodiment of the present application.
Reference numerals: 10. a wafer with light guide glue; 11. flip chip mounting; 111. a wafer body; 112. an electrode; 12. light guide glue; 13. a diffuse reflective layer; 20. packaging the cup; 30. a reflective layer; 40. a fluorescent layer; 41. fluorescent powder; 50. a substrate; 60. pasting a film; 61. a base layer; 62. a first adhesive tape; 63. a second adhesive tape; 631. a diffuse reflective structure; 70. enclosing a dam; 80. a base film.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
In the description of the present application, "plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise. In this application, unless expressly stated or limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly and encompass, for example, both fixed and removable connections or integral parts thereof; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.
In this application, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through intervening media. Also, a first feature "on," "above," and "over" a second feature may be directly on or obliquely above the second feature, or simply mean that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.
In the description of the present application, it is to be understood that the terms "inner," "outer," "upper," "bottom," "front," "back," and the like, when used in the orientation or positional relationship indicated in FIG. 1, are used solely for the purpose of facilitating a description of the present application and simplifying the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be considered as limiting the present application.
It should be noted that the same reference numerals are used to denote the same components or parts in the embodiments of the present application, and for the same parts in the embodiments of the present application, only one of the parts or parts may be given the reference numeral, and it should be understood that the reference numerals are also applicable to the other same parts or parts.
In a first aspect, as shown in fig. 1, an embodiment of the present application first provides a flip chip packaging process, including the following steps:
s10: dispensing: the flip chips 11 are respectively attached to the substrate 50, and the light guide paste 12 is dispensed between the flip chips 11 and heated to be cured.
Specifically, referring to fig. 4 to 6, a plurality of flip chips 11 are distributed on the substrate 50 at equal intervals, for example, in a circle or in a rectangular array. And dispensing the light guide glue 12 between every two adjacent flip chips 11, and heating and curing. As shown in fig. 6, since the curing speed of the light guiding glue 12 is fast due to heating, the light guiding glue 12 between two adjacent flip chips 11 has a pattern with two high ends and a concave middle part in a radian, which is relatively higher than the way of dispensing natural molding.
The light guide glue 12 is a transparent glue with a light guide effect, such as a transparent silicone.
S30: cutting: referring to fig. 7, a plurality of chips 10 with light guide glue are formed by cutting the light guide glue 12 in a waterless cutting manner.
Specifically, through the mode of anhydrous cutting for light guide glue 12 can not be by the melting of water during the cutting, has also accelerated cutting speed simultaneously, and the higher the speed then the cutting has no trace, and the cutting process can not produce pressure and make the shape of light guide glue 12 produce the deformation to light guide glue 12.
Finally, the longitudinal section of the cut light guide glue 12 is approximately a right trapezoid in fig. 9, wherein the longer base of the right trapezoid is attached to the side of the flip chip 11, the shorter base of the right trapezoid deviates from the arrangement of the flip chip 11, and the right waist of the right trapezoid is flush with the top side of the flip chip 11. Compared with the triangular light guide glue formed naturally through dispensing, the trapezoidal light guide glue can fully improve the lateral light extraction rate of the flip chip 11, improve the brightness of the flip chip 11 and has mass production feasibility.
When cutting is performed, other flip chips 11 are distributed on the periphery of the flip chip 11, that is, the light guiding glue 12 is distributed on the periphery of the flip chip 11. When cutting, the light guide glue 12 on the peripheral side of the flip chip 11 needs to be cut, so as to form a single wafer 10 with light guide glue, and further, the lateral light emitting distribution of the peripheral side of the wafer 10 with light guide glue is uniform, and the light emitting rate is high.
In addition, since cutting is required for one circle, the periphery of the light guide glue wafer 12 can be cut into a required shape, such as a circle, a square or a regular polygon, as required, so that the forming process of the light guide glue wafer 10 has high control consistency and higher production yield.
S50: and (3) crystal solidification: referring to fig. 10, the light-guiding adhesive-carrying chip 10 is mounted in the package cup 20.
Specifically, the package cup 20 is a package holder having a cup-shaped groove, and one side of the flip chip 11 having the electrode 112 is attached to the center of the bottom of the cup-shaped groove. The bottom center of the package slot has a through hole to allow electrical connection of the electrodes 112 of the flip chip 11 to an external circuit.
S70: forming the reflective layer 30: referring to fig. 11, a white reflective glue is filled around the light guide glue-containing wafer 10 to form a reflective layer 30.
Specifically, white reflective glue is filled between the cup-shaped groove and the light guide glue 12 of the light guide glue wafer 10, a reflective layer 30 is formed by heating, and light emitted from the side surface of the flip chip 11 is reflected to the front direction through the reflective layer 30, so that the side light-emitting rate of the flip chip 11 is improved.
S90: formation of the fluorescent layer 40: referring to fig. 12, a fluorescent layer 40 is formed by filling fluorescent glue on the chip with light guiding glue 10 and the white reflective glue.
Specifically, in the present embodiment, the flip chip 11 is a blue flip chip, and the corresponding fluorescent glue is a yellow fluorescent glue. It is understood that in other embodiments of the present application, the color of the flip chip 11 and the fluorescent glue can be set according to actual requirements, and is not particularly limited herein.
The flip chip packaging process comprises the steps of conducting light guide glue 12 dispensing and heating curing between flip chips 11, enabling the cured light guide glue 12 to be in an arc-shaped concave shape with two high ends and the middle between the adjacent flip chips 11, and then cutting the light guide glue 12 in the position through a waterless cutting mode, enabling the light guide glue 12 on the periphery of each flip chip 11 to be approximately trapezoidal, enabling the side face of the light guide glue 12 to be provided with a vertical regular straight face, reducing internal loss caused by multiple refraction or reflection generated inside the light guide glue 12 during lateral light taking of the flip chips 11, and improving the lateral light taking rate of the flip chips 11; in addition, the reflective layer 30 is disposed to reflect lateral light with high lateral light extraction efficiency, thereby further improving the lateral light extraction efficiency of the flip chip 11 and reducing the energy consumption of lateral light.
In one embodiment, the dispensing step of S10 includes:
s11: uniformly distributing a plurality of flip chips 11 on a substrate 50;
specifically, the flip chips 11 are sequentially bonded and fixed to the substrate 50 by a dedicated transfer apparatus according to a predetermined track, so that the flip chips 11 are uniformly distributed on the substrate 50.
S12: performing a dam 70 at the periphery of the flip chips 11;
specifically, the dam 70 is used to form the light guiding glue 12 with a certain shape on the periphery of the flip chip 11, so that the dam 70 needs to be the same distance from the peripheral flip chip 11 as the distance from two adjacent flip chips 11.
S13: the light guide glue 12 is dispensed between the dam 70 and the flip chips 11 and is heated and cured, so that a circle of light guide glue 12 is formed on the periphery of any flip chip 11, the finally formed light guide glue-containing chip 10 is guaranteed to be a good product, and the yield of the light guide glue-containing chip 10 is improved.
In addition, when the light guide glue 12 is cured, the light guide glue can be cured by hot air; it is understood that in other embodiments of the present application, the light guiding glue 12 may be heated by placing in the heating cavity according to practical applications, and is not limited herein.
In one embodiment, the spacing between two adjacent flip chips 11 is greater than or equal to half the length of the flip chips 11. When the flip chip 11 is square, the length of the flip chip 11 is the length and width of the flip chip 11; when the flip chip 11 has a rectangular shape, the length of the flip chip 11 refers to the length of the longer side of the flip chip 11. The present application ensures that the light guide glue 12 formed between two adjacent flip chips 11 can be formed into a desired shape by limiting the distance between the flip chips 11. For example, when the distance between two flip chips 11 is too small, the light guide paste 12 will be stacked between two adjacent light guide pastes 12, and finally the cut light guide paste 12 will not be trapezoidal but rectangular, resulting in a decrease in light extraction rate at the side of the flip chip 11.
In a specific embodiment, the distance between two adjacent flip chips 11 is equal to 0.5 times the length of the flip chip 11, or equal to 0.8 times the length of the flip chip 11, or equal to 1 time the length of the flip chip 11, and is not particularly limited herein.
In addition, the distance between two adjacent flip chips 11 cannot be too large, which may cause excessive sinking of the light guide glue 12 between two adjacent flip chips 11 after glue fixing, and finally cause the formed light guide glue 12 not to form a triangle shape instead of a trapezoid shape.
In one embodiment, referring to fig. 5, the flip chip 11 includes a chip body 111 and two electrodes 112, wherein the two electrodes 112 are disposed on one side of the chip body 111.
In the dispensing step, the flip chip 11 is attached to the substrate 50 with the electrodes 112 facing upward, and the dispensing height is less than or equal to the height of the chip body 111. That is, during dispensing, the height of the light guiding glue 12 can only be at most flush with the upper surface of the wafer body 111, and cannot exceed the electrode 112. Due to the design, when the die with light guide adhesive 10 is mounted in the package cup 20, the light emitted from the side surface of the flip chip 11 is not absorbed by the electrode 112, so that the light loss caused by the light absorption of the electrode 112 is avoided, and the side light extraction rate of the flip chip 11 is further improved. Of course, the dispensing height should not be too low, which would affect the light consumption reduction function of the trapezoidal light guiding glue 12, and it is preferable that the dispensing height is even with or slightly lower than the upper surface of the wafer body 111.
In one embodiment, in the cutting step, when performing the anhydrous cutting, the cutting is performed at the middle position of two adjacent flip chips 11, so that the light guide glue 12 at a circumference of each flip chip 11 is uniformly distributed, the light emitted from the side surface of the flip chip 11 is uniform, and the mass production design is also facilitated.
Wherein, in the anhydrous cutting, can adopt slice, square or polygon fretwork groove cutter to cut, the cutter is sharp to guarantee that light guide glue 12 that can not receive the extrusion force and warp when the cutting.
In one embodiment, referring to fig. 2 and 3, in the dispensing step, an adhesive film 60 is further disposed on the substrate 50, the adhesive film 60 includes a base layer 61, a first adhesive tape 62 and a second adhesive tape 63, the first adhesive tape 62 and the second adhesive tape 63 are respectively disposed on two opposite sides of the base layer 61, the first adhesive tape 62 is adhered to the substrate 50, and the flip chips 11 are respectively adhered to the second adhesive tape 63.
Wherein, the surface of the second tape 63 is printed with triangular diffuse reflection structures 631 with different heights. In the dicing step, referring to fig. 9, the surface of the diced wafer 10 with light guiding glue has a diffuse reflection layer 13 formed by rubbing the triangular diffuse reflection structure 631.
Specifically, because the surface of the second adhesive tape 63 is printed with the triangular diffuse reflection structures 631 with different heights, after each flip chip 11 is adhered to the second adhesive tape 63, each flip chip 11 is subjected to glue dispensing and curing, and due to the action of gravity, the surfaces of each flip chip 11 and the light guide glue 12 can be printed with the triangular diffuse reflection layers 13, so that the cut light guide glue-containing wafer 10 has the diffuse reflection layers 13, thereby increasing the forward light extraction of the flip chip 11, and the light extraction is more uniform. Meanwhile, a fluorescent film for improving the even gloss is removed, the even gloss is not required to be improved through mould pressing, the structure is simplified, and the packaging cost of the flip chip 11 is reduced. In addition, the flip chip packaging process has low precision requirement, the yield of mass production is better, the mass production process is simpler, the equipment investment cost is lower, and the production efficiency is higher.
In one embodiment, the roughness parameters of the diffuse reflective structure 631 are Ra > 1.5 and Rz > 6. Ra is an arithmetic mean of the absolute values of the distances between points on the contour line in the measurement direction (Y direction) and the reference line within the sampling length. Rz refers to the microscopic unevenness ten point height, the sum of the average of 5 maximum profile peak heights and the average of 5 maximum profile valley depths over the sample length. The effect of diffuse reflection is controlled within a required range by setting Ra and Rz, namely, the effect of more uniform light emission of the flip chip 11 is achieved by controlling Ra and Rz through the cylinder.
Specifically, Ra may be 1.4, 1.2, 1, 0.5, etc., and Ra may be 5, 4, 3, 1, etc.
In the dicing step, the dicing depth is at least half of the thickness of the base layer 61, so that the adjacent two light guiding adhesive wafers 10 can be completely separated, and the diffuse reflection layer 13 can be removed along with the light guiding adhesive wafers 10 when the light guiding adhesive wafers 10 are removed from the adhesive film 60. Of course, in other embodiments of the present application, the cutting depth may also be adjusted according to the specific structure and material of the adhesive film 60, for example, the cutting depth is 0.4 times of the base layer 61, and the like, which is not limited herein.
Referring to fig. 8, the dicing step at S30 and the die bonding step at S50 further include the following steps:
s40: and (4) performing reverse molding, namely, pouring the light guide adhesive wafer 10 on the base film 80 in a manner that the full reflecting layer 30 faces upwards.
Specifically, the substrate 50 is first separated from the adhesive film 60, and then the light guide adhesive-carrying wafer 10 is transferred onto the base film 80 by means of reverse molding. The base film 80 may be a UV film or other film that does not affect the light guiding adhesive wafer 10.
S42: and transferring, namely transferring the light guide glue wafer 10 onto the packaging cup 20 by a moving device and fixing.
According to the application, a reverse die procedure is added, so that the light guide adhesive wafer 10 can be separated from the adhesive film 60 firstly, and then is fixed in the packaging cup 20 in a mode that the diffuse reflection layer 13 faces upwards, and the situation that the cut light guide adhesive wafer 10 is directly transferred and fixed to the packaging cup 20 is avoided, and the damage to the diffuse reflection layer 13 is avoided.
At step S70: in the step of forming the reflective layer 30, the top surface of the white reflective glue is lower than the diffuse reflective layer 13 of the chip with light guide glue 10, so that the white reflective glue does not affect the front light emission of the flip chip 11, and meanwhile, the rear fluorescent layer 40 can be tightly attached to the flip chip 11, thereby facilitating the downward conduction of heat generated after the fluorescent powder 41 is excited, and having better reliability.
Referring to fig. 11, the step S70 of forming the light guiding layer includes:
s71: uniformly stirring silica gel mixed with titanium dioxide particles or zirconium oxide particles;
s72: the white reflective glue is filled between the inner wall of the packaging cup 20 and the light guide glue 12 in a non-contact glue spraying manner:
s73: and heating and curing the white reflective glue in a baking mode.
Referring to fig. 12, step S90: forming the fluorescent layer 40 includes:
s91: uniformly stirring the fluorescent glue;
specifically, the fluorescent glue is filled into a stirring cup to be stirred at a constant speed, so that the fluorescent glue is uniformly mixed.
S92: filling fluorescent glue on the reflecting layer 30 and the diffuse reflecting layer 13 in a dispensing manner;
specifically, the fluorescent glue is filled in the package cup 20 by dispensing, and is located on the reflective layer 30 and the diffuse reflection layer 13.
S93: precipitating the fluorescent glue in a centrifugal mode;
specifically, the package cup 20, the light guide glue-containing wafer 10 thereon, the reflective layer 30, and the fluorescent layer 40 are placed together in a centrifugal device for centrifugal deposition, so that the fluorescent glue is deposited on the reflective layer 30 and the diffuse reflective layer 13, and thus the fluorescent glue is tightly attached to the top surface of the flip chip 11, which is beneficial to downward conduction of heat after the fluorescent powder 41 is excited, and the reliability is better.
S54: and heating and curing the precipitated fluorescent glue.
Specifically, the material is placed in an oven and heated and cured by baking. It is understood that in other embodiments of the present application, the heating may be performed by hot air, and is not limited herein.
Referring to fig. 13, in a second aspect, the present application further provides a flip chip package structure fabricated by the above flip chip packaging process;
the flip chip package structure includes a package cup 20, a die with light guide glue 10, a reflective layer 30 and a fluorescent layer 40. The light guide adhesive chip 10 is arranged in the packaging cup 20; the chip with light guide glue 10 comprises a flip chip 11 and light guide glue 12 arranged around the peripheral side surface of the flip chip 11; the longitudinal section of the light guide adhesive 12 is in a right trapezoid shape, the longer bottom edge of the right trapezoid is attached to the side face of the flip chip 11, the shorter bottom edge of the right trapezoid is away from the flip chip 11, and the right-angled waist of the right trapezoid is flush with the top side of the flip chip 11; a reflective layer 30 filled between the inner wall of the package cup 20, the light guide glue 12 and the flip chip 11; and the fluorescent layer 40 is filled above the reflecting layer, the light guide glue 12 and the flip chip 11.
The flip chip packaging structure provided by the embodiment of the application, through the above flip chip packaging process, makes a week side of the flip chip 11 have the light guiding glue 12 with the longitudinal section being in the shape of right trapezoid, thereby reducing the internal loss caused by multiple refraction or reflection generated inside the light guiding glue 12 during lateral light taking of the flip chip 11, and improving the lateral light taking rate of the flip chip 11.
In one possible design, the flip chip 11 includes a chip body 111 and an electrode 112 disposed on one side of the chip body 111; the flip chip 11 is held in the package cup 20 with the electrode 112 facing down, and the bottom end of the right trapezoid is flush with the lower side of the chip body 111 or higher than the lower side of the chip body 111. Therefore, when the die 10 with the light guide adhesive is mounted in the package cup 20, the light emitted from the side surface of the flip chip 11 is not absorbed by the electrode 112, thereby avoiding light loss caused by light absorption of the electrode 112, and further improving the side light extraction rate of the flip chip 11.
In one possible design, the top side of the wafer with light guiding glue 10 is provided with a diffuse reflective layer 13. Through the design of the diffuse reflection layer 13, the forward light extraction of the flip chip 11 is increased, and the light extraction is more uniform. Meanwhile, a fluorescent film for improving the even gloss is removed, the even gloss is not required to be improved through mould pressing, the structure is simplified, and the packaging cost of the flip chip 11 is reduced.
In one possible design, the diffuse reflecting layer 13 has roughness parameters Ra > 1.5 and Rz > 6. The Ra and Rz are set to control the effect of diffuse reflection within a desired range, that is, the Ra and Rz are controlled by the barrel, so that the flip chip 11 emits light more uniformly.
The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily think of the changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
Claims (11)
1. A flip chip packaging process is characterized by comprising the following steps:
dispensing: respectively pasting a plurality of flip chips on a substrate, and carrying out light guide glue dispensing and heating curing among the flip chips;
cutting: cutting the light guide glue in a waterless cutting mode to form a plurality of light guide glue containing wafers;
and (3) crystal solidification: fixing the wafer with the light guide glue in a packaging cup;
forming a reflecting layer: filling white reflective glue on the peripheral side surface of the chip with the light guide glue to form a reflecting layer;
forming a fluorescent layer: filling fluorescent glue above the chip with the light guide glue and the white reflective glue to form a fluorescent layer;
in the dispensing step, a pasting film is arranged on the substrate, the pasting film comprises a base layer, and a first adhesive tape and a second adhesive tape which are arranged on two opposite sides of the base layer, the first adhesive tape is pasted on the substrate, and the flip chips are respectively pasted on the second adhesive tape;
triangular diffuse reflection structures with different heights are printed on the surface of the second adhesive tape;
in the cutting step, the surface of the wafer with the light guide glue after cutting is provided with a diffuse reflection layer formed by rubbing a triangular diffuse reflection structure;
the roughness parameters of the diffuse reflection structure are Ra being more than 1.5 and Rz being more than 6.
2. The flip chip packaging process of claim 1, wherein the dispensing step comprises:
uniformly distributing a plurality of flip chips on the substrate;
performing a dam on the periphery of a plurality of flip chips;
and carrying out light guide glue dispensing and heating curing between the dam and the flip chips.
3. The flip-chip packaging process of claim 1, wherein in the dispensing step, a distance between two adjacent flip-chips is greater than or equal to half of a length of the flip-chips.
4. The flip chip packaging process of claim 1, wherein the flip chip comprises a chip body and an electrode disposed on one side of the chip body;
in the dispensing step, the flip chip is pasted on the substrate in a mode that the electrodes face upwards, and the dispensing height is smaller than or equal to the height of the chip body.
5. The flip chip packaging process according to claim 1, wherein in the dicing step, dicing is performed at an intermediate position between two adjacent flip chips.
6. The flip chip packaging process of claim 1, wherein in the dicing step, the depth of the cut extends at least half the thickness of the base layer.
7. The flip chip packaging process of claim 1, further comprising the following steps between the dicing step and the die bonding step:
a reverse mold, wherein the light guide adhesive wafer is reversed on the base film in a mode that the diffuse reflection layer faces upwards;
and transferring, namely transferring the light guide adhesive wafer onto the packaging cup through a transfer device.
8. The flip chip packaging process of claim 1, wherein in the forming a reflective layer step: the top surface of the white reflecting glue is lower than the diffuse reflection layer of the wafer with the light guide glue.
9. The flip chip packaging process of claim 1, wherein the step of forming a phosphor layer comprises:
uniformly stirring the fluorescent glue;
filling the fluorescent glue on the reflecting layer and the diffuse reflecting layer in a dispensing manner;
precipitating the fluorescent glue in a centrifugal mode;
and heating and curing the precipitated fluorescent glue.
10. A flip chip package structure fabricated using the flip chip package process according to any one of claims 1 to 9;
the flip chip package structure includes:
packaging the cup;
the chip with the light guide glue is arranged in the packaging cup; the chip with the light guide glue comprises a flip chip and light guide glue arranged around the peripheral side surface of the flip chip; the longitudinal section of the light guide glue is in a right trapezoid shape, the longer bottom edge of the right trapezoid is attached to the side face of the flip chip, the shorter bottom edge of the right trapezoid is arranged away from the flip chip, and the right-angle waist of the right trapezoid is flush with the top side of the flip chip;
the reflecting layer is filled between the inner wall of the packaging cup, the light guide glue and the flip chip;
and the fluorescent layer is filled above the reflecting layer, the light guide glue and the flip chip.
11. The flip chip package of claim 10, wherein the flip chip comprises a chip body and electrodes disposed on one side of the chip body; the flip chip is fixed in the packaging cup in a mode that the electrode faces downwards, and the bottom end of the right trapezoid is flush with the lower side of the chip body or higher than the lower side of the chip body.
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