JP7020343B2 - Encapsulating resin material - Google Patents

Description

The present invention relates to a sealing resin material.

In order to realize high performance, miniaturization, and weight reduction of electronic devices, high integration and high density of semiconductor elements are required in semiconductor packages. Along with this, flip-chip mounting, which is advantageous for high-density wiring, has been widely adopted as a mounting method for semiconductor elements.

Since there is a difference in the thermal expansion rate between the wiring substrate and the semiconductor element to be joined in the flip chip mounting, thermal deformation is likely to occur due to the temperature change of the joint surface. The stress generated by the thermal deformation tends to be concentrated on the conductive member which is a joint portion, and in some cases, the member may be broken. In order to prevent breakage and alleviate physical impact, a method is used in which a thermosetting sealing resin material is filled in a gap between a wiring substrate and a semiconductor element and cured. According to this method, the sealing resin material can prevent the conductive member from dust, moisture, and air oxidation, and can also obtain the effect of improving the reliability of the device.

As a general method for filling the gap between the wiring board and the semiconductor element with the sealing resin material, the Capillary Under Fill method (hereinafter, may be abbreviated as "CUF method") is known. In the CUF method, the encapsulating resin material is dropped on the surface of the wiring substrate near the end of the semiconductor element, and the encapsulating resin material is infiltrated into the gap between the wiring substrate and the semiconductor element by utilizing the capillary phenomenon. Fill.

The performance required for the sealing resin material includes moisture resistance, peeling resistance, crack resistance and the like after curing. Further, in filling using the capillary phenomenon, the main problems are prevention of bubble generation, shortening of filling time, and prevention of excessive spreading. In particular, the spread described here is a problem in which the sealing resin material spreads to the outer peripheral region of the gap between the wiring board and the semiconductor element, which is the place to be sealed, and this is a component in the semiconductor package. It is a technical barrier in realizing the narrowing of the pitch interval between them.

The sealing resin material is mainly composed of a resin component such as an epoxy resin or a curing agent and a filler formed of silica or the like. The above-mentioned spreading is roughly classified into a fillet in which the resin component and the filler are mixed and protrude from the end of the semiconductor element to the outer peripheral side, and a bleed in which the resin component further exudes from the outer peripheral side of the fillet to the outer peripheral side. To prevent bleeding from seeping out, measures have been taken not only for wiring boards but also for sealing resin materials.

As a countermeasure for the wiring board, for example, the methods described in Patent Documents 1 and 2 are applied. Specifically, Patent Document 1 includes a step of arranging and forming a block-shaped member for blocking the encapsulating resin material to be filled on the surface of a wiring board near the four corners of a semiconductor element to be mounted. The manufacturing method of the package is described. Further, in Patent Document 2, a step of flip-chip mounting a semiconductor element on a multilayer wiring board, a step of performing a surface activation treatment on the surface insulating layer of the multilayer wiring board, and a semiconductor element of the surface insulating layer are mounted. A method for manufacturing a semiconductor package including a step of subjecting a predetermined region on the outer peripheral side of a portion to a predetermined region on a semiconductor element and a step of filling a gap between the semiconductor element and a multilayer wiring substrate with a resin. Are listed.

On the other hand, as a countermeasure for a sealing resin material, a means for adjusting the type and amount of a resin component such as an epoxy resin or a curing agent or a filler is known. For example, Patent Document 3 describes a resin material using two types of silica fillers as fillers, based on the idea of blocking the resin component exuding to the outer peripheral side as bleeding. Further, Patent Document 4 describes a resin material capable of suppressing bleeding that occurs when the resin material is cured.

Japanese Unexamined Patent Publication No. 2013-62472 Japanese Unexamined Patent Publication No. 2014-49533 JP-A-2015-105304 Japanese Patent No. 4969069

However, the measures for the wiring board as described in the above-mentioned Patent Documents 1 and 2 complicate the manufacturing process of the semiconductor package, so that the time and financial manufacturing cost tends to increase.

On the other hand, among the measures for the above-mentioned sealing resin material, in the resin material described in Patent Document 3, the resin component exudes as bleed in advance before the dampening effect of the filler is exhibited. It was difficult to suppress. Further, in the resin material described in Patent Document 4, although it is possible to suppress the resin component from seeping out as bleeding during curing, the resin component is present while the resin material is flowing due to the capillary phenomenon before curing. It was difficult to prevent bleeding out. Therefore, the suppression of bleeding out was insufficient.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a sealing resin material capable of sufficiently suppressing bleeding.

In order to solve the above problems, the sealing resin material of the present invention is composed of a first filler composed of particles having a particle size of 200 nm or more and less than 10 μm, and a second filler composed of particles having a particle size of 7 nm or more and less than 200 nm. It is characterized by having a filler, a third filler composed of particles having a particle size of 0.5 nm or more and less than 7 nm, a thermosetting resin, and a curing agent.

According to the present invention, bleeding out can be sufficiently suppressed.
Issues, configurations, and effects other than those described above will be clarified by the description of the following embodiments.

It is a schematic process sectional view (schematic diagram in the middle of filling) which shows an example of the method of filling the gap between a wiring board of a semiconductor package and a semiconductor element by the CUF method. It is a schematic process sectional view (schematic diagram after filling) which shows an example of the method of filling the gap between a wiring board of a semiconductor package and a semiconductor element by the CUF method. It is an enlarged view of the region X shown in FIG. 2 when an example of the conventional sealing resin material is filled in the gap between a wiring board and a semiconductor element. It is an enlarged view of the region Y shown in FIG. It is an enlarged view of the region X shown in FIG. 2 when an example of the sealing resin material of this invention is filled in the gap between a wiring board and a semiconductor element. It is an enlarged view of the region Y shown in FIG. It is a graph which shows an example of the particle size distribution of a filler in the conventional sealing resin material. It is a graph which shows the example of the particle size distribution of the filler in the sealing resin material of this invention. It is schematic cross-sectional view which shows the initial state in the simulation of the calculation model of Example 1 and Example 2. FIG. It is schematic cross-sectional view which shows the final state in the simulation of the calculation model of Example 1 and Example 2. FIG. It is a graph which shows the wet spread length LB _{S of the part corresponding to a bleed, and the wet spread length LB S ′} of the part corresponding to a virtual bleed in the simulation of the calculation model of Example 1, Example 2, and a comparative example. .. It is a graph which shows the time change of the movement amount per unit time of the resin molecule, the constituent particle of the 2nd filler, and the constituent particle of the 3rd filler in the simulation of the calculation model of Example 1 by the mean square displacement. It is a graph which shows the time change of the movement amount per unit time of the resin molecule in the simulation of the calculation model of Example 1, Example 2, and the comparative example by the mean square displacement. It is a graph which shows the number of simulation steps until the filling is completed in the simulation of the calculation model of Example 1, Example 2, and Comparative Example.

Hereinafter, embodiments of the sealing resin material of the present invention will be described. Specifically, as a premise of the embodiment of the encapsulating resin material of the present invention, after explaining the filling method of the encapsulating resin material by the CUF method and the conventional encapsulating resin material, the encapsulating resin material of the present invention is carried out. The form will be described.

The encapsulating resin material of the present invention, the filler and the resin component contained in the encapsulating resin material, the semiconductor element and the wiring substrate of the semiconductor package in which the encapsulating resin material is used, the bonding material for joining these electrodes, and the dispenser. In addition, the materials, arrangement, dimensions, shapes of fillets and bleeds formed when the conventional and sealing resin materials of the present invention are used, and the filling method and filling procedure at the time of formation are described below in the present invention. It is not limited to the embodiment.

(Filling method of sealing resin material by CUF method)
1 and 2 are schematic process cross-sectional views showing an example of a method of filling a gap between a wiring board of a semiconductor package and a semiconductor element with a sealing resin material by a CUF method. The filling methods shown in FIGS. 1 and 2 are similarly used for filling both conventional and encapsulating resin materials of the present invention.

As shown in FIG. 1, the semiconductor package 100 in which the sealing resin material is filled by using this filling method includes a wiring board 110 and a semiconductor element 120 provided facing the wiring board 110, and is a wiring board. The substrate electrode 112 provided on the surface 110f of the 110 and the element electrode 122 provided on the surface 120f of the semiconductor element 120 are electrically connected by the bonding material 130.

Since the wiring board 110 and the semiconductor element 120 have different thermal expansion rates, thermal deformation is likely to occur due to a temperature change of the joint surface. The wiring substrate 110 and the semiconductor element 120 are bonded via the conductive member 150 including the substrate electrode 112, the element electrode 122, and the bonding material 130, and the stress in the vicinity of the bonding surface caused by thermal deformation is the bonding portion. Since it is easy to concentrate on the conductive member 150, it may cause breakage. In order to prevent such breakage and alleviate the physical impact on the semiconductor package 100, the thermosetting sealing resin material 10 (20) is filled in the gap 115 between the wiring substrate 110 and the semiconductor element 120 and cured. The method of making it is used. According to the sealing resin material 10 (20), the effect of preventing the conductive member 150 from dust and air oxidation and improving the reliability of the device can also be obtained.

The CUF method is known as a typical method for filling the gap 115 between the wiring board 110 and the semiconductor element 120 with the sealing resin material 10 (20). In the general CUF method, as shown in FIG. 1, the sealing resin material 10 (20) is dropped onto the surface 110f of the wiring board 110 near the end 120e of the semiconductor element 120 by using the dispenser 200, and the capillary tube is formed. Utilizing the phenomenon, the sealing resin material 10 (20) is infiltrated into the gap 115 between the wiring board 110 and the semiconductor element 120 to fill the gap 115.

As a result, as shown in FIG. 2, the sealing resin material 10 (20) is filled in the gap 115 between the wiring board 110 and the semiconductor element 120, including the region around the conductive member 150. Then, after filling the sealing resin material 10 (20), a curing treatment such as heat treatment is performed to cure the sealing resin material 10 (20) to complete the sealing, thereby producing the semiconductor package 100. ..

(Conventional sealing resin material)
Here, the conventional sealing resin material will be described by way of illustration.
FIG. 3 is an enlarged view of the region X shown in FIG. 2 when an example of the conventional sealing resin material is filled in the gap between the wiring board and the semiconductor element, and the region near the end of the semiconductor element is enlarged. It is a figure that was made. FIG. 4 is an enlarged view of the region Y shown in FIG.

As shown in FIG. 3, the conventional sealing resin material 20 has a resin component 12 and a filler 14. The resin component 12 is composed of an epoxy resin 12a and a curing agent 12b. The filler 14 is composed of a first filler 14a and a second filler 14b. The first filler 14a is composed of a plurality of spherical silica particles having a particle size of 200 nm or more and less than 10 μm, and the second filler 14b is composed of a plurality of spherical silica particles having a particle size of 7 nm or more and less than 200 nm.

When the conventional sealing resin material 20 is filled in the gap 115 between the wiring board 110 and the semiconductor element 120 of the semiconductor package 100 shown in FIG. 1, the sealing resin is as shown in FIG. The material 20 wets and spreads out from the end 120e of the semiconductor element 120 to the outer peripheral side (hereinafter, may be abbreviated as “outer peripheral side”) of the semiconductor package 100 on the surface 110f of the wiring board 110. The protruding portion 22 of the sealing resin material 20 is formed so as to draw a ridge line from the end 120e of the semiconductor element 120 toward the outer peripheral side. As shown in FIGS. 3 and 4, the protruding portion 22 has a fillet 22f in which the resin component 12 and the filler 14 protrude from the end 120e of the semiconductor element 120 on the outer peripheral side in a mixed state, and only the resin component 12 from the outer periphery of the fillet 22f. Further, it is composed of a bleed 22b that exudes so as to spread in a thin film on the outer peripheral side.

Regarding the fillet 22f and the bleed 22b, when the strictness of the boundary is not obtained, it can be identified by macroscopic observation with the naked eye based on the difference in the degree of light reflection, but the strictness of the boundary is obtained. In the case, it is identified based on whether or not the filler is contained by microscopic observation using SEM (Scanning Electron Microscope) or XPS (X-ray Photoelectron Spectroscopy).

In FIGS. 3 and 4, the length of the fillet 22f (hereinafter, may be abbreviated as “fillet length”) is indicated by LF among the lengths of the protruding portion 22 and the length of the bleed 22b (hereinafter, referred to as “fillet length”). "Bleed length" may be abbreviated.) Is indicated by LB.

Here, in the fillet and bleed formed when the sealing resin material of the present invention and the conventional one is filled in the gap between the wiring substrate and the semiconductor element of the semiconductor package as shown in FIGS. 1 and 2, for example. , "Fillet length" is a constituent particle of a filler farthest from the end of the semiconductor element (for example, the second filler 14b shown in FIG. 4 or the third filler 14c shown in FIG. 6 below). The length to the outer peripheral side end of the bleed, and the "bleed length" means the length from the outer peripheral side end of the constituent particles of the filler to the outer peripheral side end of the bleed.

Of the protruding portions 22, the fillet 22f is necessary for reasons such as ensuring the bonding strength of the wiring board 110 and the semiconductor element 120, while the bleed 22b interferes with other components adjacent to the semiconductor element 120. Therefore, not only is it a technical barrier in realizing the narrowing of the pitch between the parts, but also the appearance of the semiconductor package 100 may be deteriorated.

Therefore, as described above, by taking measures such as adjusting the type and amount of the resin component 12 or the filler 14 for the sealing resin material 20, the bleed 22b made of the resin component 12 further extends from the outer periphery of the fillet 22f to the outer periphery. Attempts have been made to prevent it from seeping out to the side. As a resin material to which such measures are taken, for example, in Patent Document 3, a resin material using two types of silica fillers as fillers based on the idea of blocking the resin component exuding to the outer peripheral side as bleeding. Is described. Further, Patent Document 4 describes a resin material capable of suppressing bleeding that occurs when the resin material is cured.

However, with the resin material described in Patent Document 3, it is difficult to prevent the resin component from seeping out as bleeding in advance before the dampening effect of the filler is exhibited. Further, in the resin material described in Patent Document 4, although it is possible to suppress the resin component from seeping out as bleeding during curing, the resin component is present while the resin material is flowing due to the capillary phenomenon before curing. It was difficult to prevent bleeding out. Therefore, the suppression of bleeding out was insufficient.

(Encapsulating resin material of the present invention)
Therefore, the present inventors have studied the measures to be taken for the sealing resin material in view of the above circumstances. As a result, when the sealing resin material is filled in the gap between the wiring substrate and the semiconductor element, the mechanism by which the resin component exudes as bleeding is the movement of the resin molecules constituting the resin component and the constituent particles of the filler per unit time. We have found that it correlates with the amount, and based on such new findings, we have completed the encapsulation resin material of the present invention.

Here, in the present invention, the "movement amount per unit time" means the distance that one resin molecule constituting the resin component or one constituent particle of the filler travels in a unit time. Hereinafter, the contents of the new findings of the present inventors will be specifically described.

As described above, when the conventional sealing resin material 20 is filled in the gap 115 between the wiring substrate 110 and the semiconductor element 120, the resin molecules constituting the resin component 12 that exudes as the bleed 22b usually have a constant amount of movement. The filler in which the amount of movement of particles is maximum when the filler 14 is observed at the molecular level is the second filler 14b composed of particles having a small particle size. Comparing the amount of movement of the particles constituting the above and the resin molecules constituting the resin component 12, the resin molecules are significantly larger. This is because when the sealing resin material 20 wets and spreads on the surface 110f of the wiring substrate 110, the resin molecules constituting the resin component 12 diffuse significantly faster than the particles constituting the second filler 14b. It is shown that the resin component 12 as the bleed 22b is more likely to seep out from the outer periphery of the fillet 22f containing the second filler 14b to the outer periphery side.

From this, the following two approaches can be considered in order to prevent the resin component 12 from seeping out from the outer periphery of the fillet 22f as a bleed 22b to the outer peripheral side.

・ Approach 1
By newly using a filler as one of the fillers, which has a larger amount of movement and a higher followability to the resin molecules constituting the resin component than before, the filler is placed faster on the outer peripheral end of the fillet. When the resin component exudes from the outer peripheral side of the fillet to the outer peripheral side, the resin component is blocked by the filler at an earlier stage.

・ Approach 2
A filler that has the effect of reducing the amount of movement of resin molecules constituting the resin component is newly used as one type of filler to reduce the rate at which the resin component seeps out as bleed.

The present inventors have conducted diligent studies to use a novel filler composed of particles having a smaller particle size in addition to the filler generally used in the past. We have found that bleeding can be suppressed from both approaches.

Here, the sealing resin material of the present invention will be described by way of illustration.
FIG. 5 is an enlarged view of the region X shown in FIG. 2 when an example of the sealing resin material of the present invention is filled in the gap between the wiring board and the semiconductor element, and the region near the end of the semiconductor element is shown. It is an enlarged view. Further, FIG. 6 is an enlarged view of the region Y shown in FIG.

As shown in FIG. 5, the sealing resin material 10 of the present invention has a resin component 12 and a filler 14. The resin component 12 is composed of an epoxy resin 12a and a curing agent 12b. The filler 14 is composed of a first filler 14a, a second filler 14b, and a third filler 14c. The first filler 14a is composed of a plurality of spherical silica particles having a particle size of 200 nm or more and less than 10 μm, and the second filler 14b is composed of a plurality of spherical silica particles having a particle size of 7 nm or more and less than 200 nm. Is composed of a plurality of spherical silica particles having a particle size of 0.5 nm or more and less than 7 nm.

In the filler 14 of the sealing resin material 10 of the present invention, a third filler 14c is used in addition to the first filler 14a and the second filler 14b used in the filler 14 of the conventional sealing resin material 20 described above. Has been done. The third filler 14c has a smaller particle size than the second filler 14b, which has a smaller particle size among the first filler 14a and the second filler 14b. Therefore, the third filler 14c has a larger amount of movement and higher followability to the resin molecules constituting the resin component 12 as compared with the second filler 14b. Further, by using the third filler 14c as the filler 14, the effect of reducing the amount of movement of the resin molecules constituting the resin component 12 can be obtained.

Therefore, when the sealing resin material 10 of the present invention is filled in the gap 115 between the wiring board 110 and the semiconductor element 120, the sealing resin material 20 is the wiring board 110 as shown in FIGS. 5 and 6. When the surface 110f of the above is wet and spread, the filler 14 is placed more quickly at the end portion on the outer peripheral side of the fillet 22f as compared with the conventional sealing resin material 20 described above. Therefore, when the resin component 12 seeps out from the outer periphery of the fillet 22f to the outer peripheral side, the resin component 12 is blocked by the filler 14 at an earlier stage. Further, due to the action of reducing the amount of movement of the resin molecules, the speed at which the resin component 12 exudes as bleed 22b is reduced. As a result, the bleed length LB can be significantly shortened as compared with the case where the conventional sealing resin material 20 is used. Therefore, according to the present invention, bleeding out can be sufficiently suppressed.

In FIG. 6, the bleed length LB is the length from the outer peripheral end of the constituent particles of the third filler 14c to the outer peripheral end of the bleed, but the third filler 14c is regarded as equivalent to the resin component 12. Assuming a virtual bleed in the case of the above, the length of the virtual bleed is, as shown in FIG. 6, the constituent particles of the second filler 14b farthest from the end of the semiconductor element 120 to the outer peripheral side. The length from the outer peripheral end to the outer peripheral end of the resin component 12 is indicated by LB'. According to the present invention, the effect of shortening the virtual bleed length LB'can also be obtained.

Further, according to the present invention, there is a problem in filling the sealing resin material by utilizing the capillary phenomenon by using the third filler having a particle size smaller than that of the conventionally used filler as the sealing resin material. It is possible to shorten the filling time. That is, according to the present invention, it is possible to suppress bleeding out and shorten the filling time at the same time.

Hereinafter, each configuration of the sealing resin material of the present invention will be described in detail.

1. 1. Filler The sealing resin material of the present invention has a first filler, a second filler, and a third filler as fillers. Hereinafter, each filler will be described.

(1) Third Filler The third filler is composed of particles having a particle size of 0.5 nm or more and less than 7 nm.

The shape of the constituent particles of the third filler is, for example, spherical, but is not limited to a true spherical shape. As the spherical constituent particles, the ratio of the minor axis to the major axis (hereinafter, may be abbreviated as "sphericity") is 0.8 or more as described in, for example, Japanese Patent Application Laid-Open No. 2015-218229. However, those having a sphericity closer to 1.0 are preferable.

In the present invention, the particle size of the constituent particles of the third filler means the average value of the major axis and the minor axis of the constituent particles. Further, as a method for measuring the major axis and the minor axis of the constituent particles of the third filler, for example, a method of measuring by observing with a scanning electron microscope (SEM) or the like can be mentioned.

The particle size of the constituent particles of the third filler is preferably 1.5 nm or more and less than 6 nm, particularly preferably 2.5 nm or more and less than 5 nm. This is because bleeding can be effectively suppressed when the particle size of the constituent particles is equal to or more than these lower limits, and bleeding can be effectively suppressed when the particle size is equal to or less than these upper limits. Is.

The material of the constituent particles of the third filler is not particularly limited as long as it can exhibit the functions required for the filler, such as the function of ensuring the fluidity, thermal conductivity, and mechanical properties of the sealing resin material. , Inorganic material or organic material may be used, but mainly inorganic material is used. Examples of the inorganic material include silica, oxides typified by alumina, nitrides, metals and the like, and silica is particularly preferable. Further, the constituent particles of the third filler may be those in which these materials are coated with various coupling agents or the like.

(2) Second Filler The second filler is composed of particles having a particle size of 7 nm or more and less than 200 nm.

Since the shape and material of the constituent particles of the second filler are the same as those of the third filler, the description thereof is omitted here.

In the present invention, the particle size of the constituent particles of the second filler means the average value of the major axis and the minor axis of the constituent particles. Further, since the method for measuring the major axis and the minor axis of the constituent particles of the second filler is the same as the method for measuring the major axis and the minor axis of the constituent particles of the third filler, the description thereof is omitted here.

The particle size of the constituent particles of the second filler is preferably 7 nm or more and less than 100 nm, particularly preferably 10 nm or more and less than 50 nm. This is because bleeding can be effectively suppressed when the particle size of the constituent particles is equal to or more than these lower limits, and bleeding can be effectively suppressed when the particle size is equal to or less than these upper limits. Is.

(3) First Filler The first filler is composed of particles having a particle size of 200 nm or more and less than 10 μm.

Since the shape and material of the constituent particles of the first filler are the same as those of the third filler, the description thereof is omitted here.

In the present invention, the particle size of the constituent particles of the first filler means the average value of the major axis and the minor axis of the constituent particles. Further, since the method for measuring the major axis and the minor axis of the constituent particles of the first filler is the same as the method for measuring the major axis and the minor axis of the constituent particles of the third filler, the description thereof is omitted here.

The particle size of the constituent particles of the first filler is preferably 300 nm or more and less than 5 μm, particularly preferably 400 nm or more and less than 2 μm. When the particle size of the constituent particles is equal to or greater than these lower limits, functions such as shortening the filling time of the encapsulating resin material and improving the thermal conductivity can be realized, and the encapsulating resin material can be manufactured at a lower cost. This is because the sealing resin material can be smoothly filled even if there is a fine gap of several tens of μm or less between the wiring substrate and the semiconductor element when the value is not more than these upper limits.

(4) Mass ratio of filler to encapsulating resin material As the total mass ratio of the first filler, the second filler, and the third filler to the whole encapsulating resin material, the filler is the fluidity and heat of the encapsulating resin material. It is not particularly limited as long as it can exhibit a function of ensuring conductivity and mechanical properties, but for example, when the filler is silica, it is preferably 40% by mass to 85% by mass, particularly 45% by mass to 75% by mass. In particular, it is preferably 50% by mass to 70% by mass. This is because when the mass ratio of the filler is equal to or higher than these lower limits, the function of ensuring the thermal conductivity and mechanical properties of the encapsulating resin material can be effectively exhibited, and the mass ratio of the filler is equal to or lower than these upper limits. This is because the filler can effectively exert the function of ensuring the fluidity of the sealing resin material.

(5) Volume ratio of each filler As the volume ratio of the third filler to the second filler, bleeding can be sufficiently suppressed, and the fluidity, thermal conductivity, and mechanical properties of the encapsulating resin material can be sufficiently suppressed. Is not particularly limited as long as it can be secured, but it is preferably 0.0001 or more and 0.3 or less, and more preferably 0.03 or more and 0.2 or less, and particularly preferably 0.05 or more and 0.15 or less. When the volume ratio of the third filler to the second filler is equal to or higher than these lower limits, bleeding can be effectively suppressed and the fluidity of the sealing resin material can be effectively improved. This is because the filling time can be shortened. This is because when the volume ratio of the third filler to the second filler is not more than these upper limits, the fluidity of the sealing resin material can be effectively improved and the filling time can be shortened.

The volume ratio of the second filler to the first filler is not particularly limited as long as the fluidity, thermal conductivity and mechanical properties of the encapsulating resin material can be ensured, but it should be 0.0001 or more and 0.3 or less. Is preferable, and above all, it is preferably 0.001 or more and 0.2 or less, and particularly preferably 0.01 or more and 0.1 or less. This is because the volume ratio of the second filler to the first filler is not less than these lower limits, so that the fluidity of the sealing resin material can be effectively improved. This is because when the volume ratio of the second filler to the first filler is not more than these upper limits, the fluidity of the sealing resin material can be effectively improved and the manufacturing cost of the filler can be suppressed.

The above-mentioned Patent Document 4 describes that particles made of oxide are used in an amount of 3% by mass to 60% by mass in a resin composition capable of suppressing bleeding generated when the resin material is cured. Further, as a breakdown of particles composed of oxides, it is described that 50 to 80% by volume of particles having a diameter of 0.5 nm or more and less than 10 nm are used, and 50 to 20% by volume of particles having a diameter of 10 nm or more and less than 100 nm are used. Unlike Patent Document 4, the invention uses a first filler and a second filler that can be fillers of 100 nm or more. Fillers of 100 nm or more are used for the purpose of ensuring the fluidity of the encapsulating resin material, the purpose of ensuring the thermal conductivity of the encapsulating resin material, and the purpose of suppressing the manufacturing cost by using an inexpensive filler having a large average particle size. is necessary. Patent Document 4 exhibits a bleed-suppressing effect when the resin composition is cured, whereas the present invention is patented in that it exhibits a bleed-suppressing effect during the flow of the encapsulating resin material before curing. It is different from Document 4.

(6) Particle Size Distribution of Filler Next, the particle size distribution of the filler containing the first filler, the second filler, and the third filler in the resin material of the present invention will be described. In the following, among the particle size regions in the particle size distribution of the filler, the particle size region of 200 nm or more and less than 10 μm, the particle size region of 7 nm or more and less than 200 nm, and the particle size region of 0.5 nm or more and less than 7 nm are described respectively. Area A, area B, and area C are abbreviated.

In explaining the particle size distribution of the filler in the resin material of the present invention (hereinafter, may be abbreviated as "particle size distribution of the present invention"), first, the particle size distribution of the filler in the conventional encapsulating resin material (hereinafter, may be abbreviated). , "Conventional particle size distribution" may be abbreviated.). Here, FIG. 7 is a graph showing an example of the particle size distribution of the filler in the conventional encapsulating resin material, the horizontal axis shows the particle size [nm], and the vertical axis shows the particle content [volume%]. ] Is shown.

In the conventional particle size distribution shown in FIG. 7, the particle content is 0% by volume at all points in the region C, and each of the region A and the region B has one peak. The conventional particle size distribution is not limited to such a particle size distribution, and examples thereof include those having one peak in total in the above-mentioned regions A and B.

On the other hand, FIGS. 8 (a) to 8 (c) are graphs showing an example of the particle size distribution of the filler in the encapsulating resin material of the present invention, and the horizontal axis indicates the particle size [nm]. The vertical axis shows the particle content [volume%].

The particle size distribution of the present invention shown in FIG. 8A has one peak in each of region A, region B, and region C. The particle size distribution of the present invention shown in FIG. 8B has one peak in the region A and two peaks in the region B, but does not have a peak in the region C. .. The particle size distribution of the present invention shown in FIG. 8 (c) has one peak in each of the region A and the region B, but does not have a peak in the region C.

As shown in FIGS. 8A to 8C, the particle size distribution of the present invention is particularly limited as long as the content of any portion of the region C is larger than 0% by volume. As shown in FIG. 8 (a), the region A, the region B, and the region C may have a peak in the region C, and FIGS. 8 (b) and 8 (c) may have a peak. ) May not have a peak in the region C, but one having a peak in the region C is preferable. Among them, those having a peak in either one of the region A or the region B and the region C are preferable, and those having a peak in each of the region A, the region B, and the region C are particularly preferable. The reason for this is that bleeding can be effectively suppressed.

Further, as shown in FIGS. 8 (a) and 8 (b), the particle size distribution of the present invention is three in a region of 0.5 nm or more and less than 10 μm including the region A, the region B, and the region C. It may have the above peaks, or as shown in FIG. 8C, it may have two or less peaks in the region of 0.5 nm or more and less than 10 μm, but it may be 0.5 nm or more and less than 10 μm. Those having three or more peaks in the region of are preferable. Among them, those having two or more peaks in a region of 0.5 nm or more and less than 200 nm including region B and region C are preferable, and those having one or more peaks in each of region B and region C are particularly preferable. The reason for this is that bleeding can be effectively suppressed.

As the particle size distribution having a peak in the region A, a region having a particle size of 300 nm or more and less than 5 μm, particularly a region having a peak in a particle size of 400 nm or more and less than 2 μm is preferable. By exceeding these lower limits, functions such as shortening the filling time of the encapsulating resin material and improving the thermal conductivity can be realized, and the encapsulating resin material can be manufactured at a lower cost. This is because the sealing resin material can be smoothly filled even if there is a fine gap of several tens of μm or less between the wiring substrate and the semiconductor element. Further, as the particle size distribution having a peak in the region B, it is preferable that the particle size distribution has a peak in a region having a particle size of 7 nm or more and less than 100 nm, particularly a region having a particle size of 10 nm or more and less than 50 nm. The reason for this is that bleeding can be effectively suppressed. Further, as the particle size distribution having a peak in the region C, it is preferable that the particle size distribution has a peak in a region having a particle size of 1.5 nm or more and less than 6 nm, particularly a region having a particle size of 2.5 nm or more and less than 5 nm. The reason for this is that bleeding can be effectively suppressed.

Further, as the particle size distribution of the present invention, the content of the filler having a particle size smaller than the content of the filler having a particle size in the vicinity of 7 nm, which is the threshold value of the region B and the region C, on a volume basis is smaller than the content of the filler having a particle size in the vicinity of 7 nm. The one with a large amount is preferable. Specifically, it is preferable that the content of the filler having a particle size of 0.5 nm or more and less than 6.9 nm is larger than the content of the filler having a particle size of 6.9 nm or more and less than 7.1 nm on a volume basis. Above all, it is preferable that the content of the filler having a particle size of 0.5 nm or more and less than 6.9 nm is larger than twice the content of the filler having a particle size of 6.9 nm or more and less than 7.1 nm on a volume basis.

Examples of the method for measuring the particle size distribution of the filler include a measuring method using an SEM image.

(7) Method for Controlling Particle Size Distribution of Fillers The particle size distribution of the present invention can be controlled as the particle size distribution of a mixture by, for example, mixing two or more types of fillers having different average particle sizes. For example, when two types of fillers, a filler X having an average particle size of dx and a filler Y having an average particle size of dy (dx> dy), are mixed, the filler X and the filler Y each have a particle size distribution. , For example, the particle size distribution of the mixture has a peak at a value similar to the peak of the particle size distribution of filler X and the peak of the particle size distribution of filler Y, and the particle size is larger than dx and dy smaller than dx. It is possible to control the presence of both particles having a larger particle size and particles having a particle size smaller than dy.

Further, when two or more kinds of fillers having different average particle sizes are mixed, in order to control the particle size distribution of the mixture so as to have an intended distribution, for example, in each of the above fillers X and Y. On the other hand, it is possible to carry out a treatment for removing particles having a particle size other than the predetermined range before mixing. As such a treatment, for example, a top cut for removing particles having a particle size larger than a predetermined value is known. Therefore, for example, by selecting the average particle size and mixing ratio of the filler X and the filler Y, performing top-cut treatment, and the like, the peak particle size distribution of the filler X and the filler can be obtained from the mixture of the filler X and the filler Y. It is also possible to eliminate the peak of the particle size distribution of Y. That is, the particle size distribution of the present invention can be controlled by selecting the average particle size and mixing ratio of two or more types of fillers, performing top-cut processing, and the like.

For example, the particle size distribution of the present invention shown in FIG. 8 (a) is, for example, a filler having an average particle size of 200 nm or more and less than 10 μm, a filler having an average particle size of 7 nm or more and less than 200 nm, and a filler having an average particle size of 0.5 nm or more and 7 nm. It is obtained by mixing fillers having an average particle size of less than that, selecting the mixing ratio of these fillers, performing top-cut treatment, and controlling the mixture. The particle size distribution of the present invention shown in FIGS. 8 (b) and 8 (c) includes, for example, a filler having an average particle size of 200 nm or more and less than 10 μm and two types having different average particle sizes of 7 nm or more and less than 200 nm. It is obtained by mixing fillers, selecting the mixing ratio of these fillers, performing top-cut treatment, and controlling the mixture.

2. 2. Resin component The sealing resin material of the present invention has a thermosetting resin and a curing agent as the resin component.

(1) Thermosetting resin The thermosetting resin is not particularly limited as long as it can be used as a sealing resin material, and examples thereof include epoxy resin and phenol resin. Among them, epoxy resin and the like are used. preferable. This is because it has been widely used as a sealing resin material and has high reliability. Examples of the epoxy resin include bisphenol type, novolak type, glycidyl ether type, glycidylamine type, naphthalene type, biphenyl type, alicyclic epoxy resin and the like. These epoxy resins may be used alone or in combination of two or more.

(2) Curing agent The curing agent is not particularly limited as long as it can be used as a sealing resin material, and examples thereof include an amine-based curing agent, an acid anhydride-based curing agent, and a phenol-based curing agent. .. These curing agents may be used alone or in combination of two or more.

The mixing ratio of the curing agent is not particularly limited, but as with the thermosetting resin, the efficiency of dropping and filling the sealing resin material, ensuring the mechanical properties of the sealing resin material after curing, etc. From the viewpoint of the above, the equivalent ratio of the curing agent to the thermosetting resin is preferably 0.6 to 1.6, and more preferably 0.7 to 1.4, particularly 0.85 to 1.1. ..

(3) Others The sealing resin material of the present invention may contain an additive in addition to the thermosetting resin and the curing agent as the resin component.

The additive is not particularly limited as long as it can be used as a sealing resin material, but for example, a flexible agent, a coupling agent, a curing accelerator, a solvent, a surfactant, an ion trap agent, and a colorant. And so on. All of these may be used, selectively used, or additives other than these may be used.

3. 3. In addition, as shown in FIGS. 1 and 2, for example, the sealing resin material of the present invention uses the above-mentioned CUF method to utilize the capillary phenomenon in the gap between the wiring board of the semiconductor package and the semiconductor element. It is used for filling by infiltrating.

In the semiconductor package, for example, as shown in FIGS. 1 and 2, a substrate electrode provided on the wiring board and an element electrode provided on the semiconductor element are electrically connected by a bonding material. It is a thing. Examples of the wiring board include those having a multilayer structure having a metal-containing layer containing a metal such as copper, alumina, tungsten, and molybdenum. Further, the surface of the wiring substrate that opposes the semiconductor element at the time of joining is composed of, for example, a glass-based material layer, for example, a protective layer such as a silicon nitride film, a resin layer composed of a polyimide-based resin, or the like. .. Further, in some places, the wiring board electrodes are exposed from these layers. The bonding material is a bonding material generally used in the CUF method, and examples of the bonding material include conductive metal materials such as solder, copper, and gold.

The present invention is not limited to the above embodiment. The above embodiment is an example, and any one having substantially the same configuration as the technical idea described in the claims of the present invention and having the same effect and effect is the present invention. It is included in the technical scope of the invention.

Hereinafter, the present invention will be described in more detail with reference to Comparative Examples and Examples, but the present invention is not limited thereto.

1. 1. Evaluation of Bleed Exudation Droplets placed on a solid surface in the initial state by simulation using coarse-grained molecular dynamics using the computational models of the encapsulating resin materials of the following examples and comparative examples. The process in which the shape of the sealing resin material wets and spreads to the outer peripheral side was analyzed. As a result, the bleeding exudation when the sealing resin material modeled in these calculation models was filled in the gap between the wiring board and the semiconductor element was simulated.

Coarse-grained molecular dynamics is a molecular simulation method that is commonly used to analyze molecular dynamics, and calculation examples for liquid materials are widely known. In addition, many calculation examples of resin materials such as polymers are known, and they are frequently used for simulation of materials containing fillers (for example, K. Hagita, H. Morita, M. Doi, and). H. Takano, “Coarse-Grained Molecular Dynamics Simulation of Filled Polymer Nanocomposites under Uniaxial Elongation”, Macromolecules, pp.1972, vol.49, (2016)).

[Example 1]
A calculation model of the sealing resin material was created by modeling a sealing resin material having a resin component composed of an epoxy resin and a filler composed of a second filler and a third filler. The first filler was excluded from the calculation model because it was considered that it did not exist in the bleed as shown in FIGS. 3 and 5 above.

In modeling the calculation model of the encapsulating resin material, specifically, the epoxy resin of the resin component was regarded as one kind of bisphenol type resin molecule (long side about 1.6 nm, short side about 0.5 nm). It was modeled as being composed of linear resin molecules, and the resin molecules were modeled with four coarse-grained particles. Further, the second filler and the third filler were modeled as being composed of spherical particles having a particle size of 14 nm and spherical particles having a particle size of 3 nm, respectively. The spherical particles constituting each filler are described in known literature (K. Hagita, H. Morita, M. Doi, and H. Takano, “Coarse-Grained Molecular Dynamics Simulation of Filled Polymer Nanocomposites under Uniaxial Elongation”, Macromolecules, pp. Modeled as a hollow spherical shell shape with reference to .1972, vol.49, (2016)). The spherical particles constituting the second filler and the spherical particles constituting the third filler were modeled with 1281 coarse-grained particles and 61 coarse-grained particles, respectively. Furthermore, the ratio of the specific gravities of the spherical particles constituting each filler to the specific densities of the resin molecules is 1.8, assuming the specific densities of the epoxy resin and silica (about 1.2, 2.2 [g / cm ³ ], respectively). Was set to.

Further, in modeling the calculation model of the encapsulating resin material, the mass ratio of the epoxy resin and the filler (the total of the second filler and the third filler) was set to epoxy resin: filler = 40:60. Further, the volume ratio of the second filler and the third filler was set to 2nd filler: 3rd filler = 54: 6. In the evaluation of bleed exudation, the number of resin molecules of the epoxy resin and the number of spherical particles of each filler were set to a number capable of simulating the actual exudation of bleed.

[Example 2]
A calculation model of the encapsulating resin material was created in the same manner as in Example 1 except that the volume ratios of the second filler and the third filler were modeled as the second filler: the third filler = 48: 12.

[Comparison example]
A calculation model of the encapsulating resin material was created in the same manner as in Example 1 except that the volume ratios of the second filler and the third filler were modeled as the second filler: the third filler = 60: 0.

[Simulation using coarse-grained molecular dynamics]
The conditions for the simulation using the coarse-grained molecular dynamics method are as follows.

-Using the FENE (Fiintile Exclusive Nonliner Elastic) type potential between the bonded particles and the LJ (Lennard-Jones) type potential between the non-bonded particles, the Langevin equation is used for the time evolution of the droplet-shaped encapsulating resin material. The accompanying dynamics (dynamic processes) were analyzed.
-The length σ, mass m, and energy ε are dimensionless quantities, and the integration time is 0.004τ using time τ = σ (m / ε) ^1/2 .
-The calculation was carried out in 40 million steps, and during the execution, the solid surface was fixed and the filler was a rigid body.

9 and 10 are schematic cross-sectional views showing the initial state and the final state in the simulation of the calculation models of the first and second embodiments, respectively.

As shown in FIGS. 9 and 10, the droplet-shaped sealing resin material 30 wetted and spread on the outer peripheral side of the surface 300f of the solid 300 during the period from the initial state to the final state by the above simulation. In the wet and spread portion 32 of the sealing resin material 30 in the final state, the third filler 14c spreads on the outer peripheral side of the second filler 14b, and the resin component 12 spreads on the outer peripheral side of the third filler 14c.

Further, although not shown, in the simulation performed using the calculation model of the comparative example, the droplet-shaped encapsulating resin material is similarly formed on the outer periphery of the solid surface during the period from the initial state to the final state. In the wet and spread portion of the sealing resin material in the final state, the resin component spreads to the outer peripheral side of the second filler.

In both the examples and the comparative examples, in the wet-spreading portion in the final state, at least one of the second filler and the third filler in the wet-spreading portion in the final state is wet-spreading on the outer peripheral side in a mixed state with the resin component. The portion corresponding to the bleed is a portion in which only the resin component is wet and spread on the outer peripheral side of the portion corresponding to the fillet. The wet spread length of the portion corresponding to the bleed is shown in FIG. 10 by the length LB _S from the outer peripheral end of the constituent particles of the third filler 14c to the outer peripheral end of the resin component.

Further, in the case of assuming a virtual fillet and a virtual bleed when the second filler 14b is regarded as equivalent to the resin component 12, the virtual fillet is formed in the wet spread portion 32 in the final state of the examples and the comparative examples. The corresponding portion is a portion where the second filler 14b is mixed with the resin component 12 and spreads to the outer peripheral side, and the portion corresponding to the virtual bleed is a portion corresponding to the virtual fillet and the third filler is further on the outer peripheral side. And the part where the resin component gets wet and spreads. The wet spread length of the portion corresponding to the virtual bleed is indicated by the length LB _S ′ from the outer peripheral end of the constituent particles of the second filler 14b to the outer peripheral end of the resin component.

FIG. 11 shows the wet spread length LB _{S of the portion corresponding to the bleed and the wet spread length LB S ′} of the portion corresponding to the virtual bleed in the simulations of the calculation models of Examples 1, 2, and Comparative Examples. It is a graph which shows.

As shown in FIG. 11, as the volume ratio of the third filler increased, both LB _S and LB _S ′ shortened. From this, it can be confirmed that the third filler can suppress the bleeding out.

FIG. 12 is a graph showing the time change of the amount of movement of the resin molecule, the constituent particles of the second filler, and the constituent particles of the third filler per unit time in the simulation of the calculation model of the first embodiment by the mean square displacement.

As shown in FIG. 12, when the mean square displacements of each are compared, the mean square displacement of the resin molecule is about two orders of magnitude larger than that of the constituent particles of the second filler. This indicates that when the sealing resin material wets and spreads on the surface of the wiring substrate, the resin molecules diffuse significantly faster than the constituent particles of the second filler, so that the resin molecules easily seep out as bleeds. On the other hand, the mean square displacement of the constituent particles of the third filler is about an order of magnitude larger than that of the constituent particles of the second filler and about an order of magnitude smaller than that of the resin molecule. This indicates that the above-mentioned approach 1 can be realized by the third filler because the third filler has higher followability to the resin molecule than the second filler.

FIG. 13 is a graph showing the time change of the movement amount of the resin molecule per unit time in the simulation of the calculation model of Example 1, Example 2, and Comparative Example by the mean square displacement.

As shown in FIG. 13, in each calculation model, the larger the volume ratio of the third filler, the smaller the mean square displacement of the resin molecules. This indicates that the above approach 2 can be realized by the third filler.

2. 2. Evaluation of Filling Time of Encapsulating Resin Material In addition to evaluation of bleed exudation, simulation using coarse-grained molecular dynamics method using the calculation model of encapsulating resin material of the above Examples and Comparative Examples. We analyzed a system that simply modeled the process in which the sealing resin material was filled in the gaps between the semiconductor element and the wiring substrate by capillarity. As a result, the filling time when the sealing resin material modeled in these calculation models was filled in the gap between the wiring substrate and the semiconductor element was simulated.

As the calculation model of the encapsulating resin material in the simulation of this evaluation, the calculation models of the encapsulating resin material of Examples 1, 2 and Comparative Examples described above were used. At this time, the number of resin molecules of the epoxy resin and the number of spherical particles of each filler were set to a number capable of simulating the actual filling time. The following conditions were used as the conditions for the simulation of this evaluation.

・ Literature that analyzes capillarity by molecular dynamics calculations (for example, C. Cupelli, B. Henrich, T. Glatzel, R. Zengerle, M. Moseler, and M. Santer, “Dynamic capillary wetting studied with dissipative” Particle dynamics ”, New Journal of Physics, 043009, vol.10, (2008), etc.) A simple model was made with a system in which the sealing resin material flows into the gap. At this time, both parallel flat plates were used as fixed parallel flat plates.
-Similar to the evaluation of bleed seepage, using the FENE-type potential between bound particles and the LJ-type potential between unbound particles, it flows into the gap between the parallel plates of the modeled system by the Langevin equation. The dynamics of the encapsulating resin material over time were analyzed. During the calculation, the solid surface was fixed and the filler was rigid.
-The length σ, mass m, and energy ε are dimensionless quantities, and the integration time is 0.004τ using time τ = σ (m / ε) ^1/2 .
-The process of flowing into the gap between the parallel plates of the system modeled by the calculation model of the encapsulating resin material of Example 1, Example 2, and Comparative Example was analyzed, and the gap between the parallel plates was filled with a certain volume. The number of simulation steps until completion was calculated. This simulated the filling time of the encapsulating resin material.

FIG. 14 is a graph showing the number of simulation steps until filling is completed in the simulation of the calculation models of Example 1, Example 2, and Comparative Example.

As shown in FIG. 14, in Example 1, filling was completed with the smallest number of steps. Further, in Example 2 and Comparative Example, the number of steps for which filling was completed was close to the value. This indicates that when the volume ratio of the third filler to the second filler is in the range from Comparative Example to Example 2 or in the vicinity thereof, the effect of shortening the filling time can be obtained.

3. 3. Comprehensive evaluation From the above, it can be seen that the volume ratio of the third filler to the second filler has a preferable range from the viewpoint of suppressing bleeding out and shortening the filling time at the same time. Specifically, the volume ratio of the third filler to the second filler is preferably 0.0001 or more and 0.3 or less, and more preferably 0.03 or more and 0.2 or less, particularly 0.05 or more and 0.15 or less.

The present invention is not limited to the above-described embodiment, and includes various modifications. For example, the above-described embodiment has been described in detail in order to explain the present invention in an easy-to-understand manner, and is not necessarily limited to the one including all the described configurations. Further, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Further, it is possible to add / delete / replace a part of the configuration of each embodiment with another configuration.

100 Semiconductor package 110 Wiring board 110f Surface of wiring board 112 Board electrode 120 Semiconductor element 120f Surface of semiconductor element 120e End of semiconductor element 122 Element electrode 115 Gap between wiring board and semiconductor element 130 Bonding material 150 Conductive member 200 Dispenser 10 Encapsulating resin material (encapsulating resin material of the present invention)
20 Encapsulation resin material (conventional encapsulation resin material)
30 Encapsulation resin material (calculation model)
12 Resin component 12a Epoxy resin 12b Hardener 14 Filler 14a 1st filler 14b 2nd filler 14c 3rd filler 22 Overhanging part of sealing resin material 22b Bleed 22f Fillet 32 Wet spreading part of sealing resin material LF Fillet length LB Bleed length LB'Virtual bleed length LB _S Wet spread length of the part corresponding to the bleed LB _S'Wet spread length of the part corresponding to the virtual bleed 300 Solid 300f Solid surface

Claims (4)

A first filler composed of particles having a particle size of 200 nm or more and less than 10 μm,
A second filler composed of particles having a particle size of 7 nm or more and less than 200 nm,
A third filler composed of particles having a particle size of 0.5 nm or more and less than 5 nm,
Thermosetting resin and
Hardener and
Have,
The volume ratio of the second filler to the first filler is 0.0001 or more and 0.3 or less.
The volume ratio of the third filler to the second filler is 0.03 or more and 0.2 or less.
The particle size distribution of the first filler, the second filler, and the filler containing the third filler is as follows: region A of 200 nm or more and less than 10 μm, region B of 7 nm or more and less than 200 nm, and region C of 0.5 nm or more and less than 5 nm. A sealing resin material having a peak in each of the region A, the region B, and the region C. The first aspect of claim 1, wherein the particle size distribution of the first filler, the second filler, and the filler containing the third filler has three or more peaks in a region of 0.5 nm or more and less than 10 μm. Encapsulation resin material. The particle size distribution of the filler is characterized by having three or more peaks in a region of 0.5 nm or more and less than 10 μm and two or more peaks in a region of 0.5 nm or more and less than 200 nm. 2. The sealing resin material according to 2. The sealing resin material according to any one of claims 1 to 3, wherein the volume ratio of the third filler to the second filler is 0.05 or more and 0.15 or less.

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