JP2002201358A - Sealing material for electronic part, method for sealing electronic part, semiconductor package, and method for making semiconductor package - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealing material which can efficiently reduce the transmission loss of an electronic part such as a high frequency circuit, and to provide a method for making a semiconductor package using the same. SOLUTION: This sealing material for electronic parts comprises a base resin and a filler which has a specific gravity of <=0.7 time or >=1.7 times the specific gravity of the base resin and has a dielectric loss tangent of <=0.005. The filler includes silica, Teflon powder, and hollow glass beads. The method for making the semiconductor package with the sealing material comprises as follows. A high frequency integrated circuit is loaded on a substrate. On the other hand, the above-described sealing material is prepared. The sealing material is injected on the substrate to seal the high frequency integrated circuit. The injected sealing material is left for a prescribed time to unevenly distribute the filler having the dielectric loss tangent in a place near to the surface of the high frequency integrated circuit. Finally, the sealing material is cured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealing material for sealing an electronic component and a method for sealing an electronic component, and more particularly to a sealing material for sealing a semiconductor chip on a substrate.
The present invention relates to a semiconductor package using the sealing material and a method for manufacturing the semiconductor package.

[0002]

2. Description of the Related Art Electronic components such as semiconductor chips mounted on a substrate are made of resin or the like for the purpose of protection from the external environment and dissipation of heat energy during operation of the electronic components. Sealed and packaged. As the sealing resin, an epoxy resin or a polyimide resin excellent in workability is usually used.

However, when a high-frequency integrated circuit is mounted on a substrate, there is a problem that a conventional epoxy resin or polyimide resin sealing material has a large dielectric loss and a large signal transmission loss. The dielectric loss means that when an AC electric field is applied to a dielectric, the polarization P cannot follow the change in the electric field, and the electric flux density D (D = ε ₀ E + P) causes a phase delay with respect to the electric field E, and as a result, , Says that part of the electrical energy is lost as heat. Loss tangent is used to describe the amount of dielectric loss. That is, assuming that the phase delay at the time of applying a high frequency is δ, the tangent (tangent value) of the phase angle δ is called a dielectric tangent and is used as an amount representing a dielectric loss characteristic. As the dielectric loss tangent increases (that is, as the phase delay increases), the dielectric loss increases, and it becomes impossible to cope with an increase in the signal processing speed, and the transmission loss increases. When the frequency is higher than 100 MHz, the dielectric loss is large, which also causes heat generation.

The dielectric loss tangent of a normal resin sealant is 0.02
Generally 0.03 to 0.03. Therefore, it is conceivable to mix a filler having a low dielectric constant into the resin. In this case, the filler was uniformly mixed in the resin and sealed the high-frequency integrated circuit. However, there is a limit to the mixing of the filler into the resin, and it has not been said that the signal transmission loss is sufficiently prevented in the high-frequency integrated circuit. For example, in the case of silica powder, even if the powder is uniformly dispersed in a resin, the limit is 70 vol%.

[0005]

Accordingly, the present invention utilizes a difference in specific gravity between a base resin and a filler to reduce the dielectric loss tangent near the surface of an electronic component such as a semiconductor chip to be sealed. The filler is unevenly distributed. Thus, transmission loss of the high-frequency transmission line formed on the surface of the electronic component is effectively prevented, and as an additional effect, heat generation in the package is prevented.

Specifically, as a first object of the present invention,
Provided is a sealing material capable of reducing dielectric loss and preventing transmission loss of a high-frequency transmission line. This sealing material
It contains a base resin and a filler having a specific gravity of 0.7 times or less or 1.7 times or more of the specific gravity of the base resin, and having a dielectric loss tangent of 0.005 or less. By making the specific gravity 0.7 times or less or 1.7 times or more, the filler having a low dielectric loss tangent can be efficiently collected near the surface of the electronic component after the injection of the sealing material.

The base resin is, for example, a resin synthesized from phenol resin, urea resin, melamine resin, alkyd resin, acrylic resin, unsaturated polyester resin, diallyl phthalate resin, epoxy resin, silicone resin, cyclopentadiene, tris (2- Hydroxyethyl)
Resin containing isocyanurate, resin synthesized from aromatic nitrile, trimerized aromatic dicyanamide resin, resin containing triallyl trimethacrylate, furan resin, ketone resin, xyle resin, thermosetting containing condensed polycyclic aromatic Resin. Preferably, an epoxy resin is used, and such an epoxy resin may be any one having an epoxy group in a molecule, such as a bisphenol A epoxy resin, a bisphenol F epoxy resin,
Bisphenol S type epoxy resin, alicyclic epoxy resin, aliphatic chain epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin,
Bisphenol A novolak epoxy resin, diglycidyl etherified biphenol, diglycidyl etherified naphthalene diol, diglycidyl etherified phenols, diglycidyl etherified alcohols, and alkyl-substituted and halogenated compounds thereof ,
And hydrogenated products. These may be used in combination, and components other than the epoxy resin may be contained as impurities.

In the present invention, a halogenated bisphenol compound such as tetrabromobisphenol A such as halogenated bisphenol A type epoxy resin, halogenated bisphenol F type epoxy resin or halogenated bisphenol S type epoxy resin is reacted with epichlorohydrin. When an epoxy resin in which the ortho position is substituted with a halogen atom such as chlorine or bromine with respect to the ether group of the benzene ring to which the ether group is bonded as in the case of the epoxy resin to be used, the treatment solution of the present invention The efficiency of decomposition and / or dissolution of the cured epoxy resin is particularly good.

The curing agent for an epoxy resin used in the present invention can be used without any limitation as long as it can cure an epoxy resin. Examples thereof include polyfunctional phenols, amines, imidazole compounds, acid anhydrides, organic anhydrides, and the like. Phosphorus compounds and their halides.

Examples of the polyfunctional phenols include monocyclic bifunctional phenols such as hydroquinone, resorcinol, catechol, and polycyclic bifunctional phenols such as bisphenol A, bisphenol F, naphthalene diols, biphenols, and halides thereof. There are alkyl group substituents and the like. Further, there are novolaks and resols which are polycondensates of these phenols and aldehydes.

Examples of amines include aliphatic or aromatic primary amines, secondary amines, tertiary amines, quaternary ammonium salts and aliphatic cyclic amines, guanidines, urea derivatives and the like. is there.

Examples of these compounds include N, N-
Benzyldimethylamine, 2- (dimethylaminomethyl) phenol, 2,4,6-tris (dimethylaminomethyl) phenol, tetramethylguanidine, triethanolamine, N, N'-dimethylpiperazine, 1,
4-diazabicyclo [2,2,2] octane, 1,8-
Diazabicyclo [5,4,0] -7-undecene, 1,
5-diazabicyclo [4,4,0] -5-nonene, hexamethylenetetramine, pyridine, picoline, piperidine, pyrrolidine, dimethylcyclohexylamine, dimethylhexylamine, cyclohexylamine, diisobutylamine, di-n-butylamine, diphenylamine, N -Methylaniline, tri-n-propylamine,
Tri-n-octylamine, tri-n-butylamine,
Examples include triphenylamine, tetramethylammonium chloride, tetramethylammonium bromide, tetramethylammonium iodide, triethylenetetramine, diaminodiphenylmethane, diaminodiphenylether, dicyandiamide, tolylbiguanide, guanylurea, and dimethylurea.

Examples of the imidazole compound include imidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-methylimidazole, 2-phenylimidazole, 2-undecylimidazole,
Benzyl-2-methylimidazole, 2-heptadecylimidazole, 4,5-diphenylimidazole, 2-
Methylimidazoline, 2-phenylimidazoline, 2-
Undecylimidazoline, 2-heptadecylimidazoline, 2-isopropylimidazole, 2,4-dimethylimidazole, 2-phenyl-4-methylimidazole, 2-ethylimidazoline, 2-phenyl-4-methylimidazoline, benzimidazole, 1- And cyanoethylimidazole.

Examples of the acid anhydride include phthalic anhydride, hexahydrophthalic anhydride, pyromellitic dianhydride, benzophenonetetracarboxylic dianhydride and the like.

As the organic phosphorus compound, any phosphorus compound having an organic group can be used without particular limitation. Examples thereof include hexamethylphosphoric triamide, tri (dichloropropyl) phosphate, tri (chloropropyl) phosphate, Examples include triphenyl phosphite, trimethyl phosphate, phenylphosphonic acid, triphenylphosphine, tri-n-butylphosphine, and diphenylphosphine.

These curing agents can be used alone or in combination.

The amounts of these epoxy resin curing agents are as follows:
It can be used without any particular limitation as long as the curing reaction of the epoxy group can proceed, but is preferably in the range of 0.01 to 5.0 equivalents per 1 mol of the epoxy group.
It is particularly preferably used in the range of 0.8 to 1.2 equivalents.

The thermosetting epoxy resin composition of the present invention may optionally contain a curing accelerator. Representative curing accelerators include, but are not limited to, tertiary amines, imidazoles, quaternary ammonium salts, and the like.

On the other hand, the filler is one or a combination of silica, Teflon powder and hollow glass spheres. When a plurality of types are combined, the distribution of the filler in the base resin is easily controlled, and the dielectric loss on the chip surface can be reduced more effectively. For example, when an epoxy resin is used as a base resin and silica is used as a filler, the specific gravities are about 1.1 for the base resin and 2.2 for the filler, respectively, and the specific gravity is about twice.

The encapsulating material is also filled with a base resin having a specific gravity of 0.7 times or less or 1.7 times or more of the specific gravity of the base resin and a dielectric loss tangent of 0.005 or less. Agent and a solvent. By mixing with a volatile solvent, a resin varnish can be used as a sealing material, handling is easy, and the appearance after sealing is excellent. The ratio of the solvent to the mixture of the base resin and the filler is from 40 to 900 per 100 parts by weight of the mixture of the base resin and the filler.
Preferably it is in the range of parts by weight. When the proportion of the solvent is less than 40 parts by weight, there is a problem that the viscosity is so high that the filler is not unevenly distributed in the resin, and when it exceeds 900 parts by weight, there is a problem that the viscosity is low and the moldability may be reduced. Because there is.

As a second object of the present invention, there is provided a method of sealing an electronic component using the above-described sealing material. In this sealing method, first, an electronic component is mounted on a substrate. On the other hand,
Preparation of a sealing material including a base resin and a filler having a specific gravity of 0.7 times or less or 1.7 times or more of the specific gravity of the base resin and having a dielectric loss tangent value of 0.005 or less I do. Next, this sealing material is injected onto the substrate to encapsulate the electronic component. Leave the injected sealing material for a predetermined time,
Utilizing the difference in specific gravity between the filler and the base resin, the filler is localized near the surface of the electronic component. Finally, the sealing material is cured.

When a solvent is mixed with the sealing material, after the sealing material is injected and left for a predetermined time, the solvent is evaporated and then cured while being evaporated.

When a filler having a specific gravity lower than the specific gravity of the base resin, for example, a hollow glass sphere is used, the surface of the electronic component mounted on the substrate is directed downward (in a face-down state), and the sealing material is used. Leave for a predetermined time. The filler floats upward with time and concentrates on the surface of the electronic component. Also, when using a filler having a specific gravity larger than the specific gravity of the base resin, for example, silica or Teflon powder,
The sealing material is left for a predetermined time with the surface of the electronic component mounted on the substrate facing upward. In this case, as the time elapses, the filler having a small dielectric loss tangent sinks down, and also concentrates near the surface of the electronic component. Therefore, problems such as phase delay, loss of electric energy, and heat generation in the high-frequency transmission line formed on the surface of the electronic component are solved.

A third object of the present invention is to provide a semiconductor package in which a high-frequency integrated circuit is mounted and packaged. The semiconductor package includes a substrate, a semiconductor chip mounted on the substrate, and a sealing material for sealing the semiconductor chip on the substrate. The sealing material includes a base resin and a dielectric mixed with the base resin. And a filler having a tangent value of 0.005 or less. As a feature of this semiconductor package, a filler having a small dielectric loss tangent is concentrated and localized near the surface of the semiconductor chip. The filler has a specific gravity of 0.7 times or less or 1.7 times or more of the specific gravity of the base resin, and includes, for example, at least one selected from silica, Teflon powder, and hollow glass spheres. As a result, a semiconductor package having low transmission loss and excellent high-frequency response characteristics is provided.

A fourth object of the present invention is to provide a method for manufacturing a semiconductor package on which a high-frequency circuit is mounted. In a method for manufacturing a semiconductor package, first, a semiconductor chip is mounted on a substrate. On the other hand, the base resin has a specific gravity of 0.7 times or less or 1.7 times or more of the specific gravity of the base resin,
In addition, a sealing material containing a filler having a dielectric loss tangent of 0.005 or less is prepared. Next, the prepared sealing material is injected onto the substrate to encapsulate the semiconductor chip. The sealing material is left for a predetermined time, and the filler having a low dielectric loss tangent is concentrated near the surface of the semiconductor chip by utilizing the difference in specific gravity between the base resin and the filler. Finally, the sealing material is cured.

The method of manufacturing such a semiconductor package utilizes the difference in specific gravity between the filler and the base resin. Therefore, even if the concentration of the filler is not excessively increased, the vicinity of the surface of the high-frequency circuit can be easily determined. In this case, the filler having a low dielectric loss tangent can be concentratedly distributed.

When a solvent is mixed with the above-mentioned sealing material and used, the sealing material is injected and left for a predetermined time, and then the solvent is evaporated. By mixing the solvent and using it as a resin varnish, the viscosity can be easily adjusted, the rate of uneven distribution of the filler and the degree of uneven distribution can be easily controlled, and the storage, injection, and handling of the sealing material can be facilitated. It becomes simpler.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, the sealing material of the present invention has a specific gravity between the base resin and the base resin of 0.7.
Times or 1.7 times or more, and the dielectric loss tangent is 0.7 times or less.
005 or less. Table 1 shows the type of filler, the dielectric loss tangent value, and the difference in specific gravity between the filler and the epoxy resin when an epoxy resin is used as the base resin in the sealing material of the present invention. In addition, the transmission loss reduction ratio is shown in comparison with the case where only an epoxy resin is used as a sealing material.

The transmission loss was measured for a high-frequency integrated circuit having a transmission line width of 800 μm and a line length of 200 mm.
It was measured by applying an AC voltage of 0.1 V.

[0030]

[Table 1] Among the fillers in Table 1, the specific gravity of the hollow glass sphere is lighter than that of the epoxy resin, and the specific gravity of silica and Teflon powder is heavier than the epoxy resin. The dielectric loss tangent of each filler is 0.005 or less. When two or more fillers are mixed, the average dielectric loss tangent value and the average specific gravity difference are shown. Each filler has a particle size of 1 μm to 20 μm.
m.

When the filler shown in Table 1 is mixed with the base resin to form a sealing material, the filler sinks or floats over time due to a difference in specific gravity between the base resin and the filler.
Utilizing such characteristics, when a high-frequency integrated circuit is sealed on a semiconductor substrate, a low dielectric loss tangent value (that is,
Fillers (of low dielectric loss) can be deliberately localized near the surface of the integrated circuit. As a result, as shown in Table 1, the transmission loss was 60% to 70% as compared with the conventional resin.
Can also be reduced.

A sealing material may be prepared by mixing a volatile solvent in addition to the base resin and the filler. In this case, a resin varnish is formed to facilitate storage and handling. The resin varnish is usually stored in a container, and is uniformly stirred just before use. After application of the resin varnish, drying is performed by volatilization (evaporation) of the solvent.

FIG. 1 is a sectional view of a semiconductor package 10 using the above-described sealing material. Semiconductor package 10
Are a substrate 11, a semiconductor chip (high-frequency integrated circuit) 13 mounted on the substrate, and a semiconductor chip 13 on the substrate 11.
And a sealing material 15 for sealing. The sealing material includes a base resin and a filler 16 mixed with the base resin. The filler 16 is, for example, silica, and its dielectric loss tangent is 0.0001. In the semiconductor package 10,
The filler 16 is concentrated and localized near the surface of the semiconductor chip 13. In the example of FIG. 1, the specific gravity of the filler 16 is 1.1, which is different from the specific gravity of the epoxy resin as the base resin by about twice.

In order to manufacture the semiconductor package 10, first, the semiconductor chip 13 is mounted on the substrate 11. On the other hand, encapsulation including a base resin and a filler having a specific gravity of 0.7 times or less or 1.7 times or more of the specific gravity of the base resin and a dielectric tangent value of 0.005 or less. Prepare the ingredients.

Next, the semiconductor substrate 11 on which the semiconductor chip 13 is mounted is placed in a mold (not shown), and the prepared sealing material is injected onto the substrate inside the mold to encapsulate the semiconductor chip. The specific gravity of the filler contained in the sealing material determines whether the semiconductor substrate is placed upward or downward inside the mold. For example, when the filler is a filler having a specific gravity higher than that of the base resin such as Teflon powder, the filler is disposed inside the mold so that the surface of the semiconductor chip 13 faces upward, and the filler is formed of silica or hollow glass spheres. ,
If the specific gravity is low, the semiconductor chip 13 is placed in a mold such that the surface of the semiconductor chip 13 faces downward.

Next, the injected sealing material is allowed to stand for a predetermined time, and the filler is unevenly distributed near the surface of the semiconductor chip 13. In the case of a sealing material containing a filler having a high specific gravity, the filler having a low dielectric tangent value sinks and gathers near the surface of the semiconductor chip 13 arranged upward. When a sealing material containing a filler having a low specific gravity is used, the filler floats and gathers near the surface of the semiconductor chip 13 arranged downward.

Finally, the sealing material is cured and taken out of the mold to complete the semiconductor package 10.

According to such a method of manufacturing a semiconductor package, a component having a low dielectric loss tangent can be effectively concentrated near the surface of a high-frequency circuit by a simple method, and transmission loss can be reduced.

In some cases, a portion where a semiconductor chip is mounted on a substrate is sealed by potting without using a mold as described above. When a solvent is added to the mixture and the mixture is used in the form of a resin varnish, the solvent is allowed to evaporate after standing for a predetermined time or at the time of standing. According to this method, a glossy resin seal having a smooth surface can be formed.

[0040]

As described above, the sealing material of the present invention is easy to adjust, and is optimally used for sealing a high-frequency integrated circuit, so that transmission loss can be effectively reduced.

Since the method for sealing an electronic component of the present invention utilizes the difference in specific gravity between the base resin and the filler, the electronic component is easily and efficiently sealed, and the dielectric loss of the electronic component is reduced. be able to.

In the semiconductor package of the present invention, since the filler having a low dielectric loss tangent is concentrated and unevenly distributed near the surface of the high frequency integrated circuit mounted on the substrate, the transmission loss of the high frequency integrated circuit is effectively reduced, and Heat generation in the package can be prevented.

The method for manufacturing a semiconductor package of the present invention is as follows.
The transmission loss and heat generation of the high-frequency integrated circuit on the substrate can be significantly reduced, in the same degree of process as the conventional package manufacturing method.

[Brief description of the drawings]

FIG. 1 is a sectional view of a semiconductor package according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Semiconductor package 11 Substrate 13 LSI chip 15 Encapsulation material 16 Filler 17 Bonding wire 18 Solder ball 19 Metal wire

. Front page continued (51) Int.Cl ⁷ identification marks FI Theme coat Bu (Reference) H01L 21/56 H01L 21/56 T 23/29 B29K 101: 10 23/31 105: 16 // B29K 101: 10 B29L 31 : 34 105: 16 H01L 23/30 R B29L 31:34 (72) Inventor Yasushi Shimada 1500 Oji Ogawa, Shimodate City, Ibaraki Pref.Hitachi Chemical Industry Co., Ltd. 1,500 Hitachi Chemical Industry Co., Ltd. (72) Inventor Yoshiki Hirata 1500, Oji Ogawa, Shimodate City, Ibaraki Prefecture Hitachi Chemical Industry Co., Ltd. (72) Inventor Kazunori Yamamoto 1500 Ogawa Ogawa, Shimodate City, Ibaraki Hitachi F-term in Kasei Kogyo R & D Co., Ltd. (reference) 4F204 AA39 AB17 AB19 AH37 EA03 EA06 EB01 EE22 EF02 4J002 AA021 BD152 BF051 BG001 BK001 CC031 CC161 CC181 CD001 CD011 CD021 CD041 CD051 CD061 CF011 CF211 FA031 0 AA01 BA03 CA04 CA2 1 EA11 EB03 EB04 EB12 EB13 EB14 5F061 AA01 BA03 CA04 CA21 CB02

Claims (16)

[Claims] 1. A base resin, comprising: a filler having a specific gravity of 0.7 times or less or 1.7 times or more of a specific gravity of the base resin, and a dielectric loss tangent value of 0.005 or less. Sealing material for electronic components. 2. The sealing material according to claim 1, wherein the base resin is a thermosetting resin. 3. The filler has a particle size of 1 μm to 20 μm.
The sealing material according to claim 1, wherein 4. The sealing material according to claim 1, wherein the filler contains at least one selected from silica, Teflon powder, and hollow glass spheres. 5. A base resin, a filler having a specific gravity of 0.7 times or less or 1.7 times or more of a specific gravity of the base resin, and a dielectric loss tangent value of 0.005 or less; And a sealing material for an electronic component including: 6. The sealing material according to claim 1, wherein said filler is 20 to 80 vol%. 7. The ratio of the solvent to the mixture of the base resin and the filler is defined as a mixture of the base resin and the filler.
The sealing material according to claim 5, wherein the amount is in the range of 40 to 900 parts by weight based on 0 part by weight. 8. A step of mounting an electronic component on a substrate, comprising: a base resin; a specific gravity of 0.7 times or less or 1.7 times or more of a specific gravity of the base resin; Preparing a sealing material including a filler that is 0.005 or less; injecting the sealing material onto the substrate to encapsulate the electronic component; A method for sealing an electronic component, comprising: leaving the filler unbalanced in the vicinity of the surface of the electronic component by leaving it to stand; and curing the sealing material. 9. The step of preparing the sealing material further comprises the step of mixing a solvent with the base resin and the filler, and the method comprises the step of evaporating the solvent after leaving the sealing material for a predetermined time. The method for sealing an electronic component according to claim 8, further comprising: 10. The specific gravity of the filling material is lower than the specific gravity of the base resin, and the sealing material is left for a predetermined time with the surface of the electronic component mounted on the substrate facing downward. The method for sealing an electronic component according to claim 8. 11. The specific gravity of the filler is greater than the specific gravity of the base resin, and the sealing material is left for a predetermined time with the surface of the electronic component mounted on the substrate facing upward. Item 10. The method for sealing an electronic component according to item 8 or 9. 12. A substrate, comprising: a semiconductor chip mounted on the substrate; and a sealing material for sealing the semiconductor chip on the substrate, wherein the sealing material is a base resin; And a filler having a dielectric loss tangent value of 0.005 or less mixed therein, wherein the filler is concentrated and unevenly distributed near the surface of the semiconductor chip. 13. The semiconductor package according to claim 12, wherein the filler has a specific gravity of 0.7 times or less or 1.7 times or more of the specific gravity of the base resin. 14. The semiconductor package according to claim 12, wherein the filler is at least one selected from silica, Teflon powder, and hollow glass spheres. 15. A step of mounting a semiconductor chip on a substrate, comprising: a base resin; a specific gravity of 0.7 times or less or 1.7 times or more of a specific gravity of the base resin; Preparing a sealing material containing a filler that is 0.005 or less; injecting the sealing material onto the substrate to encapsulate the semiconductor chip; and applying the injected sealing material for a predetermined time. A method for manufacturing a semiconductor package, comprising: leaving the filler unbalanced in the vicinity of the surface of the semiconductor chip, and curing the sealing material. 16. The step of providing a sealing material,
The method according to claim 15, further comprising: mixing a solvent with the base resin and the filler; and the method further comprising, after allowing the sealing material to stand for a predetermined time, evaporating the solvent. A method for manufacturing a semiconductor package.