JP4384348B2 - Package for storing semiconductor elements - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a package for housing a semiconductor element for protecting the semiconductor element from external mechanical shock or moisture ingress, and in particular, a mobile communication device represented by a mobile phone equipped with a high-frequency semiconductor element. The present invention relates to a package for housing a semiconductor element used in the above.
[0002]
[Prior art]
2. Description of the Related Art In recent years, mobile communication devices have been rapidly becoming lighter, thinner, and smaller, and along with this, semiconductor element housing packages that hermetically seal semiconductor elements to be mounted are also becoming lighter, thinner, and smaller.
[0003]
Such a package for housing a semiconductor element is generally made of an electrically insulating material such as an aluminum oxide sintered body, an aluminum nitride sintered body, a mullite sintered body, or a silicon nitride sintered body, and has a semiconductor element on the upper surface. An insulating base having a mounting portion, a frame body joined to the upper surface of the insulating base so as to surround the mounting portion, and a substantially flat lid body joined to the upper surface of the frame body by solder, brazing material or the like. ing. As a material for the lid, a metal such as an iron-nickel-cobalt alloy that can be thinned is used in accordance with the reduction in the thickness and size of the semiconductor element housing package.
[0004]
However, such a package for housing a semiconductor element is formed by joining a frame body and a metal lid body having different thermal expansion coefficients with a metal such as solder or brazing material that has a high elastic modulus and is difficult to relieve stress such as strain. Therefore, a large stress is generated between the frame body and the metal lid body due to the heat generated when the semiconductor element is operated, and this stress acts on the frame body, and the frame body cracks. As a result, the hermetic sealing of the container is broken, and there is a problem that the semiconductor element accommodated in the container cannot be operated normally and stably over a long period of time.
[0005]
On the other hand, a method has been proposed in which the frame body and the metal lid body are joined with a resin adhesive having a low elastic modulus. According to this proposal, for example, a thermosetting epoxy resin is applied to a joint portion between the frame body and the metal lid body using a screen printing method or a dispenser method, and the joint portion between the frame body and the metal lid body is applied. By joining and pressing and heating the frame body and the metal lid body, between the frame body and the metal lid body having different thermal expansion coefficients due to the heat generated when the semiconductor element operates Even if a large stress is generated, the resin adhesive having a low elastic modulus can relieve the stress and effectively prevent the frame from cracking.
[0006]
[Problems to be solved by the invention]
However, in such a bonding with a resin adhesive, the bonding between the metallic lid and the resin adhesive is only a throwing effect due to fine irregularities on the surface. Sealing design that reduces the joint area with the metal lid does not provide sufficient joint strength, especially when a metal plate formed by a rolling process is used as the lid, and remains in the metal material rolling process. The strain stress is released by the heat generated when the semiconductor element is activated or the heat of the secondary reflow furnace, etc., and the lid body is greatly warped. As a result, the joint between the lid body and the resin adhesive is broken. However, the airtight reliability of the container is lowered.
[0007]
The present invention has been devised in view of the problems of the prior art, and an object of the present invention is to effectively prevent the destruction of the junction due to the deformation of the metal lid during heating and to provide a highly airtight and reliable semiconductor device. It is to provide a storage package.
[0008]
[Means for Solving the Problems]
The package for housing a semiconductor element according to the present invention includes an insulating base having a recess on which an upper surface of the semiconductor element is mounted, and a substantially flat lid that is bonded to the upper surface of the insulating base via a sealant so as to cover the recess. A lid for a semiconductor element containing a body, wherein the lid is made of a metal plate formed by a rolling method, and is substantially parallel to the rolling direction and has a length in the rolling direction at a portion facing the opening of the recess. And a height of 0.2 to 1.5 times the thickness of the flat plate portion, which is 3/5 or more and the length of the opening of the recess.
[0009]
According to the package for housing a semiconductor element of the present invention, the length of the lid made of a metal plate formed by a rolling method is substantially parallel to the rolling direction at a portion facing the opening of the concave portion of the insulating base. Occurs when the semiconductor element is operated because the protrusion is formed to be not less than 3/5 of the length of the lid and not more than the length of the opening of the recess, and the height is 0.2 to 1.5 times the thickness of the flat plate portion. Even if the strain stress remaining in the rolling process of the metal material is released by the heat of the reflow furnace following the secondary mounting or the heat of the secondary mounting, the projection of the lid suppresses the deformation of the lid, and the lid is greatly deformed. As a result, the joint between the lid and the resin adhesive is not broken, and the hermetic reliability of the package is not lowered.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a semiconductor element storage package of the present invention will be described in detail with reference to the drawings.
[0011]
1 and 2 are cross-sectional views showing an example of an embodiment of a package for housing a semiconductor element of the present invention. FIG. 1 is a cross-sectional view in the width direction of a protrusion of a metallic lid, and FIG. It is sectional drawing of a length direction. In these figures, 1 is an insulating substrate, 2 is a lid, 2a is a protrusion, and 4 is a sealant, and these mainly constitute the package for housing a semiconductor element of the present invention.
[0012]
The insulating base 1 is provided with a concave mounting portion 1a for mounting the semiconductor element 3 at a substantially central portion of the upper surface, and the semiconductor element 3 is made of glass, resin, brazing material, or the like on the bottom surface of the mounting portion 1a. The adhesive is fixed through an adhesive.
[0013]
Such an insulating substrate 1 is made of an electrically insulating material such as an aluminum oxide sintered body, a mullite sintered body, an aluminum nitride sintered body, a silicon nitride sintered body, or a silicon carbide sintered body. In the case of an aluminum oxide sintered body, an appropriate organic binder, solvent, plasticizer, and dispersant are added to and mixed with the raw material powder such as aluminum oxide, silicon oxide, magnesium oxide, calcium oxide, etc. The slurry is made into a sheet by using a sheet forming method such as a doctor blade method or a calender roll method, which has been conventionally known, to obtain a ceramic green sheet (ceramic green sheet), and thereafter, the ceramic green sheet is appropriately punched. It is manufactured by processing and laminating a plurality of sheets and firing them at a high temperature of about 1600 ° C.
[0014]
A plurality of wiring conductor layers 5 are deposited on the insulating base 1 from the bottom surface to the bottom surface of the mounting portion 1 a, and each electrode of the semiconductor element 3 is formed on the bottom surface portion of the mounting portion 1 a of the wiring conductor layer 5. Are electrically connected via bonding wires 7, and an external electric circuit (not shown) is electrically connected via a connecting member such as solder to a portion led out to the lower surface of the insulating substrate 1. .
[0015]
The wiring conductor layer 5 acts as a conductive path when each electrode of the semiconductor element 3 is electrically connected to an external electric circuit. For example, a suitable organic solvent, solvent, A metal paste obtained by adding and mixing a plasticizer or the like is preliminarily printed and applied to a ceramic green sheet to be an insulating substrate 1 by employing a known thick film method such as a screen printing method. By firing at the same time, a predetermined pattern is deposited from the vicinity of the mounting portion 1a of the insulating substrate 1 to the lower surface.
[0016]
The wiring conductor layer 5 is coated with a metal having good conductivity, corrosion resistance and wettability with a brazing material, such as nickel and gold, to a thickness of 1 to 20 μm by plating. The oxidative corrosion of the conductor layer 5 can be effectively prevented, and the connection between the wiring conductor layer 5 and the bonding wire 7 and the soldering between the wiring conductor layer 5 and the wiring conductor of the external electric circuit can be strengthened. Therefore, in order to prevent oxidative corrosion of the wiring conductor layer 5 and to strengthen the connection between the wiring conductor layer 5 and the bonding wire 7 and the soldering between the wiring conductor layer 5 and the wiring conductor of the external electric circuit, It is preferable to deposit nickel, gold, or the like on the surface of the layer 5 to a thickness of 1 to 20 μm by plating.
[0017]
A lid 2 is bonded to the upper surface of the insulating substrate 1 via a sealant 4. The lid 2 functions to hermetically seal the semiconductor element 3 inside the package and has a function of preventing the semiconductor element 3 from being destroyed by an external impact, and includes iron, aluminum, copper, tungsten, It is formed by rolling a metal material such as an iron-nickel alloy, an iron-cobalt alloy, or an iron-nickel-cobalt alloy.
[0018]
In the package for housing a semiconductor element of the present invention, as shown in a plan view in FIG. 3, a rolling direction ( Substantially parallel to AB), the length X is not less than 3/5 of the length of the lid 2 in the rolling direction and not more than the length of the opening of the recess, and the height is 0.2 to 1.5 times the thickness of the flat plate portion. It is important to form the protrusion 2a.
[0019]
According to the package for housing semiconductor elements of the present invention, the lid 2 made of a metal plate formed by a rolling process has a portion facing the opening of the concave portion of the insulating base 1 substantially parallel to the rolling direction (A-B). Protrusions 2a having a length X of 3/5 or more of the length of the lid body in the rolling direction (A-B) and less than or equal to the length of the opening of the recess and having a height of 0.2 to 1.5 times the thickness of the flat plate portion are formed. Therefore, even if the strain stress remaining in the rolling process of the metal material is released by the heat generated when the semiconductor element 3 is operated or the heat of the reflow furnace subsequent to the secondary mounting, the protruding portion of the lid 2 2a suppresses deformation of the lid 2 and the lid 2 is not greatly warped. As a result, the joint between the lid 2 and the sealant 4 is broken, and the hermetic reliability of the container is lowered. There is nothing.
[0020]
In addition, when the length X of the protrusion 2a is less than 3/5 of the length of the lid 2 in the rolling direction (AB), the strength for suppressing deformation of the lid 2 in the rolling direction (AB) is insufficient. However, a peeling force due to the warping of the lid body 2 between the insulating base body 1 and the lid body 2 acts, and the joint between the insulating base body 1 and the lid body 2 tends to be easily broken. In addition, when the length X of the protrusion 2a exceeds the length of the opening of the recess, the protrusion 2a is located at the joint between the insulating base 1 and the lid 2, and the thickness of the sealant 4 to be described later Therefore, it becomes difficult to make the thickness of the semiconductor device 3 appropriate, the moisture permeation amount of the sealing agent 4 increases, and the semiconductor element 3 tends to be easily deteriorated by moisture. Therefore, it is preferable that the length X of the protrusion 2a is in a range of 3/5 or more of the length of the lid 2 in the rolling direction (AB) and not more than the length of the opening of the recess.
[0021]
Moreover, when the height of the protrusion 2a is less than 0.2 times the thickness of the flat plate portion of the lid 2, the strength for suppressing deformation in the rolling direction (AB) of the lid 2 is insufficient, and the lid 2 is warped. The peeling force due to this acts between the insulating base 1 and the lid 2, and the joint between the insulating base 1 and the lid 2 tends to be broken, and when the ratio exceeds 1.5 times, the projection 2 a is formed. In this case, distortion in the direction orthogonal to the rolling direction (A-B) remains or warpage is likely to occur, and as a result, the bonding reliability in the heating process such as secondary mounting tends to be reduced. . Therefore, it is preferable that the height of the projecting portion 2 a is in the range of 0.2 to 1.5 times the thickness of the flat plate portion of the lid 2.
[0022]
Furthermore, the width Y of the protrusion 2a is preferably 1/10 to 1/4 of the width of the lid 2 in the direction orthogonal to the rolling direction (AB). The intensity | strength which suppresses the deformation | transformation of the rolling direction (AB) of the cover body 2 as the width Y of the protrusion part 2a is less than 1/10 of the width | variety of the cover body 2 in the direction orthogonal to a rolling direction (AB). There is a shortage and the peeling force due to the warping of the lid 2 acts between the insulating base 1 and the lid 2, and the joint between the insulating base 1 and the lid 2 tends to be easily broken. On the other hand, if it exceeds 1/4, in a general thin semiconductor device, the space inside the container becomes narrow, and there is a risk that the bonding wire 7 contacts the lid 2 and short-circuits. Therefore, the width Y of the protrusion 2a is preferably 1/10 to 1/4 of the width of the lid 2 in the direction orthogonal to the rolling direction (AB).
[0023]
In addition, the protrusion 2a may have other shapes such as a plurality of lines or a frame in addition to a single line as shown in FIGS. When the protrusion 2a has a frame shape or a plurality of lines, the sum of the widths Y of the protrusions 2a is 1/10 of the width of the lid 2 in the direction orthogonal to the rolling direction (AB). It is preferable to set to ¼.
[0024]
Further, the cross-sectional shape of the protrusion 2a may be various shapes such as a triangle and a trapezoid. Further, as shown in the cross-sectional views of the main part of the lid 2 in FIGS. 4 and 5, a recess is formed on the opposite side of the protrusion 2a. It may be trapezoidal or arcuate.
[0025]
If such a lid 2 is made of, for example, an iron-nickel alloy, an ingot of the iron-nickel alloy is rolled into a plate shape by a rolling method so as to correspond to a predetermined projection shape. In addition to compression press molding using a press die manufactured in this manner, the die is formed to a predetermined size by a conventionally known punching method. Alternatively, the protrusion 2a can be formed by chemical etching and molded to a predetermined outer dimension.
[0026]
When the lid 2 is made of an iron alloy such as iron-nickel alloy, iron-cobalt alloy, iron-nickel-cobalt alloy, the surface of the lid 2 is nickel, gold, solder, etc. to prevent corrosion. It is preferable to coat by various metal plating.
[0027]
The sealant 4 has a function of joining the insulating base 1 and the lid 2 and is made of glass, a resin adhesive, a brazing material, or the like.
[0028]
The sealing agent 4 is preferably a low-elasticity resin adhesive from the viewpoint of stress relaxation, and is printed and applied to the joint portion of the insulating base 1 or the lid 2 by employing a conventionally known screen printing method or the like. The insulating substrate 1 and the lid body 2 can be firmly bonded by heating and drying and by applying pressure and heating while overlapping the bonding portions of the two.
[0029]
The sealant 4 preferably has a thickness after curing of 1 to 50 μm, and if it is less than 1 μm, there is a tendency that stress relaxation does not work effectively. The amount of moisture increases and the semiconductor element 3 tends to be easily deteriorated by moisture. Therefore, the sealant 4 preferably has a thickness after curing in the range of 1 to 50 μm.
[0030]
As such a sealant 4, a thermosetting epoxy resin adhesive having a dense three-dimensional network structure is particularly preferable from the viewpoint of moisture resistance or bonding strength, and bisphenol A type epoxy resin or bisphenol A modified epoxy is preferable. Resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, special novolac type epoxy resin, phenol derivative epoxy resin, biphenol skeleton type epoxy resin, imidazole, amine, phosphorus, A hydrazine type, imidazole adduct type, amine adduct type, cationic polymerization type, dicyandiamide type or the like is used.
[0031]
Two or more types of epoxy resins may be mixed and used, and by adding soft fine particles, the elastic modulus of the epoxy resin adhesive can be further reduced. As such soft fine particles, for example, plastic powders such as silicone rubber, silicone resin, LDPE, HDPE, PMMA, crosslinked PMMA, polystyrene, crosslinked polystyrene, ethylene-acrylic copolymer, polyethyl methacrylate, butyl acrylate, and urethane are used. It is done.
[0032]
In addition, the sealing agent 4 contains a conductive filler, and the wiring conductor layer is formed on the upper surface of the insulating substrate 1 so as to surround the mounting portion 1a and to be attached to the insulating substrate 1, as shown in a sectional view in FIG. By forming the frame-like conductor layer 6 that is electrically connected to the cover 5, the lid 2 and the wiring conductor layer 5 are electrically connected to each other, and a shielding effect that prevents the radiation of electromagnetic waves to the outside and It can be set as the package for housing | casing a semiconductor element from which the immunity effect which prevents the penetration | invasion of electromagnetic waves is acquired favorably.
[0033]
The frame-like conductor layer 6 is a thick film technique such as a conventionally known screen printing method using a metal paste obtained by adding and mixing an appropriate organic solvent, solvent, plasticizer, etc. to a high melting point metal powder such as tungsten, molybdenum, manganese, etc. Is applied in advance to a ceramic green sheet to be the insulating substrate 1 and is fired simultaneously with the ceramic green sheet to form a predetermined pattern on the upper surface of the insulating substrate 1.
[0034]
Examples of the conductive filler contained in the sealant 4 include various organic resins such as acrylic resins, phenol resins, urethane resins, benzoguanamine resins, melamine resins, polydivinylbenzene, and polystyrene resins. Particles having carbon as a core and coated with a conductive material such as nickel, gold, silver, and copper on the surface, carbon powder, or metal powder such as nickel, gold, silver, copper, and solder are used.
[0035]
The conductive filler preferably contains 0.5 to 200% by weight of a filler having an average particle size of 0.1 to 30 μm. If the average particle size is less than 0.1 μm, the conduction resistance of the sealant 4 is increased. Electrical connection between the lid 2 and the frame-like conductor layer 6 tends to be difficult, and when the thickness exceeds 30 μm, the conductive particles are greatly deformed by the load applied when heat-curing while applying pressure and the metal coating is damaged. However, there is a tendency that good conductivity cannot be obtained. Therefore, the average particle size of the conductive filler is preferably in the range of 0.1 to 30 μm.
[0036]
Furthermore, if the content of the conductive filler is less than 0.5% by weight, the conductivity of the sealant 4 tends to decrease, and if it exceeds 200% by weight, the wettability of the sealant 4 tends to decrease. There is. Therefore, the content of the conductive filler is preferably in the range of 0.5 to 200% by weight.
[0037]
Thus, according to the package for housing a semiconductor element of the present invention, the semiconductor element 3 is bonded and fixed to the bottom surface of the mounting portion 1a of the insulating base 1 via an adhesive made of glass, resin, brazing material, etc. The electrode is connected to the wiring conductor layer 5 by the bonding wire 7, and then the insulating base 1 and the lid 2 are connected via the sealant 4 to the inside of the container composed of the insulating base 1 and the lid 2. A semiconductor device as a final product is completed by housing the semiconductor element 3 in an airtight manner.
[0038]
The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention. For example, the electrical connection between the semiconductor element 3 and the wiring conductor 5 is possible. The connection may be made with a conductive connection member such as a solder bump.
[0039]
【The invention's effect】
According to the package for housing a semiconductor element of the present invention, the length of the lid made of a metal plate formed by a rolling method is substantially parallel to the rolling direction at a portion facing the opening of the concave portion of the insulating base. Occurs when the semiconductor element is operated because the protrusion is formed to be not less than 3/5 of the length of the lid and not more than the length of the opening of the recess, and the height is 0.2 to 1.5 times the thickness of the flat plate portion. Even if the strain stress remaining in the rolling process of the metal material is released by heat to be performed or reflow heating subsequent to the secondary mounting, the protrusion of the lid suppresses the deformation of the lid, and the lid is greatly deformed. As a result, the joint between the lid and the resin adhesive is not broken, and the hermetic reliability of the package is not lowered.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view in the width direction of a protrusion showing an example of an embodiment of a package for housing a semiconductor element of the present invention.
FIG. 2 is a cross-sectional view in the length direction of a protrusion showing an example of an embodiment of a package for housing a semiconductor element of the present invention.
3 is a plan view of a lid in the package for housing a semiconductor element shown in FIGS. 1 and 2. FIG.
FIG. 4 is a cross-sectional view of an essential part in another example of a lid in a package for housing a semiconductor element of the present invention.
FIG. 5 is a cross-sectional view of a main part in still another example of a lid in a package for housing semiconductor elements according to the present invention.
FIG. 6 is a cross-sectional view showing another embodiment of the package for housing a semiconductor element of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Insulation base | substrate 1a ... Mounting part 2 ... Lid 2a ... Projection part 3 ... Semiconductor element 4 ... .... Sealant 5 ... Wiring conductor layer X ... Projection length Y ... Projection width AB ... Rolling direction

Claims (4)

A package for housing a semiconductor element, comprising: an insulating base having a recess on which an upper surface of a semiconductor element is mounted; and a substantially flat lid that is joined to the upper surface of the insulating base via a sealing agent so as to cover the recess. And the said cover body consists of a metal plate by a rolling process method, and the length is 3 of the length of the said cover body in the said rolling direction in the site | part facing the opening of the said recessed part, substantially parallel to a rolling direction. A package for housing semiconductor elements, characterized in that a protrusion is formed at a height not less than / 5 and not more than the length of the opening of the recess and having a height of 0.2 to 1.5 times the thickness of the flat plate portion. 2. The package for housing a semiconductor element according to claim 1, wherein the width of the protrusion is set to 1/10 to 1/4 of the width of the lid in a direction orthogonal to the rolling direction. 3. The package for housing a semiconductor element according to claim 1, wherein the sealant is an epoxy resin adhesive. 4. The package for housing a semiconductor element according to claim 3, wherein the epoxy resin adhesive contains a conductive filler.

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