JP3798969B2 - Crystal device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a temperature-compensated crystal device used as an accurate time and frequency reference source in an information processing apparatus such as a computer and an electronic apparatus such as a mobile phone.
[0002]
[Prior art]
A temperature-compensated crystal device used as an accurate time and frequency reference source in an information processing apparatus such as a computer or an electronic apparatus such as a mobile phone generally has a voltage application electrode on a rectangular plate-shaped crystal substrate. The formed crystal resonator and the semiconductor element for performing temperature compensation of the crystal resonator are hermetically housed in a crystal resonator housing package.
[0003]
The quartz crystal housing package is generally made of an electrically insulating material such as an aluminum oxide sintered body, and has a concave portion for forming a space for accommodating the quartz crystal in the central portion of the upper surface, and a semiconductor in the central portion of the lower surface. A base having a wiring layer made of a metal material such as tungsten, molybdenum, or the like, and having a wiring layer made of a refractory metal such as tungsten and molybdenum, each having a recess serving as a space for accommodating an element, and extending from the surface of each recess to the outer surface; -It is comprised from metal materials, such as a cobalt alloy and an iron-nickel alloy, or the cover body which consists of ceramic materials, such as an aluminum oxide sintered body.
[0004]
Then, the quartz oscillator is placed in the recess by attaching the electrode of the crystal oscillator to the wiring layer exposing the inner surface of the recess on the upper surface of the substrate and the surrounding substrate surface via a fixing material such as a conductive adhesive. Bonding and fixing and electrically connecting to the wiring layer, and housing the semiconductor element in a recess on the lower surface of the base, bonding and fixing via an adhesive, and electrically connecting the electrode of the semiconductor element to the wiring layer, Thereafter, the lid is attached to the upper surface of the base by a bonding means such as adhesive bonding or seam welding, and the crystal resonator is hermetically accommodated inside the container composed of the base and the lid, and within the recess on the lower surface of the base. The semiconductor device accommodated in the substrate is sealed with a lid or a sealing resin to complete a crystal device as a product.
[0005]
In general, as a conductive adhesive for attaching a crystal unit, a conductive adhesive made by mixing organic resin such as epoxy resin and conductive powder such as silver powder as the main material is used. Has been.
[0006]
Further, when the lid is attached to the base by seam welding, a frame-like brazing metallization layer is usually formed around the recess of the base in advance, and a metal frame is brazed to the metallization layer. A method of seam welding the lid to the frame is used.
[0007]
Further, the mounting of the crystal device on the external electric circuit board is performed by connecting the wiring layer led to the outer surface of the base to the wiring conductor of the external electric circuit board through a conductive connecting material such as solder, The crystal resonator is electrically connected to the external electric circuit via the wiring layer, and vibrates at a predetermined frequency according to a voltage applied from the external electric circuit, and supplies a reference signal to the external electric circuit.
[0008]
[Problems to be solved by the invention]
However, in this conventional crystal device, the linear thermal expansion coefficient of the crystal resonator is about 18 × 10 × 10. ^-6 The linear thermal expansion coefficient of the substrate made of an aluminum oxide sintered body on which the crystal resonator is mounted and fixed is about 7 × 10. ^-6 / ° C, which is greatly different, that the fixing material for fixing the crystal unit to the base is made of hard epoxy resin and conductive powder, and that the semiconductor element for temperature compensation generates heat during operation. For this reason, when the crystal device is operated, the heat generated by the temperature compensating semiconductor element repeatedly acts on both the base and the crystal unit, resulting in a difference in linear thermal expansion coefficient between the base and the crystal unit. The thermal stress that occurs repeatedly acts on the fixing material, causing mechanical damage to the fixing material, breaking the fixation of the crystal unit through the fixing material, and losing the function as a crystal device. It was.
[0009]
Therefore, in order to eliminate the above-described drawbacks, the linear thermal expansion coefficient of the base is increased so as to approximate the linear thermal expansion coefficient of the quartz oscillator, thereby preventing a large thermal stress from being generated between the base and the quartz oscillator. The method of thinking is conceivable.
[0010]
However, when the linear thermal expansion coefficient of the substrate is increased so as to approximate a crystal resonator, the linear thermal expansion coefficient is about 2.5 × 10 ^-6 The difference in linear thermal expansion coefficient between the semiconductor element made of silicon as low as / ° C (40 to 400 ° C) and the base becomes very large. As a result, a large thermal stress is generated, and this thermal stress causes a mechanical breakdown in a hard and brittle semiconductor element or an adhesive for bonding the semiconductor element to the base, and the semiconductor element does not operate normally. This makes it impossible to compensate for the temperature of the quartz crystal resonator and causes a problem that the reliability of the quartz crystal device is greatly reduced.
[0011]
In the conventional quartz device, the wiring layer formed on the substrate is formed of a refractory metal material such as tungsten, molybdenum or manganese, and the tungsten or the like has a specific electric resistance of 5.4 μΩ · cm (20 ° C. ) If the reference signal of the crystal resonator or the drive signal of the semiconductor element is propagated to the wiring layer, the reference signal or the drive signal is greatly attenuated, and the reference signal or the drive signal is transmitted to the external electric circuit or the crystal vibration. There has been a drawback that it cannot be propagated accurately and reliably between the child and the semiconductor element.
[0012]
The present invention has been devised in view of the above-described drawbacks, and it is possible to firmly fix the crystal resonator and the semiconductor element, effectively perform temperature compensation of the crystal resonator by the semiconductor element, and to transmit the reference signal of the crystal resonator to the external electric circuit. An object of the present invention is to provide a highly reliable crystal device that can be supplied accurately and reliably.
[0013]
[Means for Solving the Problems]
The present invention includes a first base having a mounting portion on an upper surface and having a first wiring layer led out from the mounting portion to the outer surface, and fixed to the mounting portion of the first base, and an electrode is the first base. A quartz resonator connected to the wiring layer; a second base having a mounting portion on the lower surface; and a second wiring layer led out from the mounting portion to the outer surface; and a mounting portion of the second base A quartz crystal device comprising a semiconductor element that is fixed and whose temperature is compensated for the quartz crystal resonator whose electrode is connected to the second wiring layer, and a bonding material that bonds the lower surface of the first substrate and the upper surface of the second substrate. The linear thermal expansion coefficient of the first base is 14 × 10 ^-6 / ° C to 20 × 10 ^-6 / ° C. (40 to 400 ° C.), the linear thermal expansion coefficient of the second substrate is 2 × 10 ^-6 / ° C to 8 × 10 ^-6 / ° C. (40 to 400 ° C.), the specific electric resistance of the first wiring layer and the second wiring layer is 2.5 μΩ · cm or less, and the elastic modulus of the bonding material is 4 GPa or less It is.
[0014]
According to the present invention, the linear thermal expansion coefficient of the first base to which the crystal resonator is fixed is 14 × 10. ^-6 / ° C to 20 × 10 ^-6 / ° C. (40 to 400 ° C.), and the linear thermal expansion coefficient of the crystal resonator (18 × 10 ^-6 / ° C .: 40 to 400 ° C.), even if heat is applied to the crystal resonator and the first base, no large thermal stress is generated between them. It is possible to firmly bond and fix to the base body and to stably operate the crystal resonator.
[0015]
According to the present invention, the linear thermal expansion coefficient of the second base to which the semiconductor element for compensating the temperature of the crystal resonator is fixed is 2 × 10. ^-6 / ° C to 8 × 10 ^-6 / ° C. (40 to 400 ° C.), and the linear thermal expansion coefficient of the semiconductor element (2.5 × 10 ^-6 / ° C .: 40 to 400 ° C.), even if heat is applied to the semiconductor element and the second substrate, no large thermal stress is generated between them. As a result, the semiconductor element is applied to the second substrate. It is possible to firmly fix and fix the crystal resonator, and it is possible to accurately perform temperature compensation of the crystal resonator over a long period of time by the semiconductor element.
[0016]
Furthermore, according to the present invention, since the elastic modulus of the bonding material for bonding the first base and the second base is 4 GPa or less, it is caused by the difference in the linear thermal expansion coefficient between the first base and the second base. Even if a large thermal stress is generated between the two, the thermal stress is effectively absorbed by appropriately deforming the bonding material, and the first base, the second base, or the first base and the second base It is possible to effectively prevent mechanical destruction of the bonding material for bonding the crystal and complete the connection between the crystal unit and the semiconductor element, thereby improving the long-term reliability of the crystal device. it can.
[0017]
Furthermore, according to the present invention, the specific electrical resistance of the first wiring layer and the second wiring layer to which the crystal resonator and the semiconductor element are connected is set to a low value of 2.5 μΩ · cm (20 ° C.) or less. When the reference signal of the crystal resonator and the drive signal of the semiconductor element are propagated to the first wiring layer and the second wiring layer, the reference signal and the drive signal are not greatly attenuated, and the reference signal and the drive signal are transmitted to the external electric circuit. In addition, it is possible to propagate accurately and reliably between the crystal resonator and the semiconductor element.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Next, the crystal device of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a sectional view showing an embodiment of a quartz crystal device according to the present invention. In FIG. 1, 1a is a first substrate, 1b is a second substrate, 2a is a first wiring layer, 2b is a second wiring layer, 3 Is a lid, 5 is a crystal resonator, 6 is a semiconductor element, and 8 is a bonding material.
[0019]
The quartz crystal resonator 5 and the semiconductor element 6 are fixedly accommodated in the first base 1a and the second base 1b, respectively, and the first base 1a and the second base 1b are bonded to each other through a bonding material. Is formed.
[0020]
The first base 1a has a linear thermal expansion coefficient of 14 × 10. ^-6 / ° C to 20 × 10 ^-6 It is made of a sintered glass ceramic, crystalline glass, or the like at / ° C. (40 to 400 ° C.), and has a recess A on its upper surface, in which the crystal unit 5 is accommodated.
[0021]
The first substrate 1a has a first wiring layer 2a deposited from the surface of the recess A on the upper surface to the outer surface, and the electrode of the crystal resonator 5 is exposed to the surface of the recess A of the first wiring layer 2a. Is bonded and fixed via a fixing material 9 such as a conductive adhesive, and a portion leading to the outer surface of the first base 1a is connected to a wiring conductor of an external electric circuit or a second wiring layer 2b of a second base 1b described later. Is done.
[0022]
The first substrate 1a has a coefficient of linear thermal expansion of 14 × 10. ^-6 / ° C to 20 × 10 ^-6 / ° C. (40 to 400 ° C.), and the linear thermal expansion coefficient of the crystal unit 5 (about 18 × 10 ^-6 / C: 40-400 ° C.), after the quartz resonator 5 is fixedly accommodated in the recess A of the first base 1a, a large thermal stress is generated between the two even if heat acts on both. As a result, the crystal unit 5 can be securely and firmly fixed in the recess A of the first base 1a.
[0023]
The linear thermal expansion coefficient is 14 × 10 ^-6 / ° C to 20 × 10 ^-6 Specifically, the first substrate 1a at / ° C. (40 to 400 ° C.) has, for example, a glass containing 5 to 60% by weight of barium oxide and a linear thermal expansion coefficient at 40 to 400 ° C. of 8 × 10. ^-6 / ZrO compound in the glass and / or filler is made of ZrO. ₂ A glass ceramic sintered body containing 0.1 to 25% by weight in terms of conversion is preferably used.
[0024]
It is important to use a glass containing 5 to 60% by weight of barium oxide as a glass component in the glass ceramic sintered body. Since this barium oxide-containing glass has a low softening point and a relatively high coefficient of linear thermal expansion, it is possible to add a small amount of glass and a large amount of high thermal expansion filler. A sintered body having an expansion coefficient can be easily obtained. If the amount of barium oxide is in the range of 5 to 60% by weight, if it is less than 5% by weight, it becomes difficult to lower the softening point of the glass, and the linear thermal expansion coefficient becomes low. This is because vitrification is difficult, vitrification is difficult if it exceeds 60% by weight, the characteristics are likely to be unstable, and the chemical resistance is remarkably lowered. In particular, the amount of barium oxide is preferably 20 to 40% by weight.
[0025]
Further, it is desirable that this glass does not substantially contain lead (Pb). This is because lead is toxic and requires special equipment and control for preventing poisoning during the manufacturing process, making it impossible to manufacture a sintered body at low cost. Considering the case where lead is inevitably mixed as an impurity, the lead content is desirably 0.05% by weight or less.
[0026]
Furthermore, the linear thermal expansion coefficient of this glass at 40 to 400 ° C. is 7 × 10. ^-6 / ° C. to 18 × 10 ^-6 / ° C, especially 8 x 10 ^-6 / ° C. to 13 × 10 ^-6 / ° C is desirable. This is because if the linear thermal expansion coefficient deviates from the above range, a difference in thermal expansion from the filler occurs, which causes a decrease in strength of the glass ceramic sintered body.
[0027]
Furthermore, it is desirable that the yield point of the barium oxide-containing glass is 400 to 800 ° C, particularly 400 to 700 ° C. In the case of molding a mixture composed of barium oxide-containing glass and filler, a molding binder such as an organic resin is added. The binder is efficiently removed and fired at the same time as the first substrate 1a, which will be described later. Necessary for matching the firing conditions with the wiring layer 2a. When the yield point is lower than 400 ° C., the glass starts sintering at a low temperature. For example, silver (Ag), copper (Cu), etc. Since the sintering start temperature of 600 ° C. to 800 ° C. cannot be simultaneously fired with the first wiring layer 2a, and the densification of the molded body starts at a low temperature, the binder cannot be decomposed and volatilized, and the binder component remains, resulting in characteristics. This is because the result is influenced. Further, if the yield point is higher than 800 ° C., it is difficult to sinter unless the amount of glass is increased. Therefore, since a large amount of expensive glass is required, the cost of the sintered body is increased.
[0028]
As the glass satisfying the above-mentioned characteristics, at least silicon oxide (SiO 2) other than the barium oxide. ₂ ) In a proportion of 25 to 60% by weight, the balance being boron oxide (B ₂ O _Three ), Aluminum oxide (Al ₂ O _Three ), Calcium oxide (CaO), magnesium oxide (MgO), titanium oxide (TiO) ₂ ) And at least one selected from the group of zinc oxide (ZnO).
[0029]
On the other hand, the filler component combined with the glass has a linear thermal expansion coefficient of 8 × 10 4 at 40 to 400 ° C. ^-6 The inclusion of at least a metal oxide at / ° C. or higher is important for achieving high thermal expansion of the sintered body. Linear thermal expansion coefficient is 8 × 10 ^-6 If the metal oxide does not contain / C or higher, the linear thermal expansion coefficient of the glass ceramic sintered body is 14 × 10 ^-6 This is because the temperature cannot be increased to more than / ° C.
[0030]
Such a linear thermal expansion coefficient is 8 × 10 ^-6 As a metal oxide at / ° C or higher, cristobalite (SiO ₂ ), Quartz (SiO ₂ ), Tridymite (SiO ₂ ), Forsterite (2MgO · SiO ₂ ), Wollastonite (CaO.SiO) ₂ ), Monticeranite (CaO / MgO / SiO) ₂ ), Nepheline (Na ₂ O ・ Al ₂ O _Three ・ SiO ₂ ), Melvinite (3CaO · MgO · 2SiO ₂ ), Achelite (2CaO · MgO · 2SiO ₂ ), Magnesia (MgO), carne gearite (Na ₂ O ・ Al ₂ O _Three ・ 2SiO ₂ ), Enstatite (MgO · SiO ₂ ), Petalite (LiAlSi _Four O _Ten ), Jade (Na ₂ O ・ Al ₂ O _Three ・ 4SiO ₂ ). At least one selected from the group of Among these, cristobalite, quartz, tridymite and other SiO ₂ A material selected from the group of system materials, forsterite and enstatite is desirable for achieving high thermal expansion.
[0031]
The glass and filler are mixed at an appropriate ratio according to the purpose such as the firing temperature and the thermal expansion characteristics of the finally obtained glass ceramic sintered body. The barium oxide-containing glass has a shrinkage start temperature of 700 ° C. or lower when no filler is added, and melts at 850 ° C. or higher, and the first wiring layer 2a and the like cannot be disposed. However, by mixing the filler, crystal precipitation occurs in the firing process, and a liquid phase for liquid phase sintering of the filler component can be formed at an appropriate temperature. In addition, since the shrinkage start temperature of the entire molded body can be increased, matching of the simultaneous firing conditions with the first wiring layer 2a can be achieved by adjusting the filler content.
[0032]
The ratio of the glass to the filler is preferably 20 to 80% by volume of the glass powder and 80 to 20% by volume of the filler powder. The amount of the glass and filler component in the above range is that the glass component amount is less than 20% by volume, in other words, if the filler is more than 80% by volume, it is difficult to liquid phase sinter, the firing temperature becomes high, There is a possibility that the first wiring layer 2a is melted at the time of simultaneous firing with the first wiring layer 2a. If the glass is more than 80% by volume, in other words, if the filler is less than 20% by volume, the properties of the sintered body greatly depend on the properties of the glass, and it becomes difficult to control the material properties, and the sintering start temperature is Since it becomes low, the problem that simultaneous baking with the 1st wiring layer 2a becomes difficult arises. Moreover, since the amount of glass is large, the cost of raw materials tends to increase.
[0033]
Further, it is desirable that the amount of the filler component is appropriately adjusted according to the yield point of barium oxide. That is, when the yield point of the glass is as low as 400 to 700 ° C., the sinterability at low temperatures is enhanced, so that the filler content can be relatively high at 40 to 80% by volume. On the other hand, when the yield point of the glass is as high as 700 to 800 ° C., the sinterability is lowered, so that the filler content is desirably 20 to 50% by volume and relatively small.
[0034]
Furthermore, the glass-ceramic sintered body is obtained by converting a zirconium compound (Zr compound) into zirconium oxide (ZrO) in the filler component and / or the glass component. ₂ ) It is important to make it contain in the ratio of 0.1-25 weight% in conversion. The Zr compound is melted in the barium oxide-containing glass to increase the oxidation resistance of the glass, thereby improving the chemical resistance of the glass ceramic sintered body, and after treatment with an acidic solution or an alkaline solution. It is possible to suppress the change in the appearance of the glass ceramic sintered body and the deterioration of the adhesion strength of the first wiring layer 2a.
[0035]
Examples of the Zr compound include ZrO. ₂ , ZrSiO _Four , CaO ・ ZrO ₂ , ZrB ₂ , ZrP ₂ O ₇ , At least one selected from the group of ZrB. This Zr compound is mixed as a compound powder as one component in the filler component. In this case, the Zr compound at the time of addition, particularly ZrO ₂ The chemical resistance of the glass ceramic sintered body tends to change depending on the BET specific surface area of the BET, and the BET specific surface area is 25 m. ² / G or more and a BET specific surface area of 25 m ² If it is smaller than / g, the chemical resistance improving effect tends to be small. Further, as other blending forms, glass powder such as barium oxide (BaO), silicon oxide (SiO2) ₂ Zirconium oxide (ZrO) as a component other than ₂ You may use the glass containing).
[0036]
The Zr compound is in the above range because if it is less than 0.1% by weight, the effect of improving chemical resistance is low, and if it is more than 25% by weight, the linear thermal expansion coefficient is 14 × 10. ^-6 This is because it becomes lower than / ° C. In particular, Zr compounds are ZrO ₂ It is preferably 0.2 to 10% by weight in terms of conversion.
[0037]
In addition, at least one selected from the group consisting of chromium oxide, cobalt oxide, manganese oxide, and nickel oxide may be blended as the coloring component.
[0038]
The glass-ceramic sintered body is formed by a doctor blade method, a rolling method, a die press method, etc. after adding an organic resin binder of an appropriate shape to the mixture of the glass powder and filler powder prepared as described above. It is manufactured by forming into an arbitrary shape, for example, a sheet shape by means, and then baking at a temperature of about 800 ° C.
[0039]
In the first base 1a, the first wiring layer 2a is led out from the surface of the recess A to the outer surface, and the electrode of the crystal unit 5 is electrically conductive at the part exposed on the surface of the recess A of the first wiring layer 2a. A portion bonded and fixed via a fixing material 9 such as an adhesive and led to the outer surface is connected to a wiring conductor of an external electric circuit board and a second wiring layer 2b of a second base 1b described later.
[0040]
The first wiring layer 2a is formed by co-firing with the first substrate 1a. Since the firing temperature of the first substrate 1a is as low as about 800 ° C., the specific electrical resistance is as low as 2.5 μΩ · cm (20 ° C.) or less. Metallic metal paste obtained by adding and mixing an appropriate organic solvent, organic binder, etc. to the copper powder can be used for the green sheet serving as the first substrate 1a. A predetermined pattern is formed at a predetermined position on the first substrate 1a by printing and applying a predetermined pattern on the surface by a screen printing method or the like.
[0041]
Since the specific electric resistance of the first wiring layer 2a can be suppressed to a low value of 2.5 μΩ · cm (20 ° C.) or less, a reference signal of the crystal unit 5 or a semiconductor element described later is provided on the first wiring layer 2a. When the drive signal 6 is propagated, the reference signal and the drive signal are not greatly attenuated, and the reference signal and the drive signal are accurately and reliably transmitted between the external electric circuit or the crystal unit 5 and the semiconductor element 6. It is possible to propagate to.
[0042]
If the exposed surface of the first wiring layer 2a is covered with a plating layer (not shown) made of a metal having good corrosion resistance and brazing material such as nickel, copper and gold, the first wiring layer 2a is first The oxidative corrosion of the wiring layer 2a can be satisfactorily prevented, and the wettability of brazing material such as solder with respect to the first wiring layer 2a can be improved, so that the first wiring with respect to the wiring conductor of the external electric circuit board can be obtained. The connection of the layer 2a can be made easier and more reliable. Accordingly, the exposed surface of the first wiring layer 2a is a plating layer of nickel, copper, gold or the like, for example, a nickel or nickel alloy plating layer having a thickness of 1 μm to 10 μm, which is sequentially deposited, and a thickness of 0.1 to 3 μm. It is preferable to coat with a gold plating layer.
[0043]
Further, when the surface of the first wiring layer 2a is covered with a plating layer of nickel, copper, gold or the like, the arithmetic average roughness (Ra) of the outermost surface is 1.5 μm or less, and the root mean square roughness (Rms) is When the thickness is set to 1.8 μm or less, the reflectance of the light on the outermost surface is 40% or more, and when the crystal unit 5 is bonded to the first wiring layer 2a through the fixing material 9, the work such as positioning is easy. Become. Therefore, when the surface of the first wiring layer 2a is covered with a plating layer of nickel, copper, gold or the like, the arithmetic average roughness (Ra) of the outermost surface is 1.5 μm or less, and the root mean square roughness (Rms). Is preferably 1.8 μm or less.
[0044]
Further, the arithmetic average roughness (Ra) of the outermost surface of the plating layer made of nickel, copper, gold or the like covering the surface of the first wiring layer 2a is 1.5 μm or less, and the root mean square roughness (Rms) is 1. To reduce the thickness to 8 μm or less, the first wiring layer 2a is immersed in an electrolytic nickel plating solution in which a brightening agent such as a sulfur compound is added to a well-known Watt bath, and the nickel plating layer is deposited on the surface of the first wiring layer 2a. Thereafter, it is carried out by dipping in a cyan electrolytic gold plating solution and depositing a gold plating layer on the surface of the nickel plating layer.
[0045]
Furthermore, the crystal unit 5 is bonded and fixed to the first wiring layer 2a via a fixing material 9, and at the same time, the electrodes of the crystal unit 5 are electrically connected to the first wiring layer 2a.
[0046]
The fixing material 9 is generally formed by adding a conductive powder such as silver powder to a thermosetting resin such as an epoxy resin, and the crystal resonator 5 is placed on the first wiring layer 2a. Positioning and setting is performed via an uncured fixing material obtained by adding conductive powder to a thermosetting resin, and the uncured thermosetting resin is heat-cured to place the crystal unit 5 in a predetermined position in the recess A. And the electrode of the crystal unit 5 is electrically connected to the first wiring layer 2a.
[0047]
The first base 1a to which the crystal unit 5 is bonded and fixed via a fixing material 9 has a lid 3 attached to the upper surface thereof, whereby the inside of the container 4 comprising the first base 1a and the lid 3 is provided. The quartz resonator 5 is housed in an airtight manner.
[0048]
The lid 3 is formed of a metal material such as an iron-nickel-cobalt alloy or an iron-nickel alloy, or a ceramic material such as an aluminum oxide sintered body. For example, an iron-nickel-cobalt alloy ingot Are formed by performing known metal processing such as rolling and punching.
[0049]
Further, the attachment of the lid 3 to the first base 1a can be performed by a method using a bonding material such as a brazing material, glass, or an organic resin adhesive, or by a welding method such as seam welding. When the lid 3 is attached by seam welding, a frame-like brazing metallization layer 12 is usually applied around the recess A on the upper surface of the first base 1a in the same manner as the first wiring layer 2a. In addition, a metal frame 13 is brazed to the brazing metallization layer 12 via a brazing material such as silver brazing, and then the metal lid 3 is placed on the metal frame 13 and the lid. This is done by seam welding the three outer edges. In this case, if the metal frame 13 is rounded with a radius of curvature of 5 to 30 μm at the corner between the upper surface and the side surface, no burr is formed on the upper surface side of the metal frame 13. When the lid 3 is seam welded to the upper surface of the metal frame 13, the two can be reliably and airtightly bonded. Therefore, it is preferable that the metal frame 13 has a round corner with a radius of curvature of 5 to 30 μm at the corner between the upper surface and the side surface.
[0050]
Furthermore, when the metal frame 13 is rounded with a radius of curvature of 40 to 80 μm at the corner between its lower surface and side surface, the metal frame 13 is brazed to the brazing metallization layer 12. When joining via the material, a space is formed between the brazing metallized layer 12 and the lower surface side corner of the metal frame 13, and a large pool of brazing material is formed in the space, and the metal frame 13 is formed. The bonding to the brazing metallization layer 12 becomes strong. Accordingly, in order to firmly bond the metal frame 13 to the brazing metallization layer 12 via the brazing material, the corner between the lower surface and the side surface of the metal frame 13 is rounded with a curvature radius of 40 to 80 μm. It is preferable to form it.
[0051]
A second base 1b for fixing and housing the semiconductor element 6 is disposed below the first base 1a in which the crystal unit 5 is fixedly housed.
[0052]
The second substrate 1b has a coefficient of linear thermal expansion of 2 × 10. ^-6 / ° C to 8 × 10 ^-6 / ° C (40-400 ° C), for example, 10-68 mol% BaO, 9-50 mol% SnO ₂ 13-72 mol% B ₂ O _Three Oxide sintered body comprising, or Si component is SiO ₂ 25 to 80% by weight in terms of B, 15 to 70% by weight in terms of Ba component, and B component to B ₂ O _Three Converted to 1.5 to 5% by weight, Al component is Al ₂ O _Three 1 to 30% by weight in terms of Ca, and a Ca component containing 0% by weight to CaO in excess of 30% by weight or less, and a recess B is provided on the lower surface thereof. Accommodates a semiconductor element 6 that performs temperature compensation of the crystal unit 5.
[0053]
The second substrate 1b has a second wiring layer 2b deposited from the surface of the recess B to the outer surface, and the electrode of the semiconductor element 6 is exposed on the surface of the recess B of the second wiring layer 2b. A portion connected through a conductive connecting member 11 such as a bonding wire and led to the outer surface is connected to the first wiring layer 2a of the first base 1a and the wiring conductor of the external electric circuit board.
[0054]
The second base 1b has a linear thermal expansion coefficient of 2 × 10. ^-6 / ° C to 8 × 10 ^-6 / ° C. (40 to 400 ° C.), and the linear thermal expansion coefficient of the semiconductor element 6 (silicon: about 2.5 × 10 ^-6 / ° C .: 40 to 400 ° C.), the semiconductor element 6 is accommodated in the concave portion B of the second base 1b and bonded and fixed via the adhesive 10; A large thermal stress does not occur in the meantime, and as a result, the semiconductor element 6 can be securely and firmly fixed in the recess B of the second base 1b.
[0055]
The linear thermal expansion coefficient is 2 × 10 ^-6 / ° C to 8 × 10 ^-6 Specifically, the second substrate 1b at / ° C. (40 to 400 ° C.) is composed of 10 to 68 mol% BaO and 9 to 50 mol% SnO. ₂ 13-72 mol% B ₂ O _Three Oxide sintered body comprising, or Si component is SiO ₂ 25 to 80% by weight in terms of B, 15 to 70% by weight in terms of Ba component, and B component to B ₂ O _Three In terms of 1.5 to 5% by weight, Al component is Al ₂ O _Three 1 to 30% by weight in terms of Ca, and a Ca component containing 0 to 30% by weight in terms of CaO. For example, 10 to 68 mol% BaO, 9 to 50 mol% SnO ₂ 13-72 mol% B ₂ O _Three In the case of an oxide sintered body made of BaO, SnO ₂ , B ₂ O _Three A green sheet (green sheet) is obtained by adding a binder mainly composed of an acrylic resin, a dispersant, a plasticizer, and an organic solvent to a raw material powder such as a slurry and adopting a doctor blade method or a calender roll method. After that, the green sheet is subjected to an appropriate punching process and a plurality of the green sheets are laminated and fired at a temperature of about 800 ° C. to 1200 ° C.
[0056]
The second substrate 1b is made of 10 to 68 mol% BaO and 9 to 50 mol% SnO. ₂ 13-72 mol% B ₂ O _Three When the BaO is less than 10 mol%, the dielectric loss increases and the electrical signal propagating through the second wiring layer 2 b is attenuated or delayed, and 68 mol%. If it exceeds, the mechanical strength of the second substrate 1b is greatly reduced. Accordingly, the amount of BaO constituting the oxide sintered body is specified to be 10 to 68 mol%.
[0057]
The oxide sintered body is SnO. ₂ If it is less than 9 mol%, the sinterability is lowered and the mechanical strength becomes insufficient, and if it exceeds 50 mol%, the dielectric loss increases and the electric signal propagating through the second wiring layer 2b is attenuated or delayed. Resulting in. Accordingly, the oxide sintered body is composed of SnO. ₂ Is specified as 9 to 50 mol%.
[0058]
Further, the oxide sintered body is B ₂ O _Three If it is less than 13 mol%, the firing temperature becomes high and it becomes difficult to fire simultaneously with the second wiring layer 2b made of a metal material such as copper, and if it exceeds 72 mol%, the chemical resistance is lowered and the crystal is reduced. The reliability as a device is low. Therefore, the oxide sintered body is composed of B constituting it. ₂ O _Three Is specified to be 13 to 72 mol%.
[0059]
The second substrate 1b has a second wiring layer 2b formed from the surface of the recess B to the outer surface, and an electrode of the semiconductor element 6 is bonded to a portion exposed on the surface of the recess B of the second wiring layer 2b. A portion connected via a conductive connecting member 11 such as a wire and led to the outer surface is connected to the first wiring layer 2a of the first base 1a and the wiring conductor of the external electric circuit board.
[0060]
The second wiring layer 2b is formed by simultaneous firing with the second substrate 1b. Since the firing temperature of the second substrate 1b is as low as about 800 to 1200 ° C., the specific electric resistance is 2.5 μΩ · cm (20 ° C.) or less. Low copper, gold, or silver can be used. For example, when it is made of copper, a metal sheet obtained by adding and mixing an appropriate organic solvent, organic binder, etc. to copper powder is used as a green sheet for the substrate 1 By printing and applying a predetermined pattern on the surface of the second substrate 1b by a screen printing method or the like, a predetermined pattern is formed at a predetermined position of the second substrate 1b.
[0061]
If the exposed surface of the second wiring layer 2b is covered with a plating layer (not shown) made of a metal having good corrosion resistance such as nickel, copper, and gold and good wettability of the brazing material, the second wiring layer 2b has a second structure. The oxidative corrosion of the wiring layer 2b can be satisfactorily prevented, and the wettability of the brazing material such as solder to the second wiring layer 2b can be improved, so that the second wiring with respect to the wiring conductor of the external electric circuit board can be obtained. The connection of the layer 2b can be made easier and more reliable. Accordingly, the exposed surface of the second wiring layer 2b is a plating layer of nickel, copper, gold or the like, for example, a nickel or nickel alloy plating layer having a thickness of 1 μm to 10 μm, which is sequentially deposited, and a thickness of 0.1 μm to 3 μm. It is preferable to coat with a gold plating layer.
[0062]
The second substrate 1b also has a semiconductor element 6 for receiving and fixing the temperature of the crystal resonator 5 accommodated and fixed in a recess B provided on the lower surface thereof. The semiconductor element 6 has a vibration frequency of the crystal resonator 5. By controlling the fluctuation with temperature change, the vibration frequency of the crystal unit 5 is always kept constant.
[0063]
The semiconductor element 6 is bonded and fixed to the bottom surface of the recess B provided on the lower surface of the second base 1b via an adhesive material 10 such as brazing material, glass, organic resin, etc. It is electrically connected to the second wiring layer 2b exposed in the concave portion B of the second base 1b through a conductive connecting member 11 such as a bonding wire.
[0064]
The semiconductor element 6 accommodated in the recess B of the second base 1b is hermetically sealed with a sealing resin 14 filled in the recess B.
[0065]
Further, the sealing of the semiconductor element 6 is not limited to that performed by the sealing resin 14, and may be performed by attaching a lid to the lower surface of the second base 1 b so as to close the recess B. Good.
[0066]
Further, the first base 1a for fixing and housing the crystal unit 5 and the second base 1b for fixing and storing the semiconductor element 6 are joined via a joining material 8 having an elastic modulus of 4 GPa or less.
[0067]
Since the bonding material 8 has an elastic modulus of 4 GPa or less and is soft and easily deformed, the heat generated by the semiconductor element 6 when the semiconductor element 6 is activated repeatedly acts on the first base 1a and the second base 1b. The heat generated by the semiconductor element 6 during operation of the semiconductor element 6 repeatedly acts on the two bases 1b, and a large thermal stress is repeatedly generated between the first base 1a and the second base 1b due to the difference in linear thermal expansion coefficient between the two bases 1b. The thermal stress is absorbed by appropriately deforming the bonding material 8, and as a result, it is disengaged between the first base 1 a and the second base 1 b and mechanically applied to the first base 1 a and the second base 1 b. There is no destruction, and the crystal resonator 5 accommodated in the first base 1a and the semiconductor element 6 accommodated in the second base 1b can be reliably electrically connected.
[0068]
The bonding material 8 is difficult to be deformed when its elastic modulus exceeds 4 GPa, and cannot effectively absorb the thermal stress generated between the first base 1a and the second base 1b. The first substrate 1a, the second substrate 1b, or the bonding material 8 is mechanically damaged, causing a problem such as breaking the hermeticity of the container 4 that accommodates the crystal resonator 5 and losing the function as a crystal device. . Therefore, the elastic modulus of the bonding material 8 is specified to be 4 GPa or less.
[0069]
As the bonding material 8 having an elastic modulus of 4 GPa or less, an epoxy resin to which rubber particles such as acrylic rubber and isoprene rubber are added is preferably used. As the epoxy resin, (ortho) cresol novolak type, phenol novolak type An epoxy resin such as naphthalene-based aralkyl type or polysulfide-modified type is preferably used.
[0070]
In this case, the elastic modulus of the bonding material 8 can be reduced by increasing the amount of rubber particles added to the epoxy resin, and the epoxy resin state (structure, degree of crosslinking, degree of polymerization, type of curing agent, etc.) can be reduced. Accordingly, the elastic modulus of the bonding material 8 can be set to 4 GPa or less by appropriately controlling the addition amount of the rubber particles. If the amount of the 3 rubber particles added to the epoxy resin exceeds 50% by weight, the shape retention of the bonding material 8 is greatly reduced, and it is difficult to firmly bond the first substrate 1a and the second substrate 1b. Tend to be. Therefore, when rubber particles are added to the epoxy resin, the addition amount is preferably set to 50% by weight or less within a range where the elastic modulus of the bonding material 8 is 4 GPa or less.
[0071]
Further, when the elastic modulus of the bonding material 8 is less than 1 GPa, the bonding material 8 tends to be deformed too easily, and it tends to be difficult to reliably and firmly bond the first base 1a and the second base 1b. Therefore, the elastic modulus of the bonding material 8 is preferably set to 4 GPa or less and 1 GPa or more.
[0072]
The first base 1a and the second base 1b are joined by the joining material 8 by positioning the first base 1a and the second base 1b through an uncured joining material obtained by adding rubber particles to an uncured epoxy resin. It can be performed by setting and curing the uncured epoxy resin by heating.
[0073]
The bonding material 8 having an elastic modulus of 4 GPa or less is not limited to the above-described epoxy resin composition, and is formed of a resin composition in which a filler component such as silica is added to a low elastic modulus thermosetting resin such as a silicone resin. May be.
[0074]
Thus, according to the crystal device 7 described above, the first wiring layer 2a and the second wiring layer 2b are connected to an external electric circuit, and a predetermined voltage is applied to the electrodes of the crystal resonator 5, whereby the crystal resonator 5 is predetermined. The crystal element 5 is compensated for temperature by the semiconductor element 6 and used as an accurate time and frequency reference source in an information processing apparatus such as a computer or an electronic apparatus such as a mobile phone. .
[0075]
It should be noted that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, as shown in FIG. 2, the first wiring layer 2a If a protrusion 15 is formed on a part of the first protrusion 15, a certain space is secured between the first wiring layer 2 a and the crystal unit 5 as a protrusion 15, and sufficient fixing material 9 is provided in this space. Can penetrate into the first wiring layer 2a and can be bonded and fixed extremely firmly.
[0076]
Further, in the above-described crystal device 7, the concave portion A is provided on the upper surface of the first base 1a, and the crystal resonator 5 is accommodated in the concave portion A. As shown in FIG. 3, this is the flat first base 1a. The present invention can also be applied to a quartz crystal device 7 in which the quartz crystal resonator 5 is mounted and fixed thereon and the fixed quartz crystal resonator 5 is hermetically sealed with a bowl-shaped lid 3.
[0077]
【The invention's effect】
According to the present invention, the linear thermal expansion coefficient of the first base to which the crystal resonator is fixed is 14 × 10. ^-6 / ° C to 20 × 10 ^-6 / ° C. (40 to 400 ° C.), and the linear thermal expansion coefficient of the crystal resonator (18 × 10 ^-6 / ° C .: 40 to 400 ° C.), even if heat is applied to the crystal resonator and the first base, no large thermal stress is generated between them. It is possible to firmly bond and fix to the base body and to stably operate the crystal resonator.
[0078]
According to the present invention, the linear thermal expansion coefficient of the second base to which the semiconductor element for compensating the temperature of the crystal resonator is fixed is 2 × 10. ^-6 / ° C to 8 × 10 ^-6 / ° C. (40 to 400 ° C.), and the linear thermal expansion coefficient of the semiconductor element (2.5 × 10 ^-6 / ° C .: 40 to 400 ° C.), even if heat is applied to the semiconductor element and the second substrate, no large thermal stress is generated between them. As a result, the semiconductor element is applied to the second substrate. It is possible to firmly fix and fix the crystal resonator, and it is possible to accurately perform temperature compensation of the crystal resonator over a long period of time by the semiconductor element.
[0079]
Furthermore, according to the present invention, since the elastic modulus of the bonding material for bonding the first base and the second base is 4 GPa or less, it is caused by the difference in the linear thermal expansion coefficient between the first base and the second base. Even if a large thermal stress is generated between the two, the thermal stress is effectively absorbed by appropriately deforming the bonding material, and the first base, the second base, or the first base and the second base It is possible to effectively prevent mechanical destruction of the bonding material for bonding the crystal and complete the connection between the crystal unit and the semiconductor element, thereby improving the long-term reliability of the crystal device. it can.
[0080]
Furthermore, according to the present invention, the specific electrical resistance of the first wiring layer and the second wiring layer to which the crystal resonator and the semiconductor element are connected is set to a low value of 2.5 μΩ · cm (20 ° C.) or less. When a reference signal of a crystal resonator, a drive signal of a semiconductor element, or the like is propagated to the first wiring layer and the second wiring layer, the reference signal and the drive signal are not greatly attenuated, and the reference signal and the drive signal are not electrically connected. It becomes possible to propagate accurately and reliably between a circuit or a crystal resonator and a semiconductor element.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of a quartz crystal device of the present invention.
FIG. 2 is a cross-sectional view of an essential part showing another embodiment of the quartz crystal device of the present invention.
FIG. 3 is a cross-sectional view showing another embodiment of the quartz crystal device of the present invention.
[Explanation of symbols]
1a: First base
1b ... the second substrate
A ... Recess
B ・ ・ ・ ・ ・ ・ Recess
2a: First wiring layer
2b ... Second wiring layer
3 .. Lid
4 ... Container
5 ・ ・ ・ ・ ・ ・ Quartz crystal unit
6. Semiconductor elements
7 ・ ・ ・ ・ ・ ・ Quartz device
8 .... Joint material
9. Fixing material
10 ... Adhesive
11 ... Conductive connection member
12 ... Metallization layer for brazing
13 ... Metal frame
14 ... Sealing resin
15 ... Protrusions

Claims (1)

A first base having a mounting portion on the upper surface and having a first wiring layer led out from the mounting portion to the outer surface, and fixed to the mounting portion of the first base, and an electrode connected to the first wiring layer A quartz resonator, a second base having a mounting portion on the lower surface and having a second wiring layer led out from the mounting portion to the outer surface, and an electrode fixed to the mounting portion of the second base A crystal device comprising: a semiconductor element for performing temperature compensation of the crystal resonator connected to the second wiring layer; and a bonding material for bonding the lower surface of the first base and the upper surface of the second base,
The linear thermal expansion coefficient of the first substrate is 14 × 10 ⁻⁶ / ° C. to 20 × 10 ⁻⁶ / ° C. (40 to 400 ° C.), and the linear thermal expansion coefficient of the second substrate is 2 × 10 ⁻⁶ / ° C. to 8 × 10 ⁻⁶ / ° C. (40 to 400 ° C.), the specific electric resistance of the first wiring layer and the second wiring layer is 2.5 μΩ · cm or less, and the elastic modulus of the bonding material is 4 GPa or less. A featured quartz device.

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