JPH07120688B2 - Micro joint structure - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a structure for electrically bonding a semiconductor chip or an electronic component to a wiring board, and in particular, a large LSI chip and a wiring board are connected horizontally. The present invention relates to a micro joint structure having a flexible structure that does not break with respect to a directional load and improves its fatigue life.

[Conventional technology]

In recent electronic devices, LSI chips are becoming highly integrated and large in size in order to miniaturize the device and improve the arithmetic processing performance. As a result, the LS mounted on the wiring board is becoming larger.
Thermal rupture and thermal fatigue life of solder joints of I-chips are becoming major problems.

On the other hand, in the case of ultra-high-performance devices such as electronic computers, the conventional 1-chip package system has been changed to the multi-chip module system in which multiple bare or chip-encapsulated LSI chips are mounted on a single multilayer wiring board. Going on,
Further, in order to remove heat from the LSI chip, a cooling body in which water is circulated is arranged directly above the chip, and a method of connecting the cooling body and the LSI chip with a high heat transfer structure is considered. Furthermore, in the future, when the integration degree of the LSI chip is improved and the heat generation amount per chip reaches a level exceeding 40 W, the structural elements of the LSI chip are cooled to the operating range of 85 ° C. or lower,
It is assumed that there will be no choice but to adopt a method in which the LSI chip and the cooling body are connected with a metal material and cooling is performed only by heat conduction.

FIG. 9 is a diagram showing an example of a basic device configuration of a multi-chip module in this assumption. Multi-phase wiring board
66 is the chip carrier 64 on it and CCB made of solder
It is joined through the joint 65, and the chip carrier
The reference numeral 64 denotes a drain pipe 61 and a water supply pipe via the cooling solder fixing portion 63.
It is joined with the cooling body 60 having 62. Since the cooling body 60 is made of metal and the multilayer wiring board 66 is made of an organic material or a ceramic material, the cooling body 60 and the multilayer wiring board are
Since it is practically difficult to match the thermal expansion coefficient of 66 with each other, in a multi-chip module with a size of 100 mm square or more, the heat shrinkage due to cooling after soldering causes
A strain of several tens to several hundreds of μm occurs between the 60 and the multilayer wiring board. For this reason, the structurally weakest CCB joint 65
Is destroyed, the thermal fatigue life thereof is significantly reduced, and the reliability of the device is significantly deteriorated. In order to reduce the reliability of the device due to the above-mentioned thermal strain, a new joint structure that is an improvement of the normal CCB joint has been devised, but even in this improvement plan, the problem of the above-mentioned destruction and thermal fatigue The reality is that we have not been able to fully solve the problem. The improvement plan is shown below.

FIG. 10 is a diagram showing an improved solder structure of an LSI chip. The LSI chip 67 and the multi-layer wiring board 71 are composed of several wiring joining pads 68 provided on the LSI chip 67 and several electrode joining pads 70 provided on the multi-layer wiring board 71 at respective solder joints 69.
They are joined together and integrated as a module. In this bonding method, first, the wiring bonding pad 68 and the electrode bonding pad 70 are vapor-deposited or plated onto the wiring bonding pad 68 and the electrode bonding pad 70.
A solder film having a predetermined composition of Pb and Sn is formed, and then this film is once heated and melted to form a hemispherical solder bump, and finally, the solder bump of the LSI chip 67 and the multilayer wiring board 7
Position the solder bumps so that they face each other, and melt the solder bumps by heating in an inert or reducing atmosphere in the furnace, and then apply the mechanical or magnetic force to the LSI chip 67 before the solder solidifies. It is pulled up by using a centrifugal force or the like to form a staggered solder joint 69. By improving the solder joint from the conventional barrel shape to the slug type, strain in the solder joint can be dispersed and stress concentration can be relieved. Than 4
It is expected to be more than doubled.

[Problems to be solved by the invention]

In the future, the number of LSI chips will be 2 to 3 times the current level or more (20 mm
If the size of the LSI chip is larger than that of the LSI chip, or if the LSI chip or chip carrier is metallically joined to the cooling body to cool the LSI chip with high efficiency, the LSI chip or chip carrier is joined via the solder joint. Due to the thermal strain generated between the solder joint and the wiring board, the solder joint is broken or the fatigue life of the solder joint is significantly reduced. To date, no fundamental solution has been found to this problem.

In the conventional improvement plan shown in FIG. 10 described above, the fatigue life of the solder is improved by changing the shape of the solder joint portion from the barrel shape to the zigzag shape.
The following equation N _f = C · (γ _max ) ^-5 (1) γ _max ^∝ δ (2) where N _f : low cycle fatigue life C: constant γ _max : maximum shear strain δ: wiring As shown in the relative displacement between the board and the LSI chip, it decreases in inverse proportion to the square of the relative displacement between the wiring board and the LSI chip. For example, when the relative displacement becomes twice as large as the conventional one, In order to obtain the same fatigue life, it is necessary to increase the solder height from the conventional 100 μm to 400 μm by making a trial calculation from the data disclosed in JP-A-61-156745. However, a practical solder bump diameter of 50-20
When the solder height is extended to 400 μm or more with respect to 0 μm, the molten solder becomes constricted and broken, which makes it practically difficult to join.

Therefore, the method of improving the fatigue life of solder joints by increasing the solder height is that the relative displacement is about twice that of the conventional method, that is, 20 μm.
It is applied below that, and it is difficult to apply to absolute displacements beyond that.

An object of the present invention is to provide a joint portion for electrically connecting a semiconductor component on a wiring board, even if the relative displacement between the semiconductor component and the wiring board reaches several tens to several hundreds μm due to temperature change. It is an object of the present invention to provide a micro joint structure that does not break and that can improve its fatigue life.

[Means for solving problems]

In a micro joint structure in which connecting terminal portions of the members to be joined which are arranged with a minute interval are opposed to each other with a joining material made of a material different from that of the connecting terminal portion, the magnetic force passed between the connecting terminals is A thin metal wire containing a metal having
The above problem is solved by a micro-joint structure characterized by comprising at least each end of the metal thin wire and a brazing material joining each of the connection terminal portions.

[Action]

 The operation will be described with reference to FIG.

The member to be joined 1 and the member to be joined 1'include a connection terminal portion 2 provided on the member 1 to be joined, a connection terminal portion 3 provided on the member 1'to be joined, and connection terminal portions 2 facing each other, According to the micro joint structure composed of the thin metal wire 6 containing the magnetic metal passed through the gap of 3, and the brazing materials 4 and 5 in which each end of the thin metal wire is joined to the connection terminals 2 and 3, respectively, Are combined.

Now, assuming that a relative displacement δ occurs between the members 1 and 1 ′ to be joined due to a temperature change, the thin metal wire 6 containing a magnetic metal is changed from the linear shape shown in FIG. 1 (a). It changes on the curve shown in FIG. At this time, since the relative displacement δ is absorbed by the bending deformation of the metal thin wire 6 containing a magnetic metal, the shear stress generated in the metal thin wire and the layers of the brazing materials 4 and 5 is extremely low.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 9.

FIG. 1 (a) is a diagram showing the basic configuration of the present invention. The semiconductor component 1 and the semiconductor component 1'include a connection terminal portion 2 provided on the semiconductor component 1, a connection terminal portion 3 provided on the semiconductor component 1 ', and a metal passed through a gap between the connection terminal portions 2 and 3. The fine wire 6 and each end of the metal fine wire 6 are joined by a micro joint structure composed of the soldering layers 4,5 in which the respective ends are joined to the connection terminal portions 2 and 3, and between the connection terminal portions 2 and 3. Is formed on the surface of each connection terminal portion and has a thin metal wire 6
The soldering layers 4 and 5 including the end portions of and the layer including only the thin metal wires 6 are included.

Now, it is assumed that the relative displacement δ occurs between the semiconductor component 1 and the semiconductor component 1'due to a temperature change, and the micro joint structure is changed from the state shown in Fig. 1A to the state shown in Fig. 1B. In terms of material mechanics, this state can be regarded as equivalent to the problem of a long column in which both ends are rigidly contacted, one end position is fixed, and the other end position is free, as shown in FIG. At this time, the relation of the following equation (2) is established between the relative displacement δ and the shearing force F at the end of the thin metal wire which is a long column, and when the cross-sectional shape of the metal thin wire is a circle, the second moment of area is It is expressed by equation (3).

F = 12 · E · I · δ / l 3 ...... (2) where, E: elastic modulus of the metal thin wires l: thin metal wires only a layer height I = πd ^4/64, where, d: Metal Diameter of fine wire That is, as can be seen from equations (2) and (3), the shearing force F generated when the relative displacement is δ is proportional to the fourth power of the diameter d of the fine metal wire 6, It can be significantly reduced by making it smaller. By the way, Ni's elastic modulus E = 1.9
X10 ¹² dyn / cm ² was used, the height l of the layer consisting of the thin metal wires 6 was 300 μm, and the diameter d of the thin metal wires 6 was 5 μm.
When the shearing force F when a relative displacement δ of 00 μm is generated is calculated, F = 2.6 × 10 ⁻² g, and the force applied to the solder material is very small. That is, the solder layer is not destroyed. Further, since the strain of the thin metal wire 6 itself can be reduced in proportion to its diameter d, the strain of the thin metal wire 6 can be kept within the elastic limit, so that low cycle fatigue does not occur within the elastic strain. It is possible to prevent fatigue fracture due to repeated deformation of the thin metal wire 6.

That is, by using a metal thin wire having a diameter of about several μm and a length of several hundred μm or more and forming a layer consisting of only a few hundred μm of metal thin wire in the micro joint structure, for example, the placement substrate and the LS
Even when the thermal strain in which the relative displacement of the I-chip reaches 100 μm is repeated, fatigue fracture does not occur and a highly reliable micro joint structure can be obtained.

On the other hand, from the point of view of electrical resistance, the micro-joint structure contains fine metal wires, which may cause an increase in its electrical resistance.However, if the fine metal wires are composed mainly of copper, the specific resistance of copper ρ
= 1.7 μΩ · cm, the diameter of the metal wire is 5 μm, the length is 300 μm, and the electrical resistance is calculated to be 26 mΩ. If 26 metal wires per terminal are used, it will be a parallel circuit of resistors. Therefore, the electric resistance of the micro joint structure is 1 mΩ, and since this value is equal to or less than the wiring resistance of the wiring board, there is no particular problem. And, the shearing force per terminal at this time is as small as 0.68 g.
This shearing force is further increased by further thinning the metal thin wire or by further heightening the layer made of only the metal thin wire.
It is possible to reduce by about 2 digits.

FIG. 3 is a diagram showing a bonding process when mounting an LSI chip on a multilayer wiring board and a cross-sectional structure of the module. LS
The I chip 7 and the alumina ceramic multilayer wiring board 8 are composed of a connection terminal 9 formed on the surface of the LSI chip 7, a connection terminal 10 formed on the surface of the multilayer wiring board 8, and a connection terminal 9,
A fine metal wire 13 containing a metal having a magnetic property that passes through the gap facing 10 and a solder layer 11, 12 formed on the surface of the connection terminals 9, 10 and including each end of the fine metal wire 13, Are joined by a micro joint structure made of.

The first step is a step of supplying the thin metal wire 13 containing a metal having magnetism. First, the diameter 50 adjusted to the position of the connection terminal 10 is set.
A non-magnetic jig 14 provided with as many through-holes as the number of connection terminals 10 is arranged above the multilayer wiring board 8. The next inside is magnetic metal Ni and the surface layer is a good conductor of electricity and heat. A thin metal wire 13 made of Cu and having a length of 200 μm and a diameter of 10 μm is dispersed on the jig 14, and a magnetic field is applied in a direction perpendicular to the surface of the jig 14 to form the jig 14
Vibrate. At this time, the thin metal wire 13 stands vertically on the surface of the jig 14 due to the magnetic field, and drops on the connection terminal 10 through the through hole while moving. The number of falling metal wires 13 can be adjusted by changing the diameter of the through hole of the jig 14. Note that the solder 12 having a predetermined composition is coated on the connection terminal 10 in advance by using a means such as plating or vapor deposition.

The second step is a step of locating the LSI chip, and the chip aligner is used to position the LSI chip 7 so that the connection terminals 10 of the multilayer wiring board 8 and the connection terminals 9 of the LSI chip 7 facing it are accurately aligned with each other. Adjust the position and gently place it from above on the forest of metal wires 13. Solder 11 is coated on the connection terminals 9 of the LSI chip 7 in the same manner as the connection terminals 10 described above. The magnetic field is continuously applied from the step II.

The final third step is the soldering step, in which the solder 11 and 12 are melted by means such as hot gas or infrared heating,
The final step is completed by soldering the thin metal wires 13 to the connection terminals 9 and 10.

The height of the thin metal wire layer depends on the length of the thin metal wire 13 and the solder 11,12.
Is adjusted according to the amount of. In the present embodiment, the thickness of each of the solders 11 and 12 is 20 μm, and the length of the thin metal wire is 200 μm, so the layer of the thin metal wire is 160 μm.

Here, let us examine the thermal strain generated between the multilayer wiring board and the LSI chip during the cooling process after soldering when a large 30 mm square LSI chip is mounted on the alumina ceramic multilayer wiring board. If the thermal strain is δ, then δ = ΔT ·
Expressed by Δα ・ W / 2, the difference between soldering temperature and room temperature ΔT = 300
℃, difference in thermal expansion coefficient between LSI chip and multilayer wiring board Δα = 5 ×
10 ^-6 , If the length of the long side of the LSI chip is W = 30 mm, δ = 30
0 × 5 × 10 ^-6 × 30/2 = 22.5 × 10 ^-6 mm, that is, δ = 22.
It is 5 μm.

According to the present embodiment, the above thermal strain can be absorbed by bending deformation within the elastic strain range of the thin metal wire, and the low cycle thermal strain that occurs during operation is also smaller than the above thermal strain, so the thin metal wire is used. Since it can be easily absorbed, it is possible to prevent thermal breakage or thermal fatigue breakage of the soldered portion, the thin metal wire and the connection terminal. Therefore, it is possible to manufacture an electronic device using a large-sized LSI chip, and at the same time, greatly improve its reliability.

FIG. 4 is a diagram showing an embodiment in which the connection terminal and the thin metal wire are made of a magnetic material containing at least one of Fe, Ni and Co.

The connection terminal 9 of the LSI chip 7 is composed of a magnetic terminal film 17 formed on the surface of the LSI chip 7 and made of the above-mentioned magnetic material, and a soldering terminal film covering the magnetic terminal film 17, and also has a multilayer structure. The connection terminal 10 of the wiring board 8 is also composed of a magnetic terminal film 16 and a soldering terminal film 18 like the connection terminal 9, and solders 11 and 12 are formed on the connection terminals 9 and 10, respectively. There is. The LSI chip 7 and the multilayer wiring board 8 are integrally joined by connecting the connection terminals 9 and 10 to each other and soldering the ends of the thin metal wires 13 arranged in the gaps with the solders 11 and 12. The soldering terminal film is for improving the wettability of the solder and widening the connection area.

According to the present embodiment, when controlling the orientation of the thin metal wires by applying a magnetic field in the above-described joining process, “the magnetic lines of force become denser than the other inside the ferromagnetic body placed in the magnetic field, As a result, the metal thin wire having magnetism is attracted to the ferromagnetic material. ”Therefore, since the metal thin wire can be gathered in the central portion of the connection terminal, when the adjacent connection terminals are close to each other, Even if a thin metal wire with some bends is mixed, it is possible to prevent the metal thin wire arranged on a certain connection terminal from contacting the adjacent connection terminal and short-circuiting, thus reducing the incidence of product defects in the bonding process. The yield can be improved. Further, in the positioning of the LSI chip in the step II described in FIG. 3, even if there is a slight misalignment between the upper and lower connecting terminals facing each other, the connecting terminal and the metal thin wire both having magnetism are attracted by the magnetic force. There is also the effect that self-alignment is achieved by interacting.

FIG. 5 is a view showing a carrier assembling method in which an intermediate substrate is used as a carrier and a cross section of a module to be assembled in a form in which an LSI chip (two) is controlled to a wiring substrate (one). In this carrier assembly method, the LSI chip 1
9 and the wiring board 20 are supplied in the following manner. That is, the LSI chip 19 is provided with several connection terminals 21 at positions near the center of the lower surface of the LSI chip 19 and solder 25 is formed in layers on the surface of the connection terminals 21, and the dummy terminals 3 are provided at both ends of the lower surface of the LSI chip 19.
8 is provided in the form of forming a ball-shaped solder 24 on the dummy terminal surface thereof, while the wiring board 20 is provided on the upper surface thereof at positions facing the connection terminals 21 and the dummy terminals 38, respectively. The connection terminals 22 and the dummy terminals 39 are provided, and the connection terminals 22 are soldered with the thin metal wires 27 containing a magnetic metal by the solder 26 formed on the connection terminals 22 substantially vertically. It is supplied in a form in which a connection terminal 23 corresponding to the connection terminal 22 on the opposite surface is provided on the lower surface of the. The thin metal wire 27 containing a metal having magnetism is fixed by soldering by heating immediately after supplying the thin metal wire in the step I of FIG.

In the step I shown in FIG. 5, since the thin metal wire 27 is fixed, it is not necessary to apply a magnetic field, and the LSI chip 1 is simply used.
All that is required is to position 9 on the intermediate substrate 20 and place it.

Next, in the step II, a magnetic field is applied in a direction perpendicular to the surface of the intermediate substrate 20 to heat the intermediate substrate 20. The solders 24, 25, 26 are all melted, and the thin metal wires 27 are soldered while standing substantially vertically by the magnetic field. At this time, the dummy terminal
The solder 24 melted between 38 and 39 plays the role of self-alignment for correcting the displacement of the connection terminals of the intermediate substrate 20 and the LSI chip facing each other due to the surface tension.

FIG. 6 is a sectional view of a portion where the LSI chip / chip carrier module described in FIG. 5 is incorporated into a large-scale computer. In FIG. 6, the module is hermetically sealed in a housing including a wiring board 32 arranged below the module and a cooling structure covering the upper part and the surroundings. More specifically, the module has an LSI chip 1 on top.
9, the lower part of which is the intermediate substrate 20 having the connection terminals 23 on the lower surface, which are joined together by the micro joint according to the present invention. The wiring board 32 has, on its upper surface, a connection terminal 34 provided at a position facing the connection terminal 23 and a metallized film 36 that receives a sidewall of the cooling structure 28. The cooling structure 28 has a housing structure, and the housing 28a corresponding to the upper lid has a water cooling passage 28e therein.
On the lower surface of the housing 28a, at a position facing the LSI chip 19, a cooling block 28d hangs down via a bellows 28c, a water cooling passage 28e leads to the inside thereof, and side walls 28b surrounding the four sides. Has reached the wiring board 32 below.

Explaining the procedure for integrally assembling the above module, wiring board, and cooling structure, first, the module is placed on the wiring board 32, and the solder 35 previously coated on the connection terminal 34 of the wiring board 32 is preliminarily attached. Therefore, solder joining is performed. Here, the solder 35 needs to have a lower melting point than the solders 24, 25, 26 used for joining the LSI chip 19 and the intermediate substrate 20, and is more than 95P _b −5S _{n of the} solders 24, 25, 26. Low melting point 60P _b −4
0S _n solder is used. Then, the cooling structure 28 is placed on the module / wiring board. The upper surface of the LSI chip 19, the lower surface of the cooling block 28d, and the housing side wall 28b.
A metal having good solder wettability is metallized in advance on the lower surface of each of the above. Solder foil with a lower melting point (170 ° C or less) than the above two types of solder when covering the cooling structure 3
3, 37 are sandwiched between the cooling block 28d and the LSI chip 19 and between the housing side wall 28b and the metallized film 36, respectively. Then, the whole is heated to a temperature of 170 ° C. or less in a He atmosphere to melt the solder foils 33 and 37, and the LSI chip 19 and the cooling block 28d are metallically coupled, and at the same time, the enclosure is hermetically sealed as a He atmosphere. To seal.

According to the present embodiment, due to the difference in thermal expansion between the cooling structure 28 and the wiring board 32, the horizontal thermal strain generated in the cooling process after solder joining during assembly can be absorbed by the bending deformation of the thin metal wire 27. Therefore, the wiring boards 32, the intermediate substrate 20, and the LSI chips 19 are not disconnected from each other, and the cooling block 28d and the LSI chips 19 can be mounted by soldering. As a result, it becomes possible to cool the LSI chip with high efficiency,
The ability to use large-scale, high-power LSI chips makes it possible to greatly improve the performance of large-scale computers, especially the processing speed. Further, by forming the wiring board and the intermediate board with the same material, fatigue breakdown of the solder is eliminated where electrical connection between them is required, and the reliability of the device is greatly improved. It should be noted that the solder in the dummy terminal portion between the LSI chip and the intermediate substrate breaks, but this does not affect the function of the device, so this break is not a problem.

FIG. 7 is a cross-sectional view of a module in which an LSI chip is mounted on a three-stage chip carrier consisting of one intermediate board and two reinforcing boards, which allows a large lateral displacement. The LSI chip 19 and the reinforcing substrate 43 are a connection terminal 46 provided on the LSI chip 19, a thin metal wire 57 containing a metal having magnetism which is passed through a gap between the connection terminals 43 and 44 facing each other,
The ends of the thin metal wires 57 are joined together by a micro joint structure composed of soldering layers 51 and 52 joined to the connection terminals 45 and 46, respectively. The reinforcing substrate 43 and the reinforcing substrate 44 have the same configuration as the above. The connection terminals 47, 48, the metal thin wires 58 containing a metal having magnetism, and the soldering layers 53, 54 are joined by a micro joint structure, and the reinforcing substrate 43 and the intermediate substrate 20 are also the same as above. The connection terminals 49 and 50 are connected to each other by a micro joint structure composed of a metal thin wire 59 containing magnetic metal and soldering layers 55 and 56.

When the relative displacement between the intermediate substrate 20 and the LSI chip 19 is much larger than 100 μm, the length of the fine metal wire must be several times or more the relative displacement in order to directly connect the intermediate substrate 20 and the LSI chip 19. Must be long. Practically a diameter of 10
If you handle a thin metal wire of about μm with a length of 1 mm (1,000 μm) or more, problems such as bending will occur and the handleability will deteriorate, and defects will often occur due to short circuits during assembly.

However, according to this embodiment, since the intermediate substrate 20 and the LSI chip and the reinforcing substrates 43 and 44 are provided in the middle, the thin metal wires 57, 58 and 59 containing magnetic metal may be short, and The deformability can be increased by raising the layer consisting of the total metal fine wires. Nevertheless, the failure rate during assembly can be reduced and the reliability of the device can be improved.

[Reference example]

FIG. 8 is a diagram showing a method of connecting a wiring board and an LSI chip and a cross section of a module when a copper wire is used as the metal thin wire. In this module, the wiring board 73 made of alumina ceramic and the LSI chip 77 include a connection terminal 74 provided on the wiring board 73 and a connection terminal 7 provided on the LSI chip 77.
8 and the copper wire passed in the gap between those connecting terminals 74 and 78 facing each other
72 and a brazing layer 75, 79 in which each end of the copper wire 72 is joined to the connection terminals 74, 78, respectively, by a micro joint structure. The positioning plate 76 on which the copper wire 72 is arranged is left as it is in the module. The positioning plate 76 is preferably electrically insulating and has the same coefficient of thermal expansion as the wiring board 73 or the LSI chip 77. Here, a 100 μm thin plate made of the same material as the wiring board 73 is made of alumina ceramic. A through hole having a diameter of about 40 μm is provided corresponding to the position of the connection terminal 74.

In step I of FIG. 8, a positioning plate 76 is arranged directly above the wiring board 73, and a copper wire 72 with a diameter of about 10 μm and a cut margin is provided at a rate of about 8 to 10 per connection terminal. Implant in the through hole. After the implantation is completed, the whole is heated in a vacuum or an inert atmosphere to a temperature equal to or higher than the melting point of the brazing material previously coated on the connection terminal 74, and the copper wire 72 is brazed to the connection terminal 74. Any brazing material may be used as long as its melting point is in the range of 200 ° C to 900 ° C. Positioning plate after brazing
Use 76 to trim the copper wire 72 to the required length.

In the second step, the positioning plate 76 is lifted up to near the upper end of the copper wire 72 to bring the bundle of copper wires 72 into a state of being bundled, and the LSI chip 77 having the solder 79 coated on the connection terminal 78 in advance is positionally adjusted to the copper wire 72. Place it on top. Then, the solder 79 is reflowed in an inert or reducing atmosphere to solder the upper end of the copper wire 72 to the connection terminal 78.

In the final third step, the positioning plate 76 made of alumina ceramic is pushed down to the wiring board 73 side to complete the entire joining step. The material of the positioning plate 76 is the LSI chip 77.
If it has a coefficient of thermal expansion equivalent to, the positioning plate 76 is retained at a position close to the LSI chip 77, and the joining process is completed. This is because the amount of deformation of the copper wire 72 can be made large between combinations of components having a large difference in thermal expansion.

According to this reference example, the thin metal wires can be aligned in the direction perpendicular to the connection terminal surface without using the action of the magnetic field, and the positioning can be accurately performed on the connection terminal. There is no problem even if a magnetic material is used for such. And since analysis of the direction and strength of the magnetic field is also unnecessary,
The assembly device can be easily designed. In addition, the metal thin wire can be made of pure copper, and the electrical resistance at the connecting portion can be reduced. Needless to say, the effect of absorbing the thermal strain due to the provision of the layer consisting of the thin metal wires, that is, the effect of preventing the fracture of the joint and the thermal fatigue fracture is effective.

In this reference example, as an example, the positioning plate is used to orient and position the metal thin wire, but the micro joint structure of the present invention can be realized by using other mechanical means.

〔The invention's effect〕

INDUSTRIAL APPLICABILITY As described above, the present invention provides a connection terminal portion provided on each member to be joined, a metal thin wire extending in a gap between the connection terminal portions facing each other, and the metal thin wire and the connection terminal portion are joined together. Since it includes a brazing filler metal and a layer made of only thin metal wires between the connecting terminal portions, relative displacement generated between the connected members is easily absorbed by bending deformation of the thin metal wires. Therefore, the stress of the thin metal wire and the shear stress of the brazing layer can be significantly reduced. Therefore, one joining member is a semiconductor component and the other joined member is a wiring board, and even if a large relative displacement occurs between the semiconductor component and the wiring board due to temperature change, the joining layer does not break. The fatigue life can be improved. In addition, even if the LSI chip becomes large, or if the chip carrier mounted on the wiring board or the electronic device configured to cool the metal by coupling the upper part of the LSI chip to the cooling body, the wiring board, the chip carrier, the LSI chip Also, it is possible to prevent breakage and thermal fatigue breakage due to thermal strain of the thermal or electrical connection between the cooling bodies, and it is possible to significantly improve the reliability of the electronic device.

[Brief description of drawings]

FIG. 1 is a diagram showing a basic structure of the present invention, FIG. 2 is a diagram mechanically showing a deformed state of a thin metal wire, and FIG. 3 is a method for connecting an LSI chip and a wiring board and a sectional structure thereof according to an embodiment. FIG. 4 is a cross-sectional view of another structure, FIG. 5 is a view showing a method of assembling a chip carrier and its cross-sectional structure according to an embodiment,
Fig. 6 is a diagram showing the cross-sectional structure of a large-sized computer using a chip carrier, Fig. 7 is a diagram showing the cross-sectional structure of a three-stage chip carrier, and Fig. 8 is an assembling method of a reference example using a copper wire as a metal thin wire FIG. 9 is a diagram showing a sectional structure, FIG. 9 is a general configuration diagram of a future large-scale computer, and FIG. 10 is a diagram showing a conventional solder joint improvement plan. 1,1 '... Joined member, 2,3 ... Connection terminal of joined member, 4,5 ... Brazing material, 6 ... Metal fine wire.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akira Matsuzaka 4026 Kuji Town, Hitachi City, Hitachi, Ibaraki Prefecture Hitachi Research Institute, Ltd. (72) Inventor Asahiko Shida 4026 Kuji Town, Hitachi City, Ibaraki Prefecture Hitachi Institute Co., Ltd. Within Hitachi Research Laboratory (56) Reference JP-A-61-51838 (JP, A)

Claims (3)

[Claims] 1. A micro-joint structure in which joining terminal portions of members to be joined which are arranged with a minute interval are opposed to each other by a joining material made of a material different from that of the joining terminal portion, and the joining terminals are passed between the joining terminals. 2. A micro joint structure comprising: a thin metal wire containing a magnetic metal and a brazing material that joins at least each terminal of the thin metal wire and each of the connection terminal portions. 2. When the members to be joined are a semiconductor chip and a wiring board, each of the connection terminal portions and the thin metal wires of the wiring board contains a magnetic material containing at least one of Fe, Ni and Co. The micro joint structure according to claim 1, characterized in that 3. The thin metal wire has a magnetic metal inside,
2. The micro joint structure according to claim 1, wherein the surface layer is made of a metal that is a good conductor electrically and thermally.