JP2004221189A - Connection method of planar multiple conductor, and electronic component including the planar multiple conductor connected with the same method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the connection method for surely connecting a minute planar multiple conductor. <P>SOLUTION: Plating layers (13, 14) of low melting point metal are respectively adhered to the surfaces of conductors (12, 22) of flexible planar multiple conductor (10) and rigid planar multiple conductor (20). The concave and convex portions are formed depending on the mold to the flexible planar multiple conductor along the axial line thereof. In the overlapping region of the flexible planar multiple conductor, a bonding agent is adhered to form a bonding agent layer (15). Under the normal temperature, both multiple conductors are aligned with the conductors thereof provided opposed with each other and these are heated for a very short period using an iron or the like to attain temporary bonding. These are then finally bonded with pressure using a bonder under the higher pressure and temperature. Consequently, the fused low melting point metal bridge-couples the corresponding conductors, and the periphery thereof is bonded through thermosetting of the bonding agent. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for connecting a plurality of conductors arranged on a substantially flat member, a method for connecting a plurality of flat conductors, an electric / electronic device including a portion connected by the method, a plurality of flat conductors connected by the method, and Regarding the connection system.
Note that the planar multiconductor includes a general printed circuit board (rigid board, flexible board) and a board having a circuit directly provided on the surface of a molded body.
[0002]
[Prior art]
2. Description of the Related Art Within an electric / electronic component, a planar multiconductor in which a plurality of conductors are arranged in a member is connected to another planar multiconductor. For example, when connecting a substrate on which various electronic components are mounted to another substrate, a planar multiconductor is formed on each of the one and the other substrates, and the two ends of the flexible planar multiconductor are overlapped on these. Connections are being made together.
[0003]
The connection of such planar multi-conductors includes soldering, anisotropic conductive adhesive (hereinafter, referred to as ACF), press connection, connection by a connector, and the like. However, the width and spacing of the conductors are becoming smaller year by year, and it is not uncommon recently to arrange conductors having a width of several tens of μm at intervals of several tens of μm. With such fineness, press connection and connection using a connector cannot be used at all, and are often performed by soldering or ACF.
[0004]
However, the soldering method has a problem that it cannot withstand the temperature in the mounting process of mounting the electronic component on the board. This is because, in the mounting process, a soldering operation is performed for mounting various electronic components, and as a result, the temperature of the substrate or the backing film on which the conductor is mounted is raised to about 260 ° C. Therefore, the mounting operation having the highest temperature has been performed first, and then the connection operation has been performed. For this reason, it is necessary to secure an area where components are not mounted on a substrate or the like for connection work, and as a result, the mounting density has been reduced.
[0005]
In addition, since the method using ACF originally obtains conduction with conductive particles in the resin, if the resistance is large and becomes thin, a sufficient amount of conductive particles cannot be secured and stable conduction cannot be obtained or the resistance becomes low. There is a problem that it becomes larger.
[0006]
Therefore, as described in Patent Document 1 (Japanese Patent Application Laid-Open No. 62-184788), a method has been developed in which opposing conductors are connected by penetrating an insulating adhesive by crimping. However, in this method, there is no metal connection between the conductors, and there is a possibility that the conduction changes due to impact, humidity, and the like.
Further, Patent Document 2 (International Publication WO0220686) has a sheet-like conductive layer having a front surface and a back surface, and an adhesive layer provided on the surface of the conductive layer. The adhesive layer is made of thermosetting resin, and when the adhesive layer is heat-pressed to the adherend, the protrusion of the conductive layer penetrates the adhesive layer and contacts the adherend. A thermosetting conductive adhesive sheet, a connection structure using the same, and a connection method are described. However, the publication does not describe specific connection conditions and does not optimize connection.
[0007]
[Patent Document 1]
JP-A-62-184788 [Patent Document 2]
International Publication WO0220686 [0008]
[Problems to be solved by the invention]
The present invention has been made in view of the above problems, and an object of the present invention is to provide a connection method capable of reliably connecting miniaturized planar multiconductors.
In addition, it is an object of the present invention to provide an electric / electronic device, a planar multiconductor, and a connection system connected by the connection method in connection with the above connection method.
[0009]
[Means for Solving the Problems]
According to the first aspect of the present invention, there is provided a method of connecting a pair of a plurality of conductors corresponding to each other in a plane multiconductor in which a plurality of conductors are aligned and arranged on a substantially flat member, by overlapping.
At least one of a pair of planar multiconductors, at least one of the conductors in the overlapping region is attached to a low-melting metal that melts at a lower temperature than the conductor,
At least one of a pair of planar multiconductors, a thermosetting adhesive is attached to an overlapping region including the conductor,
After aligning the corresponding conductors, the overlapping regions are heated and pressed, and the corresponding conductors are bridge-bonded with the molten metal having a low melting point, and the overlapping regions other than the conductors are joined with the thermosetting adhesive. Is provided.
According to such a method, in the overlapping region of the pair of planar multiconductors, the conductors are joined by metal bonding, and the periphery thereof is joined by a thermosetting adhesive, so that a very strong connection can be realized.
In addition, as shown in FIG. 13, for example, the overlap region means a region where a pair of planar multiconductors overlap.
[0010]
According to a second aspect of the present invention, in the first aspect of the present invention, the adhesive has no tackiness at room temperature, exhibits tackiness by being heated at a temperature lower than the melting point of the low melting point metal for a short time, and exhibits a low melting point metal. Is a thermosetting adhesive that does not foam even when heated to the melting point.
Here, the normal temperature refers to a temperature of about 10 to 30 ° C., and the absence of tackiness refers to a state in which the adhesive does not adhere to the adhesive even when the adhesive is touched and has no stickiness.
[0011]
According to a third aspect of the present invention, in the second aspect of the present invention, a pair of flat surfaces are formed by a first pressing force while heating the adhesive at a first heating temperature lower than the melting point of the low melting point metal for a very short time so as to exhibit adhesiveness. A first thermocompression bonding in which at least one of the multiconductors is lightly pressed against the other, and heating to a second heating temperature higher than the first heating temperature, and at least one of the pair of planar multiconductors is strongly applied to the other with a second pressing force. The thermocompression bonding including the pressing of the second thermocompression bonding is performed.
Here, the first heating temperature is about 80 to 150 ° C., the minute time is, for example, about 1 to 10 seconds, and the magnitude of the first pressing force is approximately several tens to several hundreds kPa. , The second heating temperature is about 100 to 350 ° C., and the magnitude of the second pressure is generally several tens to several thousand kPa.
According to a fourth aspect of the present invention, in the second aspect of the invention, foaming is suppressed by adding 25 to 90 parts by weight of organic particles having a diameter of 10 μm or less to the epoxy adhesive, and in the fifth aspect of the invention, caprolactone-modified An epoxy-based adhesive is mixed and has no tackiness at room temperature, but is made to exhibit tackiness by heating for a short time.
In the invention according to claim 6, the adhesive contains a flux component.
[0012]
Further, in the invention of claim 7, in the invention of claim 1, unevenness is formed on one of the pair of planar multiconductors before the superposition, so that the reliability and stability of joining are improved.
[0013]
According to an eighth aspect of the present invention, there is provided an electric / electronic device including a portion connected by the method according to any one of the first to sixth aspects.
[0014]
According to a ninth aspect of the present invention, there is provided a planar multiconductor connected by the method according to any one of the first to sixth aspects.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
There are various planar multiconductors formed by aligning a plurality of conductors on a substantially flat member. For example, there are a rigid planar multiconductor in which conductors are arranged and arranged directly on a hard substrate on which electronic components are mounted, and a flexible planar multiconductor in which conductors are arranged and arranged on a flexible film. The flexible planar multiconductor includes a so-called flexible substrate.
In the following, a case where a rigid plane multiconductor and a flexible plane multiconductor are connected will be described as an example.
[0016]
1 shows a flexible planar multiconductor 10 and a rigid planar multiconductor 20. The flexible planar multiconductor 10 is composed of a plurality of copper alloys on a flexible resin film 11. The conductors 12 are formed by arranging them at predetermined intervals, and the rigid planar multiconductor 20 is formed by arranging a plurality of copper alloy conductors 22 at predetermined intervals on a hard resin substrate 21. The arrangement of the conductors 12 and 22 is performed by, for example, a photolithography method or the like.
The heights of the conductors 12 and 22 are 5 to 250 μm, the widths of the conductors 12 and 22 are equal and several tens μm, and the interval is several tens μm. The drawings are exaggerated as appropriate.
[0017]
The flexible flat multi-conductor 10 and the rigid flat multi-conductor 20 are immersed in a low melting metal plating bath 30 shown in the middle part of FIG. 23 is deposited. The thickness of the plating layers 13 and 23 is about 20 μm.
The lower part of FIG. 1 shows a flexible flat multiconductor 10 and a rigid flat multiconductor 20 to which low-melting metal plating layers 13 and 23 are attached.
In the above description, an example using a so-called immersion plating method has been described, but other plating methods, for example, an electrolytic plating method and an electroless plating method can also be used.
[0018]
As the low melting point metal, for example, the following alloys are used.
Tin-lead alloy (melting point: about 183-320 ° C)
Lead-tin-antimony alloy (melting point: about 185 ° C)
Tin-antimony alloy (melting point: about 235 ° C)
Tin-lead-bismuth alloy (melting point: about 135-180 ° C)
Bismuth-tin alloy (melting point: about 138 ° C)
Tin-copper alloy (melting point: about 230 ° C)
Tin-lead-copper alloy (melting point: about 183 ° C)
Tin-indium alloy (melting point: about 110 ° C)
Tin-silver alloy (melting point: about 221 ° C)
Tin-lead-silver alloy (melting point: about 178-309 ° C)
Lead-silver alloy (melting point: about 304 ° C)
Gold-tin alloy (melting point: about 280-370 ° C)
Tin-silver-copper alloy (melting point: about 200-380 ° C)
Tin-zinc alloy (melting point: about 198 ° C)
[0019]
Next, irregularities 14 are formed on the conductors 12 of the flexible flat multiconductor 10 to which the low melting point metal is attached. This is to ensure that the connection between the conductor 12 of the flexible planar multiconductor 10 and the conductor 22 of the rigid planar multiconductor 20 performed at a later stage is ensured. FIG. 2 is a view for explaining the formation of the irregularities 14 on the flexible planar multiconductor 10. The flexible planar multiconductor 10 in the lower stage of FIG. 1 is formed into a mold 40 in which semi-cylindrical projections 41 are arranged. Pressed. FIG. 3 is a diagram showing the flexible flat multiconductor 10 on which the irregularities 14 are formed as described above.
[0020]
Here, the dimensions of the irregularities 14 will be described with reference to FIG.
The width R of the concave portion of the unevenness 14 is the conductor height H × (0.5 to 10), and when H = 20 μm, 10 to 200 μm,
The depth D of the concave portion of the unevenness 14 is the conductor height H × (0.2 to 0.8), and when H = 20 μm, 5 to 100 μm;
The interval L between the concave portions of the unevenness 14 is the conductor height H × (0.5 to 10), and is 10 to 200 μm when H = 20 μm.
2, 3, and 4, the plating layer 13 of the low melting point metal is omitted.
[0021]
Then, the adhesive to which the conductor to which the low-melting-point metal is attached as described above is attached to the overlapping surface of the overlapping region included in the region. Since various characteristics are required for the adhesive in the present invention, the required characteristics will be discussed below.
First, positioning is performed so that the corresponding conductors of the flexible planar multiconductor 10 and the rigid planar multiconductor 20 overlap. At this time, it takes time and effort to separate the adhesive and the adhesive if they are misaligned if they are misaligned. Therefore, it is necessary that there is no tackiness in an environment where the positioning is performed, that is, at room temperature.
[0022]
Next, it is necessary to temporarily bond the aligned flexible flat multiconductor 10 and the rigid flat multiconductor 20 so that the positions thereof do not shift. Therefore, it is required to have a property of exhibiting tackiness by heating for a short time.
[0023]
Then, one of the flexible flat multiconductor 10 and the rigid flat multiconductor 20 is pressed against the other while heating, and the low-melting metal is melted to form a metal joint. Therefore, when air bubbles are generated by heating, there is a possibility that metal joints may be disturbed or broken, moisture may re-aggregate in the air bubbles under high humidity, a short circuit may occur, and a metal portion may be oxidized. Therefore, it is required that bubbles are not generated even when heated.
[0024]
On the other hand, in the initial state of the thermocompression bonding, that is, in the temperature state where the low melting point metal does not melt, the conductor projecting from the substrate 21 or the film 11 can advance in the adhesive layer, and the conductors are separated before melting. It is necessary to make contact. That is, in this state, the low melting point metal must have a higher hardness than the adhesive. If these conditions are not met, metal connection cannot be realized.
[0025]
In the present invention, by adding 25 to 90 parts by weight of organic particles to an epoxy resin-based adhesive, a resin having suppression of foaming property and penetrability could be obtained.
Such a resin exhibits plastic fluidity. That is, it flows when a stress exceeding the yield stress acts, but is elastically deformed by an external force equal to or lower than the yield stress. When a resin having such properties is pressed against a conductor projection with a relatively high pressure, the resin flows and allows the conductor to penetrate.However, when a gas pressure is applied at a relatively low pressure, the resin becomes resin. Flows and almost no bubbles are generated.
[0026]
The epoxy resin is a bisphenol A type, a bisphenol F type, a phenol novolak type, a cresol novolak type epoxy resin, or an aliphatic epoxy resin.
The organic particles to be added are acrylic resin, styrene-butadiene resin, styrene-butadiene-acrylic resin, melamine resin, melamine-isocyanurate adduct, polyimide, silicone resin, polyetherimide, polyethersulfone, Particles such as polyester, polycarbonate, polyetheretherketone, polybenzimidazole, polyarylate, liquid crystal polymer, olefin resin, and ethylene-acrylic copolymer are used, and the size is 10 μm or less, preferably 5 μm or less. .
Preferably, a functional reactive group is mixed in order to increase the compatibility between the epoxy resin and the organic particles.
[0027]
Then, in order to satisfy the above-mentioned temporary adhesiveness, a caprolactone-modified epoxy resin is added as an adhesive.
Further, a rosin-based or other organic acid-based fluxing agent may be added. By adding such a flux agent, connection can be easily made even when the circuit surface is oxidized.
[0028]
FIG. 5 schematically shows the mixing of various materials to obtain the above-mentioned adhesive. In FIG. 5, reference numeral 90 denotes a mixer as an adhesive preparation means, and the mixer 90 is driven by a motor 91.
The adhesive obtained as described above is adhered to the surface of the flexible flat multiconductor 10, and the adhesive may be a dry film and may be thermally laminated, or may be applied in a liquid state. Further, it is not necessary to limit the adhesion range of the adhesive to a certain range of the conductor, and there is no problem even in the surrounding area.
[0029]
FIG. 6 is a diagram showing a flexible flat multiconductor 10 in which an adhesive formed into a dry film is heat-laminated at 80 to 120 ° C., where (A) is a diagram viewed from the axial direction of the conductor 12, and (B) is a diagram. FIG. 3 is a diagram viewed from a direction perpendicular to an axis of a conductor 12. Reference numeral 15 indicates an adhesive layer. The thickness of the adhesive 15 is 0.2 to 2.5 times the height of the conductor, and is about 5 to 200 μm, preferably 10 to 50 μm, and more preferably 10 to 20 μm.
FIG. 7 is a view showing a roller laminator 50 for thermally laminating an adhesive formed into a dry film on the flexible flat multi-conductor 10, and has a pair of rollers 51 and includes a heating device (not shown).
[0030]
The flexible flat multiconductor 10 to which the adhesive is applied is aligned using a microscope 60 as shown in FIG. In this embodiment, the flexible flat multi-conductor 10 is moved onto the rigid flat multi-conductor 20 with the adhesive layer 15 facing down as shown in FIG. The conductors 22 of the multiconductor 20 are each aligned such that their counterparts are at the same location. This alignment is performed at room temperature, but since the adhesive has the property of not having tackiness at room temperature, it can be performed smoothly without stickiness.
[0031]
When the positioning is completed, for example, a slight heating of about 120 ° C. × 1 second is performed with a iron 70 as shown in FIG. Then, the adhesive exhibits tackiness, and the aligned flexible flat multiconductor 10 and rigid flat multiconductor 20 are temporarily bonded and do not move with each other.
[0032]
The flexible planar multiconductor 10 and the rigid planar multiconductor 20 temporarily bonded as described above are subjected to more full-scale crimping (final crimping). FIG. 11 is a view for explaining the state of the final compression bonding. As a result, the low melting point metal of the flexible planar multiconductor 10 and the rigid planar multiconductor 20 melts to form a metal bond, and the conductor 11 of the flexible planar multiconductor 10 and the conductor 21 of the rigid planar multiconductor 20 are strongly joined. . Then, the adhesive fills the gap. The heating condition depends on the melting temperature of the low melting point metal plated on the conductor, but is generally (100-350 ° C.) × (0.1-30 seconds). The pressure is about 2 × 10 ² to 10 × 10 ² kPa.
Then, post-cure (post-curing treatment) is performed at a temperature lower than the melting temperature of the low melting point metal for about 2 hours.
[0033]
Here, a repair method, that is, a repair method in a case where a failed product such as a position shift is generated will be described.
In such a case, the connection can be released by swelling the cured adhesive with an organic solvent and then heating. As the solvent, THF (tetrahydrofuran), acetate, ketone, alcohol, or the like can be used.
[0034]
Hereinafter, specific examples of the connection between the flexible planar multiconductor and the rigid planar multiconductor and the performance test results thereof will be described.
[0035]
The rigid planar multiconductor is FR-4 (0.4 mm), the number of conductors is 50 (conductor width 100 μm, interval 100 μm), and tin / silver / copper = 95.8 / 3.5 / 0 on the conductor surface. .7 low melting point alloy is deposited.
[0036]
The flexible planar multiconductor is a Base film (Kapton) manufactured by DuPont, the number of conductors is 50 (conductor width: 100 μm, interval: 100 μm), and the surface of the conductor is electroless tin-plated.
Then, a metal mold press (having a linear projection having a pitch of 200 μm and a height of 30 μm) was pressed on the conductor of the flexible flat multiconductor with a pressing force of 1 ton and the linear projection and the conductor were pressed perpendicularly to form irregularities. .
[0037]
The adhesive is
Phenoxy resin (30): YP50S, manufactured by Toto Kasei, number average molecular weight 11,800,
Epoxy resin (34): DER ^TM 332, Dow Chemical Japan, epoxy equivalent 174,
Polycaprolactone-modified epoxy resin (30): Praxel ^™ G402, manufactured by Daicel Chemical Industries,
Acrylic particles (80) having a functional group: EXL2314, KUREHA PARARAID ^™ EXL, manufactured by Kureha Chemical Industry,
Dicyandiamide (2.9): CG-NA, melamine / isocyanuric acid adduct (PTI Japan) (20): MC-600, manufactured by Nissan Chemical Industries, Ltd. dissolved in a solvent consisting of methyl alcohol (40) and tetrahydrofuran (550) Formed at room temperature with stirring.
The numerical values in parentheses are values for indicating the mixing ratio and are expressed in parts by weight.
[0038]
The resulting adhesive is coated on a siliconized PET film and dried in an oven at 100 ° C. for 30 minutes to obtain a film having a thickness of 20 μm. And laminated at 100 ° C. while heating.
[0039]
FIG. 12 shows the relationship between the shearing force and the shearing speed at 120 ° C. of the above-mentioned adhesive. In the case of ordinary Newtonian viscosity, the relationship between the shearing force and the shearing speed is a straight line passing through the origin. However, as shown, even when the shear rate is 0 (zero), the adhesive has a shear stress of about 4000 MPa, and this value can be regarded as the yield stress of plastic flow.
[0040]
Then, after aligning the rigid planar multi-conductor and the flexible planar multi-conductor, they are temporarily bonded at about 100 ° C./about 1 second, and then 150 ° C./9 with a bonder of model TCW-215 / NA-66 manufactured by Nippon Avionics. The main bonding was performed by heating at + 270 ° C. for 9 seconds / second, and post-curing (post-curing treatment) at 150 ° C. for 2 hours was performed.
[0041]
When the portion connected as described above was cut and observed with an electron microscope, the presence of bubbles was not observed.
In addition, it was confirmed that all the corresponding conductors of the rigid plane multiconductor and the flexible plane multiconductor were connected with a resistance of 1Ω or less.
Furthermore, even after various environmental tests, the connection resistance hardly changed, and it was confirmed that the connection was good.
[0042]
The results are shown below.
(1) Heat cycle test:
[−55 ° C./30 minutes + 25 ° C./1 minute + 85 ° C./30 minutes] × 200 cycles Resistance before test: 0.602Ω
Resistance after test: 0.605Ω
[0043]
(2) Wet-heat aging test:
85 ° C./85% RH × 168 hours Resistance before test: 0.636Ω
Resistance after test: 0.636Ω
[0044]
(3) Heat resistance test:
Resistance before heating / cooling at 25 ° C-280 ° C at 30 ° C / min for 3 cycles: 0.464Ω
Resistance after test: 0.474Ω
[0045]
FIG. 13 is a diagram showing a state in which two rigid planar multiconductors 20 are connected by one flexible planar multiconductor 10 inside the mobile phone 100.
[0046]
【The invention's effect】
The invention according to claim 1 is a method of connecting a pair of a plurality of conductors by aligning corresponding conductors of a planar multiconductor formed by arranging the conductors on a substantially flat member,
At least one of the pair of planar multiconductors, a low-melting metal that is melted at a lower temperature than the conductor is attached to the conductor in the overlapping region, and at least one of the pair of planar multiconductors includes the conductor. A thermosetting adhesive is applied to the overlapping area, the corresponding conductors are aligned, and then the overlapping area is heat-pressed, and the corresponding conductor is bridge-bonded with the molten low-melting metal and the overlapping area other than the conductor Are bonded by the thermosetting adhesive.
Therefore, in the overlapping region of the pair of planar multiconductors, the conductors are joined by a metal bond and the periphery thereof is joined by a thermosetting adhesive, so that a very strong connection can be realized.
[0047]
As in the invention of claim 3, the adhesive has no tackiness at room temperature, exhibits adhesiveness by being heated at a temperature lower than the melting point of the low melting point metal for a very short time, and is heated to the melting point of the low melting point metal. It is a thermosetting adhesive that does not foam even when it is heated at a first heating temperature lower than the melting point of the low-melting metal for a very short time to cause the adhesive to exhibit tackiness while a pair of flat sheets are applied by a first pressing force. A first thermocompression bonding method in which at least one of the conductors is lightly pressed against the other; heating to a second heating temperature higher than the first heating temperature; If the thermocompression bonding is performed, including the second thermocompression bonding in which at least one of the conductors is pressed strongly against the other, the alignment at room temperature can be performed without tackiness, and the temporary bonding can be performed by the first thermocompression bonding. , Work can be done efficiently by making and storing up to the middle process
Further, as in the seventh aspect of the present invention, unevenness is formed on one of the pair of planar multiconductors before the superposition, so that the reliability and stability of the joining are enhanced.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating plating of a low-melting-point metal on a conductor of a flexible planar multiconductor and a rigid planar multiconductor.
FIG. 2 is a view for explaining formation of irregularities on a conductor of a flexible planar multiconductor by a mold.
FIG. 3 is a view for explaining a conductor of a flexible flat multiconductor in which irregularities are formed in a mold.
FIG. 4 is a diagram for explaining dimensions of unevenness formed on a conductor.
FIG. 5 is a diagram illustrating preparation of an adhesive.
FIG. 6 is a view showing a flexible planar multiconductor on which an adhesive is laminated,
(A) is a diagram viewed from the axial direction of the conductor,
(B) is the figure seen from the direction perpendicular to the axis of the conductor.
FIG. 7 is a diagram showing a roller laminator.
FIG. 8 is a diagram for explaining alignment using a microscope.
FIG. 9 is a diagram showing a state in which a flexible planar multiconductor and a rigid planar multiconductor are aligned.
FIG. 10 is a view showing an iron used for temporary bonding.
FIG. 11 is a view for explaining main bonding.
FIG. 12 is a diagram showing a relationship between a shear rate of an adhesive and a shear stress in the embodiment of the present invention.
FIG. 13 is a diagram showing a state in which two rigid planar multiconductors are coupled via one flexible planar multiconductor according to the present invention inside a mobile phone.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Flexible planar multi-conductor 11 ... Film 12 ... Conductor 13 ... Low-melting-point metal plating layer 14 ... Unevenness 15 ... Adhesive layer 20 ... Rigid planar multi-conductor 21 ... Substrate 22 ... Conductor 23 ... Low-melting-point metal plating layer 30 ... Plating tank 40 Mold 50 Roller laminator 60 Microscope 70 Iron 80 Bonder 90 Mixer 100 Cellular phone

Claims (9)

A method for connecting a pair of, corresponding conductors of a planar multiconductor formed by arranging a plurality of conductors on a substantially flat member, by superimposing,
At least one of a pair of planar multiconductors, at least one of the conductors in the overlapping region is attached to a low-melting metal that melts at a lower temperature than the conductor,
At least one of a pair of planar multiconductors, a thermosetting adhesive is attached to an overlapping region including the conductor,
After aligning the corresponding conductors, the overlapping regions are heated and pressed, and the corresponding conductors are bridge-bonded with the molten metal having a low melting point, and the overlapping regions other than the conductors are joined with the thermosetting adhesive. And how. The adhesive has no tackiness at room temperature, exhibits adhesiveness by heating at a temperature lower than the melting point of the low melting point metal for a short time, and does not foam even when heated to the melting point of the low melting point metal. 2. The method of claim 1, wherein the method is an agent. The thermocompression bonding is a method in which the adhesive is heated at a first heating temperature lower than the melting point of the low-melting metal for a short period of time to exert adhesiveness, and at least a light pressure is applied to at least one of the pair of planar multiconductors with the first pressing force. A first heat compression bonding,
A second heating / compression bonding step of heating to a second heating temperature higher than the first heating temperature and strongly pressing at least one of the pair of planar multiconductors against the other with a second pressing force. Item 3. The method according to Item 2. 3. The method according to claim 2, wherein the adhesive suppresses foaming by adding 25 to 90 parts by weight of organic particles having a diameter of 10 [mu] m or less to the epoxy adhesive. 3. The method according to claim 2, wherein the adhesive is mixed with a caprolactone-modified epoxy-based adhesive to cause the adhesive to exhibit tackiness by heating for a short time. The method according to claim 1, wherein the adhesive comprises a flux component. The method according to any one of claims 1 to 6, wherein one of the pair of planar multiconductors is made uneven before the superposition. An electric / electronic device including a part connected by the method according to claim 1. A planar multiconductor connected by the method according to claim 1.

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