JP7033285B2 - Fine wiring joint and its manufacturing method - Google Patents

Description

INDUSTRIAL APPLICABILITY The present invention relates to a fine wiring joint between an ultra-small ASIC-integrated magnetic sensor used in a living body and a fine flexible wiring for power supply / communication to an ultra-small ASIC-integrated magnetic sensor, and a manufacture thereof. It's about the method.

Research is underway to mount a magnetic sensor on an in-vivo motion device such as a catheter to measure the position and orientation, and to realize remote control treatment using the measured value (Patent Documents 1, 2, and 3). Further, a compact and highly sensitive GSR sensor has been developed for mounting in an in-vivo motion device (Patent Document 4).

In order to reduce the size of magnetic sensors, the development of magnetic sensors such as tMR sensors and GSR sensors that integrate magnetic sensor elements and integrated circuits for specific applications (hereinafter referred to as ASICs) is in progress. (Patent Document 5, Non-Patent Document 1).

In order to drive the magnetic sensor, it is essential to electrically connect the power supply function to the magnetic sensor and the fine flexible wiring having the communication function from the magnetic sensor. In order to reduce the size, the development of a direct bonding technology between the electrode terminal of the ASIC and the connection terminal of the fine flexible wiring having a communication function from the magnetic sensor is being worked on.
However, the direct connection between the electrode terminal of the ASIC and the connection terminal of the flexible wiring lacks mechanical strength, so that special measures are required. Generally, a PCB board is provided between an ASIC board and a flexible printed circuit board, an electrode terminal on the ASIC board and a connection terminal on the flexible printed circuit board are joined, and then a connection terminal on the flexible printed circuit board is joined. And the connection terminal on the PCB board are joined to maintain the mechanical strength. (Patent Document 6).

Further, the width of the circuit pattern on the printed wiring board (width of the connection terminal portion) is as large as 0.2 to 1.0 mm (200 to 1000 μm), and the circuit pattern of the corresponding flexible printed wiring board to be connected is also 0. It is as large as 2 to 1.0 mm (200 to 1000 μm), and both can be easily soldered together, and its strength can be sufficiently secured. The size of the flexible wiring (FIG. 1: width of a plurality of circuit patterns, width of intervals between circuit patterns and width of both ends) is 1.5 mm or more and cannot be applied to a catheter or the like. (Patent Document 7).
However, in order to reduce the size, it is necessary to omit the PCB board, and it is also necessary to reduce the size of the large printed wiring. If the width of the connection terminal (electrode terminal) is reduced and the printed wiring is made smaller and the fine flexible wiring is directly bonded to the small ASIC, the strength thereof is reduced and a short circuit between the terminals is likely to occur. In particular, a magnetic sensor mounted on an in-vivo motion device needs to be connected to an external electronic device by fine flexible wiring, but it is required to solve the problem of breakage when pulled.

Japanese Unexamined Patent Publication No. 2015-134166 JP-A-2017-12840 Patent No. 6256962 Patent No. 5839527 Special Table 2017-516987 Gazette Special Table 2017-512353 Gazette Jitsukaihei 6-23274 Gazette

sensor devices 20181-40-28008

As the size of the magnetic sensor is further reduced, the joint portion between the magnetic sensor and the flexible wiring is also reduced in size, and the joint strength is inevitably reduced.
Therefore, it is an object of the present invention to provide a fine wiring joint body that satisfies both the miniaturization and the improvement of the joint strength, which are the contradictory characteristics.

Since the ASIC integrated magnetic sensor is built in the catheter, the length of the ASIC is 0.5 to 2.5 mm and the width is 0.3 to 0.8 mm, and the electrode terminals having a width of 80 μm or less formed on the upper surface of the ASIC are 4 We have diligently studied a method of finely joining the pieces and four connection terminals having a width of 80 μm or less for the flexible wiring.
As a result, if the electrode terminal and the connection terminal are simply joined by soldering, only the adhesive strength of the flat interface portion can be obtained. It was found that by overfilling 1.1 to 1.3 times as much as the above and soldering, the resistance due to the soldering of the dents perpendicular to the tensile direction of the flexible wiring is added and the joining strength is greatly improved. rice field. If it is less than 1.1, the bond strength decreases, and if it exceeds 1.3 times, the solder overflows and there is a risk of short-circuiting with the adjacent electrode.

The first invention relates to a fine wiring joint including an electrode terminal of a magnetic sensor, a connection terminal of flexible wiring, and a solder joint portion connecting both the electrode terminal and the connection terminal. Here, the number of electrode terminals is 4 or more, and the number of corresponding connection terminals is also 4 or more.
The magnetic sensor consists of an ASIC-integrated magnetic sensor in which a magnetic sensor element is directly formed from one end to the center of the ASIC surface.
The electrode terminal is located on the resist layer formed at the other end on the ASIC surface, has a length of 40 to 80 μm and a width of 40 to 80 μm, and has a length of 30 to 60 μm at the center of the electrode terminal. A depression with a width of 30 to 60 μm and a depth of 5 to 10 μm is formed.
In the electrode terminal with a dent, the entire surface of the electrode terminal including the dent is covered with a conductive material coating.
The flexible wiring is wiring having a width of 0.3 to 0.8 mm for connecting the magnetic sensor and the external electronic device, and has connection terminals and wiring corresponding to the electrode terminals.
The solder joint is composed of a square pillar solder formed in a recess and a disk-shaped solder extending from the upper surface of the square pillar solder.

The second invention relates to a method for manufacturing a solder joint portion of a fine wiring joint.
In advance, a recess is formed in the central portion of each of the four electrode terminals on the resist layer on the ASIC surface, and the entire surface of the electrode terminal including the recess is covered with a conductive material coating.
(1) The size of the electrode terminal is 40 to 80 μm in width and 40 to 80 μm in length, and the size of the connection terminal is 40 to 80 μm in width and 40 to 80 μm in length.
The size of the recess of the electrode terminal consists of a width of 30 to 60 μm, a length of 30 to 60 μm, and a depth of 5 to 10 μm.
(2) Using a solder paste injection device, a solder paste containing solder fine particles corresponding to 1.1 to 1.3 times the volume of the depression is injected into the depression.
(3) Using a microscope and a positioning device, align the electrode terminals of the magnetic sensor with the connection terminals of the flexible wiring.
(4) Using a solder joining device, heat and crimp the electrode terminal, connection terminal, and solder paste.
It consists of two terminals, a square pillar solder formed by injecting into the depression, and a disk-shaped solder formed by solder fine particles having a volume of 0.1 to 0.3 times the volume of the depression overflowing from the depression. Form a solder joint.

According to the present invention, the size of the magnetic sensor is reduced, the bonding strength between the electrode terminal and the connection terminal is improved, and a failure such as breakage can be prevented. It enables a fine wiring joint with a fine flexible wiring board for power supply and communication to the ASIC integrated magnetic sensor.

It is a top view of the electrode terminal with a dent on the ASIC in the ASIC integrated magnetic sensor. It is a top view of the flexible wiring. It is sectional drawing of the fine wiring joint body. It is an enlarged sectional view of a fine wiring joint. It is sectional drawing in A1-A2 line of FIG. It is the figure which mounted the magnetic sensor on the jig. It is the figure which the solder bonding agent is injected into the recess of the electrode terminal of a magnetic sensor. It is a figure which aligns the electrode terminal of a magnetic sensor, and the connection terminal of a flexible wiring. It is a figure which heats and crimps an electrode terminal, a connection terminal, and a solder paste.

Embodiments and examples of the present invention will be described with reference to FIGS. 1 to 9.
As shown in FIG. 3, the fine wiring joint 3 joins the electrode terminal 14 formed in the resist layer 13 of the magnetic sensor 1 to the connection terminal 21 of the flexible wiring 2 and the electrode terminal 14 to the connection terminal 21. It is composed of a solder joint 142.

The magnetic sensor 1 is an ultra-small ASIC-integrated magnetic sensor in which the magnetic sensor element 11 is directly formed on the surface of the ASIC 12. Magnetic sensors include tMR sensors, MI sensors, GSR sensors and the like. Although the conventional magnetic sensor is miniaturized, it is not a size that can be inserted into a catheter having an inner diameter of 0.5 to 1.5 mm. The present invention enables fine bonding between an ASIC-integrated magnetic sensor and a fine flexible wiring of 0.3 to 0.8 mm or less as a small size that can be built in a catheter, that is, an ultra-small magnetic sensor.

Four electrode terminals 14 of the magnetic sensor 1 are provided on a resist layer 13 having a thickness of 7 to 15 μm formed at the end of the upper surface of the ASIC 12, and the connection with the ASIC 12 is from the ASIC electrode terminal 121 to the ASIC electrode. It is connected via wiring 122. Therefore, the electrode terminal 14 is provided on the upper surface of the ASIC 12 (FIGS. 1 and 3).
The electrode terminals and connection terminals are terminals required for the power supply function and communication function for connecting the magnetic sensor and the external electronic circuit, and at least four are required for each, and the communication content from the magnetic sensor increases. By doing so, the number of both terminals will be required, so the number will be 4 or more.

The electrode terminal 14 of the ASIC 12 has a bottomed shape of a square pipe with a flange having a recess 141 formed in the center of the electrode terminal 14 (FIGS. 1 and 5). In addition to the disc-shaped solder 142b, which is the joint between the planes of the connection terminal 21 of the flexible wiring 2 and the conventional flat electrode terminal (bonding of the interface portion), the solder 142a of a square pillar inside the recess 141 ( By forming a recessed portion) and forming a three-dimensional shape of the solder joint portion 142 (FIG. 4) consisting of a disk-shaped solder 142b and a square pillar solder 142a, the joint strength between the ASIC 12 and the flexible wiring 2 is improved against tensile breakage. Will be done.

試験方法は、磁気センサ１の幅は０．４ｍｍ（４００μｍ）にて、長さ４０μｍ、幅４０μｍ、深さ７μｍからなる窪みを有する長さ５０μｍ、幅５０μｍの電極端子１４を４個並列して、電極端子１４の間隔を１０～６０μｍに変えて試験した。判定基準は、製造の可否、接合体の小型化の可否について判定する。製造の可否は、レジスト層１３に窪み１４１を形成して窪み１４１にハンダ接合剤４２１を注入して溶融することから、電極端子１４間の短絡が発生する場合は×とする。電極端子１４とレジスト層１４の端部との間隔（図１の上端または下端と電極端子１４：ａ）が窪み１４１の幅（ｂ）との比（ａ／ｂ）が１未満となるとａ部に応力が集中して破損しやすくなるので、ａ部の強度を高めるために大きくすると磁気センサの小型化に反することにもなるので▲とする。
その結果、１０μｍの間隔では溶融したハンダによる短絡が発生したので判定は×であった。他方、電極端子１４の６０μｍの間隔（窪み１４１の間隔は７０μｍに相当）ではａ部を１０μｍから７０μｍと大きくすることとなり磁気センサ１の小型化に反したので▲であった。
そこで、電極端子１４の間隙は溶融したハンダによる短絡防止のために２０μｍ以上とし、小型化のために５０μｍ以下とする。 The electrode terminals 14 have a length of 40 to 80 μm and a width of 40 to 80 μm, and four electrode terminals 14 are arranged at equal intervals of 20 to 50 μm in the width direction (FIG. 2). The size of the electrode terminal 14 is 40 μm or more in length and width in order to improve the bonding strength, and 80 μm or less in order to reduce the size.
Next, Table 1 shows the test results for the distance between the electrode terminals 14.

In the test method, the width of the magnetic sensor 1 is 0.4 mm (400 μm), and four electrode terminals 14 having a length of 40 μm, a width of 40 μm, and a depth of 7 μm having a recess of 50 μm in length and 50 μm in width are arranged in parallel. , The distance between the electrode terminals 14 was changed to 10 to 60 μm for the test. Judgment criteria are whether or not manufacturing is possible and whether or not the bonded body can be miniaturized. Whether or not the product can be manufactured is marked with x when a short circuit between the electrode terminals 14 occurs because the recess 141 is formed in the resist layer 13 and the solder bonding agent 421 is injected into the recess 141 to melt the resist layer 13. When the distance (a / b) between the electrode terminal 14 and the end of the resist layer 14 (the upper end or the lower end of FIG. 1 and the electrode terminal 14: a) is less than 1 with the width (b) of the recess 141, the a portion Since stress is concentrated on the surface and it is easily damaged, increasing it in order to increase the strength of part a is against the miniaturization of the magnetic sensor.
As a result, a short circuit occurred due to the molten solder at an interval of 10 μm, so the judgment was x. On the other hand, at a distance of 60 μm between the electrode terminals 14 (the distance between the recesses 141 corresponds to 70 μm), the portion a was increased from 10 μm to 70 μm, which was contrary to the miniaturization of the magnetic sensor 1, which was ▲.
Therefore, the gap between the electrode terminals 14 is set to 20 μm or more to prevent a short circuit due to molten solder, and 50 μm or less to reduce the size.

The electrode terminal 14 has a recess 141, and the shape thereof is composed of a bottomed square pipe 141p and a flange 141f (FIG. 4).
Regarding the relationship between the size of the electrode terminal 14 and the recess 141, the size of the recess 141 is smaller in length and width than the size of the electrode terminal 14. This is to prevent the solder overflowing from the recess 141 from staying on the flange 141f of the electrode terminal 14 and short-circuiting with the adjacent electrode terminal.

試験方法は、磁気センサ１の幅は０．４ｍｍ（４００μｍ）にて電極端子１４の個数は４個とした。窪み１４１の幅（長さも窪みの幅と同一）を１５～７５μｍ、深さ２～１５μｍに変えて、小型引張試験装置を用いて引張荷重は１５０ｇで引張試験した。なお、窪みの長さは窪みの幅と同一にし、電極端子１４の大きさは長さおよび幅を４０～８０μｍとし窪み１４１の長さおよび幅より大きくし、フランジ１４１ｆを確保している。
判定基準は、引張試験により微細配線接合体が破断したものは接合強度を×と判定し、破断はしていないが磁気センサの小型化に反するものは△と判定し、平均サイズ１０μｍのハンダ粒が分散しているハンダペースト４２１を窪み１４１に充填が困難な場合はハンダ接合部１４２の形成ができないので▲と判定する。
その結果、先ず、窪み１４１の深さが１５μｍの場合は、窪み１４１の幅に関係なくハンダ粒のサイズより大きいことによる充填が難しかったので▲であった。次に、窪みの深さ２μｍの場合は、窪みの幅１５～６０μｍでは引張荷重１５０ｇで破断した。
また、窪みの幅を７５μｍの場合は、窪みの深さに関係なく引張荷重１５０ｇでは破断しなかったが、電極端子のサイズ（長さおよび幅）８０μｍに対して窪みのサイズ（長さおよび幅）７５μｍとの差が僅少（電極端子１４間の間隔は２０μｍとする）のために溶融したハンダがフランジ１４１ｆから流れ出して電極端子１４間で短絡が発生していた。その解決のためには、電極端子１４のサイズを８０μｍから、９０～９８μｍ程度まで大きくする必要があるために磁気センサの小型化に反することとなるので△であった。
窪みの深さ５μｍ、１０μｍにて窪みの幅３０～５０μｍの場合、引張荷重１５０ｇでは微細配線接合体は破断しなかったので〇であった。
したがって、接合強度の確保のために窪みの幅は３０μｍ以上、深さは５μｍ以上とする。小型化のために窪みの幅は６０μｍ以下とし、製造可能な深さは１０μｍ以下とする。 Table 2 shows the results of investigating the relationship between the size of the depression and the joint strength.

In the test method, the width of the magnetic sensor 1 was 0.4 mm (400 μm) and the number of electrode terminals 14 was four. The width of the recess 141 (the length is also the same as the width of the recess) was changed to 15 to 75 μm and the depth was 2 to 15 μm, and a tensile test was performed with a tensile load of 150 g using a small tensile test device. The length of the recess is the same as the width of the recess, and the size of the electrode terminal 14 is 40 to 80 μm in length and width, which is larger than the length and width of the recess 141 to secure the flange 141f.
As for the judgment criteria, if the fine wiring joint is broken by the tensile test, the joint strength is judged to be x, and if it is not broken but is contrary to the miniaturization of the magnetic sensor, it is judged to be △, and the solder grains having an average size of 10 μm are judged. If it is difficult to fill the recess 141 with the solder paste 421 in which the solder paste is dispersed, the solder joint portion 142 cannot be formed, so it is determined as ▲.
As a result, first, when the depth of the dent 141 was 15 μm, it was difficult to fill the dent 141 because it was larger than the size of the solder grains regardless of the width of the dent 141. Next, when the depth of the depression was 2 μm, the fracture was performed with a tensile load of 150 g when the width of the depression was 15 to 60 μm.
When the width of the dent was 75 μm, the dent did not break under a tensile load of 150 g regardless of the depth of the dent, but the size (length and width) of the dent was 80 μm with respect to the size (length and width) of the electrode terminal. ) Because the difference from 75 μm is small (the distance between the electrode terminals 14 is 20 μm), the molten solder flows out from the flange 141f and a short circuit occurs between the electrode terminals 14. In order to solve this problem, it is necessary to increase the size of the electrode terminal 14 from 80 μm to about 90 to 98 μm, which is contrary to the miniaturization of the magnetic sensor, which is Δ.
When the depth of the dent was 5 μm and 10 μm and the width of the dent was 30 to 50 μm, the fine wiring joint was not broken under a tensile load of 150 g, so the value was 0.
Therefore, in order to secure the joint strength, the width of the recess is 30 μm or more and the depth is 5 μm or more. For miniaturization, the width of the recess is 60 μm or less, and the manufacturable depth is 10 μm or less.

The square pipe 141p and the flange 141f are made of a conductive material such as gold or copper, and have a thickness of 1 to 3 μm.

The flexible wiring 2 is a wiring having a width of 0.8 mm or less and an arbitrary length for connecting the magnetic sensor 1 and an external electronic device (not shown), and is a plurality of connection terminals 21 corresponding to the electrode terminals 14. And wiring 22 (FIG. 2).
Since the width of the flexible wiring corresponds to the width of the magnetic sensor 1 and is composed of a plurality of electrode terminals 14, the distance between the electrode terminals 14 needs to be 20 μm to prevent a short circuit. On the other hand, in order to make the ASIC-integrated magnetic sensor ultra-miniaturized, the width of the flexible wiring to be connected is preferably fine 0.3 to 0.8 mm. It should be 0.3 mm or more for arranging at least 4 connection terminals, and 0.8 mm or less for miniaturization.

The size of the connection terminal 21 is 80 μm or less in width and 80 μm or less in length, preferably 40 to 80 μm in width and 40 to 80 μm in length (FIG. 2). The width and length are set to 40 μm or more in order to secure the adhesive strength with the disk-shaped solder 142b, which is the flat interface portion of the solder joint portion 142. The width and length shall be 80 μm or less for miniaturization.
The relationship between the size of the connection terminal 21 and the size of the electrode terminal 14 is preferably the same because the molten solder is pressed between both terminals to form a disk-shaped solder. Further, the shape of both terminals is preferably square because the molten solder is pressed between both terminals to form a disk-shaped solder.

The solder joint portion 142 that joins the electrode terminal 14 and the connection terminal 21 is a recessed portion of the solder 142a of the square pillar (the depth is the height of the pipe 141p of the square pillar plus the thickness of the flange 141f). And a disk-shaped solder 142b (FIG. 4).
The disc-shaped solder 142b is not necessarily a perfect circle but a circular to elliptical thick solder shape because the molten solder overflowing from the square pillar pipe 141p is formed by pressure.

The bonding strength of the electrode terminal 14 is determined in addition to the adhesion between the upper surface of the flange 141f (only the portion corresponding to the interface with the lower surface of the solder 142b of the disk) and the flat interface portion consisting of the upper surface of the solder 142a of the quadrangular prism. , The resistance of one surface of the quadrangular prism 141p (the surface on the right side of the quadrangular prism 141p in FIG. 4) to the tension of the flexible wiring 2 in the solder 142a of the quadrangular prism, and the other three surfaces of the solder 142a and the quadrangular prism 141p of the quadrangular prism (FIG. 4). The bonding strength is further increased by the adhesive force of the interface between the left side surface and the front and back of the quadrangular prism 141p in FIG. 4 and the lower surface of the quadrangular prism 141p. The solder joint portion 142 composed of the solder 142a of the square pillar and the solder 142b of the disk is integrally molded by molten solder (FIG. 4).

The shapes of the electrode terminal 14 and the connection terminal 21 are not limited to a rectangular shape. Even in the case of a circular shape such as a circle or an ellipse, the solder joint portion becomes three-dimensional due to the electrode terminal 14 having a recess, and is included as long as the effect of resistance is obtained in addition to the adhesion force of the interface portion of the flat surface. It is something that can be done.

According to this embodiment, the fine bonding between the electrode terminal 14 on the ASIC of the ultra-small magnetic sensor and the tangent terminal 21 of the fine flexible wiring is performed by the solder 142a of the square column connecting both terminals and the disk. It is performed via a solder joint portion integrally molded with the solder 142b, and a fine wiring joint body having a size of 1/2 to 1/5 and ensuring the joint strength can be obtained.
That is, even if the PCB substrate is omitted and the fine wiring joint is composed of fine electrode terminals and fine connection terminals, the joint strength between the ASIC and the fine flexible wiring can be improved and secured.

Next, the second invention is a method for manufacturing a fine wiring joint 3.
The fine wiring joint 3 is composed of an electrode terminal 14 of the magnetic sensor 1, a connection terminal 21 of the flexible wiring 2, and a solder joint portion 142 that joins the electrode terminal 14 and the connection terminal 21. The feature is that the solder joint 142 is integrally molded with the solder 142a of the square pillar and the solder 142b of the disk.
The method for forming the solder joint is as follows.

First, in order to form the recess 141 of the electrode terminal 14, a recess is formed in the resist layer 13 on the upper surface of the ASIC 12, and the electrode terminal 14 including the recess is formed by vapor deposition of gold, copper or the like (FIG. 6).
(1) The size of the electrode terminal 14 is 40 to 80 μm in width and 40 to 80 μm in length, and the size of the connection terminal is 40 to 80 μm in width and 40 to 80 μm in length.
The size of the recess of the electrode terminal has a width of 30 to 60 μm, a length of 30 to 60 μm, and a depth of 5 to 10 μm.

(2) Using the solder paste injection device 42, the solder paste 421 containing the solder fine particles corresponding to 1.1 to 1.3 times the volume of the recess is injected into the recess 141 (FIG. 8). Make it 1.1 times or more so that the molten solder spreads to every corner of the dent, and 1.3 to prevent short-circuiting with the adjacent electrode terminal or the disk-shaped solder so that the disk-shaped solder can be formed. Double or less.

A magnetic sensor 1 having an electrode terminal 14 composed of a recess 141 is fixed to a jig 41 of a fine wiring joining device (not shown), and solder fine particles are placed in the position of the recess 141 and the recess 141 of the fixed electrode terminal 14. The positioning device 43 is used for positioning with the solder paste injection device 42 for injecting the containing solder paste (FIGS. 7 and 8).

The jig 41 for fixing the magnetic sensor 1 has a width of 20 to 40 mm and a length of 40 to 80 mm, and has a groove (not shown) having a width of 1 mm or less for charging the magnetic sensor 1 in the groove. Charge and fix.

The positioning device 43 is a fixed type positioning device for positioning by sliding the jig 41 having the electrode terminals 14 fixed to the position of the solder paste injection device 42 installed at a predetermined position to the positioning device 43. The positioning device should be set with an accuracy of ± 1 μm.

After the alignment of the two, the solder paste injection device 42 is used to inject the solder paste 421 containing the solder fine particles corresponding to 1.1 to 1.3 times the volume of the recess 141 into the recess 141.

The solder paste device 42 is a dispenser type device and can be applied from a nozzle having a diameter of 50 μm. In the solder paste 421, the solder particles have a size of 7 to 15 μm and are dispersed in the paste.

(3) Using the microscope 44 and the positioning device 43, the positions of the electrode terminal 14 of the magnetic sensor and the connection terminal 21 of the flexible wiring are aligned.

The microscope 44 can observe with an accuracy of ± 2 μm with respect to the magnetic sensor 1 composed of the electrode terminals 14. The positioning device 43 can adjust the X-axis and the Y-axis with an accuracy of ± 1 μm in order to align the electrode terminal 14 of the fixed magnetic sensor with the position of the connection terminal 21 of the flexible wiring.
This is to ensure the joint position between the electrode terminal 14 and the connection terminal 21 (FIG. 9).

(4) Using a solder joining device, the electrode terminal 14, the connection terminal 21, and the solder paste 421 are heated and crimped from the two terminals, the solder 142a of the square column formed by injecting into the recess, and the recess. A solder joint portion 142 made of a disk-shaped solder 142b formed of solder fine particles having a volume 0.1 to 0.3 times the volume of the overflowing depression is formed.

When the volume of the dent 141 is 1.1 times or more, the solder fine particles are melted by heating in the dent 141, and when the electrode terminal 14 and the connection terminal 21 are crimped, the dent is filled with the melted solder and the square pillar. Solder 142a can be formed, and a disk-shaped solder 142b that serves as an interface portion of the flange portion of the electrode terminal 14 can be formed, and is integrally formed from the square column solder 142a and the disk-shaped solder 142b. A solder joint 142 is formed.
On the other hand, the volume of the recess 141 is 1.3 times or less so that the molten solder does not expand beyond the sizes of the two terminals (14 and 21) when crimping both terminals. This is because it does not contribute to the improvement of the bonding strength and is short-circuited with the adjacent electrode terminal or connection terminal (FIGS. 9 and 3).

The solder joining device 45 has a function of heating to 100 to 280 ° C. and a function of pressurizing the solder.
The solder joining device 45 heats to a predetermined temperature, contacts the upper surface of the flexible wiring 2, and pressurizes in the lower direction. By this heating and pressurization, the solder particles contained in the solder bonding agent in the depression 141 are melted and liquefied, and at the same time, the paste is vaporized and scattered from the depression 141. The inside of the recess 141 is filled with molten solder to form a square pillar solder 142a, and a part thereof extends to the flange portion of the electrode terminal 14 to form a disk solder 142b. The upper surface of the molten solder (solder 142a of the disk) is crimped to the connection terminal 21. In this way, a solder joint portion 142 including an interface portion and a recessed portion for joining the two terminal surfaces of the electrode terminal 14 and the connection terminal 21 is formed (FIGS. 9 and 3).

A large bonding strength can be obtained by both the adhesion force of the interface portion (disk-shaped solder 142b) and the tensile resistance force and the adhesion force of the recessed portion (square pillar solder 142a) (solder joint portion 142).

An embodiment of the fine wiring joint will be described.
<Magnetic sensor 1>
The magnetic sensor 1 is provided at the GSR sensor element 11 of the magnetic sensor in which the element of the GSR sensor disclosed in Japanese Patent No. 5839527 is directly mounted on the upper part of the ASIC 12, and the end portion of the resist layer 13 formed on the upper part of the ASIC 12. It is composed of an electrode terminal 14 having a recess 141 and an ASIC electrode wiring portion 122 extending from the ASIC electrode terminal 121 of the ASIC 12.
The size of the magnetic sensor 1 is 0.4 mm in width and 1.6 mm in length.

The electrode terminal 14 of the magnetic sensor 1 has a size of 60 μm in width and 60 μm in length on the upper portion of the insulating resist layer 13 formed on the upper surface of the ASIC 12, and has a distance of 100 μm between the electrode terminals 14 and a distance between the electrode terminals 14. Four electrode terminals 14 are juxtaposed in series in the width direction with a length of 30 μm. The electrode terminal 14 is covered with a 1 μm-thick conductive material made of gold plating.
All four electrode terminals 14 have recesses 141 having a width of 40 μm, a width of 40 μm, and a depth of 7 μm.

<Flexible wiring 2>
The flexible wiring 2 includes a connection terminal 21 and a wiring 22, and the width of the flexible wiring 2 is 0.4 mm and the length of the flexible wiring 2 is 200 mm.

<Solder joint 142>
The solder joint portion 142 has a disk-shaped solder 142b (interface portion) formed between a flat surface formed by the flange 141f of the electrode terminal 14 and the upper surface of the solder 142a of the square pillar and the connection terminal 21 and the soldering portion 142. It is formed from the solder 142a (recessed portion) of the square pillar formed in the square pipe.

<Fine wiring joint>
Therefore, the fine wiring joint 3 is composed of an electrode terminal 14, a connection terminal 21, and a solder joint 142.

<Joining strength of fine wiring joint>
A tensile strength test of a fine wiring joint including an electrode terminal 14, a connection terminal 21, and a solder joint 142 was performed.
As a result of fixing the magnetic sensor 1 including the electrode terminal 14 with a chuck and pulling the flexible wiring 2 including the connection terminal 21 with a small tensile test device, the flexible wiring 2 was broken at 250 g. At this time, it can be said that the bonding strength exceeded 250 g because the portion of the bonded body was not broken.
On the other hand, for comparison, the same device was used for a fine wiring joint made by applying solder paste on a flat electrode terminal that does not have a dent in the magnetic sensor, placing the connection terminal of the flexible wiring on it, and heating and crimping it. As a result of pulling, it broke at 80 g between the electrode terminal and the connection terminal.
From the results of the above tensile test, the fine wiring joint of the present invention can obtain a joint strength of 3.1 times or more as compared with the joint by the conventional joining method.
From this result, it can be said that when the recess 141 is provided in the electrode terminal 14, the resistance force and the adhesion force due to the solder 142a of the recessed portion are improved by 2.1 times the adhesion force due to the conventional flat surface only.

Next, a method for manufacturing a fine wiring joint will be described.
The fine wiring joint 3 is composed of an electrode terminal 14 of the magnetic sensor 1, a connection terminal 21 of the flexible wiring 2, and a solder joint portion 142 that joins the electrode terminal 14 and the connection terminal 21. The feature is that the solder joint 142 is composed of a disk solder 142b and a square pillar solder 142a, and the manufacturing method thereof is a method of forming a solder joint 142 in which the electrode terminal 14 and the connection terminal 21 are joined.
The method for forming the solder joint 142 is as follows.

(1) The size of the electrode terminal 14 (formed on the upper portion of the insulating resist 13) of the magnetic sensor 1 is 60 μm in width and 60 μm in length, and the size of the connection terminal 21 of the flexible wiring 2 is 60 μm in width and 60 μm in length. The size of the recess 141 of the electrode terminal 14 is 40 μm in width, 40 μm in length, and 7 μm in depth.

(2) The solder paste injection device 42 is used to inject the solder paste 421 containing the solder fine particles corresponding to 1.2 times the volume of the depression into the recess 141 (FIG. 8).

The magnetic sensor 1 having the electrode terminal 14 composed of the recess 141 is fixed to the jig 41, and the position of the recess 141 of the fixed electrode terminal 14 and the solder paste injection device 42 are aligned by the positioning device 43.

The jig 41 for fixing the magnetic sensor 1 has a width of 25 mm and a length of 40 mm, and is inserted into a groove having a width of 0.45 mm into which the magnetic sensor 1 is inserted and fixed.

The positioning device 43 is a fixed type positioning device for positioning by sliding the jig 41 having the electrode terminal 14 fixed to the position of the paste injection device 42 installed at a predetermined position to the positioning device 43. The positioning device should be set with an accuracy of ± 1 μm.

After aligning the two, the solder paste injection device 43 is used to inject the solder paste 21 containing the solder fine particles corresponding to 1.2 times the volume of the recess 141 into the recess 141.

The solder paste device 42 is a dispenser type device and can be applied from a nozzle having a diameter of 50 μm. In the solder paste, the average size of the solder grains is 10 μm and the solder paste is dispersed in the paste.

(3) Using the microscope 43 and the positioning device 44, the positions of the electrode terminal 14 of the magnetic sensor 1 and the connection terminal 21 of the flexible wiring 2 are aligned (FIG. 9).

The microscope 43 can be observed with an accuracy of ± 2 μm based on the GSR sensor element composed of the electrode terminals 14. The positioning device 44 can adjust the X-axis and the Y-axis with an accuracy of ± 1 μm in order to align the electrode terminal 14 of the fixed magnetic sensor with the position of the connection terminal 21 of the flexible wiring.

(4) Using the solder bonding device 45, the electrode terminal 14, the connection terminal 21, and the solder bonding agent are heated to 250 ° C. and pressed. A solder joint portion 142 composed of an interface portion (disk-shaped solder 142b) for joining the two terminal surfaces and a recessed portion (square pillar solder 142a) is formed (FIGS. 9 and 4).
By this heating and pressurization, the solder particles contained in the solder bonding agent in the depression 141 are melted and liquefied, and at the same time, the paste is vaporized and scattered from the depression 141. The inside of the recess 141 (141p) is filled with molten solder, and a part thereof extends to the flange portion 141f of the electrode terminal 14. The upper surface of the molten solder is crimped to the connection terminal 21. In this way, a solder joint portion 142 is formed, which is composed of an interface portion (disk-shaped solder 142b) for joining the two terminal surfaces of the electrode terminal 14 and the connection terminal 21 and a recessed portion (square pillar solder 142a).

A fine wiring joint having a large joint strength due to both the adhesion of the interface portion (disk-shaped solder 142b) and the tensile resistance and adhesion of the recessed portion (square pillar solder 142a) (solder joint 142). Easy to manufacture.

Since the present invention can increase the joint strength of the fine wiring joint, it is expected that an ultra-compact ASIC-integrated magnetic sensor will be used in a living body.

1: Magnetic sensor (ultra-compact ASIC integrated magnetic sensor)
11: Magnetic sensor element, 12: ASIC, 121: ASIC electrode terminal, 122: ASIC electrode wiring part, 13: Insulating resist layer, 14: Electrode terminal, 141: Recess (formed in electrode terminal 14), 141f : Flange (upper peripheral part of bottomed square pillar pipe), 141p: Bottomed square pillar pipe, 142: Solder joint, 142a: Square pillar solder, 142b: Disc-shaped solder 2: Flexible wiring 21: Connection terminal, 22: Wiring 3: Fine wiring joint 41: Jig, 42: Solder paste injection device, 421: Solder paste, 43: Positioning device, 44: Microscope, 45: Solder joining device

Claims (2)

From the solder joints that join the four or more electrode terminals on the ASIC surface of the magnetic sensor, the number of connection terminals corresponding to the number of the electrode terminals of the flexible wiring, and both terminals of the electrode terminals and the connection terminals. In the fine wiring joint
The magnetic sensor comprises an ASIC-integrated magnetic sensor in which a magnetic sensor element is directly formed on the ASIC surface.
The electrode terminal is located on the edge resist layer on the ASIC surface and has a length of 40 to 80 μm and a width of 40 to 80 μm, and has a length of 30 to 60 μm, a width of 30 to 60 μm, and a depth in the central portion. It consists of an electrode terminal with a recess in which a recess of 5 to 10 μm is formed.
In the electrode terminal with a recess, the entire surface of the electrode terminal including the recess is covered with a conductive material coating.
The flexible wiring is wiring having a width of 0.3 to 0.8 mm for connecting the magnetic sensor and an external electronic device, and has the connection terminal and wiring corresponding to the electrode terminal.
The solder joint is a fine wiring joint comprising a square pillar solder formed in the recess and a disk-shaped solder extending from the upper surface of the square pillar solder. In the method for manufacturing a fine wiring joint according to claim 1,
The solder joint is
(1) The size of the electrode terminal is 40 to 80 μm in width and 40 to 80 μm in length, and the size of the connection terminal is 40 to 80 μm in width and 40 to 80 μm in length.
The size of the recess of the electrode terminal is 30 to 60 μm in width, 30 to 60 μm in length, and 5 to 10 μm in depth.
(2) Using a solder paste injection device, a solder paste containing solder fine particles corresponding to 1.1 to 1.3 times the volume of the recess is injected into the recess.
(3) Using a microscope and a positioning device, align the electrode terminal of the magnetic sensor with the connection terminal of the flexible wiring.
(4) Using the solder joining device, the electrode terminal, the connection terminal, and the solder paste are heated and crimped to each other.
A disk-shaped solder formed by the two terminals, a square pillar solder formed by being injected into the recess, and solder fine particles having a volume 0.1 to 0.3 times the volume of the recess overflowing from the recess. A method for manufacturing a fine wiring joint, which comprises forming a solder joint made of solder.

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