JP2011028923A - Coated wire joining device and coated wire joining method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a joining device and a joining method, suitable for joining a coated wire with a terminal on a printed wiring board. <P>SOLUTION: The coated wire joining device for joining a coated wire with a joined part formed on the printed wiring board includes: a heater chip melting and peeling off coating of the coated wire; and two welding electrodes for flowing welding current between the joined part and the heater chip through core wires of the coated wire after the peeling off. In the joining method, welding current is made to flow between the welding electrodes and the heater chip through core wires after melting and peeling off of the coating of the coated wire and the joined part. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a coated wire bonding apparatus suitable for bonding a terminal of an electronic component formed of a coated wire, particularly a coil such as a small motor or a microphone, to a terminal on a printed wiring board, and a coated wire using this bonding apparatus. The present invention relates to a joining method.

Conventionally, a reflow soldering method by instantaneous heating using a thermocompression bonding apparatus has been used as a method for joining such covered wires (for example, Patent Document 1).
FIG. 6 is a diagram showing components of a thermocompression bonding portion of such an apparatus, and is a heating chip (also referred to as a heater chip) formed in a plate shape by a high resistance material such as molybdenum (Mo) or titanium (Ti). ) 2 and a thermocouple 3 connected to the tip of the heating chip 2.
The heating chip 2 has a thickness of about 0.8 mm and is heated by a pulse heat method. The pulse heat method is a heating method in which a large pulse current is passed and the Joule heat generated at this time is used.

The covered wire 6 has a diameter of several tens of μm to 1 mm, and the surface of the core wire 8 is covered with an insulating film (also referred to as coating) 9 such as urethane resin. In order to thermocompression-bond the coated wire 6, a solder layer 7 is formed in advance on a bonded portion 5 (also referred to as a terminal) such as a land portion formed on a circuit board (also referred to as a printed wiring board) 4 by plating or the like. In addition, the covered wire 6 to be joined is placed thereon.
After that, when the tip of the heating chip 2 is brought into contact with the covered wire 6 and a pulsed large current is passed at intervals of 100 ms to several 100 ms, the heating chip 2 is heated by Joule heat and melts the insulating film 9 and the solder 7. Then, the bonded portion 5 and the core wire 8 of the covered wire 6 are thermocompression bonded.

  In addition, in the catalog (cited in Patent Document 2) distributed by the applicant of the present invention for sale of the joining device, as a method for joining the covered wire, the covered wire placed on the joined portion is connected to the heater chip from the covered wire side. Pressurizing and heating at a position where the welding electrode is pressed against the welded portion from the opposite position of the heater chip, and the coating of the coated wire is melted and peeled off by pressing and heating the heater chip. Describes a technique in which a welding current is passed between the bonded portion and the core wire after peeling off the coating of the covered wire.

JP 2000-101229 A (Prior Art) JP 2004-167570 A (prior art)

  However, in the prior art described in Patent Document 1, not only the heat transmitted from the heater chip becomes energy for melting and peeling the coating of the coated wire, but also energy for bonding the core wire after the melting and peeling to the joined portion. It has become. For this reason, if the wire diameter of the coated wire core is increased, the amount of heat that escapes into the wire of the core wire increases, so if the heater chip is kept at a constant temperature regardless of the wire diameter, the bonding surface cannot be raised to the bonding interface temperature. Therefore, there arises a problem that the required bonding strength cannot be obtained at the bonding surface.

  In consideration of the amount of heat that escapes into the core wire, the temperature of the heater chip must be set high when trying to raise the temperature to the bonding interface temperature. There arises a problem that the lifetime is shortened.

  In addition to this problem, since only the heater chip is a heat source, a sufficient temperature rise cannot be obtained even on the terminal side which is the joint surface of the covered wire, so the necessary joint strength cannot be obtained on the joint surface. Has also occurred.

On the other hand, the above-described problem does not occur in the conventional technique described in Patent Document 2.
However, the method for joining a covered wire as described in [Technical Field] has the following drawbacks.
(1) Since the part to be joined is a terminal formed on a printed wiring board, an insulator is interposed between the welding electrode and the heater chip, so that no welding current can flow and the coating can be melted and peeled off. However, the core wire cannot be joined to the joined portion.
(2) Even if the welding electrode is on the same side as the heater chip and the terminal formed on the printed wiring board is pressed to allow a welding current to flow between the heater chip and one welding electrode, However, the reliability of uneven bonding is low.

  The present invention has been made in order to solve the above-mentioned problems. The first object of the present invention is to provide a coated wire bonding apparatus that employs an indirect method using two welding electrodes and a heater chip. It is a second object to provide a method for bonding a coated wire using the above.

  The coated wire bonding apparatus according to the first aspect of the present invention is a coated wire bonding apparatus for bonding a coated wire to a portion to be bonded formed on a printed wiring board, and heating for melting and peeling the coated wire. A heater chip for passing an electric current, and two welding electrodes for flowing a welding current between the joined portion and the core wire of the coated wire after the coating is peeled off, are provided. It is.

  The covered wire joining apparatus according to the invention described in claim 2 includes, instead of the two welding electrodes according to claim 1, a single welding electrode in which the side contacting the joined portion is divided into two. It is characterized by.

  A covered wire joining apparatus according to a third aspect of the invention is characterized in that the interval between the two welding electrodes according to the first aspect of the present invention is a width that sandwiches the covered wire in a range that does not contact the covered wire. Is.

  According to a fourth aspect of the present invention, there is provided a coated wire joining apparatus according to the present invention, characterized in that a fork interval setting of one welding electrode is a width that sandwiches the covered wire in a range that does not contact the coated wire.

  According to a fifth aspect of the present invention, there is provided a coated wire joining apparatus including a heater chip position measuring means in addition to the configuration of the first aspect.

The covered wire joining method according to the invention of claim 6 is a covered wire joining method for joining a covered wire to a part to be joined formed on a printed wiring board, and includes the following steps: To do.
a) A step of abutting a heater chip on the covered wire and applying a current to the heater chip to heat the heater chip to melt and peel off the covering of the covered wire. b) A welding electrode is applied to the bonded portion by sandwiching the covered wire. The heater chip is brought into contact with the core wire portion after coating melt peeling of the coated wire placed on the bonded portion, and the welding electrode and the heater chip are interposed via the bonded portion and the core wire portion. The process of flowing welding current during

The covered wire joining method according to the seventh aspect of the invention includes the following step between the step a) and the step b) described in the sixth aspect.
A step of measuring a position of the heater chip at the time of melt peeling of the coating of the coated wire by the heater chip, and instructing permission of energization of the welding current when exceeding a predetermined position

  According to invention of Claims 1-5, in order to join the electric current which flows only to a heater chip | tip in order to melt-peel the coating | cover of a covered wire, the core wire after a melt-peeling, and a to-be-joined part, Since the current flowing through the core wire and the bonded portion is controlled separately during the period, Joule heat sufficient to reach the bonding interface temperature can be obtained for both the core wire and the bonded portion. It is possible to provide a coated wire joining apparatus having a high height.

  Also, the core wire after the coating melt peeling is abutted with a heater chip, the tips of the two welding electrodes are brought into contact with the joined portion at intervals of contact with the coating wire, and a current is passed as described above. Since the nugget is uniformly formed on the contact surface between the core wire and the bonded portion because the bonded portion is bonded to the bonded portion, a coated wire bonding apparatus with high bonding reliability can be provided from this point. In addition, even when one welding electrode is used, this effect can be obtained even if the tip of the electrode is bifurcated so that the tip is sandwiched by the width of the covered wire.

  Then, when the heater chip is heated, the melted and peeled state of the coating of the coated wire is detected, and the position variation of the heater chip is detected. Since the welding current is passed after the peeling of the metal is completed, the current is supplied to the heater chip and the welding current simultaneously, and the welding current is monitored to judge the peeling of the coating and control the welding current to the required magnitude. Since control becomes simple compared with the method to do, a low-cost covered wire joining apparatus can be provided.

  According to the sixth aspect of the present invention, there is provided an electric current step that flows only to the heater chip in order to melt and peel the coating of the coated wire, and a welding electrode and the heater chip to join the core wire and the joined portion after the melt peeling. Since the coated wire is joined to the joined portion separately in the current process that flows between the core wire and the joined portion, the Joule heat that only reaches the joining interface temperature of the core wire and the joined portion. Therefore, it is possible to provide a coated wire bonding method with high bonding reliability.

  Further, since the contact portion of the welding electrode with the welded portion in the joining process of the core wire and the welded portion is made into two places with the covered wire sandwiched therebetween, the nugget is a contact surface between the core wire and the welded portion. Since it can form in the whole, the covering wire joining method with high joining reliability can be provided also from this point.

  According to the seventh aspect of the invention, a step of measuring the position of the heater chip and determining whether or not the position exceeds a predetermined position is added, and when the determination exceeds the predetermined position, the covering is performed. As a result, it is decided that the process of flowing the welding current will be performed after the melting and peeling of the heater is completed, so that the heating current of the heater chip and the welding current are not allowed to flow together. Can do.

It is a principal part schematic diagram of one Embodiment of the covered wire bonding apparatus which becomes this invention. It is the flowchart which shows one Embodiment of the covering wire joining method which becomes this invention, and is the first half part. It is the latter half part in the flowchart which shows one Embodiment of the covered wire bonding method which becomes this invention. It is a figure which shows typically a specific process among the covered wire joining processes using the covered wire joining method which becomes this invention. It is a figure which shows typically the flow of the welding current in the process of joining the core wire of a covered wire. It is a figure explaining the conventional covered wire joining method.

Next, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic diagram of a main part of an embodiment of a covered wire bonding apparatus according to the present invention. 2 and 3 are flow charts showing an embodiment of the coated wire joining method according to the present invention. FIG. 2 is the first half thereof, and FIG. 3 is the second half thereof. FIG. 4 is a diagram schematically showing a specific step in the covered wire bonding process using the covered wire bonding method according to the present invention, and FIG. 5 is a view particularly showing a core wire of the covered wire in FIG. It is a figure which shows typically the flow of the welding current in a process.

  1, 4 and 5, 1 is a work table for performing the joining of the covered wire, and 2 is a “heating electrode” for melting and peeling off the covering of the covered wire, and the core wire of the covered wire is joined to the joined portion. It is a heater chip that also serves as a “welding electrode”.

  When it becomes a “heating electrode”, a heating current 33 i is supplied to the energization portions 2 b and 2 c at both ends. And when it becomes the "welding electrode" to the to-be-joined part of the core wire of a covered wire, the front-end | tip of the welding electrodes 11 and 12 is contact | abutted to the terminal 5, and the welding electrodes 11 and 12 are functioned as an "energization electrode".

  On the other hand, the tip of the heater chip 2 is brought into contact with the core wire 8 after the coating is peeled off to function as a “welding electrode”. In this way, the welding current 31 i flows from the energizing portions 11 a and 12 a of the welding electrodes (“conducting electrodes”) 11 and 12 to the energizing portion 2 b of the heater chip (“welding electrode”) 2 via the terminals 5 and the core wires 8. Of course, the welding current 31i may be supplied to the energization part 2c instead of the energization part 2b. Moreover, the same code | symbol is attached | subjected to the same thing as a prior art example.

  Reference numeral 4 denotes a printed wiring board on which a terminal 5 to which a covered wire is bonded is formed, 6 is a covered wire, 8 is its core wire, and 9 is its covering.

  21 controls the entire coated wire bonding apparatus, but the following control is executed for the present invention. The heater chip 2 is positioned at a predetermined position of the covered wire 6 and the welding electrodes 11 and 12 are positioned at predetermined positions sandwiching the covered wire 6 while controlling the positioning means and lifting means (not shown). The welding electrodes 11 and 12 are moved up and down. At this time, the degree of pressing of the heater chip 2 against the covered wire 6 is regarded as a change in the position of the heater chip 2 by the displacement detection unit 41, and this detection information is used.

  Further, the first welding power source 33 is controlled to allow the heating current 33 i to flow through the heater chip 2. Then, the second welding power source is controlled to pass a welding current 31 i between the welding electrodes 11 and 12 and the heater chip 2 via the terminal 5 and the core wire 8 of the covered wire 6.

  Next, a method for joining a coated wire, which has not been previously peeled, to a terminal of a printed wiring board will be described in the order of steps with reference to FIGS. In addition, since all the joining operation | movement of a covered wire is based on control from the control part 21, it does not specify clearly by control of the control part 21 in particular.

[Preparation]
First, as a preparation stage, the printed wiring board 4 is placed on the work table 1 with a surface on which the terminals 5 are formed on the work table 1 by using a conveying means (not shown) (S201 in FIG. 2). Then, the coated wire to be welded onto the terminal 5 formed on the printed wiring board 4 is positioned and placed in advance without peeling off the coating (S202 in FIG. 2). In addition, a well-known conveyance means and a positioning means can each be used for this conveyance means and a positioning means.

[Peeling of coated wire]
Next, descending onto the covered wire 6 is started while positioning the heater chip 2 at a predetermined position (S203 in FIG. 2). This lowering is detected by the displacement detector 41, and the tip of the heater chip 2 reaches the first predetermined position while continuing the lowering (YES in S204 in FIG. 2, (a) in FIG. 4).

  Here, not only the heater chip 2 is lowered, but the heating current 33i is supplied from the first welding power source 33 to the heater chip 2 to start heating (S205 in FIG. 2, (b) in FIGS. 1 and 4). This is because Joule heat is generated in the heater chip 2 by flowing the heating current 33i, and the covering 9 of the covered wire 6 pressed by the tip of the heater chip 2 is melted and peeled off by this heat.

  As described above, since the heater chip 2 continues to descend during this heating, the heater chip 2 presses the coated wire 6, so that the coating 9 at the portion where the tip of the heater chip 2 abuts is melted. It peels and the core wire 8 is exposed ((b) of FIG. 4). In FIG. 4B, reference numeral 2a denotes a Joule heat generating portion where the coating 9 is melted and peeled off by the heating current 33i.

  The position variation of the heater chip 2 is detected by the displacement detector 41, and the coating is melted and peeled, and the heater chip 2 reaches the second predetermined position, which is a displacement corresponding to a width substantially equal to the diameter of the core wire 8 (see FIG. 2), the flow of the heating current 33i to the pulse heat 2 is stopped and the heating of the pulse heater 2 is terminated (S207 in FIG. 2). In this way, the melt peeling of the coated wire is completed.

[Joint of core wire of coated melt-released part to terminal]
After the coating is melted and peeled as described above, the heater chip 2 holds the position as it is. This is because the heater chip 2 operates as a “heating electrode” when the coating is melted, but operates as a “welding electrode” when the core wire 8 of the coating melt peeling portion is joined to the terminal 5.

  Next, descending is started so as to sandwich the covered wire 6 from both sides while positioning the welding electrodes 11 and 12 at predetermined positions (S208 in FIG. 3). This lowering also measures the force with which the welding electrodes 11 and 12 press the terminal 5 by a load detection unit (not shown), and continues the lowering until a predetermined pressing force is reached (YES in S209 in FIG. 3).

  Here, preliminary energization is performed in the order of the welding electrodes 11 and 12 (the current-carrying portions 11a and 12a), the terminal 5, the core wire 8 after the coating melt peeling, and the heater chip 2 (the current-carrying portion 2a) from the second welding power source 31 (FIG. 3 S210). This pre-energization not only preheats the contact portion between the terminal 5 and the core wire 8 as a joining location, but also confirms whether or not the coating of this portion is sufficiently peeled so that a welding current can actually flow. It is also to do.

  After preliminary energization is performed for a predetermined time at this predetermined current value, a welding current 31i necessary and sufficient for actual welding is supplied from the second welding power source 31 in this order (S211 in FIG. 3). At this time, the welding electrodes 11 and 12 operate as “energizing electrodes”, the heater chip 2 operates as “welding electrodes”, and Joule heat is generated between the core wire 8 and the terminals 5 abutted by the heater chip 2. Due to this heat, the core wire 8 and the terminal 5 are joined at this portion by this heat ((c) in FIG. 4, FIG. 5). In FIG. 4C, 85 is a nugget formed at this time.

  In this way, the core wire 8 and the terminal 5 are joined. Even after the welding current 31i no longer flows, the joined portion may leave when the pressing force disappears due to residual heat, so the pressing force is maintained for a predetermined time. (S212 in FIG. 3), the heater chip 2 is then raised (S213 in FIG. 3), and the welding electrodes 11 and 12 are raised (S214 in FIG. 3).

  In this way, the coated wire can be joined to the terminal formed on the printed wiring board without removing the coating in advance.

  In the above embodiment, two welding power sources are used. Even if one welding power source is used, one welding power source is used by adopting a circuit configuration that switches the flow path between the heating current and the welding current. Thus, the present invention can be realized.

  In the above embodiment, the welding electrode lowering is performed after the heater chip lowering. However, the present invention can be realized even when the heater chip lowering and the welding electrode lowering are performed at the same timing.

DESCRIPTION OF SYMBOLS 1 Worktable 2 Heater chip 4 Printed wiring board 5 Terminal 6 Covered wire 8 Core wire 9 Covered 11, 12 Welding electrode 21 Control part 31 2nd welding power supply 33 1st welding power supply 41 Displacement detection part

Claims (7)

A coated wire joining apparatus for joining a coated wire to a joined portion formed on a printed wiring board,
A heater chip for supplying a heating current for melting and peeling the coating of the coated wire;
Two welding electrodes for flowing a welding current between the joined portion and the core wire of the coated wire after coating peeling, and the heater chip;
A device for joining coated wires, comprising:   2. The apparatus for joining covered wires according to claim 1, further comprising: one welding electrode having a bifurcated side in contact with the joined portion, instead of the two welding electrodes.   2. The apparatus for joining covered wires according to claim 1, wherein the interval between the two welding electrodes according to claim 1 is a width for sandwiching the covered wire within a range not contacting the covered wire.   3. The coated wire joining apparatus according to claim 1, wherein the distance between the forked portions of one welding electrode is a width for sandwiching the coated wire in a range not contacting the coated wire. A coated wire joining apparatus for joining a coated wire to a joined portion formed on a printed wiring board,
The apparatus for bonding a covered wire according to claim 1, further comprising a position measuring unit for the heater chip. A method for joining covered wires, comprising: bonding a covered wire to a portion to be joined formed on a printed wiring board, the method comprising:
a) A step of abutting a heater chip on the covered wire and applying a current to the heater chip to heat the heater chip to melt and peel off the covering of the covered wire. b) A welding electrode is applied to the bonded portion by sandwiching the covered wire. The heater chip is brought into contact with the core wire portion after coating melt peeling of the coated wire placed on the bonded portion, and the welding electrode and the heater chip are interposed via the bonded portion and the core wire portion. The process of flowing welding current during A method for joining covered wires according to claim 6,
A covered wire joining method comprising the following steps between step a) and step b):
A step of measuring a position of the heater chip at the time of melt peeling of the coating of the coated wire by the heater chip, and instructing permission of energization of the welding current when exceeding a predetermined position

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