JP2017062945A - Heater chip, joining device and joining method - Google Patents

Abstract

An object of the present invention is to improve the temperature monitoring accuracy and reliability when a thermocouple is attached to a heater chip to prevent uneven oxidization from occurring and to prolong its service life and to measure the temperature of the iron part. A heater chip 10 has a thermocouple 22 attached to an arm portion 20R of a connection terminal portion 14R on one side (right side in the illustrated example) at a position close to the iron portion 12. The left and right iron peripheral portions 24L and 24R located near the boundary between the iron portion 12 and the arm portions 20L and 20R of the both connection terminal portions 14L and 14R are JL and JR, respectively. Assuming that the amount of heat generated when the right iron remote portion 24P located on the opposite side (right side) of the right iron peripheral portion 24R as viewed from the thermocouple 22 on the 14R arm portion 20R is JP, JP <JL <JR Or the condition is satisfied. [Selection] Figure 1

Description

  The present invention relates to a heater chip, a bonding apparatus, and a bonding method used for bonding a conductive wire and a terminal member.

  In general, in an automatic joining apparatus, a lead wire (for example, a lead wire from an electrical component or an external circuit) 100 having a wire diameter (thickness) of several hundreds μm or less is connected to a terminal member (eg, a wiring conductor or a connection pad) on the circuit board 102. When joining to 104 by thermocompression bonding, a heater chip 106 as shown in FIG. 12 is used as a joining tool (see, for example, Patent Document 1).

  This type of heater chip 106 is formed as a substantially U-shaped or V-shaped plate body having a refractory metal such as tungsten or molybdenum as a base material, and is diagonally upward and laterally from a rectangular parallelepiped shaped iron part 108. A pair of extending connection terminal portions 110 </ b> L and 110 </ b> R are attached to the heater head 112. The illustrated heater head 112 physically connects both connection terminal portions 110L and 110R of the heater chip 106 with bolts 116L and 116R on one side of a pair of power supply conductors 114L and 114R that communicate with an output terminal of a heater power source (not shown). In addition, they are electrically coupled to each other, and have an elevating mechanism for moving the heater chip 106 up and down via the power feeding conductors 114L and 114R, and a pressurizing mechanism (not shown) for pressing toward the object to be joined. Yes. An insulator 118 is electrically sandwiched between the power supply conductors 114L and 114R to electrically separate them.

  In FIG. 12, the circuit board 102 is horizontally supported by a work table (for example, an XY table) or a jig (not shown), and one end of the conducting wire 100 is placed on the terminal member 104. When the heater head 112 lowers the heater chip 106, as shown in FIG. 13, the terminal member 104 in which the iron tip surface 108 a of the iron part 108 of the heater chip 106 overlaps the part W to be joined, that is, the circuit board 102, and The conductor 100 is brought into contact with an appropriate pressure. When the heater power supply is turned on and a current is passed through the heater chip 106 in a state where the iron part 108 of the heater chip 106 is pressed against the bonded part W (100, 104), the heater chip 106 generates resistance heat. And the to-be-joined part W (100,104) is heated at high temperature normally 750 degreeC or more. As a result, when the conductive wire 100 is a covered wire, the insulating coating melts and peels off by heat, and the exposed conductor of the conductive wire 100 is simultaneously subjected to pressure and heating from the heater chip 106 and is plastically deformed to heat the terminal member 104. Bonded by crimping.

  In order to measure or monitor the temperature of the iron part 108, this type of heater chip 106 is usually provided with a thermocouple 120 as a temperature sensor on a back surface 108b opposite to the iron tip surface 108a. At the time of energization, much of the Joule heat generated around the iron part 108 and its periphery is supplied to the joined part W (100, 104) via the iron tip surface 108a, while part of the heat is supplied via the thermocouple 120. Escape to the outside. Normally, the temperature of the iron part 108 detected by the thermocouple 120 and the temperature of the iron tip surface 108a corresponding to the bonded part W (100, 104) do not coincide with each other, but between the characteristics of change with time (temperature waveform). The temperature of the tip surface 108a of the iron part 108 (heating temperature) can be monitored based on the output signal of the thermocouple 120.

JP 2005-66636 A

  In the conventional heater chip 106, oxidation that occurs on the chip surface while repeating the high-temperature (750 ° C. or higher) energization heating operation for thermocompression bonding as described above (if the heater chip material is tungsten, it is changed to tungsten oxide). In the vicinity of the boundary between one of the left and right connecting terminal portions 110L and 110R and the iron portion 108, and the uneven oxidization only shortens the life of the heater chip 106. In addition, there is a problem in that the accuracy and reliability of the tip temperature monitoring using the thermocouple 120 is reduced.

  14A and 14B, the mechanism of ubiquitous oxidation in the conventional heater chip 106 will be described. In this specification, the ubiquitous oxidation means that the oxidation of some parts appears or proceeds significantly more than the oxidation of other parts on the current path of the heater chip.

  As shown in FIG. 14A, in the heater chip 106 being energized, the current I from the heater power source is on the path of the left connection terminal portion 110L → the iron portion 108 → the right connection terminal portion 110R or the opposite direction. And Joule heat is generated in proportion to the square of the effective value of the current I in each part through which the current I flows. In this case, since the material of each part of the heater chip 106 is the same and the electrical resistivity is constant, the current is concentrated and the more Joule heat is generated at the portion having a smaller cross-sectional area on the current path.

As shown in the drawing, the smallest portion of the heater chip 106 having a cross-sectional area on the current path at first glance is a portion in the vicinity of the boundary between the connecting terminal portions 110L, 110R on the left and right sides and the iron portion 108 (hereinafter referred to as “the iron peripheral portion”). ”) 122L and 122R. Since the iron part 108 protrudes downward between the iron peripheral parts 122L and 122R on both the left and right sides, and the cross-sectional area on the current path is much larger than both the iron peripheral parts 122L and 122R (particularly, the iron tip surface). There is not much Joule heat generated (near 108a). For this reason, in the heater chip 106 that is energized, with respect to heat conduction, the iron moves from the iron peripheral portions 122L and 122R on the left and right sides to the bonded portion W through the intermediate portion of the iron portion 108 and the iron tip surface 108a. Lower heat conduction h _1L , h _1R and heat conduction h _2L , h _2R at the upper part of the iron where heat is transferred from both iron peripheral parts 122L, 122R to the thermocouple 120 through the back surface 108b side of the iron part 106 Two routes coexist.

Here, as long as the Joule heats generated in the left and right iron peripheral portions 122L and 122R are balanced with each other, uneven oxidization on either one side does not occur, and the lower heat conduction h _1L , h in the iron portion 108 occurs. _1R and the upper heat conduction h _2L and h _2R are both balanced on the left and right sides, and the monitoring of the tip temperature using the thermocouple 120 functions stably.

  However, actually, even if both the connection terminal portions 110L and 110R of the heater chip 106 are manufactured symmetrically, there is an error in their dimensions (especially the cross-sectional area on the current path). Even if it is slight, the Joule heat imbalance generated in the peripheral portions 122L and 122R on both sides of the iron increases as the heating temperature becomes higher in one energizing heat generating operation, and the imbalance is repeated each time the energizing heat generating operation is repeated. This increases the degree of equilibrium, which causes the phenomenon of ubiquitous oxidation and makes the tip temperature monitoring unstable.

  For example, it is assumed that there is a relationship (dimensional error) between the connecting terminal portions 110L and 110R in which the cross-sectional area of the right iron peripheral portion 122R is somewhat smaller than the cross-sectional area of the left iron peripheral portion 122L. In this case, when the heater chip 106 is energized, the resistance heat generated in the left iron peripheral portion 122L and the right iron peripheral portion 122R at the start of energization is not the same, and the heat generation in the right iron peripheral portion 122R having a relatively small cross-sectional area. Is superior to the heat generation in the left iron peripheral portion 122L having a relatively large cross-sectional area. As a result, the resistance of the right iron peripheral portion 122R that rises with a constant temperature coefficient due to heat generation is higher than the resistance of the left iron peripheral portion 122L that rises with the same temperature coefficient. The imbalance of the heat generation amounts of the iron peripheral portions 122L and 122, and hence the imbalance of the heat generation temperature, is enlarged.

  In this way, the right iron peripheral portion 122R generates heat at a significantly higher temperature in the heater chip 106 than other parts (particularly the left iron peripheral portion 122L) during energization, so that as shown in FIG. The oxide 124 is locally thick with a large growth rate. Each time the energization heat generation operation is repeated, the effective cross-sectional area (cross-sectional area of the portion excluding the oxidation 124) of the conductive path in the vicinity thereof is further reduced due to the uneven increase of the oxidation 124 in the right iron peripheral portion 122R. The protruding heat generation in the right iron peripheral portion 22R, and hence the uneven distribution of the oxidation 124 becomes more prominent, and eventually the vicinity of the iron peripheral portion 122R is broken or broken.

Even if the heater chip 106 is not damaged, the heat conduction h _1L , h _{1R at the} bottom of the iron and the heat conduction h _2L , h _{2R at the} top of the iron generated in the iron part 108 during energization are not balanced left and right, Since this imbalance increases during the energization time and increases each time the energization heat generation operation is repeated, the accuracy and reliability of the tip temperature monitoring using the thermocouple 120 is greatly impaired.

  The present invention solves the problems of the prior art as described above, and makes it difficult to cause uneven oxidization, thereby prolonging the life, and when attaching a thermocouple for measuring the temperature of the iron part, Provided are a heater chip, a bonding apparatus using the same, and a bonding method that improve the accuracy and reliability of temperature monitoring.

  A heater chip according to a first aspect of the present invention is a heater chip for joining a conductive wire to a terminal member, from a resistance heating element that contacts or contacts one end of the conductive wire disposed on the terminal member. In order to make a physical and electrical connection between the iron part and the power supply conductor from the heater power source, it is made of the same resistance heating element as the iron part, and is symmetrical with the iron part integrally from the left and right ends thereof Alternatively, the first and second connection terminal portions extending asymmetrically, and a thermocouple attached to the first connection terminal portion at an appropriate position close to the iron portion, the iron portion and the first portion when energized. With respect to the resistance heat generated in the second connection terminal portion and the second connection terminal portion, the amount of heat generated in the first portion located near the boundary between the iron portion and the first connection terminal portion is represented by J1, the iron portion and the second connection portion. Boundary with the connection terminal The heat value of the second part located in the vicinity is J2, and the heat value of the third part located on the opposite side of the first part with respect to the thermocouple on the first connection terminal is J3. Then, there is a relationship that J3 <J2 <J1.

  A heater chip according to a second aspect of the present invention is a heater chip for joining a conductive wire to a terminal member, from a resistance heating element that contacts or contacts one end of the conductive wire disposed on the terminal member. In order to make a physical and electrical connection between the iron part and the power supply conductor from the heater power source, it is made of the same resistance heating element as the iron part, and is symmetrical with the iron part integrally from the left and right ends thereof Alternatively, the first and second connection terminal portions extending asymmetrically, and a projecting heat radiating body attached to the first connection terminal portion near the iron portion, the iron portion and the first and Regarding the resistance heat generated in each of the second connection terminal portions, the amount of heat generated in the first portion located near the boundary between the iron portion and the first connection terminal portion is represented by J1, the iron portion and the second portion. Boundary with connection terminal The amount of heat generated in the second part located nearby is J2, and the amount of heat generated in the third part located on the opposite side of the first part when viewed from the radiator on the first connection terminal is J3. Then, there is a relationship that J3 <J2 <J1.

  In the heater chip having the above-described configuration, a thermocouple (or a heat radiating body) is attached to the connection terminal part on one side near the iron part, and the first part located near the boundary between the iron part and the first connection terminal part Heat generation amount during energization of the (first iron peripheral portion) J1, heat generation amount during energization of the second portion (second iron peripheral portion) located near the boundary between the iron portion and the second connection terminal portion J2, J3 between the amount of generated heat J3 during energization of the third part (iron remote part) located on the opposite side of the first part when viewed from the thermocouple (or radiator) on the first connection terminal part By providing the relationship <J2 <J1, the peripheral portions of the first and second irons, which generate heat at a higher temperature than other parts when energized, generate heat autonomously even if the cross-sectional areas of both current paths are different. Since the temperature is balanced, ubiquitous oxidation occurs on either side of both irons. Difficult Ri.

  In addition, when a thermocouple is attached to measure the temperature of the iron part, the heat conduction in the left and right directions in the iron part is stabilized in a balanced state, so that heat conduction from the iron peripheral part near the thermocouple to the thermocouple is also possible. It is stable and the correspondence between the temperature detected by the thermocouple and the temperature of the iron part (particularly the temperature near the tip of the iron) is kept constant, so the accuracy and reliability of temperature monitoring is maintained stably. .

  In a preferred aspect of the present invention, assuming that the cross-sectional areas of the first, second, and third portions on the path of the current that flows during energization are S1, S2, and S3, respectively, there is a relationship of S1 <S2 <S3. Make it. Further, assuming that the cross-sectional area of the intermediate part between the left and right ends of the iron part on the path of the current flowing when energized is S4, the relationship of S3 <S4 is established.

  The joining device of the present invention supports the heater chip of the present invention and the heater chip, and presses the tip surface of the iron part to the conductor on the terminal member when joining the conductor to the terminal member. And a heater power supply for supplying a resistance heating current to the heater chip.

  The joining method in the 1st viewpoint of this invention is a joining method joined to a terminal member using the joining apparatus of this invention, Comprising: The 1st process of mounting the said conducting wire on the said terminal member, The said heater head is used. A second step of controlling and applying a predetermined pressing force to the lead wire on the terminal member by applying the iron part of the heater chip to the terminal member, and energizing the heater chip by controlling the heater power source, A third step of promoting diffusion bonding by bringing the conductive wire into close contact with the terminal member by heating and pressurization; and controlling the heater power supply to stop energization of the heater chip at a predetermined timing; And a fourth step of controlling the head to separate the iron part from the thin conductor wire.

  In the bonding method according to the second aspect of the present invention, a first step of placing the thin conductor wire on the terminal member via solder, and a solder head of the heater chip is controlled on the terminal member by controlling the heater head. A second step of applying a predetermined pressing force to the thin conductor wire, a third step of controlling the heater chip to energize the heater chip, and melting the solder by heating from the iron part, And a fourth step of controlling the heater power supply to stop energization of the heater chip at a predetermined timing, and controlling the heater head after a predetermined time to separate the iron part from the thin conductor wire.

  According to the heater chip of the present invention, due to the above-described configuration and operation, the uneven oxidation phenomenon is unlikely to occur and the life is extended, and when a thermocouple is attached to measure the temperature of the iron part, the temperature Monitoring accuracy and reliability can be improved.

  Moreover, according to the joining apparatus or joining method of this invention, the quality and productivity of joining processing of a conducting wire and a terminal member can be improved by using the heater chip of this invention.

It is a perspective view which shows the structure of the heater chip in one Embodiment of this invention. It is a figure which shows the whole structure of the joining apparatus in the said embodiment. It is a perspective view which shows the mode of one Example which joins conducting wire to a terminal member by thermocompression bonding using the said joining apparatus. It is a partial cross section front view which shows one step of the said thermocompression bonding process. It is a partial cross section front view which shows one step of the said thermocompression bonding process. It is a partial cross section front view which shows one step of the said thermocompression bonding process. It is a figure for demonstrating the effect | action of the heat conduction around the iron part in the heater chip of embodiment. It is a perspective view which shows one modification regarding the structure around the iron part in the heater chip of embodiment. It is a perspective view which shows another modification regarding the structure around the iron part in the heater chip of embodiment. It is a partial cross section side view which shows one step of the thermocompression bonding process using the heater chip by the modification of FIG. It is a partial cross section side view which shows one step of the reflow type soldering using the heater chip by the modification of FIG. It is a partial cross section side view which shows one step of the reflow type soldering using the heater chip by the modification of FIG. It is a partial cross section side view which shows one step of the reflow type soldering using the heater chip by the modification of FIG. It is a partial cross section side view which shows one step of the reflow type soldering using the heater chip by the modification of FIG. It is a partial cross section side view which shows one step of the reflow type soldering using the heater chip by the modification of FIG. It is a partial cross section side view which shows one step of the reflow type soldering using the heater chip by the modification of FIG. It is a perspective view which shows the structure of the heater chip | tip in another modification. It is a perspective view which shows an example of the thermocompression bonding process using the conventional heater chip. It is a partial cross section front view which shows the state which is energizing a heater chip in the thermocompression-bonding process of FIG. It is a figure for demonstrating typically the effect | action of the heat_generation | fever around the iron part in a conventional heater chip, and heat conduction. It is a figure for demonstrating the ubiquitous oxidation phenomenon in the said conventional heater chip.

Hereinafter, a preferred embodiment of the present invention will be described with reference to FIGS.
[Configuration of Heater Chip in Embodiment]

  FIG. 1 shows a configuration of a heater chip in an embodiment of the present invention. The heater chip 10 in this embodiment is made of a hard plate-like refractory metal having a thickness of about 3 mm, for example, rolled tungsten or sintered tungsten, and is substantially U-shaped in front view as shown in the figure by wire electric discharge machining, for example. Or it is manufactured in a substantially V shape.

  The heater chip 10 has a iron part 12 positioned at the lowermost end in a posture of normal use, and a pair of connection terminal parts integrally extending with the iron part 12 and extending symmetrically (or asymmetrically) from the left and right ends of the upper part. 14L, 14R.

  The iron part 12 has a substantially rectangular parallelepiped shape, and protrudes downward from the lower ends of the connection terminal parts 14L and 14R on the left and right sides. Both connection terminal portions 14L and 14R are wide flat plate portions 18L and 18R provided with fixing bolt through holes 16L and 16R, and arm portions extending obliquely between the flat plate portions 18L and 18R and the iron portion 12. 20L, 20R.

In the heater chip 10, a thermocouple 22 is attached to the arm portion 20 </ b> R of the connection terminal portion 14 </ b> R on one side (right side in the illustrated example) at a position close to the iron portion 12. And the resistance at the time of electricity supply of the 1st and 2nd site | part located in the vicinity of the boundary of the iron part 12 and the arm parts 20L and 20R of both connection terminal parts 14L and 14R, that is, the left and right iron peripheral parts 24L and 24R, respectively. the calorific value J _L, and J _R, the third part, namely the right trowel remote unit located on the right side trowel periphery 24R opposite side when viewed from the thermocouple 22 on the arm portion 20R of the right connecting terminal portion 14R (right) When the resistance heating value during energization of 24P is J _P , the relationship or condition of J _P <J _L <J _R is established.

In this embodiment, J _P <J _L <J in order to satisfy the relationship of _R (Condition), left iron periphery 24L, right trowel periphery 24R, S respectively the area of the current path of the right trowel remote unit 24P _L , S _R , S _P , the heater chip 10 is manufactured so that the relationship (condition) of S _R <S _L <S _P is satisfied. That is, the arm portions 20L and 20R of the connection terminal portions 14L and 14R are formed in a tapered shape so that the cross-sectional area gradually decreases from the flat plate portions 18L and 18R toward the iron portion 12 (thereby, S _R <S _P, conditions S _L <S _P is satisfied) is provided with a notch (or constriction) 26 for moderately reducing the cross-sectional area of the current path near the right trowel periphery 24R (This , S _R <S _L is satisfied).

  More specifically, the thermocouple 22 is attached to a protrusion 28 formed on the back surface of the arm portion 20R of the right connection terminal portion 14R (the surface on the same side as the back surface 12b of the iron portion 12). The end (temperature measuring end) of the thermocouple 22 is joined to the protrusion 28 by, for example, arc welding.

Similarly to the conventional heater chip 106 (FIGS. 12 and 13), the heater chip 10 is attached to the heater head 112 (FIG. 12) with bolts 116L and 116R, and is preset for a given object to be joined. The predetermined pressurization operation and energization heat generation operation are performed according to the procedure and processing conditions.

[Overall Configuration of Joining Device in Embodiment]

  In FIG. 2, the whole structure of the joining apparatus 30 in this embodiment is shown. The joining device 30 includes a heater chip 10 having the above-described configuration, and a heater head 112 that supports the heater chip 10 and presses and contacts the iron part 12 to the workpiece from above when joining the workpiece. The heater power supply 32 that supplies a current for resistance heating to the heater chip 10 and a control unit 46 that controls each part in the apparatus and the overall operation are provided.

  The heater power supply 32 uses an AC waveform inverter type power supply circuit. The inverter 34 in this power supply circuit has four transistor switching elements 36, 38, 40, 42 made of GTR (giant transistor) or IGBT (insulated gate bipolar transistor).

Among these four switching elements 36 to 42, the first set (positive electrode side) switching elements 36 and 40 have a predetermined inverter frequency by in-phase drive pulses G ₁ and G ₃ from the control unit 46 via the drive circuit 44. Switching (on / off) is simultaneously controlled (for example, 4 kHz), and the second set (negative side) switching elements 38 and 42 are driven by in-phase drive pulses G ₂ and G ₄ from the control unit 46 via the drive circuit 44. Switching control is performed simultaneously with the inverter frequency.

The input terminals (L ₀ , L ₁ ) of the inverter 34 are connected to the output terminal of the three-phase rectifier circuit 48. The three-phase rectifier circuit 48 is formed by connecting, for example, six diodes in a three-phase bridge, and full-wave rectifies the commercial-frequency three-phase AC voltage input from the three-phase AC power supply terminals (R, S, T) to generate a direct current. Convert to voltage. The DC voltage output from the three-phase rectifier circuit 48 is smoothed by the capacitor 50 and then applied to the input terminals [L ₀ , L ₁ ] of the inverter 34.

Output terminals (M ₀ , M ₁ ) of the inverter 34 are respectively connected to both ends of the primary coil of the welding transformer 52. Both ends of the secondary side coil of the welding transformer 52 are connected to the connection terminal portions 14L and 14R of the heater chip 10 via the secondary side conductors 114L and 114R without passing through the rectifier circuit.

  The control unit 46 includes a microcomputer, and performs all the controls in the heater power source 32, such as energization control (particularly inverter control), various heat condition setting and display processing, etc., and is also required for the heater head 112. Control.

In the heater power source 32, an electric signal (iron temperature measurement signal) indicating the temperature of the iron portion 12 of the heater chip 10 is transmitted via the cable 25 from the thermocouple 22 attached to the right connection terminal portion 14 </ b> R of the heater chip 10. This is given to the control unit 46. When performing current feedback control, a current sensor 54 made of, for example, a current transformer is attached to the conductor of the primary circuit. A measured value (for example, effective value, average value, or peak value) of the primary current or the secondary current is obtained from the output signal of the current sensor 54 in the current measurement circuit 56, and the current measurement signal is given to the control unit 46.

[Examples related to thermocompression bonding]

  Next, with reference to FIG. 3 to FIG. 7, an embodiment will be described in which a conducting wire is joined to a terminal member by thermocompression processing using the joining device 30 having the above configuration.

  As shown in FIG. 3, in this embodiment, similarly to the conventional example (FIGS. 12 and 13) described above, a lead member 100 (for example, a wiring conductor) on an electric component (not shown) or a lead wire 100 from an external circuit is connected. ) Bonded to 104 by thermocompression bonding. The conducting wire 100 is, for example, a copper wire or an aluminum wire having a wire diameter of 300 μm or less, and may be either a covered wire or a bare wire. The material of the circuit board 102 is ceramic (for example, alumina), and the material of the terminal member 104 is, for example, a silver-based or gold-based conductor.

  First, before starting the joining apparatus 30, one end part of the conducting wire 100 is horizontally arranged in a predetermined direction on the terminal member 104 of the circuit board 102 on a work table or a supporting jig (not shown), and the heater The joined portion W (100, 104) is positioned immediately below the heater chip 10 attached to the head 112 (FIG. 2).

When the joining device 30 (FIG. 2) is activated, the heater head 112 is first activated. The heater head 112 lowers the heater chip 10 so that the tip surface 12a of the tip portion 12 touches the top of the conductor 100 as shown in FIG. 4A. Next, the heater power source 32 (FIG. 2) is activated to start energization of the heater chip 10, and the heater head 112 applies a predetermined pressure or load to the bonded portion W (100, 104) through the heater chip 10. Then, when the lead wire 100 is a covered wire, the insulating coating is melted and peeled off by the heat from the heater chip 10, and the exposed conductor of the lead wire 100 is pressed by the heater chip 106 and heated at a high temperature of usually 750 ° C. or higher. As shown in FIG. 4B, it is crushed and plastically deformed, and the conducting wire 100 and the terminal member 104 are joined by diffusion bonding. When a predetermined time has elapsed from the start of energization, the heater power supply 32 stops energization, stops the resistance heat generation of the heater chip 10, and holds the bonded portion W (100, 104) for a certain period of time. Then, after the holding time elapses, the heater head 112 pulls the heater chip 10 upward as shown in FIG. 4C.

[Operation of Heat Conduction in Heater Chip in Embodiment]

  The heater chip 10 in this embodiment performs a high-temperature energization heat generation operation for thermocompression bonding as described above many times by the action of heat conduction around the iron part as described below with reference to FIG. However, uneven oxidation is less likely to occur, and the accuracy and reliability of the tip temperature monitoring using the thermocouple 22 can be stably maintained.

As described above, the heater chip 10 has a thermocouple 22 attached to the arm portion 20R of the right connection terminal portion 14R near the iron portion 12 (between the right iron peripheral portion 24R and the right iron remote portion 24P). The relationship S _R <S _L <S _P is established among the cross-sectional areas S _L , S _R , S _P on the current path of the left iron peripheral portion 24L, the right iron peripheral portion 24R, and the right iron remote portion 24P. .

  As shown in FIG. 5, during energization, the current I from the heater power source flows on the path of the left connection terminal portion 14L → the iron portion 12 → the right connection terminal portion 14R or the opposite direction, and the current I Joule heat is generated in proportion to the square of the effective value of the current I in each flowing part. In this case, since the material of each part of the heater chip 10 is the same and the electric resistivity is constant, the current is concentrated in the portion where the cross-sectional area on the current path (area perpendicular to the path of the current I) is smaller, A lot of heat is generated.

In the heater chip 10, the smallest portion sectional area on the current path is a right iron periphery 24R, the cross-sectional area S _L of the left trowel periphery 24L is somewhat than the cross-sectional area S _R of the right iron periphery 24R Large, the cross-sectional area S _P of the right iron remote portion 24P is somewhat larger than the cross-sectional area S _L of the left iron peripheral portion 24L. That is, there is a relationship of S _R <S _L <S _P. Therefore, the left trowel periphery 24L of the heater chip 10 during conduction, the heating value J _L on the right iron periphery 24R and the right iron remote unit 24P, J _R, between the J _P J _P <of J _L <J _R A relationship is established. The iron part 12 protrudes downward from the iron peripheral parts 24L and 24R on the left and right sides, and the cross-sectional area on the path of the current I is much larger than the both iron peripheral parts 24L and 24R. not so much, the amount of heat generated near the tip surface 12a when the J _K, is a J _K <J _P.

For this reason, during energization, a part (most part) of the Joule heat generated in the left iron peripheral part 24L in the iron part 12 passes through the intermediate part of the iron part 12 and the iron tip surface 12a to the welded part W. The rightward heat conduction H _1L that moves and the leftward heat conduction H in which a part of the Joule heat generated in the right iron peripheral portion 24R moves to the welded portion W through the intermediate portion of the iron portion 12 and the iron tip surface 12a. _1R coexists.

On the other hand, in the arm portion 20R of the right connection terminal portion 14R, the thermocouple 22 is attached between the right iron peripheral portion 24R and the right iron remote portion 24P. The rightward heat conduction H _{2L in} which another part of the generated Joule heat moves to the thermocouple 22 and the leftward heat conduction H _{2R in which} a part of the Joule heat generated in the right iron remote portion 24P moves to the thermocouple 22 And coexist.

Here, left-handed heat conduction H _1R toward the iron part 12 side and right-handed heat conduction H _2L toward the thermocouple 22 side from the right-hand iron peripheral part 24R with the largest amount of heat generation coexist in two left and right hands. This is very important. As described above, the condition that the heat is divided into the left and right hands from the right iron peripheral portion 24R that generates the largest amount of heat and the above-described condition of J _P <J _L <J _R is combined. The heat conduction H _{1R in} the opposite direction (leftward) from the right iron peripheral portion 24R is balanced with each other rather than forcibly superior to the heat conduction H _{1L in} the right direction from the iron peripheral portion 24L. Therefore, excess heat flows to the thermocouple 22.

In this way, both the left and right iron peripheral portions 24L and 24R that generate heat at a higher temperature than other parts when energized in the heater chip 10 autonomously balances the heat generation temperature even if the cross-sectional areas on the current paths of both are different. The ubiquitous oxidation that occurs in either one of the iron peripheral portions 24L and 24R hardly occurs. In addition, by stabilizing the heat conduction in the left and right directions in the iron part 12 in a balanced state, the heat conduction from the right iron peripheral part 24R to the thermocouple 22 is also stabilized, and the temperature detected by the thermocouple 22 and the iron part 12 Correspondence between temperature (particularly the temperature near the tip 12a) is kept constant. As a result, the accuracy and reliability of the tip temperature monitoring using the thermocouple 22 is stably maintained.

[Other Embodiments or Modifications]

  6 and 7 show a modified example of the configuration around the iron part 12 in the heater chip 10 of the above embodiment.

  In the first modification shown in FIG. 6, the heater chip 10 is provided with a recess or a tip recess 30 leading to the tip end surface 12a on one side surface (front side in the figure) 12c of the tip portion 12 having a substantially rectangular parallelepiped shape. More specifically, the iron tip recessed portion 30 extends from the upper end while expanding the depth inward while expanding laterally in an inversely tapered manner toward the bottom at the center of the side surface 12c of the iron portion 12. It has a structure that is scraped down to the bottom (the tip surface 12a). In this hollow structure, the ceiling of the iron tip recess 30 is gradually lowered from the side surface 12c toward the inner depth, and the bottom is notched from the entrance to the inner depth.

  When performing the thermocompression bonding as described above using the heater chip 10 of the first modified example, as shown in FIG. 8, even if the tip surface 12a is in pressure contact with the tip of the conductor 100, the shaft The tip recess 30 facing the conductive wire 100 in the direction is covered without contacting the conductive wire 100. In this modification, since the iron part 12 is constricted in the vicinity of the iron tip surface 12a by the iron tip recess 30, the concentration of pressurization and heating applied to the conductive wire 100 is increased, and the bonding strength of thermocompression bonding is improved. .

  As shown in FIGS. 9A to 9C, the heater chip 10 of the first modification can be suitably used for reflow soldering. In reflow soldering, as shown in FIG. 9A, the surface of the terminal member 104 is preliminarily coated with cream solder 32, and the lead wire 100 placed on the cream solder 32 is heated from above. The chip 10 comes into pressure contact. The conducting wire 100 may be either a covered wire or a bare wire, but a copper plated aluminum wire or a copper clad aluminum wire is particularly suitable. Further, the circuit board 102 may be a resin, and the terminal member 104 may be a copper-based conductor.

  In this case, when the iron part 12 presses the tip part 100a of the conducting wire 100 against the terminal member 104 with the iron tip surface 12a, the conducting wire 100 is not in close contact with the surface of the terminal member 104 directly under the iron tip recessed part 30, or A gap is formed between the two (100, 104). When energization is started, each part of the heater chip 10 generates resistance heat, and an insulating coating (for example, urethane) is formed on the front end portion 100a of the conducting wire 100 that is pressurized and heated by the iron portion 12 (particularly the iron tip surface 12a). 9) is peeled off, and as shown in FIG. 9B, the leading end portion 100a of the conducting wire 100 is flattened and joined to the surface of the terminal member 104 by thermocompression bonding, whereby the thermocompression bonding portion 34 is formed. Then, the heat of the iron part 12 is transmitted to the terminal member 104 via the tip part 100a and the thermocompression bonding part 34 of the conductive wire 100, and further, a portion 100b (hereinafter referred to as “proximal tip end”) extending into the solder tip recess 30 of the conductive wire 100. Also, the heat of the iron part 12 is transmitted to the tip part 12), and the insulating coating melts and peels even at the tip vicinity part 100b of the conductive wire 100.

  Thus, when the insulation coating of the tip proximity portion 100b of the conductive wire 100 is peeled off in the iron tip recess 30, the inner copper plating layer (or copper clad layer) is exposed in a pure state, and even if the flux is not used, The exposed copper plating layer wraps the molten solder <32> by wetting. In this case, in the space (gap) between the iron part 12 and the terminal member 104, most of the melted solder <32> on the terminal member 104 gathers in the iron tip recess 30 due to wetting and surface tension. Thus, the copper plated layer (or copper clad layer) of the tip proximity portion 100b of the conductive wire 100 is covered.

  When a predetermined time elapses from the start of energization and the joining device 30 cools the iron part 12 to a temperature (base temperature or room temperature) lower than the solder freezing point, all the molten solders <32> are connected to the terminals 104, respectively. Solidify in position. That is, as shown in FIG. 9C, the molten solder portion <32M> in the solder tip recess 30 is changed to a solid solder portion [32M] that covers the copper plating layer (or copper clad layer) of the tip proximity portion 100b of the conductive wire 100. The molten solder portion <32K> remaining under the front surface 12a is changed to a low-layer solid solder portion [32K] extending around the thermocompression bonding portion 34.

  In the second modified example shown in FIG. 7, a plurality of (two in the illustrated example) groove portions 36 </ b> A and 36 </ b> B each extending vertically in the chip width direction are formed on the tip surface 12 a of the iron portion 12 in the heater chip 10. They are arranged side by side in the chip thickness direction. Even when the heater chip 10 of the second modification is used for reflow soldering, cream solder is applied to the surface of the terminal member 104 in advance. For example, as shown in FIG. 10A, sleeper-shaped cream solders 32A and 32B may be applied in advance to positions facing the grooves 36A and 36B.

  In this case as well, the same effect as in the first modified example can be obtained. However, as shown in FIGS. 10B and 10C, the melted solder <32A> and <32B> and thus the solid solder portion [32A] are provided in the grooves 32A and 32B. ] And [32B] are formed, and the thermocompression bonding part 34 is formed in the middle.

  In the heater chip 10 of the said embodiment, the structural example which attaches the thermal radiation body 40 instead of the thermocouple (22) to the arm part 20R of the connection terminal part 14R of the one side (illustration example right side) is shown in FIG. The heat radiating body 40 may be integrally formed of the same material as the heater chip 10, and may be preferably formed in a fin shape (or block shape) as shown in the drawing in order to improve heat dissipation to the atmosphere. May be plated with gold. When the heater chip 10 is energized, part of the Joule heat generated in the right iron peripheral portion 24R and the right iron remote portion 24P is released into the atmosphere via the radiator 40. That is, the same heat release effect as the case where the thermocouple (22) is attached to the same position is exhibited.

DESCRIPTION OF SYMBOLS 10 Heater chip 12 Iron part 12a Iron tip surface 12b (Iron part) Back surface 12c (Iron part) Side surface 14L, 14R Connection terminal part 20L, 20R Arm part 22 Thermocouple 24L Left iron peripheral part 24R Right iron peripheral part 24P Right iron remote Part 30 Bonding device 32 Heater power supply 40 Heat dissipator 100 Conductor 102 Circuit board
104 Terminal material

Claims (7)

A heater chip for joining a lead wire to a terminal member,
A trowel portion made of a resistance heating element that comes into contact with or contacts one end of the conducting wire disposed on the terminal member;
In order to make a physical and electrical connection with a power supply conductor from a heater power supply, the resistance heating element is the same as the iron part, and extends symmetrically or asymmetrically from the left and right ends integrally with the iron part. First and second connection terminal portions;
A thermocouple attached to the first connection terminal part near the iron part,
Regarding the resistance heat generated in the iron part and the first and second connection terminal parts when energized, the amount of heat generated in the first part located near the boundary between the iron part and the first connection terminal part is calculated. J1, the amount of heat generated in the second part located in the vicinity of the boundary between the iron part and the second connection terminal part is J2, and the first part when viewed from the thermocouple on the first connection terminal part A heater chip characterized in that there is a relationship of J3 <J2 <J1, where J3 is the amount of heat generated in the third part located on the opposite side of J3. A heater chip for joining a lead wire to a terminal member,
A trowel portion made of a resistance heating element that comes into contact with or contacts one end of the conducting wire disposed on the terminal member;
In order to make a physical and electrical connection with a power supply conductor from a heater power supply, the resistance heating element is the same as the iron part, and extends symmetrically or asymmetrically from the left and right ends integrally with the iron part. First and second connection terminal portions;
A projecting heat dissipating body attached to the first connection terminal portion near the iron portion;
Regarding the resistance heat generated in the iron part and the first and second connection terminal parts when energized, the amount of heat generated in the first part located near the boundary between the iron part and the first connection terminal part is calculated. J1, the amount of heat generated in the second part located near the boundary between the iron part and the second connection terminal part is J2, and the first part when viewed from the radiator on the first connection terminal part A heater chip characterized in that there is a relationship of J3 <J2 <J1, where J3 is the amount of heat generated in the third part located on the opposite side of J3.   The relationship of S1 <S2 <S3 is established, where S1, S2, and S3 are the cross-sectional areas of the first, second, and third portions on the path of the current that flows during energization, respectively. The heater chip described.   3. The heater chip according to claim 1, wherein a relationship of S <b> 3 <S <b> 4 is established, where S <b> 4 is a cross-sectional area of an intermediate portion between the left and right ends of the iron portion on a path of a current that flows during energization. The heater chip according to any one of claims 1 to 4,
A heater head that supports the heater chip and pressurizes and contacts the iron tip surface of the iron part to the conductor on the terminal member when joining the conductor to the terminal member;
And a heater power supply for supplying a current for resistance heating to the heater chip. A joining method for joining to a terminal member using the joining device according to claim 5,
A first step of placing the conducting wire on the terminal member;
A second step of controlling the heater head to apply a predetermined pressing force by applying a soldering portion of the heater chip to the conductive wire on the terminal member;
A third step of energizing the heater chip by controlling the heater power supply, and promoting diffusion bonding by bringing the conductor into close contact with the terminal member by heating and pressing from the iron part;
And a fourth step of controlling the heater power supply to stop energization of the heater chip at a predetermined timing, and controlling the heater head after a predetermined time to separate the iron part from the thin conductor wire. A joining method for joining to a terminal member using the joining device according to claim 5,
A first step of placing the conductor fine wire on the terminal member via solder;
A second step of controlling the heater head to apply a predetermined pressing force by applying the iron portion of the heater chip to the conductor thin wire on the terminal member;
A third step of controlling the heater chip to energize the heater chip and melting the solder by heating from the iron part;
And a fourth step of controlling the heater power supply to stop energization of the heater chip at a predetermined timing, and controlling the heater head after a predetermined time to separate the iron part from the thin conductor wire.