JPH05315391A - Bonding method of lead of ic part - Google Patents

Abstract

PURPOSE:To bond a lead to an electrode of a circuit board with high reliability by heating each lead of an IC part and a bonding metallic layer by irradiation of optical energy and by fixing the lead of the IC part simultaneously with thermocompression of the bonding metallic layer with the lead by sequentially pressing each lead one by one or a plurality of leads at a time. CONSTITUTION:Each lead 2 of an IC part 1 is arranged on a plurality of electrodes 3 provided with a bonding metallic layer 5. Then, each lead 2 of the IC part 1 and the metallic layer 5 are heated by irradiation of optical energy. Each lead 2 is sequentially pressed one by one or a plurality of leads are pressed at a time by a pressing means 7 for thermocompression between the lead 2 and the bonding metallic layer 5. Then, the lead 2 of the IC part is fixed simultaneously with thermocompression. Thereby, it is possible to prevent a lead from rising due to warp of the IC part before a molten bonding metallic layer coagulates and to acquire bonding of higher reliability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of mounting an IC component on a circuit board and joining its leads to electrodes on the circuit board.

[0002]

2. Description of the Related Art Conventionally, IC parts are mounted on a circuit board,
As a method of joining the lead to the electrode of the substrate, a reflow method of melting cream solder on the electrode is generally used.
There is a problem that the liquid crystal panel to which the parts are joined is exposed to high temperature, which is not preferable, and the equipment structure becomes large.

Therefore, as a method for joining leads of IC parts having low heat resistance, a joining metal layer is provided on the electrodes of the substrate by solder plating or the like, and the leads of the IC parts are placed thereon, and then a heating tool is used. Press the lead toward the electrode,
A method has been proposed in which a lead and a bonding metal layer are heated and pressed to bond them to each other. Known heating tools include a heater with a built-in heater and a heater with a pulsed current for instantaneous heating.

[0004]

However, in the joining method using the above heating tool, since the leads are heated by the heating tool at a high temperature, the flux of the joining metal adheres to this heating tool, and uniform heating or pressurization is applied. However, there is a problem that reliable bonding cannot be performed.

Further, when a substrate or an IC component to be joined by heating is stretched at the time of joining and the joining is finished and the substrate is cooled, the lead of the IC component is cut or the solder joined to the liquid crystal. The connection sometimes came off on the side opposite to the attachment surface. Further, there is a problem that a tool for heating by applying a pulse current is likely to be thermally deformed.

Further, since all the leads extending from one side of the IC component are collectively pressed by the heating tool, when the IC component becomes large in size as in recent years, the heating tool is parallel to the circuit board. It becomes difficult to adjust the degree, and it is easily affected by the warp of the substrate and the variation of the thickness of the bonding metal layer, which may lead to imperfectly bonded leads, resulting in the problem that reliable bonding cannot be performed. Came.

In view of the above conventional problems, the present invention prevents the flux applied to the joining metal layer and the leads of the IC component from adhering, causing warpage of the IC component, warpage of the substrate, and variation in the thickness of the joining metal layer. Also aims to bond the leads to the electrodes of the circuit board with high reliability.

[0008]

A method for joining an IC component according to the present invention comprises a step of arranging each lead of the IC component on a plurality of electrodes provided with a joining metal layer, and each lead of the IC component and a joining metal. It has a step of heating the layer by irradiation of light energy, a step of sequentially pressing one or a plurality of leads to thermocompression-bond the leads and the bonding metal layer, and a step of fixing the leads of the IC component at the same time as thermocompression bonding. It is characterized by

Preferably, a step of arranging each lead of the IC component on each of the plurality of electrodes provided with a joining metal layer, and one or more leads are sequentially pressed to bring the leads into contact with the connecting metal layer. After that, each lead of the IC component and the bonding metal layer are heated by irradiation of light energy to melt the bonding metal layer, and the pressing of the IC component is stopped after the irradiation of the light energy is finished, thereby fixing the leads of the IC component. It is characterized by

Further, irradiation of light energy is performed from the rear in the scanning direction toward the lead and the bonding metal layer in front of the pressing means, and the pressing means absorbs the light energy when the pressing means descends and presses the lead. It is characterized by exerting the effect of a hot iron. The pressing means is silicon nitride,
It may be made of carbon, ruby, or alumina (Al ₂ O ₃ ), and a heater may be built in the pressing means in order to exert more effect.

Also, a step of arranging each lead of the IC component on each of the plurality of electrodes provided with the bonding metal layer, and I
A TAB pressing step for fixing the lead of the C component, a step of heating each lead of the IC component and the joining metal layer by irradiation of light energy, and a step of pressing each lead one by one or more by thermocompression bonding of the lead and the joining metal layer. And a timer is provided when joining the last lead in a line,
After the predetermined time has elapsed and the joining metal is solidified, the fixing portion (T
It is characterized in that the AB pressing step is completed).

The pressing means is hollow, and a thermocouple is arranged inside the pressing means to control the irradiation time and power of light energy based on the measured temperature.

[0013]

According to the present invention, since the heating of the lead and the bonding metal layer is performed in a non-contact manner by irradiation of light energy such as laser light or infrared rays, the pressing means does not adhere to the flux at a low temperature. Since the leads 1 or more are sequentially pressed, even if the leads are lifted,
Even if the substrate warps or the thickness of the joining metal layer varies, each lead can be pressed reliably, and since there is a step of fixing the leads, even if the IC component is warped, the joining metal layer is melted. Leads do not float, and highly reliable bonding is possible.

Further, one or a plurality of leads are sequentially pressed to bring the leads into contact with the joining metal layer, and then the leads of the IC component and the joining metal layer are heated by irradiation of light energy to melt the joining metal layer and to emit light. Since the leads of the IC component are fixed by terminating the pressing after the energy irradiation is completed, the leads do not float up due to the warp of the IC components before the bonding metal layer is melted and solidified, and a highly reliable joining is achieved. can get.

Further, when the pressing means descends and presses the lead, the pressing means absorbs light energy, or a heater incorporated in the pressing means exerts the effect of a thermal iron to thereby make the IC component of the bonding metal layer. The connection to the lead is improved, the joint strength is increased, and the joint inspection is facilitated.

Further, when the pressing means is made of silicon nitride, carbon, ruby, or alumina (Al ₂ O ₃ ) or is sprayed with carbon or ceramic, the same effect as described above is exhibited and the durability is excellent. The number of maintenance can be reduced.

Further, a timer is provided for joining the last lead arranged in a row, and the fixing portion (the TAB holding step is completed) is lifted after the predetermined time has elapsed and the joining metal is solidified, so that the lead of the IC component is removed. Even if it is warped, the fixing portion rises after the joining metal layer is solidified, so that the lead is not lifted up and highly reliable joining is possible.

Further, the pressing means is hollow, a thermocouple is arranged inside the pressing means, and the irradiation of the light energy is controlled based on the measured temperature, whereby the light energy varies and the thickness of the bonding metal layer varies. However, the substrate is not burned, the bonding metal layer is not completely melted, and the bonding strength is not lowered, so that the bonding can be performed with high reliability.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a lead joining method for an IC component according to the present invention will be described below with reference to FIGS. 1 is a perspective view of the pressing means and the lead fixing means, FIG. 2 is a cross-sectional view of the portion AA 'in FIG. 1, and FIG. 3 is a movement timing chart of each means in this embodiment.

In FIG. 1, reference numeral 1 denotes an IC component, which has a plurality of leads 2 extending from four sides or two or one side. 3 is each lead 2 of the IC component 1 on the substrate 4.
The electrodes are arranged corresponding to the above, and solder is previously provided on the upper surface thereof as the joining metal layer 5 and solid solder obtained by reflowing solder plating or cream solder is provided. The joining metal layer 5 is coated with flux in advance. Also, the flux may be applied to the upper surface of the lead 2.

Reference numeral 6 is a light energy means for irradiating light energy such as laser light, infrared light, and light beam, and 7 is a pressing means for pressing the lead 2 toward the electrode 3.
Is attached to a scanning body (not shown) that intermittently moves in the parallel direction with the arrangement pitch of the leads, and the pressing means 7 is configured to be able to urge downward and retract as shown by arrow B. .. The lead fixing means 8 is also attached to the scanning body (not shown), is coaxially attached to the pressing means 7, and moves at the same time as the pressing means as indicated by an arrow C. Further, the lead fixing means 8 is biased and presses both sides (may be one side) of the end surface of the lead 2.

The light energy irradiating means 6 is tilted backward or forward in the scanning direction by an appropriate angle θ in order to secure a space for disposing the driving means with respect to the pressing means 7, so that the pressing means 7 and the lead fixing means are provided. The lead 2 facing 8 is irradiated with light energy.

In the above structure, the IC component 1 is mounted on the substrate 4 so that each lead 2 is arranged on the corresponding electrode 3, and then the lead fixing means 8 presses both ends of the lead 2 to press the pressing portion 7. After pressing on the lead, the light energy irradiation means 6 is operated to melt the joining metal layer 5 and join the lead 2 and the electrode 3. The operation of the light energy irradiating means is stopped, and then the pressing means 7 moves up in the direction of the arrow B to move the scanning body to I
The lead 2 is intermittently moved by the arrangement pitch of the leads 2 along the row of the leads 2 on each side of the C component 1. At this time, the lead fixing means 8 moves in the same direction as the scanning body while pressing both ends of the lead 2.

All the leads 2 are joined to the electrodes 3 through the joining metal layer 5 by sequentially repeating this joining operation.

Since the heating of the lead 2 and the bonding metal layer 5 is performed by the irradiation of the light energy from the light energy irradiating means 6, the IC component 1 and the substrate 4 are at a low temperature, and therefore the substrate and the IC component are heated by the heat. Does not expand or contract. Moreover, since the lead 2 is fixed to the electrode 3 while being pressed by the lead fixing means 8, the lead 2 of the IC component 1 is
Even when it is warped and peeled upward, it is pressed all the time while it is bonded to the bonding metal layer 5, and is fixed to the electrode 3 even after pressing and contact (with the bonding metal layer 5) by the pressing means 7. Has been done.

Further, as shown in FIG. 3, one or a plurality of leads 2 are sequentially pressed to bring the leads 2 into contact with the bonding metal layer 5, and then the leads 2 and the bonding metal layer 5 of the IC component 1 are exposed to light energy. Since the lead of the IC component is fixed by heating by irradiation to melt the joining metal layer 5 and ending the light energy irradiation and then pressing, the lead is caused by the warp of the IC component before the joining metal layer is melted and solidified. Does not rise, and more reliable bonding can be obtained.

Further, when the position of the light energy irradiating means 6 is set so that the light energy is applied to the pressing means 7 as shown in FIG. 4, or when the pressing means 7 is heated by the heater 11, the pressing means 7 descends and leads. When the pressing means 7 presses the light energy, the pressing means 7 absorbs the light energy and exerts the effect of a heat iron, so that the bonding metal layer 5 can be easily routed to the leads 2 of the IC component 1, and the bonding metal is also bonded to the upper surface of the leads 2. When the layer 5 wraps around and, for example, solder is used for the bonding metal layer 5 and tin or gold plating is used on the surface of the lead 1, the surface of the lead 1 becomes the color of the bonding metal layer 5, increasing the bonding strength and facilitating the inspection of the bonding. become.

Further, the absorption efficiency of light energy is high,
When the pressing means is made of silicon nitride, carbon, ruby, or alumina (Al ₂ O ₃ ) or is sprayed with carbon or ceramic, the above effects are further exhibited and the heat resistance and durability are excellent. It is possible to reduce the number of times of maintenance such as replacement of No. 7.

Next, a second embodiment of the present invention will be described with reference to FIGS. 5 and 6. The IC component 1 is mounted on the substrate 4 so that each lead 2 is arranged on the corresponding electrode 3, and then the lead fixing means 8 presses both ends of the lead 2 and the pressing portion 7 presses on the lead. The energy irradiating means 6 is operated to melt the joining metal layer 5 and join the lead 2 and the electrode 3. The operation of the light energy irradiating means is stopped, and then the pressing means 7 rises in the direction of the arrow B (FIG. 5A), and the scanning body is arranged with the leads 2 along the row of the leads 2 on each side of the IC component 1. Move intermittently by pitch. At this time, the lead fixing means 8
Moves in the same direction as the scanning body while holding both ends of the lead 2.

By repeating this bonding operation sequentially, all the leads 2 are bonded to the electrodes 3 via the bonding metal layer 5. At this time, a timer t _D shown in FIG. 6 is provided at the time of joining the last lead 2a lined up in a row as shown in FIG. 5B, and the fixing portion 8 (TAB When the IC component 1 is warped as shown in FIG. 5C, the fixing portion 5 rises after the joining metal layer 5 is solidified, so that the fixing portion 5 rises. It is possible to achieve highly reliable bonding without floating.

Next, a third embodiment of the present invention will be described with reference to FIG. The pressing means 8 is hollow, and the thermocouple 10 is arranged inside thereof. The IC component 1 is mounted on the substrate 4 so that each lead 2 is arranged on the corresponding electrode 3, and then the lead fixing means 8 presses both ends of the lead 2 and the pressing portion 7 presses on the lead. The energy irradiating means 6 is operated to melt the joining metal layer 5 and join the lead 2 and the electrode 3. At this time, the irradiation of light energy is controlled based on the temperature measured by the thermocouple 10 and the temperature measured by the light energy irradiation control device 9. When a predetermined temperature is reached and a predetermined time elapses (the temperature may be integrated and control by the amount of energy may be used in some cases), the operation of the light energy irradiating means is stopped, and then the pressing means 7 moves up in the direction of the arrow B to move the scanning member. I
The lead 2 is intermittently moved by the arrangement pitch of the leads 2 along the row of the leads 2 on each side of the C component 1. At this time, the lead fixing means 8 moves in the same direction at the same time as the scanning body while pressing both ends of the lead 2. Then, by sequentially repeating this bonding operation, all the leads 2 are bonded to the electrodes 3 via the bonding metal layer 5.

Even if the light energy varies or the thickness of the bonding metal layer varies due to the operation of FIG. 7, the substrate is not burned, and the bonding metal layer is not completely melted and the bonding strength is lowered. There is no problem, and highly reliable bonding is possible. In addition, it is unnecessary to set the irradiation time condition.

In this embodiment, the power generation pair 10 is built in the pressing means 7, but it is installed on the side surface of the pressing means 7 on the opposite side to which the light energy is irradiated by the light energy irradiation means 6. Sometimes

[0034]

According to the lead joining method for an IC component of the present invention, the leads and the joining metal layer are heated in a non-contact manner by irradiation with light energy such as laser light or infrared rays.
At the low temperature, the pressing means does not adhere to the flux. One or more leads are sequentially pressed to contact the leads and the joining metal layer, and then each lead of the IC component and the joining metal layer are heated by irradiation of light energy to melt the joining metal layer, and the irradiation of light energy is completed. Since the lead of the IC component is fixed by ending the pressing after that, the lead does not float up due to the warp of the IC component before the joining metal layer is melted and solidified, and more reliable joining can be obtained.

Further, the pressing means absorbs light energy,
Alternatively, the heater attached to the pressing means exerts the effect of a thermal iron to improve the circumference of the bonding metal layer to the leads of the IC component, and the bonding metal layer also wraps around the upper surface of the lead, for example, the bonding metal layer. When solder or tin or gold plating is used on the surface of the lead, the surface of the lead becomes the color of the joining metal layer, the joining strength increases and the joining inspection becomes easy.

Further, when the pressing means is made of silicon nitride, carbon, ruby, alumina (Al ₂ O ₃ ) or is sprayed with carbon or ceramic, the above effect is further exhibited and the heat resistance and durability are further enhanced. In addition, it is possible to reduce the number of times of maintenance such as replacement of the pressing portion.

Further, a timer is provided for joining the last lead in a row, and the fixing portion (the TAB holding step is completed) is raised after the predetermined time has elapsed and the joining metal layer is solidified, so that the IC component leads Even if the warp occurs, the fixing portion rises after the joining metal layer is solidified, so that the lead is not lifted up and highly reliable joining is possible.

When the power generation pair is built in the pressing portion and the light energy irradiation is controlled by the temperature thereof, even if the light energy varies or the thickness of the bonding metal layer varies,
The substrate is not burnt out, and the joining metal layer is not completely melted and the joining strength is not lowered, so that highly reliable joining is possible.

[Brief description of drawings]

FIG. 1 is a perspective view of a pressing unit and a lead fixing unit according to a first embodiment of the present invention.

FIG. 2 is a transverse cross-sectional view of a portion AA ′ in FIG.

FIG. 3 is a movement timing chart of each means in the first embodiment of the present invention.

FIG. 4 is a longitudinal sectional view showing a light energy irradiation position in the first embodiment of the present invention.

5 (a) and 5 (b) are perspective views showing a pressed state of leads in the second embodiment of the present invention, and FIG. 5 (c) is a diagram showing a warped state of an IC component before joining.

FIG. 6 is a timing chart at the time of joining in the second embodiment of the present invention.

FIG. 7A is a vertical sectional view of a pressing means in a third embodiment of the present invention, and FIG. 7B is a flow chart of joining in the same embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 IC component 2 Lead 3 Electrode 4 Substrate 5 Bonding metal layer 6 Light energy irradiation means 7 Pressing means 8 Lead fixing means 9 Temperature measuring unit and light energy irradiation means control device 10 Thermocouple

Claims (8)

[Claims] 1. A step of disposing each lead of an IC component on each of a plurality of electrodes provided with a bonding metal layer, a step of heating each lead of the IC component and the bonding metal layer by irradiation of light energy, and an IC component. The method for joining leads of an IC component, comprising: a step of fixing the leads by a fixing means; and a step of sequentially pressing one or a plurality of the leads to thermocompress the leads and the joining metal layer. 2. A step of arranging each lead of an IC component on each of a plurality of electrodes provided with a joining metal layer, and one or more leads are sequentially pressed to bring the leads into contact with the joining metal layer. Fixing the leads of the IC component by heating each lead of the IC component and the joining metal layer by irradiation of light energy to melt the joining metal layer and ending the pressing after finishing the irradiation of the light energy. Characteristic IC component lead connection method. 3. The irradiation of light energy is performed from the rear side in the scanning direction toward the lead and the bonding metal layer in front of the pressing means, and when the pressing means descends and presses the lead, the pressing means absorbs the light energy, The lead joining method for an IC component according to claim 1 or 2, which exhibits the effect of a heat iron. 4. The irradiation of light energy is performed from the rear side in the scanning direction toward the lead and the bonding metal layer in front of the pressing means, and the pressing means is made of silicon nitride, carbon, ruby, or
The lead joining method for an IC component according to claim 1 or 2, which is made of alumina (Al ₂ O ₃ ). 5. The irradiation of light energy is performed from the rear side in the scanning direction toward the lead and the joining metal layer in front of the pressing means, and the pressing means is made of silicon nitride, carbon, ruby, or
The lead bonding method for an IC component according to claim 1 or 2, wherein carbon coating or ceramic spraying is performed on alumina (Al ₂ O ₃ ). 6. The lead joining method for an IC component according to claim 1 or 2, wherein a heater is built in the pressing means, and the pressing means itself is heated to exert the effect of a thermal iron. 7. A step of arranging each lead of an IC component on each of a plurality of electrodes provided with a joining metal layer, a TAB pressing step of fixing the lead of the IC component, and a lead of the IC component and a joining metal layer. It has a step of heating by irradiation of light energy and a step of sequentially pressing one or more leads one by one to thermocompression-bond the leads and the joining metal layer, and a timer is provided when joining the last lead in a row. , The fixed part (TAB
3. The lead joining method for an IC component according to claim 1, wherein the pressing step is completed). 8. The I according to claim 1, wherein the pressing means is hollow, and a thermocouple is arranged inside the pressing means to control irradiation of light energy based on the measured temperature.
Lead joining method for C parts.