JP2006222170A - Method of soldering - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of soldering which makes minimum by adjusting timing which gives the minimum head required for solder melting and assures conduction between an electronic part and a solder firmly. <P>SOLUTION: The method of soldering includes a mounting means for arranging the electronic part in the predetermined position of a substrate, and a precision controlling heating means which heats the electronic part. The precision controlling heating means has capability for this precision controlling heating means to make possible the rapid temperature rising and rapid heat falling. The mounting means supports the electronic parts one by one, and performs an operation for arranging in the predetermined position of the substrate. At the predetermined position of the substrate, a cream solder is beforehand given using techniques, such as a required amount printing, and the electronic part is mounted here. The precision controlling heating means is put at this mounting means on the predetermined position of the substrate in the electronic part, and preheated until the electronic part becomes a necessary temperature until the electronic part is brought into contact with the solder. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a soldering method for mounting an electronic component or the like on a substrate using a solder material.

  Conventionally, in the manufacture of electronic circuit boards, when mounting and joining electronic components etc. to a board, solder is applied to the printed circuit board where necessary using a technique such as printing, and the electronic parts are mounted at this predetermined position Then, reflow soldering is performed by heating the entire board.

  As a conventional heating means, a method using hot air or a method using an infrared heater is known in which air heated by a heating wire is blown. A device using hot air will be briefly described with reference to FIG.

  In FIG. 8A, 1 is a substrate, 50 is a furnace body, 51 is a hot air heating chamber, 52 is a heating wire, 53 is a blowing mechanism, 54 is a substrate transport belt (with a transport mechanism), and 55 is a substrate heating chamber. 56 are substrate heating chamber openings.

  FIG. 8A is a schematic cross-sectional view showing an example of a conventional reflow soldering apparatus, and FIG. 8B is a schematic side view of the entire apparatus viewed from the side of the reflow soldering apparatus.

  In FIG. 8B, 1 is a substrate, 40 is a dotted line schematically showing the observation position of FIG. 10A, 54 is a substrate transport belt, 60 is a substrate introduction port, and 61 is a substrate take-out port.

  As shown in FIG. 8 (b), the reflow soldering apparatus usually has several similar heating chambers connected to the cross section of FIG. 8 (a) in the vertical direction (the back and front of the drawing). The heating chamber is heated to a predetermined temperature. The substrate 1 is fed through each heating chamber by the substrate transport belt 54, whereby the substrate 1 is heated step by step, and finally the solder is melted, whereby the electronic component and the substrate 1 are soldered. .

  As shown in FIG. 8 (a), a blowing mechanism 53 is provided in the heating chamber 51, and the wind sent from here flows as shown by the dashed arrow 41 and is heated through the heating heating wire 52, For example, it becomes hot air of several hundred degrees. The hot air moves as indicated by a dotted line and is blown toward the substrate 1 in the substrate heating chamber 55 from the substrate heating chamber opening 56 to heat the substrate 1.

  Soldering by such an apparatus has the advantage of processing many soldering points at once by uniformly heating the entire substrate. On the other hand, a part having a large heat capacity naturally has a temperature lower than that of the surroundings, whereas a part having a small heat capacity warms earlier than the surroundings, and eventually becomes a high temperature.

  In recent years, lead-free solder has been used for cream solder used in reflow soldering equipment, and the melting temperature is high, so the reflow temperature is also high. Therefore, there is a problem that the temperature unevenness that occurs when the substrate is placed in the furnace becomes larger, and the chip component is damaged due to heat.

  As a technique for canceling temperature unevenness on the substrate surface during reflow and supplying heat to a necessary part or removing heat from an excessive part, there is a technique described in Patent Document 1, for example.

  According to Patent Document 1, two temperature sensors in a reflow furnace detect temperature unevenness or a defective heating portion of a substrate, and when the temperature is out of a set temperature range, a valve for high-temperature air or low-frequency air is opened and closed. Temperature control at a predetermined position is performed to control to compensate for temperature defects in the substrate during reflow.

Japanese Patent Laid-Open No. 9-219582

  However, in the above-described conventional example, the temperature mismatch of the reflow soldering apparatus is determined by a sensor and compensated by additional heat increase / decrease, and thus has the following drawbacks.

  That is, there is a problem that the electronic component is exposed to the solder melting temperature in the reflow soldering apparatus, and the component is easily damaged by heat. In particular, electronic components that are easily affected by heat cannot be used, or have to be dealt with individually in separate processes.

  In order to reduce these problems as much as possible, if the solder melting time and reflow temperature are shortened and kept to a very low level, there is a problem that soldering defects increase rapidly due to slight temperature unevenness for each electronic component. It was. In particular, a small electronic component has a problem that the required heat capacity is relatively small, and the electronic component slightly moves during reflow melting, so that the reliability of soldering is lowered.

  Therefore, an object of the first invention of the present invention is to provide a soldering method that minimizes the timing by applying the timing for applying the minimum heat necessary for melting the solder and secures the electrical connection between the electronic component and the solder. There is to do.

  The second object of the present invention is to provide a method of soldering by minimizing the heat transmitted to the electronic component main body by limiting the portion to which heat is applied to the soldering cost of the electronic component, and preventing damage due to the heat. There is.

  A third object of the present invention is to provide a soldering method suitable for mass production that does not significantly exceed the time required for the conventional mounting process.

  A fourth object of the present invention is to provide a soldering method that can perform soldering with high reliability with minimum necessary heating in response to individual variations of electronic components.

  In order to achieve the above object, the present invention comprises a mounting means for arranging electronic components at predetermined positions on a substrate and a precision control heating means for heating the electronic components, and the precision control heating means is used for rapid temperature rise and temperature drop. It has the ability to enable

  In the above configuration, the mounting means supports the electronic components one by one and performs an operation of arranging them at predetermined positions on the substrate. A predetermined amount of cream solder is applied to a predetermined position of the substrate in advance using a technique such as printing, and an electronic component is mounted thereon. The precision control heating means is characterized in that the mounting means places the electronic component in a predetermined position on the substrate and preheats the electronic component to a required temperature until it is brought into contact with the solder.

  The present invention also includes mounting means for arranging the electronic components at predetermined positions on the substrate and precision control heating means having a mechanism for partially heating the electronic components. The temperature can be lowered.

  In the above configuration, the mounting means supports the electronic components and performs an operation of arranging them at predetermined positions on the substrate. A predetermined amount of cream solder or the like is previously placed at a predetermined position of the substrate, and an electronic component is mounted at this position. The precision control heating means is characterized in that the mounting means places the electronic component at a predetermined position on the substrate and preheats only the soldered portion of the electronic component until the solder and the electronic component come into contact with each other.

  Furthermore, the present invention provides a mounting means for supporting an electronic component and arranging it at a predetermined position, and at least a part of movement of the mounting means between the mounting means supporting the electronic component and thereafter releasing the electronic component. And a precisely controlled heating means having a mechanism capable of following.

  In the above configuration, the mounting means supports the electronic component and is mounted on a substrate to which solder has been applied in advance. At this time, the precision control heating unit heats the electronic component for at least a part of time from when the mounting unit supports the electronic component until the electronic component comes into contact with the solder, and raises the temperature to a predetermined temperature. It is characterized by doing.

  The present invention also includes a mounting means for supporting the electronic components and arranging them at a predetermined position, a precision control heating means for heating the electronic components, and a means for monitoring the temperature of at least a part of the electronic components. The control heating means is characterized by having a capability of enabling rapid temperature increase and temperature decrease.

  In the above configuration, the mounting means supports the electronic component and mounts it at a predetermined position on the substrate. At this time, the precision control heating means heats the electronic component until the mounting means brings the electronic component into contact with the solder on the substrate, and the monitoring means monitors the temperature of the heated portion. Further, the monitoring temperature is reflected in the control of the precision control heating means.

  According to the present invention, since each electronic component is heated individually, the heating temperature can be changed according to the component to be heated, and an adverse adverse effect on the electronic component can be avoided.

  Moreover, since soldering can be performed while mounting each of the components, it is possible to reduce solder defects.

  Further, it is not necessary to keep the reflow soldering device at a high temperature at all times as in the prior art, and the amount of heat sufficient to melt the solder can be given to each component, so that significant energy saving can be achieved.

  When only the soldering cost of the electronic component is heated, the heart of the electronic component can be kept away from the heat, and the soldering cost is locally heated, so that the adhesion of the solder can be improved. , Can improve the reliability of soldering.

  In addition, when the heating means is used by utilizing the mounting operation time of the electronic component, the time required for soldering can be minimized, so that mass productivity can be improved.

  In particular, when electronic components are made smaller as in recent years, the amount of heat required becomes small, so soldering can be performed during mounting operations on the board, which is inferior to reflowing again. The mounting process can be completed without any problems.

  In addition, when a heating monitor is combined with a temperature monitor and used for controlling the heating means, it is possible to realize a defect-free mounting substrate by using a minimum amount of heat corresponding to the variation of each chip.

  Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

<Embodiment 1>
1A to 1D are perspective views illustrating a soldering method according to Embodiment 1 of the present invention, and FIGS. 2A to 2D are side views.

  1 and 2, 1 is a mounting board, 2 is a mounting electronic component, 3 is cream solder, 4 is a mounting component suction nozzle, and 5 is a heat shield. 1 (c), (d) and FIGS. 2 (c), (d), 9 indicated by a broken line is a near-infrared spot light which is a heating means in this embodiment ((this light source is not shown) ).

  In the above configuration, FIG. 1A and FIG. 2A show a state before the electronic component suction nozzle 4 goes to pick up the mounted electronic component 2.

  The component 2 is preheated before the electronic component suction nozzle 4 takes it (not shown).

  Next, a predetermined position of the electronic component 2 is sucked by the electronic component suction nozzle 4 (FIGS. 1 (b) and 2 (b)) as indicated by a broken line arrow in the figure, and then the mounted electronic component. 2 is irradiated with near-infrared rays, and a portion protruding from the heat shield plate 5 is particularly heated so that the solder can be melted (FIGS. 1C and 2C). However, this heat shield is not a configuration essential to the present invention, but merely a configuration for further reducing the influence of heat received by the electronic component.

  The preheated electronic component 2 is mounted so as to be pushed onto the cream solder 3 previously applied to the electronic component installation position provided on the substrate 1 as indicated by the broken arrow in the figure while maintaining the preheat temperature ( FIG. 1 (d) and FIG. 2 (d)).

  At this time, since the electronic component 2 is preheated to an appropriate temperature in advance, the flux in the cream solder 3 is instantly melted to wet the surface of the mounted electronic component 2, and then the solder balls in the cream solder 3 are melted at once. This crawls up to the part and soldering is complete.

  During this time, the near-infrared spot light 9 serving as a heating means stops heating at the same time that the solder ball starts to melt, and when the soldering is completed, the electronic component suction nozzle 4 moves to pick up the next mounted component. Start (not shown).

<Embodiment 2>
3A to 3D are side views illustrating a soldering method according to Embodiment 2 of the present invention. In the figure, 1 is a mounting substrate, 2 is a mounting electronic component, 3 is a cream solder, 4 is an electronic component suction nozzle, 6 is a solder melting precision control iron, 7 is a trowel support, and 11 is an electronic component soldering on the substrate. A location 12 indicates the state of solder after completion of soldering.

  After the mounting electronic component 3 is sucked by the electronic component suction nozzle 4, the solder melting precision control iron 6 contacts the soldered portion of the mounting electronic component 3 as shown in FIG. start.

  After the soldered portion is sufficiently warmed, it is pressed onto a predetermined position where the cream solder 3 is applied on the substrate 1 as shown in FIG. Since the electronic component 2 is preheated to an appropriate temperature in advance, the flux in the cream solder 3 is instantly melted to wet the surface of the mounted electronic component 2, and then the solder balls in the cream solder 3 are melted all at once. Climbing up sufficiently, soldering is complete.

  As soon as the solder ball starts to melt, release the trowel 7 so as not to overheat.

<Embodiment 3>
4A to 4C are perspective views for explaining a soldering method according to Embodiment 3 of the present invention. In the figure, 1 is a mounting substrate, 2 is a mounting electronic component, 4 is an electronic component suction nozzle, 8 is a near infrared lamp, and 9 is a near infrared spot light.

  FIG. 4A shows a state in which the electronic component suction nozzle 4 is going to suck the mounted electronic component 2, and the infrared lamp 8 is brought closer to the mounted electronic component 2 fixed by the suction. This near-infrared lamp 8 is turned on, and the near-infrared spot light 9 is irradiated only on the solder melting portion of the mounted electronic component 2.

  While maintaining the above state, the mounting component suction nozzle 4 is moved and mounted at a predetermined position on the substrate 1. The near-infrared lamp 8 follows this movement and performs necessary heating.

  The component is placed at a predetermined position, and at the timing when the solder starts to melt, the irradiation of the near infrared lamp 8 is stopped, and the next mounted electronic component 2 is started together with the electronic component suction nozzle 4.

<Embodiment 4>
FIG. 6 is a simplified diagram for explaining a soldering method according to Embodiment 4 of the present invention.

  In FIG. 6, 2 is a mounting electronic component, 4 is a mounting component suction nozzle, 9 is a near infrared spot light, and 13 is a temperature sensor.

  As shown in FIG. 6, the temperature of the heated part is measured by the temperature sensor 13 when the electronic component 2 is heated, and the temperature management is fed back to the temperature control of the heating means depending on how far the measurement result is from the set value. Make it more certain.

  Specific examples will be described below.

  Any type of mounting means may be used for the present invention. If an electronic component can be carried and placed in a predetermined position, it can be used in the present invention.

  Any component can be used as long as the component can be fixed with appropriate accuracy depending on the size of the substrate and the electronic component used. For example, the accuracy may be about ± 10% of the pitch between the components of the electronic component to be placed.

  In this example, all the suction nozzles using electromagnetic valves were made by themselves.

  In addition, when heating is performed during the movement of a part, the higher the rigidity at the time of movement, the more accurate the heating can be.

  The heating means used in the present invention may be any type such as a contact type or a non-contact type.

  For shortening the heating time, a non-contact type using near infrared rays is more preferably used. In the case of using near-infrared rays, the size, shape, heating strength, etc. of the heating location can be greatly changed by using a synthetic quartz lens, which is convenient when dealing with various circuits.

  In addition, when heating is performed during the movement of a part, it must be provided with a movement capability capable of following at least a part of the movement of the mounter. Furthermore, it is necessary to take measures such as increasing rigidity and considering the length and thickness of the arm so that the heating position is not subjected to vibration during heating.

  There is also a method in which heating means is included in the mounting means so that the heating means always follows the mount.

  The temperature sensor used in the present invention may be either a contact type such as a thermocouple or a non-contact type such as a radiation thermometer.

  Any solder may be used in the present invention. Sn-Ag-Cu (tin-silver-copper) -based solder, Sn-Cu (tin-copper) -based solder, Sn-Zn (tin-zinc) -based solder, etc. have higher melting point than Sn-Pb eutectic solder Materials can also be used. In this example, Sn—Ag—Cu (tin-silver-copper) -based solder was used.

  Although any electronic component can be used in the present invention, a 1005 capacitor chip (Panasonic ECJ0CB1A104K) and a transistor (NEC SC-70) were used in the examples.

  For comparison, in this embodiment, the 1005 chip is not a perfect rectangular parallelepiped, but has a trapezoidal shape with one end widened, a chip lacking electrodes, Tests of all examples and comparative examples were conducted by mixing defective chips such as those having non-symmetrical dimensions into non-defective products at a ratio corresponding to 10% of the whole.

  FIG. 1 is a drawing that best represents the characteristics of the present invention. In this embodiment, the same configuration as that of FIG.

  1005 chips are used as electronic components, and the chip is adjusted to 120 ° C just before the mounter picks up, and then the chip is taken with the mounter and brought to the mounting position. At the same time as heating to 230 ° C., the substrate was taken to a predetermined position and fixed. This operation was repeated to mount 50 1005 chips.

  Similarly, ten transistors (NEC SC-70) were mounted.

  FIG. 3 shows a second embodiment of the present invention. In the second embodiment, the configuration is the same as that of FIG.

  As the electronic component 2, 1005 chips were used, and an electronic component suction nozzle 4 on both sides was provided with a trowel 6 that conducts heat by touching the side surface of the chip. After the electronic component 2 is supported by the electronic component suction nozzle 4, the trowel support 7 moves so that the trowel 6 comes into close contact with the electronic component 2 and applies necessary heating. After the soldering portion of the electronic component 2 was sufficiently heated, the electronic component suction nozzle moved to a predetermined position on the board to fix the electronic component.

  This operation was repeated to mount 50 1005 chips. Similarly, ten transistors (SC-70 manufactured by NEC) were mounted.

  FIG. 5 shows the third embodiment of the present invention.

  In FIG. 5, 2 is an electronic component, 4 is an electronic component suction nozzle, 8 is a near infrared lamp, 9 is a near infrared spot, and 10 is a synthetic quartz lens.

  In the above configuration, first, the electronic component 2 is sucked by the electronic component suction nozzle 4 and moved to the vicinity of the mounting site, and then the infrared lamp 8 is irradiated, the spot 9 is narrowed by the synthetic quartz lens 10, and the solder of the electronic component Irradiate only the attachment position and apply the necessary heating. When the required temperature is reached, the part is pressed and fixed in place.

  This operation was repeated to mount 50 1005 chips. Similarly, ten transistors (SC-70 manufactured by NEC) were mounted.

  FIG. 4 is a diagram showing a fourth embodiment of the present invention. In this embodiment, 1005 chips are used for the electronic component 2, the chip is supported by the electronic component suction nozzle, and the near-infrared lamp 8 is approached thereto. At the same time as heating is started, it moves to the mounting location. After the predetermined part of the electronic component was sufficiently heated, the electronic component was pressed to a predetermined position on the substrate and soldered.

  This operation was repeated to mount 50 1005 chips. Similarly, ten transistors (SC-70 manufactured by EC) were mounted.

  FIG. 6 is a diagram showing Embodiment 5 of the present invention. In this embodiment, the near-infrared lamp 8 shown in FIG. 4 is used as a heating means.

  The operation was performed in the same manner as in Embodiment 4, and the operation was performed while monitoring the chip temperature using a temperature sensor. The intensity of the near infrared lamp for heating was adjusted so that the monitor temperature did not exceed ± 2 ° C. from the setting.

  With the above configuration, the operation was repeated to mount 50 1005 chips. Similarly, ten transistors (SC-70 manufactured by NEC) were mounted.

For comparison, mounting was performed in the same manner by using a conventional reflow soldering apparatus shown in FIG.
The same mounting parts as those in the embodiment were used, and 50 1005 chips and 10 transistors (SC-70 manufactured by EC) were used.

  The temperature of the reflow furnace was set so that the peak temperature would be 230 ° C. × 15 seconds, and the time from when the substrate was introduced into the reflow furnace at room temperature until it was taken out of the reflow furnace through the peak temperature was 6 minutes. The temperature profile at this time is schematically shown in FIG.

  Table 1 summarizes the above results.

表１において、はんだ不良とは、良好なはんだ付けができなかったものを指し、具体的には部品が所定位置からずれたり、はんだ同士がくっついて不良な接点ができているものを指し、この個数を示したものである。又、性能不良とは、実装したトランジスタ１０個をそれぞれ機能評価し、実装する前の性能平均から１０％以上の差異が認められたものの個数を示した。

In Table 1, a defective solder refers to a solder that could not be satisfactorily soldered. Specifically, this indicates that a component is displaced from a predetermined position or that solder is stuck together to form a defective contact. The number is shown. Further, the performance failure indicates the number of transistors in which 10 mounted transistors were functionally evaluated and a difference of 10% or more was recognized from the average performance before mounting.

  The mounting time indicates the time (unit: second) required to mount 50 1005 chips. The mounting preparation time indicates the time (unit: time) that the heating means must be heated in advance when starting the mounting experiment.

  The effects of the present invention determined from the summary are as follows.

  That is, in the first embodiment of the present invention, it is possible to reduce soldering defects caused by uneven heating of components.

  Compared with the mounting using the reflow soldering apparatus which is the prior art, it is not necessary to continue heating the furnace, and mounting can be performed with energy saving.

  Since heating according to the heat resistance of the component can be performed, functional damage of the component can be reduced.

  Moreover, in Embodiment 2 of this invention, the thermal influence of components can further be reduced. Further, energy can be further saved by performing heating in a more narrow range.

  In the third embodiment of the present invention, it is possible to easily and accurately cope with various electronic components by using a non-contact type heating means and a lens for adjusting the same. As a result, it is possible to reduce the thermal effect of soldering on any component and to save energy in the soldering process.

  In the fourth embodiment of the present invention, the mounting time can be shortened, and as a result, the mass productivity can be improved.

  In the fifth embodiment of the present invention, since the heating state can be individually monitored and fed back, it is possible to perform soldering without any defects or defects in response to individual differences for each electronic component.

  In addition, since the temperature can be finely adjusted, the energy consumption of the soldering process can be minimized.

It is a perspective view explaining the soldering method which concerns on Embodiment 1 of this invention. It is a side view explaining the soldering method which concerns on Embodiment 1 of this invention. It is a side view explaining the soldering method which concerns on Embodiment 2 of this invention. It is a perspective view explaining the soldering method which concerns on Embodiment 3 of this invention. It is a side view explaining the soldering method which concerns on Embodiment 3 of this invention. It is a perspective view explaining the soldering method which concerns on Embodiment 4 of this invention. It is a schematic diagram of the temperature profile explaining a conventional example. It is sectional drawing explaining a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Board | substrate 2 Mounted electronic component 3 Cream solder 4 Mounted electronic component adsorption nozzle 5 Heat shield board 6 Solder melting precision control iron 7 Trowel support 8 Near-infrared lamp 9 Near-infrared spot light 10 Synthetic quartz lens 11 Electronic component solder on board Place 12 Solder (after soldering)
13 Temperature sensor 40 Schematic cross-sectional view position 50 Furnace body 51 Hot air heating chamber 52 Heating wire for heating 53 Blowing mechanism 54 Substrate transport belt 55 Substrate heating chamber 56 Substrate heating chamber opening 60 Substrate inlet 61 Substrate outlet

Claims (4)

  A method of soldering a mounted electronic component to a substrate, wherein the mounted electronic component is preheated before contacting the mounted electronic component with the solder.   The soldering method according to claim 1, wherein the preheating portion is limited to a soldering portion of the mounted electronic component.   3. The soldering method according to claim 1, wherein the mounting electronic component is preheated during a time period for supporting the mounting electronic component and bringing the mounting electronic component to a predetermined mounting position of the substrate.   The soldering method according to any one of claims 1 to 3, wherein a temperature of the preheating portion is monitored to control a heating state.

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