JP4408643B2 - Soldering method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a soldering method and apparatus for performing soldering on a soldering portion of a soldering target object such as a board to which components such as electronic components and connectors are attached.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a soldering method is known in which a soldering iron member is relatively moved along a soldering position of a substrate, which is an object to be soldered, while supplying thread-like solder to the iron tip of the soldering iron member. ing. In this soldering method, when the iron tip of the soldering iron member is heated and the solder is supplied to the iron tip by the solder supply means, the solder contacting the iron tip is melted. The molten solder reaches a soldering spot adjacent to the tip of the solder and is soldered. In addition, when soldering a plurality of soldering points arranged in a straight line on a soldering object using this soldering method, the soldering iron member has a plurality of soldering points. It is moved relatively along the line direction. Thereby, a several soldering location can be soldered continuously.
[0003]
[Problems to be solved by the invention]
However, if soldering is performed while relatively moving the tip of the substrate along a plurality of soldering points on the substrate using the above-described soldering method, conduction failure or shorting between leads (bridge) at a specific soldering point. In some cases, poor soldering occurs.
FIG. 16 is a partial plan view showing an example of the substrate on which the soldering failure has occurred. As shown in the figure, the substrate 200 is relatively moved in the order of arrows A and B along a plurality of rows of soldering points 205 where the leads 201 protrude from the through holes 204 from the surface of the substrate 200. Was moved and soldered. When each soldered portion 205 after the soldering was observed, a soldering defect in which solder did not enter the through hole 204 occurred at the soldered portion 205 of the lead 201 of the 72nd pin and the 74th pin in the figure. I found out. Further, the solder that has not entered the through hole 204 in this way will be excessively attached to the tip of the iron, and this extra solder at the tip of the iron may be supplied between the leads to form a bridge. all right. These soldering defects tend to occur frequently in solder joints using lead-free solder having a high melting point and high viscosity. When such a soldering failure occurs, conduction between the lead 201 and the surface of the through hole 204 may be insufficient or may not be conducted at all. The solder bridge between the leads causes a short circuit between the leads.
[0004]
Therefore, the present inventors tried to identify the cause of the soldering failure by performing a soldering test with various soldering conditions changed and a detailed analysis of the soldering result. In this soldering test and analysis, the basics of soldering are (1) soldering location and soldering of the substrate, (2) solder supply and (3) oxide removal (cleaning) by flux. Attention was paid to the following various items. In other words, items such as substrate temperature, solder flow into the through-hole, soldering state, soldering point state, solder tip relative movement speed, solder supply amount, tip contact state, tip temperature, etc. Considering. As the state of the soldered portion, a lead insertion state, a substrate warp, a wiring position, and the like were considered. As a result of conducting a detailed soldering test and analysis taking these into consideration, the present inventors have found that the temperature of the soldering point on the substrate when starting soldering at the tip has not sufficiently increased, It has been found that it is the cause of the above soldering failure.
[0005]
In the conventional soldering method, in order to prevent oxidation of the soldered portion and the molten solder supplied thereto, heated inert gas (nitrogen gas) is applied to the soldered portion along the side surface of the soldering tip. There was a case of spraying. However, it is necessary to spray the heated inert gas for preventing the oxidation to such an extent that the molten solder does not blow off, and the temperature of the soldering portion when starting soldering at the tip can be sufficiently heated. It was not a thing.
[0006]
The present invention has been made in view of the above problems, and an object of the present invention is to provide a soldering method and apparatus capable of preventing a soldering failure due to insufficient heating temperature at a soldering point when starting soldering. Is to provide.
[0007]
[Means for Solving the Problems]
  In order to achieve the above-mentioned object, the invention of claim 1 is characterized in that the tip of the solder is relative to the object to be soldered along the arrangement of a plurality of soldering points.Moved toA soldering method for performing continuous soldering on the plurality of soldering points by moving the soldering object prior to soldering each of the plurality of soldering points of the soldering object. The step of preheating the soldered portion before the solder is supplied to 140 ° C. or more by spraying a heating gas to the portion, and after the preheating of the soldered portion, the temperature of the soldered portion is 140 ° C. Starting to supply molten solder to the soldering location in a state where the soldering location is not below, the spraying direction of the heating gas for the preheating is perpendicular to the surface of the soldering object where the soldering location is located A direction inclined relative to the direction of relative movement of the tip with respect to a different direction.TransferDuring the movement, the preheating is continuously performed on the plurality of soldering points by continuously blowing the heating gas to the plurality of soldering points on the downstream side in the relative movement direction of the tip. It is characterized by this.
  According to a second aspect of the present invention, in the soldering method according to the first aspect, the heated inert gas is sprayed onto the soldering portion to which the molten solder is supplied during the soldering of the soldering portion of the soldering object. The preliminary heating is performed by spraying a heating gas on the soldering portion prior to spraying the inert gas.
[0008]
  According to a third aspect of the present invention, there is provided a soldering iron member having a iron tip and a heating means for heating the iron tip, a solder supply means for supplying solder to the iron tip, and the iron for the soldering object. Relative position variable means for changing the relative positional relationship between the soldering object and the soldering iron member so as to move relative to the tip, and a plurality of relative positions of the soldering object. Relative to the soldering pointMoved toA soldering device for continuously soldering the plurality of soldering points by moving the soldering object, wherein the soldering device moves relative to the soldering tip and moves downstream of the soldering tip in the relative movement direction of the soldering target. A preheating nozzle for spraying a heating gas to the soldering portion so as to preheat the soldering portion before the solder is supplied to 140 ° C. or more, and a heating gas supply for supplying the heating gas to the preheating nozzle Means for supplying molten solder to the soldering point in a state where the temperature of the soldering point heated by the preheating does not fall below 140 ° C. Is set so that the direction of spraying the heating gas for the preheating is perpendicular to the surface of the soldering object where the soldering portion is located. As will become inclined direction relative movement direction, it is characterized in that provided with the preliminary heating nozzle.
  According to a fourth aspect of the present invention, there is provided the soldering apparatus according to the third aspect, further comprising an inert gas nozzle for spraying a heated inert gas to a soldering portion to which solder melted by the iron tip is supplied. The heating nozzle is provided separately from the inert gas nozzle.
  According to a fifth aspect of the present invention, in the soldering apparatus according to the third or fourth aspect of the present invention, preheating temperature switching means for switching the heating temperature of the soldering portion heated by the preheating is provided.
  According to a sixth aspect of the present invention, in the soldering apparatus according to the fifth aspect, the preheating is performed so as to switch a heating temperature of the soldering portion heated by the preheating according to a soldering condition for the soldering portion. Control means for controlling the temperature switching means is provided.
[0009]
  As described above, the result of the soldering test and analysis by the present inventors is that the soldering temperature at the start of soldering is not sufficiently increased, which is the cause of the soldering failure. I understood. Based on such knowledge, the present inventors changed the conditions such as the type of solder and the type of the soldering object with respect to the temperature of the soldering point at the start of soldering, and the heating experiment or soldering experiment of the soldering spot. Was repeated. As a result, it was found that it is important that the soldering location at the start of soldering does not fall below 140 ° C. in order to prevent the above-described soldering failure.
  Therefore, in the soldering method of claim 1,pluralSoldering pointsRespectivelyPrior to solderingBy spraying heated gas on the soldering points,The soldering part before supplying the solder is preheated to 140 ° C. or higher. Then, after preheating the soldered portion, supply of molten solder to the soldered portion is started in a state where the temperature of the soldered portion does not fall below 140 ° C. By performing preheating in this way,Of soldering objectIt is possible to start supplying the molten solder to the soldering point in a state where the soldering point is thermally activated so that the soldering point does not fall below 140 ° C., and to prevent soldering failure due to insufficient heating temperature of the soldering point. it can.
Furthermore, while moving the soldering tip relatively along the arrangement of the plurality of soldering points with respect to the soldering object, heated gas is blown to the soldering point on the downstream side in the relative movement direction of the soldering tip. By spraying the heating gas, the preliminary heating and soldering can be continuously performed on each soldering portion.
Further, the heating gas is blown in a direction inclined toward the relative movement direction side of the iron tip with respect to the direction perpendicular to the surface of the soldering object where the soldering portion is located. Therefore, the solder melted at the soldering location during soldering is not easily blown off by the heated gas.
  In addition, in order to prevent oxidation of the molten solder supplied to the soldering location of the soldering object, an inert gas heated to the soldering location where the molten solder is supplied during soldering of the soldering location May spray. However, according to experiments conducted by the present inventors, the soldering location at the start of soldering may not be at a sufficiently high temperature only by spraying the heated inert gas during soldering. I understood.
  Therefore, in the soldering method according to the second aspect, prior to the spraying of the inert gas, the heating gas is sprayed to the soldering site before the solder is supplied to perform preliminary heating. By performing preliminary heating prior to blowing the heated inert gas in this way, it is possible to start supplying molten solder to the soldering location in a state where the soldering location is thermally activated. Thereby, it is possible to prevent a soldering failure due to insufficient heating temperature of the soldering portion.
  In addition, it is preferable to perform the preheating of the soldering portion in the soldering method according to the first and second aspects of the present invention within a temperature range that does not cause thermal damage to the soldering object itself or burning of the flux..
[0010]
  Claim3The soldering apparatus according to claim 11'sIt can be used for soldering by a soldering method.
  Claim4The soldering apparatus according to claim 12Can be used for soldering by soldering method.
SpecialAnd claims5In this soldering apparatus, the heating temperature of the soldering spot heated by the preheating is switched according to the soldering condition for the soldering spot. Examples of the soldering conditions include the type of solder, the type of soldering object, and the moving speed of the tip. By switching the heating temperature, even when the soldering conditions are changed, proper preheating is performed on the soldering portion, and excessive preheating can be avoided.
  In particular, the claims6In this soldering apparatus, the heating temperature by the preheating can be automatically switched when the soldering condition for the soldering location is changed.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which the present invention is applied to a soldering method and a soldering apparatus (soldering robot) for automatically soldering a substrate (PCB) as an object to be soldered will be described.
FIG. 2 is a front view showing a schematic configuration of a soldering robot as a soldering apparatus according to the present embodiment. The soldering robot includes an apparatus main body 100 having a work table 101 at the top, stand members 102 and 103, an X-axis guide member 104, and a soldering unit 10. The stand members 102 and 103 are attached to both side portions of the apparatus main body 100. The X-axis guide member 104 is attached so as to be bridged between the stand members at the upper part of the stand members 102 and 103. The soldering unit 10 is attached to the X-axis guide member 104 so as to be movable in the X-axis direction (left-right direction in the figure).
[0012]
Two guide rails 105 and 106 extending in the Y-axis direction (the front-rear direction in the figure) are formed at the center of the work table 101, and the movable brackets 107 and 108 extend along the guide rail in the Y-axis direction. It is attached to be movable. A work table 109 is mounted on the movable brackets 107 and 108, and a substrate 200 as a soldering object is mounted on the work table 109 via substrate support stands 110 and 111. The driving of the movable brackets 107 and 108 in the Y-axis direction is controlled by a control unit described later based on information on the soldering location on the substrate. Data on the information on the soldering portion on the substrate is acquired by a data fetching operation (teaching operation) executed in advance. The acquired data is stored in the memory card 113 inserted in the memory card slot 112 together with data such as various parameters at the time of soldering.
[0013]
The soldering unit 10 includes a unit main body 11, solder supply subunits 20 </ b> A and 20 </ b> B, and a soldering head 30. The solder supply subunits 20 </ b> A and 20 </ b> B are attached to both sides of the unit body 11. The soldering head 30 is attached to an elevating slide shaft 12 extending downward from the unit main body 11 via a relay member 13, a swing arm 14, and the like.
A movable bracket (not shown) is provided on the back side of the unit body 11, and this movable bracket is guided by a guide rail (not shown) formed on the X-axis guide member 104 side. By being guided in this way, the soldering unit 10 can be moved in the X-axis direction.
[0014]
The elevating slide shaft 12 extending downward from the unit main body 10 is driven and controlled so as to move in the Z-axis direction (vertical direction in the figure), and is rotated so as to rotate around the central axis in the Z-axis direction. Can be done. An air pressure mechanism (not shown) is incorporated in the relay member 13 connected to the elevating slide shaft 12 so that the tip of the soldering head 30 can be pressed against the substrate 200 with a predetermined pressure. Further, the swing arm 14 connected to the relay member 13 is configured so that the soldering head 30 can be fixed at a predetermined angle.
[0015]
The soldering head 30 includes a soldering iron member (hereinafter referred to as “steel member”) 32 and solder supply heads 34A and 34B. The iron member 32 has a flat iron tip 31 at the tip, and incorporates a heater as a iron tip heating means. The solder supply heads 34A and 34B are fixed to both sides of the iron member 32 by fixed arm members 33A and 33B. At the tip of the solder supply heads 34A, 34B on the tip 31 side, there are provided hollow needle members 35A, 35B through which thread-like solder can pass as solder guide members. The solder supply heads 34A and 34B are supplied with thread-like solder from the solder supply subunits 20A and 20B, which can be controlled independently of solder supply, via the solder supply tubes 21A and 21B.
[0016]
The solder supply heads 34A and 34B are provided with heaters as solder preheating means for preliminarily heating the thread-like solder 40 before discharging it from the needle members 35A and 35B. By preliminarily heating in this way, it is possible to suppress a rapid temperature rise of the flux and to prevent solder balls / flux scattering.
[0017]
The solder supply subunits 20A and 20B are provided with solder supply devices 23A and 23B having a pair of delivery rollers 22A and 22B and a motor (not shown), and solder reels 24A and 24B as solder accommodating portions. The delivery roller pair 22A, 22B is configured to feed the solder 40 toward the solder supply tubes 21A, 21B by rotating while holding the thread-like solder 40. One roller of the feed roller pair is a driving roller driven by a motor, and the other roller is a driven roller. Further, the interval between the two feeding rollers is adjusted so as to hold the thread-like solder 40 with a predetermined pressure, and the drive roller can feed the thread-like solder 40 at a predetermined speed and selectively turn on / off the thread-like solder. The rotation is controlled as follows. A threaded solder 40 is wound around the solder reels 24A and 24B by a certain amount.
The solder supply subunits 20A and 20B, the solder supply tubes 21A and 21B, and the solder supply heads 34A and 34B constitute solder supply means for supplying solder to the tip 31 of the iron member 32.
Note that the solder supply devices 23A and 23B may be appropriately provided with a sensor for detecting solder breakage, a sensor for detecting solder clogging, and the like. The solder supply devices 23A and 23B are not limited to those using the delivery roller pair 22A and 22B, and may be configured to send the thread-like solder by another mechanism.
[0018]
1 and 3 are an enlarged side view and an enlarged front view of the distal end portion of the iron member 32. FIG. The iron tip 31 of the iron member 32 is formed in a flat plate shape, and has solder supply surfaces 310A and 310B on two outwardly exposed side surfaces extending along the direction of relative movement of the iron tip with respect to the substrate 200, respectively. . The tips of the needle members 35A and 35B of the solder supply heads 34A and 34B are arranged so as to be close to and face each of the solder supply surfaces 310A and 310B. The thread-like solder 40 discharged from the tips of the needle members 35A and 35B comes into contact with the solder supply surfaces 310A and 310B of the tip 31 and melts. The melted solder 40 ′ is supplied so as to cover the leads 201 that are protruding members protruding from the soldering portions on the substrate 200 by flowing down along the solder supply surfaces by gravity.
[0019]
Further, as shown in FIG. 1, the tip surface of the iron tip 31 is processed into a surface inclined at a predetermined angle with respect to the central axis of the iron member 32. By tilting the tip surface in this way, when the iron member 32 is moved while being tilted, the tip surface of the tip 31 and the surface of the substrate 200 are substantially parallel to each other so that they are in contact with each other. When the iron member 32 is inclined, the iron member 32 can be smoothly moved on the substrate 200, and the driving load of the iron member 32 can be reduced.
[0020]
As shown in FIG. 4, the width W1 of the tip 31 is set to be narrower than the interval W2 of the leads 201, which is the interval between the solder supply locations. By setting the width W1 of the iron tip 31 in this way, the solder 40 ′ melted on the solder supply surface of the iron tip 31 can surely flow down onto the lead 201 without causing interference between the iron tip 31 and the lead 201. be able to. Therefore, it is possible to reliably solder the soldering portion.
Further, in this embodiment, the solder is melted by the two solder supply surfaces 310A and 310B on the exposed side surface of the tip 31 and is allowed to flow down onto the lead 201 positioned outside the solder supply surfaces 310A and 310B. Therefore, even if the component 202 exists in the vicinity of the lead 201 as in the case of a double-sided mounting board, the component 202 and the iron tip 31 do not interfere with each other, and the soldering location can be reliably soldered (see FIG. 4). ). Further, since the tip 31 does not come into contact with the component 202, damage to the component 202 can be avoided.
[0021]
Further, as shown in FIGS. 1 and 3, the iron member 32 is provided with an inert gas nozzle 321 for blowing nitrogen gas F1 as a heated inert gas onto a soldering portion. The inert gas nozzle 321 is formed in a gap between the inner peripheral surface of the tip holding case 320 and the outer peripheral surface of the tip heating holding unit 311. Nitrogen gas supplied from a nitrogen gas supply device (not shown) is received by a nitrogen gas receiving portion 323 provided on the top of the iron member 32 through a gas pressure regulator (not shown) and a nitrogen gas supply hose 322. When the nitrogen gas introduced from the nitrogen gas receiving portion 321 passes through the gap between the inner peripheral surface of the tip holding case 320 and the outer peripheral surface of the tip heating holding portion 311, the tip heating holding portion with a built-in heater. 311 is heated. The heated nitrogen gas is emitted from the blowout port at the lower end of the inert gas nozzle 321 and blown to the soldered portion. By blowing the inert gas F1, it is possible to prevent oxidation of the melted solder and oxidation of the surfaces of the lead 201 and the land 203 heated by the iron tip. In addition, since the nitrogen gas is blown onto the soldering portion in a state of being heated to some extent, it is possible to prevent the soldering portion from being cooled by the inert gas F1.
[0022]
In the soldering robot having the above-described configuration, the thread-like solder 40 is supplied to the two solder supply surfaces 310A and 310B of the iron tip 31 of the iron member 32, and the molten solder 40 is melted in two rows of solder supply locations facing each solder supply surface. 'Can be reached. Therefore, continuous automatic soldering of two rows of solder supply locations can be performed more efficiently than in the case where solder is supplied from one direction to one solder supply surface of a conventional iron tip.
However, when soldering is performed while moving the tip 31 along a plurality of soldering locations of the substrate 200 as described above, a soldering failure (conducting failure) may occur at a specific soldering location. . As a result of the soldering test and analysis by the present inventors, it was found that the soldering temperature was not sufficiently increased when soldering was started, which was the cause of the soldering failure. . It has also been found that the shortage of the heating temperature at the soldering point when starting the soldering occurs in the same manner when the heated nitrogen gas (inert gas) is sprayed.
[0023]
Therefore, the soldering robot according to the present embodiment is configured to preheat to a predetermined temperature by spraying a heating gas to a soldering point prior to the spraying of the heated nitrogen gas (inert gas). Specifically, as shown in FIG. 1, apart from the inert gas nozzle 321, a preheating nozzle 36 that blows the heated gas F <b> 2 at the soldering location on the downstream side in the relative movement direction of the tip 31 is provided. .
The blowing port 36a of the preheating nozzle 36 is such that the blowing direction of the heating gas F2 is inclined in the direction of relative movement of the tip 31 with respect to the direction perpendicular to the substrate surface 200a where the soldering portion is located. Is formed. By tilting the blowing direction of the heating gas F2 in this way, it is possible to avoid the heating gas injected from the blowing port 36a of the preheating nozzle 36 being directly blown to the soldering portion. Accordingly, it is possible to prevent a soldering failure caused by blowing off the molten solder by the blowing gas flow of the heated gas.
[0024]
Further, since the heating gas for the preheating does not directly contact the molten solder, compressed air obtained by compressing normal air can be used instead of the inert gas such as nitrogen gas. This compressed air is supplied from a compressed air line (not shown) and is received by a compressed air receiving part 361 provided on the heating holding part 360 of the preheating nozzle 36 through a gas pressure regulator and a compressed air supply hose 362 (not shown). The compressed air introduced from the compressed air receiving part 361 is heated by a heater (for example, a ceramic heater) built in the center of the heating and holding part 360 when passing through the inside of the heating and holding part 360. The heated compressed air F2 exits from the blowout port 36a at the lower end of the preheating nozzle 36 and is blown to the soldering location before soldering. A current is supplied to the heater via a power cable 363 connected to the upper part of the heating holding unit 360 of the preheating nozzle 36. The current supplied to the heater is controlled based on the heater temperature detected by a thermocouple 364 provided so that the tip is in contact with the heater. By this control, the temperature of the compressed air emitted from the preheating nozzle 36 is maintained at a predetermined temperature.
[0025]
In addition, the present inventors have found out preheating conditions in which soldering defects do not occur by conducting heating experiments and soldering experiments with the heating gas from the preheating nozzle 36 on various solders and various substrates / leads. .
First, only the preliminary heating with the heating gas was performed while moving the substrate without retracting the iron tip 31 and soldering. In this experiment, the substrate 200 shown in FIG. 5 was used. This board 200 has a total of 120 soldering locations where the lead (30 pins × 4 rows) of the connector parts protrudes. The temperature change profile was measured for 5 soldered locations (62nd pin, 21st pin, 82nd pin, 51st pin, 118th pin) among the plurality of soldered locations. Of these 5 soldering locations, the 21st pin and 51st pin soldering locations are locations where soldering failure has occurred in the conventional soldering method, and heat is easily lost due to wiring patterns, etc. It is a place where it seems that it is hard to rise.
The temperature change profile is 1 while using the thermocouple fixed to the land (electrode portion exposed on the surface) of each soldering position and moving the spraying position of the heating gas F2 in the directions of arrows A and B in FIG. Measured every second.
[0026]
6 to 13 show the results of a heating experiment in which only the preliminary heating with the heating gas is performed while moving the substrate without performing soldering with the iron tip 31. FIG. 6-13, the heater temperature in the heating holding part 360 of the preheating nozzle 36 was set to 400 ° C., 500 ° C., 525 ° C., 550 ° C., 575 ° C., 600 ° C., 625 ° C. and 650 ° C., respectively. It is a temperature change profile at the time. In addition, the curves (1), (2), (3), (4) and (5) in each figure are the 62nd pin, 21st pin, 82nd pin, 51st pin and the like on the substrate 200, respectively. It is a temperature change profile of the soldering location of the 118th pin.
From these results of FIGS. 6 to 13, it can be seen that the temperature change profiles are greatly different even though the heating gas F <b> 2 is blown under the same conditions. And it turned out that temperature rise is especially small in two soldering locations (No. 21 pin and No. 51 pin) where defective soldering has occurred in the conventional soldering method. Moreover, in FIG. 11 (preheating heater temperature: 600 degreeC)-FIG. 13 (preheating heater temperature: 650 degreeC), the peak temperature of the soldering location at the time of preheating is 140 degreeC or more. Moreover, it is found that the temperature does not fall below 140 ° C. after a predetermined time has elapsed since the temperature of the soldering point has reached a peak due to preheating (corresponding to the soldering start timing when the tip 31 is at the predetermined position). It was.
[0027]
Next, preheating was performed under the same conditions as in FIGS. 6 to 13, and the soldering tip 31 was set at a predetermined position and soldering was continuously performed. In this experiment, thread solder composed of lead-free solder (melting point: 217 ° C.) having a diameter of 0.65 mm and a relatively high melting point was supplied from both sides of the tip 31. The heating temperature of the iron tip 31 was controlled to 380 ± 20 ° C.
According to the preliminary heating and soldering experimental results, when the same preheating as in FIGS. 11 to 13 was performed, good soldering was obtained at all the five soldering points. On the other hand, when the same preheating as in FIG. 6 (preheating heater temperature: 400 ° C.) to FIG. 12 (preheating heater temperature: 575 ° C.) is performed, two soldering locations (the 21st pin and the 51st pin) ), Soldering failure occurred.
[0028]
FIG. 14 shows a typical temperature change profile when the preheating and the subsequent soldering are continuously performed on the soldering portion where the soldering failure does not occur. In the figure, To is the time from when the soldering point passes through the spraying center of the preheating heating gas until the soldering tip comes into contact with the soldering point and soldering starts (in this embodiment, approximately 2.7 seconds).
As shown in FIG. 14, the soldering part is preheated to 140 ° C. or more once, and soldering is started by starting the soldering part in a state where the temperature of the soldering part does not fall below 140 ° C. Defects could be reliably prevented. In this experiment, lead-free solder having a relatively high melting point was used. However, it is considered that soldering defects can also be reliably prevented when lead-containing eutectic solder (melting point: about 183 ° C.) having a low melting point is used. For eutectic solder, preheating and soldering experiments were conducted as in the case of the lead-free solder described above. As a result, pre-heating the soldered part to 110 ° C or higher, and starting the soldering of the soldered part in a state where the temperature of the soldered part does not fall below 110 ° C, it is possible to ensure soldering defects. I found that it can be prevented.
[0029]
As described above, according to the present embodiment, by performing preliminary heating on each soldering portion of the substrate 200, poor soldering due to insufficient heating temperature at the soldering portion when soldering is started at the tip 31. Can be prevented. That is, solder can be surely inserted into the through hole of each soldering location, and no extra solder adheres to the iron tip 31, so a short between the leads due to the extra solder at the iron tip (bridge) Does not occur. In particular, in the case of lead-free solder having a high melting point and high viscosity, shorts (bridges) between the leads tend to occur frequently. However, according to the present embodiment, even when such lead-free solder is used, the shorts between the leads ( (Bridge) does not occur, and soldering robots can automatically and quickly perform high-quality soldering.
Also, if the soldering conditions such as the type of solder and the type of soldering object are the same, the relative moving speed of the iron tip 31 can be increased as compared with the case where preheating is not performed, and the soldering speed can be increased. It can be improved dramatically. Further, even if the relative movement speed of the soldering tip is increased, good soldering is possible. Therefore, the solder supplied to the soldering point is not excessively heated by the soldering tip 31, and the solder is prevented from being oxidized. You can also.
Further, by spraying the heating gas F2 for preheating using the preheating nozzle 36, it is possible to preheat only the necessary soldering spot in a spot manner. Therefore, it is possible to avoid thermal adverse effects such as melting of the solder in the soldered part near the preheating portion and the strength being lowered. Actually, a preheating experiment was performed on a substrate on which components were already soldered by reflow or the like, and the temperature change profile of the preheating location at that time and the adjacent components was measured using a thermocouple. As a result, the temperature rise of the parts that were about 5 to 10 mm away from the preheating location was 110 ° C. or less, even though the preheating location was heated to about 140 ° C.
Here, the diameter of the outlet 36a of the preheating nozzle 36 is preferably set as follows. That is, it is preferable to set the width dimension of the diameter of the blowout port 36a in the direction (lateral direction) orthogonal to the iron tip traveling direction to the full width of the point to be preheated (the full width of the row of leads to be soldered), In the preheating experiment, it was set to 8 to 10 mm. Moreover, it is preferable to set so that the width dimension of the diameter of the blower outlet 36a in the iron tip advancing direction (longitudinal direction) becomes narrower as the width dimension in the lateral direction becomes wider, and in the preliminary heating experiment, 1 to 2.5 mm. Set to.
In addition, if the distance between the blow-out port 36a of the preheating nozzle 36 and the substrate to be soldered is too close, damage to the substrate may occur. There is a high probability that the target gas will be difficult to adjust and the heated gas will hit the excess. Accordingly, the distance between the blowout port 36a of the preheating nozzle 36 and the substrate to be soldered is such that there is no damage to the substrate, and the substrate can be preheated to the target temperature by heating at a predetermined heating efficiency and heated. It is preferable to set an adjustable range so that the heating gas can be applied to the points to be limited. In the preheating experiment, the distance between the blowing port 36a of the preheating nozzle 36 and the substrate to be soldered was set in the range of 5 to 10 mm, and the optimum distance was 5 mm.
The area for spraying the preheating heating gas F2 from the preheating nozzle 36 is based on the circuit pattern of the board to be soldered, the arrangement of components, etc. It can be adjusted by the distance between the outlet 36a and the substrate.
[0030]
In the soldering robot used in the experiment, the separation distance between the spraying position of the heating gas F2 for preheating and the soldering position by the tip 31 is about 10 mm. In this configuration, soldering with the tip 31 is started 2.7 seconds after the peak of the preheating temperature at the soldering location. However, if the separation distance between the spraying position of the heating gas F2 for preheating and the soldering position by the tip 31 is changed, the preheating condition of 140 ° C. may not be ensured. In addition, even when the soldering conditions such as the relative moving speed of the iron tip 31 change, the 140 ° C. preheating condition may not be ensured.
Therefore, it is preferable to switch the heating temperature of the soldering portion heated by the preheating according to the soldering conditions such as the type of solder and the relative movement speed of the tip. In this case, even when the soldering conditions are changed, it is possible to perform appropriate preheating for the soldering portion and to avoid excessive preheating.
As the preheating temperature switching means for switching the preheating temperature at the soldering location, a heater power source capable of changing the current supplied to the preheating heater built in the heating holding unit 360 of the preheating nozzle 36 can be used. In addition, a gas pressure regulator that can adjust the flow rate of the compressed air, an electromagnetic valve that can turn ON / OFF the compressed air flowing through the air supply path, and the like can also be used.
[0031]
Further, the flow rate of the compressed air and the current supplied to the preheating heater are controlled according to a control sequence determined based on the measurement result of the preheating temperature obtained in advance through experiments or the like for the substrate to be soldered. Also good. The experiment for measuring the preheating temperature is performed, for example, when the substrate to be soldered changes, and is performed by attaching temperature sensors such as thermocouples to a plurality of measurement points at the soldering locations on the substrate. With the temperature sensor attached in this manner, the temperature change profile at each measurement point is measured while switching the preheating conditions such as the flow rate of the compressed air. From this measurement result, the optimum preheating conditions such as the flow rate of the compressed air are determined and stored in a memory card 113 described later as part of control sequence data. The actual soldering of the substrate is performed while switching the preheating conditions such as the compressed air based on the control sequence data read from the memory card 113.
[0032]
Further, the preheating temperature switching means is controlled so that the heating temperature of the soldering portion heated by the preheating is automatically switched according to the soldering conditions such as the type of solder and the relative movement speed of the tip. Control means may be provided.
[0033]
FIG. 15 is a block diagram showing the main part of the control system of the soldering robot. The control unit 500 serving as a control unit is configured using a CPU, RAM, ROM, I / O interface, and the like. The control unit 500 is connected to a memory card drive device 501 for writing data to and reading data from the memory card 113 and various motor drive circuits 502A, 502B, 503 to 505. These various motor drive circuits 302A, 302B, 303 to 305, motors connected to the respective circuits, movable brackets driven by the respective motors, guide rails for guiding the movable brackets, and the like between the substrate 200 and the iron member 32 The relative position variable means is configured to change the relative positional relationship (linear distance and rotation angle).
The control unit 500 is connected to a heater power supply 510 that supplies current to the preheating heater built in the heating holding unit 360 of the preheating nozzle 36. Further, a gas pressure adjuster 511 that can adjust the flow rate of the compressed air and a temperature sensor 512 that detects the temperature of the preheater heater are also connected. The output of the temperature sensor 512 is used to control the current supplied from the heater power supply 510.
[0034]
Further, as described above, data relating to the soldering location of the substrate 200 to be soldered and various parameters during soldering (such as the discharge amount of the threaded solder and the relative movement speed of the iron member) are stored in the memory card 113. ing. Data in the memory card 113 is taken into the control unit 500 via the memory card drive 501. Based on this data, a command signal for each motor drive unit is generated and transmitted. Each motor drive unit rotationally drives the corresponding pulse motor 306A, 306B, 307 to 309 based on the command signal.
[0035]
Further, based on the data in the memory card 113, for example, when it is determined that the soldered portion of the substrate 200 is harder to heat than the standard substrate, the temperature setting of the preheating heater is increased or the flow rate of the compressed air is increased. To control. The same control is performed when it is determined that the relative movement speed of the iron member is set higher than the standard.
On the contrary, when it is determined that the soldered portion of the substrate 200 is easy to heat, the temperature setting of the preheater is controlled to be lower or the flow rate of the compressed air is reduced. Also, control is performed in the same way when it is judged that lead-containing eutectic solder with a low melting point is used instead of standard lead-free solder, or when the relative moving speed of the iron member is set lower than the standard. To do.
By controlling in this way, even when the soldering conditions are changed, it is possible to perform appropriate preheating on the soldering portion and to avoid excessive preheating.
[0036]
In addition, you may comprise so that the data regarding the said soldering location etc. may be memorize | stored and used for other storage media, such as a magnetic disk (flexible disk, hard disk), a magnetic tape, and an optical disk. Further, it may be configured to take in data relating to the soldering location from an external device such as a personal computer connected to the apparatus main body 100.
[0037]
【The invention's effect】
  Claims 1 to7According to this invention, it is possible to prevent poor soldering due to insufficient heating temperature at the soldering point when soldering is started by preheating the soldering point before supplying the solder. In other words, it is possible to securely put the solder into the through hole of each soldering point, and there is no adhesion of extra solder to the tip of the iron, so there is no short (bridge) between the leads due to the extra solder at the tip of the iron. There is an effect that it does not occur. In particular, even when lead-free solder with a high melting point and high viscosity is used, there is no short-circuit (bridge) between the leads, and a soldering device can automatically and quickly perform high-quality soldering.. Moreover,The above preheating and soldering can be continuously performed on each soldering point.WithThere is an effect that it is possible to prevent a soldering failure caused by blowing the solder melted at the soldering position during the soldering with the heated gas.
SpecialAnd claims6According to this invention, even when the soldering conditions are changed, the appropriate preheating for the soldering portion is ensured, and the occurrence of the thermal damage of the soldering object itself due to excessive preheating or the burning of the flux is prevented. There is an effect that can be.
  In particular, the claims7According to the invention, it is possible to automatically switch the preheating temperature when the soldering condition is changed.
[Brief description of the drawings]
FIG. 1 is an enlarged side view of a tip portion of a iron member in a soldering apparatus according to an embodiment of the present invention.
FIG. 2 is a front view showing a schematic configuration of the soldering apparatus.
FIG. 3 is an enlarged front view of a tip portion of the iron member.
FIG. 4 is an enlarged view of the iron tip of the iron member.
FIG. 5 is a partial plan view of a substrate used in a preheating experiment.
FIG. 6 is a temperature change profile of a soldering portion when the preheater temperature is 400 ° C.
FIG. 7 is a temperature change profile of a soldered portion when the preheater temperature is 500 ° C.
FIG. 8 is a temperature change profile of a soldering portion when the preheater temperature is 525 ° C.
FIG. 9 is a temperature change profile of a soldered portion when the preheater temperature is 550 ° C.
FIG. 10 is a temperature change profile of a soldered portion when the preheater temperature is 575 ° C.
FIG. 11 is a temperature change profile of a soldered portion when the preheater temperature is 600 ° C.
FIG. 12 is a temperature change profile of a soldered portion when the preheater temperature is 625 ° C.
FIG. 13 is a temperature change profile of a soldering portion when the preheating heater temperature is 650 ° C.
FIG. 14 is an explanatory diagram of a typical temperature change profile when preheating and subsequent soldering are continuously performed on a soldering portion where no soldering failure has occurred.
FIG. 15 is a block diagram showing a main part of a control system of the soldering apparatus.
FIG. 16 is a partial plan view of a substrate on which a soldering failure has occurred.
[Explanation of symbols]
200 substrates
200a Substrate surface
201 leads
202 parts
203 rand
204 Through hole
205 Soldering points
30 Soldering head
31 tips
310A, 310B Solder supply surface
311 Iron heating holding part
32 Iron parts
320 Tip holding case
321 Nozzle for inert gas
322 Nitrogen gas supply hose
323 Nitrogen gas receiver
34A, 34B Solder supply head
35A, 35B Needle member
36 Preheating nozzle
36a outlet
360 Heating holding part
361 Compressed air receiver
362 Compressed air supply hose
363 Power cable
364 thermocouple
40 Threaded solder
40 'molten solder
500 Control unit
510 Heater power supply
511 Gas pressure regulator
512 Preheater temperature sensor
F1 Flow of nitrogen gas
F2 Heating gas flow for preheating

Claims (6)

A soldering method is carried out continuously soldered to soldering points of the plurality of by relatively moving the tip along the arrangement of a plurality of soldering points against soldering object,
Prior to soldering each of the plurality of soldering points of the soldering object, the soldering point before the solder is supplied is preheated to 140 ° C. or more by blowing a heating gas to the soldering point. And steps to
After the preheating of the soldering part, starting the supply of molten solder to the soldering part in a state where the temperature of the soldering part does not fall below 140 ° C,
The blowing direction of the heating gas for the preheating is a direction inclined toward the relative movement direction side of the iron tip with respect to the direction perpendicular to the soldering target surface where the soldering portion is located,
Upon moving the tip, with the tip of the relative movement direction downstream side by blowing the heated gas continuously to the plurality of soldering points, with respect to the soldering portions of the plurality of the preliminary heating Soldering method characterized by being performed continuously. The soldering method according to claim 1,
The soldering part to which the molten solder is supplied during soldering of the soldering part of the soldering object is sprayed with heated inert gas,
A soldering method, wherein the preheating is performed by spraying a heating gas on the soldering portion prior to spraying the inert gas. A soldering iron member having a soldering tip and a heating means for heating the soldering tip, solder supply means for supplying solder to the soldering tip, and moving the soldering tip relative to the soldering object And a relative position varying means for changing a relative positional relationship between the soldering object and the soldering iron member, and a plurality of soldering points along the soldering object. Te a soldering apparatus for performing continuous soldered to soldering points of the plurality of by relatively moving the tip,
A gas that moves relative to the soldering tip and heats the soldering point before pre-heating the soldering point before the solder of the soldering target is supplied to the soldering point at 140 ° C. or higher. A preheating nozzle for spraying and a heating gas supply means for supplying the heating gas to the preheating nozzle,
The distance between the preheating nozzle and the iron tip is such that the supply of molten solder to the soldering point is started in a state where the temperature of the soldering point heated by the preheating does not fall below 140 ° C. Set to
The preparatory heating gas blowing direction for the preheating is such that the soldering point is inclined to the direction of relative movement of the soldering tip with respect to a direction perpendicular to the surface of the soldering target object. A soldering apparatus comprising a heating nozzle. The soldering apparatus according to claim 3.
An inert gas nozzle that blows the heated inert gas onto a soldering point where solder melted by the iron tip is supplied;
A soldering apparatus, wherein the preheating nozzle is provided separately from the inert gas nozzle. The soldering apparatus according to claim 3 or 4,
A soldering apparatus comprising preheating temperature switching means for switching a heating temperature of a soldering portion heated by the preheating. The soldering apparatus according to claim 5, wherein
Control means for controlling the preheating temperature switching means so as to switch the heating temperature of the soldering spot heated by the preheating according to the soldering conditions for the soldering spot is provided. Soldering device.

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