JP2018067698A - Soldering evaluation method and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To evaluate the quality of soldering from a soldered substrate surface side.SOLUTION: A soldering evaluation method includes: a terminal inserted into a land that has a through hole penetrating through a soldered substrate; a soldering iron supplying a molten solder in the through hole; and a heat transfer body transferring heat of solder fusion of the through hole on the back side of the substrate to the surface side of the substrate. In the soldering evaluation method, during soldering or after the completion of soldering, temperatures of the heat transfer body are detected to evaluate the soldering, and the quality of a back fillet can be determined from the solder surface side of the substrate.SELECTED DRAWING: Figure 3

Description

 The present invention relates to a soldering evaluation method and apparatus for inspecting soldering by heating and melting a solder piece.

In recent years, electronic circuits on which electrical components are mounted are mounted on various devices. In the formation process of the electronic circuit, soldering using a soldering iron is performed for the process of joining the lead wire to the wiring pattern (land) on the substrate. In addition, in order to mechanically realize the soldering process, a solder processing apparatus having a hook portion is used.
For example, such a solder processing apparatus melts downward by supplying solder pieces (cut from thread solder) into a heated tip and heating and melting the solder pieces using the heat of the tip. It is configured to supply solder. Thereby, the soldering process with respect to the board | substrate arrange | positioned below is realizable.
However, solder bonding may not be sufficient depending on soldering conditions, solder materials, or board variations, and inspection for assuring the reliability of soldering is required. In particular, when soldering is performed by inserting a component terminal into a through hole, it is required to form a back fillet in which the through hole is filled with solder and the solder rises on the back side of the substrate.

The technique described in Japanese Patent Laid-Open No. 2004-151867 is to detect that the solder is properly melted by detecting the temperature outside the solder tub where the solder is melted inside the cylinder.
The technique described in Patent Document 2 measures the temperature of molten solder with a radiation thermometer, and determines the quality of the solder joint from the temperature waveform.
This back fillet inspection is difficult to discriminate in the conventional electrical continuity inspection and appearance inspection using a camera, and automatic inspection cannot be performed.

JP, 2006-059923, A JP 2013-251488 A

However, the technique described in Patent Document 1 has a drawback that the temperature of the molten solder cannot be accurately measured because the temperature is detected from the outside of the cylinder, and the accuracy of solder quality determination is low. Discrimination of fillet formation was difficult.
The technique described in Patent Document 2 measures the temperature of the solder near the center of the through hole on the surface of the substrate, and since electrical components are attached to the terminals to be soldered, the temperature is measured from the back surface of the substrate. It was difficult to determine the quality of the back fillet by measurement or appearance inspection.
In view of the above-described problems, an object of the present invention is to provide a method for discriminating whether soldering is good such as a back fillet from the surface of a soldering substrate.

  According to the soldering evaluation method of the present invention, a solder rod that flows molten solder into a land having a through-hole penetrating the soldering substrate and a solder melting heat on the back surface side of the through-hole substrate are transmitted to the front surface side of the substrate. A heat element, and detects the temperature of the heat transfer element to determine that the soldering has been performed normally.

Specifically, as the above method, the heat transfer body is composed of a terminal inserted into the through-hole and a branched measurement terminal, and the quality of the soldering is determined by measuring the temperature of the measurement terminal. Is.
Specifically, as the above method, a heat transfer body is provided by extending a land, and the temperature of the land is measured to determine whether soldering is good or bad.

Specifically, as the above method, the terminal is provided with an enlarged portion that is widened in the circumferential direction, and heat conduction is promoted by the enlarged portion to measure the temperature, thereby determining whether soldering is good or bad.
Specifically, as the above method, the heat transfer body is provided at a position away from the through hole in a radial manner, and the quality of the soldering is determined by measuring the temperature of the heat transfer body.
The solder evaluation method according to the present invention detects a land having a through hole penetrating a soldering substrate, a solder iron for supplying molten solder into the through hole, and a temperature of an outer peripheral portion of the land. .

  The soldering apparatus according to the present invention also includes a land having a through-hole penetrating the soldering substrate, a tip for supplying molten solder into the through-hole, and solder melting heat on the back side of the through-hole substrate. A heat transfer body to be transmitted to the surface side and a temperature detection means for detecting the temperature of the heat transfer body are provided, and the quality of the soldering is evaluated by the temperature detection means.

 According to the soldering evaluation method according to the present invention, the heat of the molten solder supplied from the through hole to the back surface of the substrate is transferred to the substrate surface side by the heat transfer body, and the temperature is measured from the substrate surface side. Evaluation of soldering can be performed, and the quality of soldering can be determined at the time of soldering.

It is a perspective view of the soldering apparatus concerning the Example of this invention. It is sectional drawing cut | disconnected by the II-II line | wire of the soldering apparatus shown in FIG. It is a figure which shows the structure of Example 1 which shows the soldering evaluation method of this invention, (a) is sectional drawing, (b) is A arrow view of (a). It is a perspective view which shows the terminal for a measurement of the Example 1. FIG. It is sectional drawing which shows the soldering state of the Example 1, (a) is a figure which shows the case where soldering is favorable, (b) is a figure which shows the case where soldering is bad. It is a figure which shows the structure of Example 2 which shows the soldering evaluation method of this invention, (a) is sectional drawing, (b) is B arrow view of the principal part of (a). It is a perspective view which shows the terminal for a measurement of the Example 2. It is sectional drawing which shows the soldering state of the Example 2. 3 is an example showing another measurement terminal of Example 2. FIG. It is a figure which shows the structure of Example 3 of the soldering evaluation method of this invention, (a) is sectional drawing, (b) is C arrow directional view of the principal part of (a). It is sectional drawing which shows the state of soldering of the Example 3, (a) is a figure which shows the normal case of soldering, (b) is a figure which shows the state in which soldering is unsatisfactory. It is an Example which shows the other land shape of the Example 3. It is explanatory drawing which shows the state of incomplete soldering. It is a figure which shows the structure of Example 4 of the soldering evaluation method of this invention, (a) is sectional drawing in the case of favorable soldering, (b) is D arrow view of the principal part. It is a perspective view which shows the terminal shape of the Example 4. It is sectional drawing in the case of the defect of soldering of Example 5. It is a figure which shows the normal soldering state of the Example 5, (a) is sectional drawing, (b) is E arrow view of the principal part of (a). It is a figure which shows the defective soldering state of the Example 5, (a) is sectional drawing, (b) is an E arrow directional view of the principal part of (a). It is sectional drawing of the conventional soldering apparatus.

  Embodiments of the present invention will be described below from Example 1 with reference to the drawings. The contents of the present invention are not limited to these embodiments.

  FIG. 1 is a perspective view of a soldering apparatus in a soldering evaluation method according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line II-II of the soldering apparatus A shown in FIG. In FIG. 1, a part of the housing and the support portion 1 is cut to display the inside of the soldering apparatus A.

As shown in FIG. 1 and FIG. 2, the soldering apparatus A supplies the wire solder W from above and uses the tip 5 provided at the lower portion to connect the wiring board Bd disposed below the tip 5 This is a device for soldering the electrical component Ep. The thread solder W has a structure in which a flux layer is provided inside a tubular solder layer. Accordingly, the solder piece generated by cutting the thread solder W similarly has a structure in which a flux layer is provided inside the tubular solder layer. The soldering apparatus A includes a support unit 1, a cutter unit 2, a drive mechanism 3, a heater unit 4, a tip 5, and a solder feed mechanism 6. A combination of the heater unit 4 and the tip 5 constitutes a soldering iron part.
The support portion 1 includes a flat plate-like wall body 11 that is erected. In the following description, for convenience, as shown in FIG. 1, the horizontal direction along the wall body 11 is the X direction, the horizontal direction perpendicular to the wall body 11 is the Y direction, and the vertical direction along the wall body 11 is the Z direction ( Vertical direction). For example, as shown in FIG. 1, the wall 11 has a ZX plane.

The soldering apparatus A supplies the molten solder to the wiring board Bd attached to the jig Gj and the terminal P of the electrical component Ep arranged on the wiring board Bd, and performs connection fixing. When soldering, the jig Gj is moved in the X direction and the Y direction to position the wiring board Bd with the land Ld. Further, the soldering apparatus A is movable in the Z direction, and the tip of the hook 5 can be brought into contact with the land Ld by moving in the Z direction after positioning.
The support portion 1 includes a holding portion 12 provided at a position shifted from a lower end portion of the wall body 11 in the Z direction, and a sliding guide 13 fixed to the edge portion (lower portion) of the wall body 11 in the Z direction. And a heater unit fixing portion 14 provided at an end portion (lower end portion) of the wall body 11 in the Z direction.

 The cutter unit 2 is for cutting the thread solder W fed by the solder feeding mechanism 6 into solder pieces Wh (FIG. 2) having a predetermined length. The cutter unit 2 includes a cutter lower blade 22 (fixed blade portion) fixed to the sliding guide 13 and a cutter upper blade 21 (movable) disposed on the cutter lower blade 22 and slidable in the X direction. Blade part) and a pusher pin 23 (solder pressing part) that is provided on the cutter upper blade 21 and slides in a direction (Z direction) intersecting the sliding direction of the cutter upper blade 21.

 As shown in FIG. 2, the cutter upper blade 21 has an upper blade hole 211 that is a through hole into which the thread solder W fed by the solder feeding mechanism 6 is inserted, and a rod portion 231 of the pusher pin 23 inserted therein. The pin hole 212 which is a through-hole is provided. The lower edge of the upper blade hole 211 is formed in a cutting edge shape. The cutter lower blade 22 includes a lower blade hole 221 that is a through hole into which the thread solder W penetrating the upper blade hole 211 is inserted. The edge part of the upper end of the lower blade hole 221 is formed in a cutting blade shape. The upper blade hole 211 and the lower blade hole 221 are displaced in a direction intersecting with the thread solder W in a state where the thread solder W is inserted, whereby the thread solder W is cut by the mutual cutting blade. The pusher pin 23 is a solder pressing part, and pushes down the solder piece Wh cut by the cutter upper blade 21 and the cutter lower blade 22 and remaining in the lower blade hole 221.

 As shown in FIGS. 1 and 2, the drive mechanism 3 passes through an air cylinder 31 held by the holding portion 12 and a through hole provided in the holding portion 12, and is driven to slide in the Z direction by the air cylinder 31. And a cylindrical guide shaft 35 that is supported by both the holding rod 12 and the cutter lower blade 22 and extends in the Z direction. The drive mechanism 3 includes a cam member 33 supported by the guide shaft 35 so as to be slidable in the Z direction, and a slider portion 34 having a cam groove 340 with which a later-described pin 332 provided on the cam member 33 is engaged. It has.

As shown in FIG. 2, the heater unit 4 is a heating device for heating and melting the solder piece Wh, and is fixed to the heater unit fixing portion 14 provided at the lower end portion of the wall body 22. The heater unit 4 includes a heater 41 that generates heat when electricity is passed, and a heater block 42 for attaching the heater 41. The heater 41 is wound around the outer peripheral surface of a cylindrical heater block 42.
The tip 5 is a cylindrical heatable member extending in the vertical direction, and has a solder hole 51 extending in the axial direction at the center. The tip 5 is inserted into the recess 421 of the heater block 42 and is prevented from coming off by a member not shown. Further, the solder hole 51 of the tip 5 communicates with the solder supply hole 421 of the heater block 42, and the solder piece Wh is sent from the solder supply hole 421.
The tip 5 is transferred with heat from the heater 41 and melts the solder piece Wh with the heat.

 As shown in FIGS. 1 and 2, the solder feeding mechanism 6 supplies thread solder W, a pair of feed rollers (61a, 61b) for feeding the thread solder W, and the thread solder W fed thereto by a cutter. And a guide tube 62 for guiding the upper blade 21 into the upper blade hole 211. The pair of feed rollers (61a, 61b) are attached to the support unit 1, sandwich the yarn solder W, and rotate to feed the yarn solder W downward. The guide tube 62 is a tube body that can be elastically deformed, and its upper end is disposed in the vicinity of a portion of the feed roller 61 where the thread solder W is fed out.

 The lower end of the guide tube 62 is provided so as to communicate with the upper blade hole 211 of the cutter upper blade 21. Note that the lower end of the guide tube 62 moves following the sliding of the cutter upper blade 21, and the guide tube 62 is not excessively pulled or stretched within the range in which the cutter upper blade 21 slides. Is provided. Each feed roller (61a, 61b) determines the length of the thread solder fed out by the rotation angle (number of rotations).

 When soldering is performed by the soldering apparatus A, the entire soldering apparatus A is lowered by a driving device such as a robot, and the tip of the tip 5 is brought into contact with the land Ld of the wiring board Bd to be soldered. , Surrounding the land Ld and the terminal P of the electrical component Ep. At this time, heat from the heater 41 is transmitted to the tip 5, and when the tip 5 comes into contact, the land Ld and the terminal P of the electric component Ep are heated to a temperature suitable for soldering (preheating). )

 Next, the operation of the soldering apparatus A will be described. As shown in FIG. 2, after the tip 5 is heated by the heater 41, the thread solder W is fed by a set length by the solder feeding mechanism 6, and the upper blade 21 is slid by the cylinder 31 via the cam member 33. Then, the thread solder W is cut, and the cut solder piece Wh passes through the solder hole 51 of the tip 5, contacts the terminal P, receives heat from the tip 5 and melts.

  Next, the soldering evaluation method of the present invention will be described. Conventionally, soldering to a substrate having a through hole has a configuration shown in FIG. The electrical component Ep having the terminal P is soldered to the wiring board Bd having the through hole Th and the land Ld. FIG. 19A shows a case where the soldering is performed well, where the melted solder Wh passes through the through hole Th and is supplied to the back surface (lower side) of the substrate Bd, and FIG. This is a case where the solder Wh is not supplied to the back side of the substrate Bd. In the state of FIG. 19 (b), although electrically conductive, the mechanical strength is insufficient, and the electrical component Ep may be detached when repeatedly exposed to a temperature up / down cycle or vibration. However, at the beginning of soldering, the terminal P of the electrical component Ep and the land Ld of the wiring board Bd are electrically connected, and no abnormality is found in the continuity test. Further, since the back side of the wiring board Bd has the electrical component Ep, it is difficult to perform an appearance inspection.

  A wiring board Bd according to the first embodiment of the present invention is shown in FIG. FIG. 3B is a view taken in the direction of arrow A in FIG. In FIG. 3, lands Ld having through holes Th penetrating the wiring board Bd are provided on both surfaces of the wiring board Bd. An L-shaped heat transfer body Dt is provided on the back side of the substrate Bd, and one of the heat transfer bodies Dt is in the vicinity of the land Ld and in the vicinity of the terminal Td inserted into the through hole Th during soldering. The other is penetrating the substrate Bd through the insertion opening Ks and the end is exposed on the surface side of the substrate Bd. FIG. 4 is a perspective view showing the shape of the heat transfer body Dt. Zt is an insulator.

  Next, the state during soldering will be described. FIG. 5A shows an example in which the soldering is normally performed, and the top fillet Ft and the back fillet Fb are formed. FIG. 5B shows the abnormal state of the soldering and the back. Fillets are not formed. In the figure (a), the heat of the molten solder Wh is transmitted to the heat transfer body Dt by the back fillet Fb, and the temperature of the upper part of the heat transfer body Dt located on the surface side of the substrate Bd increases. This temperature is detected by a radiation thermometer Ho which is a temperature detecting means. Heat transfer from the molten solder Wh to the heat transfer body Dt is performed not only from the molten solder Wh but also from the land Ld and the terminal Td via the molten solder Wh by forming the back fillet Fb. Therefore, the temperature rise can be increased. Whether the soldering is good or bad can be determined from the temperature characteristic of the heat transfer body Dt, the degree of temperature change, or the change characteristics with respect to time of the temperature change of the heat transfer body Dt from melting of the solder pieces. When the detected temperature is high or the temperature change rate is large, it is determined that the soldering has been normally performed. In a portion where the heat transfer body Dt penetrates the wiring board Bd, a heat transfer other than the back fillet Fb can be reduced by providing a gap in part or all between the heat transfer body Dt and the insertion port Ks. Therefore, the detection accuracy is improved.

In FIG. 5B, since the back fillet Fb is not formed, the amount of heat transfer from the lower part of the molten solder Wh to the heat transfer body Dt is small, the temperature of the heat transfer body Dt is low, or the temperature change degree with respect to time is small. small. In this case, it is determined that the soldering has not been performed normally, and an alarm is given or the soldering operation is stopped.
The thermometer may be not only a radiation thermometer but also a thermocouple thermometer or a resistance temperature detector, or a color whose color changes depending on the temperature. The thermometer may be driven by a robot or the like integrally with the soldering apparatus A, and the position thereof may be synchronized with the movement of the soldering location.

  6A and 6B show a second embodiment of the present invention, in which FIG. 6A is a cross-sectional view of a wiring board Bd, and FIG. The difference from the first embodiment is that, as shown in FIG. 6A, the terminal Td to be inserted into the through hole Th is branched to form the heat transfer body portion Dt1. FIG. 7 is a perspective view of the terminal Dt1. FIG. 8 shows a state when the soldering is normally performed, and by forming the back fillet Fb, the heat of the molten solder Wh is transferred to the heat transfer portion Dt1, and the temperature is measured by the radiation thermometer Ho. To detect. FIG. 9 is provided with a thermal resistance Nt that suppresses heat transfer by narrowing the branch portion of the terminal Td to the heat transfer body portion Dt1, and reduces heat transfer from the terminal Td to reduce heat transfer to the heat transfer body portion Dt1. The heat from the molten solder Wh is mainly used to improve the detection accuracy of the back fillet Fb.

  10A and 10B show a third embodiment of the present invention, in which FIG. 10A is a cross-sectional view of a wiring board Bd, and FIG. 10B is a C arrow view thereof. The difference from the first embodiment is that the heat transfer body is composed of lands. A first land Ld1 is formed around the through hole Th, and a second land Ld2 is further disposed on the outer periphery of the first land Ld1 via the groove Mz. The first land Ld1 communicates with the third land Ld3 by the measurement pattern Ps. The first land Ld1, the second land Ld2, the third land Ld3, and the measurement pattern Ps are all made of a material having good solder wettability, and the groove Mz is made of a material having no solder wettability.

FIG. 11 shows a state when soldering is performed. (A) shows a state when soldering is normally performed, and (b) shows a state when a back fillet is not formed. Show. When the back fillet Fb is formed in FIG. 11A, the molten solder Wh flows from the first land Ld1 over the groove Mz to the second land Ld2, and further from the measurement pattern Ps to the third land Ld3. The temperature of the third land Ld3 rises. This temperature is measured with a radiation thermometer Ho.
On the other hand, since the back fillet is not formed in FIG. 11B, the flow of the molten solder Wh from the first land Ld1 to the second land Ld2 is blocked by the solder non-wetting groove Mz, and the temperature of the third land Ld3 increases. Is small. By detecting this low temperature by the radiation thermometer Ho, a soldering abnormality is determined.

  FIG. 12 shows an embodiment in which the shape of the land is changed, and is an example in which the groove Mz1 is formed between the concave portion Ldo of the first land Ld1 and the convex portion Ldt of the third land Ld3. In this case as well, the same effect as described above can be obtained by forming the groove Mz1 with a material that is not wettable to solder.

FIG. 13 shows an example of insufficient soldering although a back fillet is formed. In the soldering shown in FIG. 13, the back fillet Fb1 is formed and flows through the first land Ld1, but does not reach the second land Ld2, and the best back fillet is not formed.
FIG. 14 shows a fourth embodiment of the present invention. The difference from the third embodiment is that an enlarged portion is provided on the terminal. FIG. 14 shows a state at the time of soldering. By providing an enlarged portion Kd of the terminal Td1 in the vicinity of forming the back fillet Fb, the molten solder can easily flow from the first land Ld1 to the second land Ld2. The back fillet Fb is spread to increase the soldering strength. At this time, since the heat of the molten solder is transferred to the third land Ld3, the temperature rise is detected by the radiation thermometer Ho. FIG. 15A shows a perspective view of the terminal Td1.
As the shape of the terminal Td1, a shape in which the axis of the terminal is shifted as shown in FIG. 15B, an enlarged portion formed in one direction as shown in FIG. 15C, or a circle as shown in FIG. The thing expanded in the circumferential direction is also considered.

  In each of Examples 1 to 4, the position of the heat transfer body on the surface side of the wiring board Bd can be arranged outside the outer diameter of the tip of the tip when the tip 5 contacts the wiring board Bd. . As a result, it is possible to measure the temperature of the heat transfer body during the soldering operation, and it is possible to determine whether the soldering is good or not by capturing the temperature change during the soldering operation.

FIGS. 16A and 16B show a fifth embodiment of the present invention, in which FIG. 16A shows a cross-sectional view of the wiring board Bd, and FIG. 16B shows a main part of FIG. (A) The position where the radiation thermometer Ho shown in the figure measures the temperature of the land Ld is set to the outside Po of the land Ld as shown in (b).
FIG. 17 shows a state in which soldering is normally performed. FIG. 17A is a cross-sectional view of the wiring board Bd, and FIG. 17B is a view of the main part of FIG. The top fillet Ft extends over the entire land Ld, and the radiation thermometer Ho detects the temperature of the top fillet Ft, and detects the high temperature of the molten solder.
18A and 18B show a state where soldering is not normally performed. FIG. 18A shows a cross-sectional view of the wiring board Bd, and FIG. 18B shows a main part of FIG. When the solder or the wiring board is not sufficiently heated or when the supply of flux is insufficient, the top fillet Ft becomes spherical and becomes smaller than the entire land Ld, so that the solder is not supplied into the through hole, and the back fillet Is not formed. The radiation thermometer Ho detects a temperature outside the top fillet Ft, and detects a relatively low temperature. The position for detecting the temperature is arranged after performing normal soldering and defective soldering in advance.
As described above, the quality of soldering can be determined by detecting the temperature of the outer peripheral portion of the land Ld.

The land Ld and the terminal Td each have good solder wettability, and the detection accuracy is increased by selecting a material having high thermal conductivity.
In addition, it is possible to further increase the accuracy of determination by performing a plurality of temperature measurements and performing an average value and data processing.

 As mentioned above, although embodiment of this invention was described, this invention is not limited to this content. The embodiments of the present invention can be variously modified without departing from the spirit of the invention.

5 Tip 51 Solder hole A Soldering device Bd Wiring board (board)
Dt Heat transfer body Dt1 Branch terminal Ho Radiation thermometer (temperature detection means)
Ks insertion slot Ld, Ld1, Ld2, Ld3 Land Bd Wiring board (board)
Th Thru hole Wh Solder piece

Claims (10)

  A land having a through-hole penetrating the soldering substrate, a tip for supplying molten solder into the through-hole, and a heat transfer for transferring the solder melting heat on the back surface side of the substrate to the through-hole to the surface side of the substrate A soldering evaluation method comprising: detecting a temperature of the heat transfer body and evaluating soldering.   2. The solder according to claim 1, wherein the heat transfer body is disposed in a non-contact state with at least one of a terminal of the electrical component inserted into the through hole and the land and is transferred by the molten solder. Evaluation method.   The soldering evaluation method according to claim 1, wherein the heat transfer body includes a branch terminal formed integrally with the terminal.   The soldering evaluation method according to any one of claims 1 to 3, wherein the heat transfer body is provided with a gap at least in part with the substrate in a portion penetrating the substrate.   The soldering evaluation method according to claim 1, wherein the heat transfer body is configured by extending the land on the back side of the substrate.   6. The soldering evaluation method according to claim 5, wherein the land is separated and heat is transferred by the molten solder.   The soldering evaluation method according to claim 5, wherein the terminal includes an enlarged portion that is widened in a direction perpendicular to the axis of the terminal.   The soldering evaluation method according to any one of claims 1 to 7, wherein the heat transfer body is disposed away from a radius of the tip on the surface of the substrate.   A land having a through hole penetrating the soldering substrate, and a tip for supplying molten solder into the through hole, the land being provided around the through hole on the surface side of the substrate, A soldering evaluation method characterized by detecting the temperature of the outer peripheral portion and evaluating soldering. A land having a through-hole penetrating the soldering substrate, a tip for supplying molten solder into the through-hole, and a heat transfer for transferring the solder melting heat on the back surface side of the substrate to the through-hole to the surface side of the substrate A soldering apparatus comprising: a body; and temperature detection means for detecting a temperature of the heat transfer body, wherein the temperature detection means evaluates soldering.