JP6843341B2 - Soldering evaluation method and its equipment - Google Patents

Description

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

In recent years, various devices are equipped with electronic circuits on which electrical components are mounted. In the process of forming an electronic circuit, soldering using a soldering iron is performed for a process of joining a lead wire to a wiring pattern (land) on a substrate. Further, in order to mechanically realize the soldering process, a soldering apparatus provided with a soldering tip is used.
In such a solder processing apparatus, for example, a solder piece (a piece obtained by cutting a thread solder) is supplied into a heated iron tip, and the solder piece is heated and melted by using the heat of the iron tip, thereby melting downward. It is configured to supply solder. As a result, the soldering process for the substrate arranged below can be realized.
However, the solder bonding may not be sufficient depending on the soldering conditions, the solder material, or the variation of the substrate, and an inspection for guaranteeing the reliability of soldering is required. In particular, when soldering is performed by inserting the terminals of parts into the through holes, it is required to form a back fillet in which the through holes are filled with solder and the solder swells on the back side of the substrate.

The technique described in Patent Document 1 detects the temperature of the outside of the soldering iron that melts the solder inside the cylinder and determines that the solder is properly melted.
The technique described in Patent Document 2 measures the temperature of the molten solder with a radiation thermometer, and determines the quality of the solder joint from the temperature waveform.
This back fillet inspection was difficult to discriminate by the conventional electrical continuity inspection and visual inspection using a camera, and it was not possible to carry out an automatic inspection.

Japanese Unexamined Patent Publication No. 2016-059923 Japanese Unexamined Patent Publication No. 2013-251488

However, the technique described in Patent Document 1 has a drawback that the temperature of the molten solder cannot be measured accurately because the temperature is detected from the outside of the cylinder, and the accuracy of determining the quality of the solder is low. It was difficult to determine the formation of fillets.
The technique described in Patent Document 2 measures the temperature of 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 visual inspection.
In view of the above-mentioned problems, an object of the present invention is to provide a method for determining the quality of soldering of a back fillet or the like from the surface of a soldering substrate.

In the soldering evaluation method according to the present invention, a soldering iron 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. It is provided with a hot body, and detects the temperature of the heat transfer body to determine whether soldering has been performed normally.

Further, as the above method, specifically, the heat transfer body is composed of a terminal inserted in the through hole and a branched measurement terminal, and the quality of soldering is determined by measuring the temperature of the measurement terminal. It is a thing.
Further, as the above method, specifically, a heat transfer body is provided by extending a land, and the quality of soldering is determined by measuring the temperature of the land.

Further, as the above method, specifically, the terminal is provided with an enlarged portion expanded in the circumferential direction, and the enlarged portion promotes heat transfer to measure the temperature and determine the quality of soldering.
Further, as the above method, specifically, the heat transfer body is provided at a position distant from the through hole in the radial method, and the quality of soldering is determined by measuring the temperature of the heat transfer body.
Further, the solder evaluation method according to the present invention detects the temperature of a land having a through hole penetrating the soldering substrate, a soldering iron for supplying molten solder into the through hole, and the outer peripheral portion of the land. ..

Further, in the soldering apparatus of the present invention, a land having a through hole penetrating the soldering substrate, a tip for supplying molten solder into the through hole, and a solder melting heat on the back surface side of the through hole substrate are applied to the substrate. A heat transfer body that transmits to the surface side and a temperature detecting means for detecting the temperature of the heat transfer body are provided, and the quality of soldering is evaluated by the temperature detecting 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 surface side of the substrate by a heat transfer body, and the temperature is measured from the front surface side of the substrate. The soldering can be evaluated, and the quality of the soldering can be judged at the time of soldering.

It is a perspective view of the soldering apparatus which concerns on embodiment of this invention. FIG. 5 is a cross-sectional view taken along the line II-II 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 the sectional view, and (b) is the A arrow view of (a). It is a perspective view which shows the measurement terminal of the same Example 1. FIG. It is sectional drawing which shows the soldering state of Example 1, (a) is the figure which shows the case where the soldering is good, and (b) is the figure which shows the case where the 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 the sectional view, (b) is the B arrow view of the main part of (a). It is a perspective view which shows the measurement terminal of the same Example 2. FIG. It is sectional drawing which shows the soldering state of Example 2. FIG. It is an Example which shows the other measurement terminal of the same Example 2. It is a figure which shows the structure of Example 3 of the soldering evaluation method of this invention, (a) is a sectional view, and (b) is the C arrow view of the main part of (a). It is sectional drawing which shows the soldering state of Example 3, (a) is a figure which shows the normal case of soldering, and (b) is the figure which shows the defective state of soldering. It is an Example which shows the other land shape of the same 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 the sectional view in the case of good soldering, (b) is the D arrow view of the main part. It is a perspective view which shows the terminal shape of Example 4. FIG. It is sectional drawing in the case of defective soldering of Example 5. It is a figure which shows the normal soldering state of Example 5, (a) is the sectional view, (b) is the E arrow view of the main part of (a). It is a figure which shows the defective soldering state of Example 5, (a) is the sectional view, (b) is the E arrow view of the main part of (a). It is sectional drawing of the conventional soldering apparatus.

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

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

As shown in FIGS. 1 and 2, the soldering apparatus A supplies the thread solder W from above, and utilizes the solder tip 5 provided at the bottom to connect with the wiring board Bd arranged below the solder tip 5. , A device for soldering electrical components Ep. The thread solder W has a structure in which a flux layer is provided inside a tubular solder layer. Therefore, the solder piece produced by cutting the thread solder W also has a structure in which the flux layer is provided inside the tubular solder layer. The soldering device A includes a support portion 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 iron tip 5 constitutes the soldering iron portion.
The support portion 1 includes an erected flat plate-shaped wall body 11. 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 body 11 has a ZX plane.

The soldering device A supplies molten solder to the wiring board Bd attached to the jig Gj and the terminal P of the electric component Ep arranged on the wiring board Bd to fix the connection. When soldering, the jig Gj is moved in the X and Y directions to position the wiring board Bd with the land Ld. Further, the soldering device A is movable in the Z direction, and by moving in the Z direction after positioning, the tip of the trowel tip 5 can be brought into contact with the land Ld.
The support portion 1 includes a holding portion 12 provided at a position shifted upward from the lower end portion of the wall body 11 in the Z direction, and a sliding guide 13 fixed to an 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 cuts the thread solder W sent by the solder feed mechanism 6 into solder pieces Wh (FIG. 2) having a predetermined length. The cutter unit 2 has a cutter lower blade 22 (fixed blade portion) fixed to the sliding guide 13 and a cutter upper blade 21 (movable) arranged above the cutter lower blade 22 so as to be slidable in the X direction. A blade portion) and a pusher pin 23 (solder pressing portion) provided on the cutter upper blade 21 and sliding in a direction (Z direction) intersecting the sliding direction of the cutter upper blade 21 are provided.

As shown in FIG. 2, in the cutter upper blade 21, the upper blade hole 211, which is a through hole into which the thread solder W sent by the solder feeding mechanism 6 is inserted, and the rod portion 231 of the pusher pin 23 are inserted. It is provided with a pin hole 212 which is a through hole. The edge portion at the lower end of the upper blade hole 211 is formed in a cutting edge shape. The cutter lower blade 22 includes a lower blade hole 221 which is a through hole into which the thread solder W penetrating the upper blade hole 211 is inserted. The edge of the upper end of the lower blade hole 221 is formed in a cutting edge shape. The upper blade hole 211 and the lower blade hole 221 are displaced in the direction intersecting with the thread solder W in a state where the thread solder W is inserted, so that the thread solder W is cut by the mutual cutting blades. The pusher pin 23 is a solder pushing portion, and pushes the solder piece Wh that is cut by the cutter upper blade 21 and the cutter lower blade 22 and remains in the lower blade hole 221 downward.

As shown in FIGS. 1 and 2, the drive mechanism 3 penetrates the air cylinder 31 held by the holding portion 12 and the through hole provided in the holding portion 12, and is slid driven in the Z direction by the air cylinder 31. The piston rod 32 is supported by both the holding portion 12 and the lower blade 22 of the cutter, and a columnar guide shaft 35 extending in the Z direction is provided. The drive mechanism 3 includes a cam member 33 slidably supported by the guide shaft 35 in the Z direction, and a slider portion 34 having a cam groove 340 with which a pin 332, which will be described later, is engaged with the cam member 33. 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 by passing electricity, and a heater block 42 for attaching the heater 41. The heater 41 is wound around the outer peripheral surface of the cylindrical heater block 42.
The trowel tip 5 is a cylindrical heatable member extending in the vertical direction, and is provided with a solder hole 51 extending in the axial direction in a central portion. The trowel 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 trowel 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.
Heat from the heater 41 is transferred to the trowel tip 5, and the heat melts the solder piece Wh.

As shown in FIGS. 1 and 2, the solder feed mechanism 6 supplies the thread solder W, and the pair of feed rollers (61a, 61b) for feeding the thread solder W and the fed thread solder W are cutters. It is provided with a guide tube 62 that guides the upper blade hole 211 of the upper blade 21. The pair of feed rollers (61a, 61b) are attached to the support portion 1, sandwich the thread solder W, and rotate the thread solder W to feed the thread solder W downward. The guide tube 62 is an elastically deformable tube body, and the upper end thereof is arranged close to a portion of the feed roller 61 to which the thread solder W is fed.

Further, 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. The lower end of the guide tube 62 moves following the sliding of the cutter upper blade 21, so that the guide tube 62 is not excessively pulled or stretched within the range in which the cutter upper blade 21 slides. It is provided. Each feed roller (61a, 61b) determines the length of the delivered thread solder by the rotation angle (rotation speed).

When soldering is performed by the soldering device A, the entire soldering device A is lowered by a driving device such as a robot, the tip of the soldering tip 5 is brought into contact with the land Ld of the wiring board Bd to be soldered, and the soldering tip 5 is used. , Land Ld and terminal P of electrical component Ep. At this time, the heat from the heater 41 is transferred to the trowel tip 5, and when the trowel 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 (preheat). ).

Next, the operation of the soldering apparatus A will be described. As shown in FIG. 2, after heating the iron tip 5 with the heater 41, the solder feed mechanism 6 feeds the thread solder W with a set length, and the cylinder 31 slides the upper blade 21 via the cam member 33. The thread solder W is cut, and the cut solder piece Wh passes through the solder hole 51 of the iron tip 5, abuts on the terminal P, receives heat from the iron 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. An electric component Ep having a terminal P is soldered to a wiring board Bd having a through hole Th and a land Ld. FIG. 19A shows a case where soldering is performed well, and FIG. 19B shows a case where the molten solder Wh passes through the through hole Th and is supplied to the back surface (lower side) of the substrate Bd. This is a case where the solder Wh is not supplied to the back surface side of the substrate Bd. In the state of FIG. 19B, the electrical component is electrically conductive, but the mechanical strength is insufficient, and the electric component Ep may be detached when repeatedly exposed to a temperature cycle or vibration. However, at the beginning of soldering, the terminal P of the electric component Ep and the land Ld of the wiring board Bd are electrically conductive, and no abnormality is found in the continuity test. Further, it is difficult to perform an visual inspection because there is an electric component Ep on the back side of the wiring board Bd.

The wiring board Bd of Example 1 of the present invention is shown in FIG. FIG. 3B is a view taken along the arrow A of FIG. 3A. In FIG. 3, lands Ld having through holes Th penetrating the wiring board Bd are provided on both sides of the wiring board Bd. An L-shaped heat transfer body Dt is provided on the back surface side of the substrate Bd, and one of the heat transfer bodies Dt is near the land Ld and near the terminal Td inserted into the through hole Th during soldering. The other side penetrates the insertion port Ks through the substrate Bd and the end portion 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 at the time of soldering will be described. FIG. 5 (a) shows an example in which soldering was normally performed, and top fillet Ft and back fillet Fb are formed, and FIG. 5 (b) shows an abnormal state of soldering and back. No fillet is formed. In FIG. (A), the heat of the molten solder Wh is transferred 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 rises. This temperature is detected by a radiation thermometer Ho, which is a temperature detecting means. The heat transfer from the molten solder Wh to the heat transfer body Dt is performed not only from the heat transfer 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. The quality of soldering can be determined from the temperature value of the heat transfer body Dt, the degree of temperature change, or the change characteristic with respect to the time of the temperature change of the heat transfer body Dt from the melting of the solder pieces. If the detection temperature is high or the temperature change rate is large, it is determined that soldering has been performed normally. At the portion where the heat transfer body Dt penetrates the wiring board Bd, heat transfer other than the back fillet Fb can be reduced by providing a gap in part or all of 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 transferred 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 degree of temperature change with time is high. small. In this case, it is determined that the soldering has not been performed normally, an alarm is issued, and the soldering work is stopped.
The thermometer may be not only a radiation thermometer but also a thermocouple thermometer, a resistance thermometer, or a thermometer whose color changes depending on the temperature. Further, the thermometer may be driven by a robot or the like integrally with the soldering device A, and its position may be synchronized with the movement of the soldering portion.

6A and 6B show the second embodiment of the present invention, in which FIG. 6A is a cross-sectional view of a wiring board Bd, and FIG. 6B is a view taken along the line B. 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 soldering is normally performed. Due to the formation of the back fillet Fb, the heat of the molten solder Wh is transferred to the heat transfer body portion Dt1, and the temperature is transferred by the radiation thermometer Ho. To detect. In FIG. 9, the branch portion of the terminal Td to the heat transfer body portion Dt1 is narrowed to provide a thermal resistance Nt that suppresses heat transfer, and the heat transfer from the terminal Td is reduced to transfer heat 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 view taken along the line C. The difference from the first embodiment is that the heat transfer body is composed of lands. The first land Ld1 is formed around the through hole Th, the second land Ld2 is further arranged on the outer periphery thereof via the groove Mz, and the second land Ld2 is communicated 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 that is not solder wettable.

11A and 11B show a state when soldering is performed, FIG. 11A shows a state when soldering is normally performed, and FIG. 11B shows a state when a back fillet is not formed. Shown. 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 propagates 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 rises. Is small. The radiation thermometer Ho detects this low temperature to determine the soldering abnormality.

FIG. 12 is an example in which the shape of the land is modified, 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 action as described above can be obtained by forming the groove Mz1 with a non-wetting material for solder as described above.

FIG. 13 shows an example of soldering in which the back fillet is formed but is insufficient. In the soldering shown in FIG. 13, the back fillet Fb1 is formed and flows through the first land Ld1, but the second land Ld2 is not reached and the best back fillet is not formed.
FIG. 14 shows Example 4 of the present invention, and the difference from Example 3 is that the terminal is provided with an enlarged portion. 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.
The shape of the terminal Td1 is a shape in which the axis of the terminal is deviated as shown in FIG. 15 (b), an enlarged portion is formed in one direction as shown in (c), or a circle as shown in (d). It is also possible that it is enlarged in the circumferential direction.

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 trowel when the tip 5 comes into contact with the wiring board Bd. .. As a result, the temperature of the heat transfer body can be measured during the soldering operation, and the quality of the soldering can be determined by capturing the temperature change during the soldering operation.

16A and 16B show the fifth embodiment of the present invention, in which FIG. 16A shows a cross-sectional view of a wiring board Bd, and FIG. (A) The position where the radiation thermometer Ho shown in the figure measures the temperature of the land Ld is set to the outer Po of the land Ld as shown in (b).
17A and 17B show a state in which soldering is normally performed, FIG. 17A shows a cross-sectional view of a wiring board Bd, and FIG. 17B shows an arrowhead E of a main part of FIG. 17A. The top fillet Ft spreads 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.
FIG. 18 shows a state in which soldering has not been performed normally, (a) shows a cross-sectional view of the wiring board Bd, and (b) shows an F arrow view of a main part of (a). If the solder or wiring board is not sufficiently heated or the flux is insufficiently supplied, the top fillet Ft becomes spherical and smaller than the entire land Ld, solder is not supplied into the through hole, and the back fillet is used. Is not formed. The radiation thermometer Ho will detect the temperature outside the top fillet Ft, and will detect a relatively low temperature. The position to detect 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 improved by selecting a material having a high thermal conductivity.
Further, it is possible to further improve the accuracy of the determination by performing a plurality of temperature measurements and processing the average value and data.

Although the embodiments of the present invention have been described above, the present invention is not limited to this content. Further, the embodiments of the present invention can be modified in various ways as long as they do not deviate from the gist of the invention.

5 Iron 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 port Ld, Ld1, Ld2, Ld3 Land Bd wiring board (board)
Th Through Hole Wh Handa 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 that transfers solder melting heat on the back surface side of the substrate through the through hole to the front surface side of the substrate. A soldering evaluation method comprising a body and detecting the temperature of the heat transfer body to evaluate soldering. The heat transfer body is arranged in a non-contact state before the molten solder is supplied to at least one of the terminals or lands of the electric component inserted into the through hole, and the heat is transferred by the molten solder. The soldering evaluation method according to claim 1, which is characterized. The soldering evaluation method according to claim 2 , wherein the heat transfer body is composed of a branch terminal integrally formed 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 partially with the substrate at a portion penetrating the substrate. The soldering evaluation method according to claim 1, wherein the heat transfer body is formed by extending the land on the back surface side of the substrate. The soldering evaluation method according to claim 5, wherein the heat transfer body is configured to separate the lands, and heat is transferred by connecting the lands with the molten solder. Any of claims 5 to 6, wherein the terminal of the electric component inserted into the through hole is provided with an enlarged portion widened in a direction perpendicular to the axis of the terminal at a position on the back surface side of the substrate. The soldering evaluation method according to item 1. The soldering evaluation method according to any one of claims 1 to 7, wherein the heat transfer body is arranged on the surface side of the substrate at a distance from the radius of the trowel tip. A land having a through hole penetrating the soldering substrate, a tip for supplying molten solder into the through hole, and a heat transfer that transfers solder melting heat on the back surface side of the substrate through the through hole to the front surface side of the substrate. A soldering apparatus comprising a body and a temperature detecting means for detecting the temperature of the heat transfer body, and evaluating soldering by the temperature detecting means. The soldering apparatus according to claim 9 , wherein the trowel tip has a tubular shape that can be heated, has a solder hole extending in the axial direction at a central portion, and supplies a fixed amount of solder pieces to the solder hole. ..