JP6281352B2 - Solder inspection apparatus and solder inspection method - Google Patents

Description

  The present invention relates to a solder inspection apparatus and a solder inspection method, and more particularly to a solder inspection apparatus and a solder inspection method for fixing leads of surface mount components.

  In appearance inspection after reflow in surface mount technology (SMT), it is important to measure and calculate the amount of solder in the back fillet. For flat gull wing lead shaped parts such as the Quad Flat Package (QFP), the amount of solder in the back fillet affects the soldering strength (see FIG. 1).

  Even in international standards such as the IPC (Institute for Interconnecting and Packaging Electronics Circuits) standard, the solder wetting height of the back fillet is defined, and it is necessary to measure the solder wetting height of the back fillet.

  In the post-reflow visual inspection used in the surface mounting technology, an optical appearance inspection machine (AOI: Automatic Observation Inspection machine) and an X-ray inspection machine are used. Since the optical appearance inspection machine 13 inspects the parts to be inspected as shown in FIG. 2, the top fillet 2 can be inspected, but the back fillet 3 cannot be inspected. This is because the back fillet 3 becomes a shadow of the soldered lead component in the optical appearance inspection machine 13. In order to cope with such a problem, an X-ray inspection machine is used.

  However, the back fillet 3 cannot be accurately measured depending on the mounting state (component / solder arrangement) on the back surface of the substrate. In addition, the X-ray inspection machine is expensive and has a low inspection speed, so it may not be used.

To deal with these problems, Patent Document 1 proposes a method for predicting the solder amount of the back fillet 3 using a solder paste inspection machine (SPI) and an AOI. This prediction method is performed in the following procedure.
(1) Measure solder amount with SPI
(2) Measure top fillet solder amount with AOI
(3) Measure part height
(4) Based on the results of (1), (2) and (3) above, the solder amount of the back fillet is predicted to determine pass / fail.For example, the solder amount measured in (1) is small and the solder measured in (2) If the amount is large and the part height measured in (3) is large, the amount of solder in the back fillet is expected to be small. In this way, Patent Literature 1 predicts the solder amount of the back fillet using the measurement result and makes a pass / fail judgment.

JP 2013-221861 A

  However, the solder inspection apparatus related to Patent Document 1 described above has the following problems. The solder amount of the back fillet 3 derived by the inspection apparatus of Patent Document 1 is a predicted value. Also, the solder wetting height is affected by the land length behind the lead root existing in the back fillet 3 portion. Further, the land length behind the lead base is not constant because it depends on the mounting accuracy and the accuracy of components and the board. In the inspection apparatus of Patent Document 1, since the land length behind the lead root is not considered, the solder wetting height that affects the strength of the soldered portion cannot be determined.

  The object of the present invention is a solder inspection apparatus that solves the above-described problem that, in the related solder inspection apparatus, the solder wetting height that affects the strength of the soldering portion cannot be predicted with high accuracy. And providing a solder inspection method.

  In order to achieve the above object, a solder inspection apparatus according to the present invention includes a solder print inspection machine for measuring a printed solder volume, a solder amount of a top fillet of a lead, a land length behind a root of the lead, and the above Appearance inspection machine for measuring the lead component height, the amount of solder after reflow is calculated, the measured solder amount of the top fillet of the lead, the land length behind the lead root, and the lead component And processing means for estimating the solder fill height of the back fillet from the height.

  In the solder inspection method according to the present invention, after solder printing, the printed solder volume is measured, the solder amount after reflow is calculated, the solder amount of the top fillet of the lead is measured, and the land behind the root of the lead is measured. Measure the length, measure the height of the lead part, calculate the amount of solder located under the lead based on this, and determine the amount of solder after the reflow, the solder amount of the top fillet, the root of the lead From the back land length and the amount of solder located under the lead, the solder fill height of the back fillet is estimated.

  According to the solder inspection apparatus and the solder inspection method of the present invention, the solder wetting height of the back fillet can be predicted with higher accuracy.

It is a side view which shows the state by which the flat gull wing lead of the mounting component was soldered. It is a conceptual diagram for demonstrating the external appearance inspection by an optical type external appearance inspection machine. It is a block diagram which shows the structure of the test | inspection apparatus by 1st Embodiment of this invention. It is a flowchart for demonstrating the inspection method by 1st Embodiment of this invention. (A) is an external view which shows the state of the solder at the time of printing, (b) is an external view which shows the solder after reflow. It is a flowchart which shows step S4 of FIG. 4 in detail. It is an external view for demonstrating how to obtain | require land length behind a lead root. (A) is an external view showing the fillet wetting spread when the land length behind the lead root is long, and (b) is an external view showing the fillet wetting spread when the land length behind the lead root is short.

  Preferred embodiments of the present invention will be described in detail with reference to the drawings.

[First Embodiment]
First, the solder inspection apparatus and the solder inspection method according to the first embodiment of the present invention will be described. FIG. 3 is a block diagram showing the configuration of the inspection apparatus according to the first embodiment of the present invention. As shown in FIG. 3, the solder inspection apparatus 10 according to the present embodiment includes a solder print inspection machine 12 that measures a printed solder volume. Furthermore, the solder inspection apparatus 10 according to the present embodiment includes an appearance inspection machine 13 that measures the solder amount of the top fillet of the lead of the mounted component, the land length behind the root of the lead, and the height of the lead.

  Furthermore, the solder inspection apparatus 10 according to the present embodiment includes an information processing apparatus 11 as an example of a processing unit that calculates the solder amount of the back fillet. This processing means calculates the solder amount after reflow, and calculates the back fillet from the measured solder amount of the top fillet of the lead, the land length behind the root of the lead, the angle of the lead, and the height of the lead. Estimate the height of solder wetting.

  The solder printing inspection machine 12 measures the volume of solder printed on the printed circuit board 3 three-dimensionally. The appearance inspection machine 13 is a three-dimensional optical appearance inspection machine (Three Dimensional AOI machine) that inspects the appearance three-dimensionally by an optical method. The information processing apparatus 11, the solder printing inspection machine 12, and the appearance inspection machine 13 are connected to each other by a communication line such as a local area network (LAN) and can transmit and receive data. .

  Next, a solder inspection method using this solder inspection apparatus will be described together with component mounting processing and soldering processing on a printed circuit board. FIG. 4 is a flowchart showing a solder inspection method according to the first embodiment of the present invention.

  First, a solder printing process is performed on the land of the printed circuit board 17 by the printing machine 14. When the solder printing process for the printed circuit board 17 is completed, the printed circuit board 17 is unloaded from the printing machine 14 in the transport direction and sent to the mounting machine 15.

  Next, the solder printing inspection machine 12 of the solder inspection apparatus 10 according to the present embodiment performs an optical three-dimensional appearance inspection regarding the amount of solder on the printed circuit board 17. The solder printing inspection machine 12 collects three-dimensional data regarding the amount of solder on the printed circuit board 17 (step S1). Then, as shown in FIG. 3, the collected three-dimensional data vd1 regarding the inspection target component is output to the information processing apparatus 11 as the 3D SPI inspection result 18.

  Next, the information processing apparatus 11 calculates the amount of solder after reflow based on the three-dimensional data vd1 (3D SPI inspection result 18) relating to the solder on the printed circuit board 17 from the solder printing inspection machine 12 (step). S2).

  Here, as a method of calculating the solder amount after reflow, for example, a means as shown in FIG. 5 may be used. FIG. 5A shows the state of solder during printing, and FIG. 5B shows the state of solder after reflow. In advance, the volume is measured with SPI for a certain amount of solder and reflowed. For the solder after reflow, measure the solder volume with 3D AOI, and obtain α (coefficient) in the following correspondence equation for the solder amount before reflow and the solder amount after reflow. The solder amount (S_r) after reflow is obtained by subtracting the flux volume.

Solder amount after reflow S_r = Solder amount during printing S x α (coefficient)
This correspondence formula is obtained for each type of solder. This is because α (coefficient) differs when the component composition of the solder changes. In addition, the component composition may change depending on the lot even with the same type of solder. Therefore, it is desirable to obtain the same type of solder for each lot.

  Furthermore, the lead of the mounting component is aligned with the land of the printed circuit board 17 by the mounting machine 15, and the mounting component is mounted. The printed circuit board 17 is unloaded from the mounting machine 15 in the transport direction and sent to the reflow furnace 16. A reflow process is performed on the printed circuit board 17 in a reflow furnace 16 to perform soldering. When the soldering to the mounted components mounted on the printed circuit board 17 is completed, the printed circuit board 17 is carried out from the reflow furnace 16 in the conveying direction. In the optical appearance inspection machine 13 of the solder inspection apparatus 10, an optical three-dimensional appearance inspection relating to the inspection target component mounted on the printed circuit board 17 is performed (step S3). Here, the lead length of the mounted component is also measured.

  The optical appearance inspection machine 13 receives three-dimensional data (information including at least the solder amount (S_r_t) of the top fillet and the height of the component) related to the inspection target component mounted on the printed circuit board 17 carried out from the reflow furnace 16. collect. Then, as illustrated in FIG. 3, the collected three-dimensional data vd2 regarding the inspection target component is output to the information processing apparatus 11 as the 3D AOI inspection result 19.

  Here, as a method for calculating the solder amount (S_r_t) and the component height of the top fillet, there is a method using a three-dimensional optical inspection. The three-dimensional optical inspection machine has several measurement methods as follows. For example, in measurement using a laser or measurement laser using a fringe pattern projection method, laser light having a certain angle is applied to a measurement target, and the reflected light is received by a sensor. The position received by the sensor changes depending on the height of the measurement object. Based on this position information, the height of the measurement target is obtained. Further, in the measurement by the fringe pattern projection, the fringe pattern light is applied to the measurement object from illumination (usually a projector) having a certain angle. A shift amount of the stripe pattern light according to the height of the measurement target is generated. From the amount of deviation of the stripe pattern light and the incident angle of the light, the height of the measurement object is obtained. In both methods, the measurement target is identified using color information in an image captured by a camera installed above.

  Next, the information processing apparatus 11 calculates the solder amount of the back fillet 3 (step S4). Here, with reference to FIG. 6, the calculation method of the solder amount of the back fillet 3 is demonstrated in detail. As shown in FIG. 6, the calculation of the solder amount of the back fillet 3 is performed by calculating the solder amount of the solder 4 under the lead from the component height and component thickness measured in step S3 (step S4-1). More specifically, the amount of solder under the lead is calculated based on the information vd2 (3D AOI inspection result 19) on the three-dimensional shape from the appearance inspection machine 13. As a method of calculating the solder amount (S_r_u) of the solder 4 under the lead shown in FIG. 8A and FIG. 8B, first, the part height obtained by AOI is described in the part specification. Subtract the part thickness. Thus, the thickness of the solder 4 under the lead is obtained, and this solder thickness is obtained by multiplying the lead area described in the component specification.

  Next, the information processing apparatus 11 calculates the solder amount of the back fillet (step S4-2). From the solder amount after reflow (S_r), the solder amount of the solder 4 under the lead (S_r_u), and the measured solder amount of the top fillet 2 (S_r_t), the information processing apparatus 11 determines the solder amount of the back fillet 3 (S_r_b). Calculate The amount of solder (S_r_b) of the back fillet 3 can be obtained by the following calculation formula.

Solder amount of back fillet 3 S_r_b = Solder amount after reflow S_r-(Solder amount of top fillet 2 S_r_t + Solder amount of solder 4 under lead S_r_u)
Next, returning to the flowchart of FIG. 4, the information processing apparatus 11 estimates the solder wetting height of the back fillet 3 from the solder amount of the back fillet 3, the land length behind the lead root, and the lead angle (step). S5). For estimating the solder wetting height, the land length (l_b) behind the lead root obtained from the solder amount of the back fillet 3, the lead length / position and the land position / length described in the board specifications is used. Furthermore, the lead angle described in the component specification is used for estimating the solder wetting height.

  FIG. 7 shows a state in which the lead 1 of the mounted component is fixed to the land 5 of the printed board with solder. A top fillet 2 exists at the tip of the lead 1, and a back fillet 3 exists under the lead 1. As shown in FIG. 7, the land length (l_b) is obtained by subtracting the lead length and the distance from the leading end of the lead to the land end from the total length of the land 5. Here, the lead length obtained in step S3 is the length of the upper portion of the lead because the AOI measurement is from above. The length of the lower part of the lead is obtained by the following calculation formula.

Lead bottom length = Lead top length x Lead top length to lead bottom length ratio At this time, the ratio of the lead top length to the lead bottom length is the one described in the information component specifications. May be used.

  The distance from the lead tip to the land end may be obtained as the length of the top fillet 2. Alternatively, since the lead tip position on the substrate with the positioning mark as the origin is obtained from the inspection result by AOI, the lead tip position may be subtracted from the land end position. Thus, the solder wet height of the back fillet 3 is estimated.

As shown in FIG. 8A, when the land length (l_b) behind the lead root is long, the solder fills the land portion so that the back fillet 3 does not get so wet. As shown in FIG. 8B, even if the solder amount (S_r_b) of the back fillet 3 is the same, if the land length (l_b) behind the lead root is short, the wetting of the back fillet 3 increases. Further, when the lead angle is steep, the solder is difficult to wet, and when the lead angle is gentle, the solder is likely to wet. Based on the estimated solder wetting height of the back fillet 3, the information processing apparatus 11 determines whether or not the inspection target component is soldered. (Step S6)
With the above-described configuration, it is possible to inspect the solder wet height of the lead back fillet at low cost and at high speed with only SPI and AOI. In other words, the amount of solder of the back fillet 3 can be obtained more accurately without preparing an expensive X-ray inspection machine. It is possible to inspect the solder wet height of the back fillet of a mounted part in a flat gull wing form such as a quad flat package.

  As an example, the estimation of the backfillet wetting height and the pass / fail judgment based on this in the above-described embodiment of the present invention will be described more specifically. For example, the land length (l_b), the lead angle, and the solder amount of the back fillet 3 (S_r_b) at the rear of the lead root are assigned to several levels in advance, and the experiment for obtaining the wetting height of the back fillet 3 relative thereto Do. Based on the experimental results, a table of the wetting height of the back fillet 3 with respect to the land length (l_b) behind the lead root, the lead angle, and the solder amount (S_r_b) of the back fillet 3 is created. Table 1 shows the wetting height of the back fillet 3 with respect to the land length (l_b) behind the lead root and the solder amount (S_r_b) of the back fillet 3.

  Refer to this table for pass / fail judgment. When the calculated solder fill height of the back fillet 3 is equal to or greater than the threshold value, it is determined that the back fillet 3 is sufficiently wet and soldering (reflow treatment) with the solder is good. On the other hand, if the wetting height threshold is not reached, it is determined that the soldering (reflow process) using the solder is defective.

  The estimation of the solder wetting height of the back fillet 3 may be performed as follows. First, the land length behind the root of the lead, the lead angle, and the solder amount of the back fillet are assigned to several levels, and the wetting height of the back fillet 3 relative to it is obtained. Next, using the result of wetting of the back fillet 3 measured after reflow, the wetting height of the back fillet 3 is estimated from the land length behind the lead root, the lead angle, and the solder amount of the back fillet. Create a formula.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to this. The information processing apparatus 11 may be realized by dedicated hardware capable of executing the above-described calculation process, estimation process, and pass / fail determination process, or may be realized by software. The calculation process, the estimation process, and the pass / fail judgment process executed by the information processing apparatus 11 can also be realized by a program that causes the information processing apparatus 11 to execute such a process. Such a program can be recorded on a recording medium and distributed in the form of an information recording medium readable by the information processing apparatus 11.

  Each process shown by FIG. 4 of embodiment mentioned above is not restricted to this order. For example, there is no problem even if the solder amount calculation after reflow (step S2) is performed after measurement by 3D AOI (step S3). Since three-dimensional data related to the amount of solder on the printed circuit board 17 is collected and output to the information processing apparatus 11 in step S1 of FIG. 4, the solder amount calculation after reflow (step S2) It can be done before or after mounting. It goes without saying that various modifications are possible within the scope of the invention described in the claims, and these are also included in the scope of the present invention.

A part or all of the above-described embodiment can be described as in the following supplementary notes, but is not limited thereto.
(Appendix 1) A solder printing inspection machine for measuring the printed solder volume;
An appearance inspection machine that measures the amount of solder in the top fillet of the lead, the land length behind the base of the lead, and the component height of the lead;
Processing means for calculating the solder amount after reflow and calculating the solder amount of the back fillet from the measured solder amount of the top fillet of the lead, the land length behind the root of the lead, and the component height of the lead And a solder inspection apparatus.
(Supplementary note 2) The solder inspection apparatus according to supplementary note 1, wherein the processing means calculates the amount of solder after the reflow from the composition formula of the solder.
(Additional remark 3) The said processing means estimates the wetting height of the said back fillet from the land length behind the base of the said lead, the angle of the said lead, and the calculated amount of solder of the said back fillet, Additional remark 1 Or the solder inspection apparatus according to Appendix 2.
(Additional remark 4) The said processing means is a solder inspection apparatus of Additional remark 3 which determines the quality of soldering from the estimated wet-up height of the said back fillet.
(Additional remark 5) The said solder printing inspection machine calculates the solder volume after reflow by subtracting the flux content from the said solder composition formula as a difference, The solder inspection as described in any one of Additional remark 1 thru | or Additional remark 4 apparatus.
(Additional remark 6) The said processing means measures the volume of the printed solder beforehand, measures the solder volume after the reflow of the solder, calculates | requires the correspondence type of the solder amount before reflow, and the solder amount after reflow, and this The solder inspection apparatus according to any one of Supplementary Note 1 to Supplementary Note 4, which is calculated based on the corresponding formula and the solder volume before reflow.
(Appendix 7) After solder printing, measure the printed solder volume,
Calculate the amount of solder after reflow,
Measure the amount of solder in the top fillet of the lead,
Measure the land length behind the base of the lead,
Measure the component height of the lead, based on this, calculate the amount of solder located under the lead,
A solder inspection method of calculating a solder amount of a back fillet from a solder amount after the reflow, a solder amount of the top fillet, a land length behind a root of the lead, and a solder amount located under the lead.
(Supplementary note 8) The solder inspection method according to supplementary note 7, wherein the calculation of the amount of solder after the reflow is calculated from the composition formula of the solder.
(Supplementary note 9) The solder inspection according to supplementary note 7, wherein the wetting height of the back fillet is estimated from the land length behind the root of the lead, the angle of the lead, and the calculated solder amount of the back fillet. Method.
(Additional remark 10) The solder inspection method of Additional remark 9 which performs the quality determination of soldering from the estimated wet-up height of the said back fillet.
(Supplementary note 11) The solder inspection method according to any one of supplementary notes 7 to 10, wherein the solder volume after reflow is calculated by subtracting a flux content from the solder composition formula as a difference.
(Supplementary note 12) Pre-measure the volume of the printed solder, measure the solder volume after reflow of the solder, and obtain a correspondence formula between the solder amount before reflow and the solder amount after reflow. The solder inspection method according to any one of appendix 7 to appendix 11, wherein the solder volume is calculated based on the solder volume of.
(Appendix 13) After solder printing, measure the printed solder volume,
Calculate the amount of solder after reflow,
Measure the amount of solder in the top fillet of the lead,
Measure the land length behind the base of the lead,
Measure the component height of the lead, based on this, calculate the amount of solder located under the lead,
The computer executes calculation of the back fillet solder amount from the solder amount after the reflow, the solder amount of the top fillet, the land length behind the root of the lead, and the solder amount located under the lead. Program to make.
(Supplementary note 14) A computer-readable information recording medium on which the program according to supplementary note 13 is recorded.

  As an application example of the present invention, mounting inspection of an electronic device can be considered. In particular, it is useful for solder inspection of back fillets for mounted parts with flat gull wing leads such as QFP.

DESCRIPTION OF SYMBOLS 10 Solder inspection apparatus 11 Information processing apparatus 12 Solder printing inspection machine 13 Appearance inspection machine 14 Printing machine 15 Loading machine 16 Reflow furnace 17 Printed circuit board

Claims (10)

A solder printing inspection machine for measuring the printed solder volume;
An appearance inspection machine that measures the amount of solder in the top fillet of the lead, the land length behind the base of the lead, and the component height of the lead;
Processing means for calculating the solder amount after reflow and calculating the solder amount of the back fillet from the measured solder amount of the top fillet of the lead, the land length behind the root of the lead, and the component height of the lead And having
Solder inspection device.   The solder inspection apparatus according to claim 1, wherein the processing unit calculates a solder amount after the reflow from a composition formula of the solder.   The said processing means presumes the wetting height of the back fillet from the land length behind the root of the lead, the angle of the lead, and the calculated solder amount of the back fillet. 2. The solder inspection apparatus according to 2.   The solder inspection apparatus according to claim 3, wherein the processing unit determines whether or not the soldering is good based on the estimated height of the back fillet.   5. The solder inspection apparatus according to claim 1, wherein the solder printing inspection machine calculates a solder volume after reflowing by subtracting a flux content as a difference from the composition formula of the solder. 6.   The processing means measures the volume of the printed solder in advance, measures the solder volume after reflow of the solder, obtains a correspondence formula between the solder amount before reflow and the solder amount after reflow, and this correspondence formula and reflow The solder inspection apparatus according to any one of claims 1 to 4, wherein calculation is performed based on a previous solder volume. After solder printing, measure the printed solder volume,
Calculate the amount of solder after reflow,
Measure the amount of solder in the top fillet of the lead,
Measure the land length behind the base of the lead,
Measure the component height of the lead, based on this, calculate the amount of solder located under the lead,
From the amount of solder after the reflow, the amount of solder of the top fillet, the land length behind the root of the lead, and the amount of solder located under the lead, the amount of solder of the back fillet is calculated,
Solder inspection method.   The solder inspection method according to claim 7, wherein the calculation of the amount of solder after the reflow is calculated from a composition formula of the solder.   The solder inspection method according to claim 7, wherein the wetting height of the back fillet is estimated from the land length behind the root of the lead, the angle of the lead, and the calculated solder amount of the back fillet.   The solder inspection method according to claim 9, wherein the soldering quality is determined from the estimated wetting height of the back fillet.

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