JP2010014594A - Solder creep strength testing device and solder creep strength test method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a load of an operator, and to acquire proper creep rupture measurement data, by detecting a soldered portion subjected to a creep rupture test of a printed board for the test, and by executing automatically the creep rupture test. <P>SOLUTION: A solder shape is measured beforehand, and the soldered portion which is an inspection object is discriminated automatically, and elongation of the soldered portion is measured by a load control mechanism placed on an X-Y moving mechanism, while applying a prescribed load onto a component soldered on the printed board for the test. Continuity between a plurality of terminals is monitored, and when some continuity is lost, it is determined that a rupture occurs, and an applied load, and an elongation, a time and a rupture mode until reaching rupture are preserved as data. The rupture mode, such as a solder rupture or a through-hole rupture, is determined by presence/absence of continuity between the plurality of terminals. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an apparatus and method for a solder creep strength test when a component is soldered to a printed circuit board or the like.

A method for measuring the creep rupture time by machining a metal to be measured and applying a certain tensile force to the test piece under a test piece having a defined shape is disclosed in JIS Z 2271 Creep rupture test method ".
In the case of this method, it is a useful test method as a creep test for metal materials such as steel.
However, this technique cannot perform a creep test at the joint between the substrate and the solder.
As a creep test method for a soldered portion, a method has been proposed in which a creep test is performed by applying various loads simultaneously to a plurality of soldered portions of a test printed circuit board soldered using a solder bath (for example, (See Patent Document 1).

This method is effective when a creep test is performed in parallel with a plurality of objects.
However, in this method, a joint to be tested is selected for each substrate, and the tester makes preparations such as loading a weight. Moreover, since the creep rupture time of the soldering part using a solder bath is influenced by the solder joint state, it is necessary to confirm the joint state in advance. Since the creep test is a destructive test, it is difficult to confirm this after the test. These preparations become very complicated when there are a plurality of test objects.
Further, although the rupture mode differs depending on the load, this method cannot be automatically determined.

JP 59-072042 A

  In view of these problems, the present invention detects a soldered portion to be subjected to a creep rupture test, and automatically performs a creep rupture test, thereby reducing the burden on the operator and obtaining appropriate creep rupture measurement data. Objective.

According to the first aspect of the present invention, the solder creep strength test apparatus includes means for measuring the solder shape of the soldered portion, and automatic determination means for automatically determining the object of the creep strength test based on the measurement result. It is characterized by that.
According to a second aspect of the present invention, in the solder creep strength test apparatus according to the first aspect, a load means for continuously applying a load in a direction perpendicular to the substrate surface to the solder joint portion to be tested. And means for measuring the time since the load was applied and recognizing the fracture state.

According to a third aspect of the present invention, in the solder creep strength test apparatus according to the second aspect, the load means includes a load control mechanism.
According to a fourth aspect of the present invention, in the solder creep strength test apparatus according to the third aspect, the load control mechanism has a mechanism that can move independently in each axial direction of orthogonal coordinates provided in one plane. It is characterized by that.

According to a fifth aspect of the present invention, in the solder creep strength test apparatus according to any one of the second to fourth aspects, the means for recognizing the rupture state is a mechanism for detecting that the test object has undergone a creep rupture. It is characterized by including.
According to a sixth aspect of the present invention, in the solder creep strength test apparatus according to any one of the first to fifth aspects, the means for recognizing the rupture state further includes a mechanism for determining a rupture mode. It is characterized by that.
According to a seventh aspect of the present invention, in the solder creep strength test apparatus according to any one of the first to sixth aspects, the means for recognizing the fracture state includes a mechanism for measuring the elongation of the solder during the creep test. It is characterized by having.

In the invention according to claim 8, in the solder creep strength test apparatus according to claim 1 or 7, the means for measuring the solder shape of the soldering portion is an X-ray imaging means, and the automatic determination means is The image processing apparatus includes a feature detection unit that detects a feature portion of a solder shape by performing image processing on an imaging result.
The invention according to claim 9 is a solder creep strength test method, a step of measuring a solder shape of a soldering portion, a step of automatically determining a creep strength test object based on the measurement result, and a test object It is characterized by comprising a step of continuously applying a load to the solder joint portion thus obtained in a direction orthogonal to the substrate, and a step of measuring the rupture time and recognizing the rupture state.
According to a tenth aspect of the present invention, in the solder creep strength test method according to the ninth aspect, the creep strength test target is an evaluation board on which a U-shaped component is mounted.

  According to the present invention, since the state of the soldered portion to be subjected to the creep rupture test can be measured in advance and the creep rupture test can be automatically performed, the burden on the operator can be reduced and appropriate creep rupture measurement data can be obtained. Obtainable.

FIG. 1 is a perspective view showing a mechanism portion of an embodiment of the present invention.
In the figure, reference numerals 1 and 2 are moving members, 3 and 4 are XY moving mechanisms, 5 is a load control unit, 6 is an engaging unit, 10 is a substrate holding unit, 11 is a member that regulates substrate deflection, and 20 is Reference numeral 21 denotes a test printed wiring board, and 22 denotes a conductive common terminal.
The test printed wiring board 21 is held by the board holding unit 10. The test printed wiring board 21 has a plurality of soldered components 20 that are subjected to a creep test. The X movement required stage 3 and the Y movement required stage 4 constitute a well-known XY movement mechanism, and both stages can move to arbitrary positions. The load control unit 5 is installed in the XY movement mechanisms 3 and 4, and the engagement unit 6 of the load control unit 5 is also movable up and down (in a direction orthogonal to the printed circuit board surface). The load control unit 5 includes a load detection mechanism and an extension displacement detection mechanism. At the tip of the load controller 5, there is an engaging part 6 that engages with the soldering part. The engaging portion may be a hook or an automatic chucking unit as shown in FIG. There may be a member 11 that regulates the deflection of the substrate in accordance with the size of the substrate.
In the figure, the XY moving mechanism is shown as having a coordinate axis in a horizontal plane, but the coordinate axis may be provided in a vertical plane and the test printed wiring board 21 may be arranged corresponding to it. The point is that the load control mechanism only needs to be able to move the engaging portion 6 to an arbitrary position in the test printed wiring board 21, so that it can move independently in each axial direction of orthogonal coordinates provided in one plane. As long as it has a simple mechanism. In the figure, the drive source and the transmission mechanism of the XY moving mechanism can be any conventional technique and are not shown.

FIG. 2 is a block diagram showing a functional configuration of the test apparatus of the present invention.
In the figure, reference numeral S denotes each step corresponding to the flowchart of FIG.
The CPU controls the entire apparatus and stores necessary calculations and data.
When a plurality of soldered test printed boards are set at predetermined positions and a test start button (not shown) is pressed, the CPU instructs the imaging apparatus as a shape measuring means to start the test. The imaging device is constituted by, for example, an optical camera or an X-ray imaging device. A part to be selected as a test object is discriminated from the imaging result by comparison with pattern data stored in advance by feature detection means including image analysis means. The position data is passed to the load means with these as test objects. Here, the criterion to be selected as a test object is a part where creep strength data is likely to be obtained, and a part where soldering is normally performed, that is, a part where the solder finish is 100%. In addition, it is possible to select, as necessary, a portion that is considered to be able to obtain creep strength data although it is out of the normal state.
Based on the position data, the load means drives the XY stage so that the engagement portion 6 is brought into contact with or hooked to the soldered component 20 to apply a slight load. The magnitude of the load is set to, for example, a substantially intermediate value in the optimum range examined in advance by the load control mechanism.

First, the rupture state recognition means causes conduction between the engagement portion 6 and the common electrode (to be described later) facing the engagement portion 6 side (front surface side), and breakage between the common electrode and the back surface side. Check the mode detection terminal (described later).
If either continuity does not occur from the beginning, it is determined that soldering has not been performed normally, and another test object is selected.
If no elongation is confirmed within a predetermined time, it is possible to select whether to exclude this part as a test object or to repeat the same test with a larger load.
If the occurrence of elongation is confirmed, continue to apply the same weight until breakage occurs. Then, the applied load, the time to break, and the break mode determined by the break state recognition means are stored as data.
As the break mode, when only the conduction between the engaging portion 6 and the common electrode is lost, it is determined that the solder portion is broken. In addition, when both the conduction between the common electrode and the break mode detection terminal on the back side is lost, it is determined that the through hole portion has broken.
These determination results can be displayed on the result display section.

FIG. 3 is a flowchart showing the test method of the present invention.
In the figure, symbol S indicates a flow step.
In response to the test start command (S00), the soldered portion of the board is imaged (S01). The imaging means may be an optical camera or an X-ray imaging device capable of imaging the inside. A feature part of the solder shape is calculated from the obtained image by image processing (S02). For example, in the case of X-ray imaging, the feature portion uses a solder rising length in a through hole. In the case of optical imaging, the measurement target is determined from the result of the characteristic part such as excluding the ball-shaped solder shape (S03). For example, in the case of the solder rising length, only the solder that is sufficiently high can be selected, or depending on the type of data to be obtained, it can be selected to distribute the long and short soldering length. Further, the load applied to the object is determined by the load control mechanism (S04). As a determination method, a prescribed load can be applied, or the load can be changed for each measurement object determined in (S03). Under the determined conditions, a load is applied to the object and a creep test is started (S05).

During the test, breakage is detected (S06), and solder elongation is also detected (S07). If there is solder elongation, it indicates that creep has continued, so the test is continued, but if the solder elongation does not exceed the specified time (S08), the heavier load is applied to the same measurement object. Measurement can be resumed (to S04). Alternatively, if there are remaining measurement objects (S12), a new object is determined and remeasured (to S03). Whether to change the measurement load can be determined in advance using a selection switch or the like.
When it breaks, the break mode is identified by conduction between the engaging portion and the common electrode (S09). When there is continuity, it is a solder rupture (S10), and when there is no continuity, it is a through-hole rupture (S11). Finally, the presence / absence of the remaining measurement object is detected (S12). If there is a remaining measurement object, the process returns to (S03). If there is no remaining measurement object, the measurement ends (S13).

  In step S02, information on the solder shape inside the joint is obtained by observing with X-rays in particular. Thereby, accurate creep rupture measurement data can be obtained for each solder shape.

  The determination of breakage may be performed by either passing a current through the engaging portion 6 and the common electrode at the tip of the load control unit to see conduction or by determining the displacement of the load control unit 5. If breakage occurs during the measurement, the load suddenly drops at that point, so it can be determined that the breakage occurred in some mode. Which mode is broken can be further determined by observing conduction between the common electrode and the break mode detection terminal. When there is continuity, it is determined that the solder part is broken, and when there is no conduction, it is determined that the through hole is broken.

FIG. 4 is a diagram showing a test printed wiring board used in the present invention.
The test printed wiring board is provided with a conduction common terminal 22 and a break mode detection terminal 23 as common electrodes, and the conduction between the terminals is observed.
FIG. 5 is a diagram showing a state in which the solder finish is insufficient. When the solder fills the entire length of the through hole, the solder finish is expressed as 100%. Even when the solder finish is not 100%, it may be selected as a test object when it is desired to collect creep strength data.
6 and 7 are diagrams showing different modes of the solder fracture state.
In the solder rupture state of FIG. 6, the continuity is maintained, but in the through hole rupture state of FIG. 7, the continuity between the continuity common terminal 22 and the rupture mode terminal 23 which are common electrodes cannot be obtained. Can be determined.
According to the present invention, since the rupture mode can be specified, accurate creep rupture measurement data can be obtained.

FIG. 8 is a diagram showing a load application state.
In the drawing, the component 20 is a U-shaped component, but in this case, the component 20 is easily engaged with the engagement portion 6 at the tip of the load control unit 5. In this case, the load by the load control unit 5 becomes a pulling force on the component 20.
If the test printed wiring board 21 is configured as a U-shaped component, it can be easily engaged with the engagement portion 6 at the tip of the load control portion, so there is no engagement portion displacement or disconnection during the test. Accurate creep measurement data can be obtained.

It is a perspective view which shows the Example of this invention. It is a block diagram which shows the function structure of the test apparatus of this invention. It is a flowchart showing the test method of this invention. It is a figure which shows the printed wiring board for a test used for this invention. It is a figure which shows one mode of a solder fracture state. It is a figure which shows the other mode of a solder fracture state. It is a figure which shows a load application state. It is a figure which shows a load application state.

Explanation of symbols

3, 4 XY movement mechanism 5 Load control unit 6 Engagement unit 20 Parts 21 Test printed wiring board 22 Conduction common terminal 23 Break mode detection terminal

Claims (10)

  Solder creep strength test apparatus, comprising: means for measuring a solder shape of a soldered portion; and automatic determination means for automatically determining a creep strength test object based on the measurement result. apparatus.   2. The solder creep strength test apparatus according to claim 1, wherein a load means for continuously applying a load in a direction orthogonal to the substrate surface to the solder joint portion to be tested, and a time after the load is applied. And a means for recognizing a ruptured state, and a solder creep strength test apparatus.   3. The solder creep strength test apparatus according to claim 2, wherein the load means includes a load control mechanism.   4. The solder creep strength test apparatus according to claim 3, wherein the load control mechanism has a mechanism that can move independently in each axial direction of orthogonal coordinates provided in one plane. apparatus.   5. The solder creep strength test apparatus according to claim 2, wherein the means for recognizing the rupture state includes a mechanism for detecting that the test object is creep ruptured. Strength test equipment.   6. The solder creep strength test apparatus according to claim 1, wherein the means for recognizing the rupture state further comprises a mechanism for determining a rupture mode. apparatus.   The solder creep strength test apparatus according to any one of claims 1 to 6, wherein the means for recognizing the fracture state includes a mechanism for measuring the elongation of the solder during the creep test. Creep strength test equipment.   The solder creep strength test apparatus according to claim 1 or 7, wherein the means for measuring the solder shape of the soldering part is an X-ray imaging means, and the automatic determination means performs image processing on the imaging result to obtain a solder shape. A solder creep strength test apparatus comprising a feature detection means for detecting a feature of the solder.   A solder creep strength test method for measuring a solder shape of a soldered portion, a step of automatically determining a creep strength test target based on the measured result, and a solder joint portion to be tested A solder creep strength test method comprising: applying a load continuously in a direction perpendicular to the substrate; and measuring a rupture time and recognizing a rupture state.   The solder creep strength test method according to claim 9, wherein the creep strength test target is an evaluation board on which a U-shaped component is mounted.

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