JP2939876B2 - Free judgment criteria setting method for mounted PCB inspection equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection apparatus for detecting whether or not a soldering state between an electronic component mounted on a printed circuit board and a pad on the printed circuit board is normal. The present invention relates to a method for freely setting a criterion in a mounted printed circuit board inspection apparatus that allows a user to freely set the criteria.

[0002]

2. Description of the Related Art Conventionally, as a device for inspecting the soldering state of a mounted printed circuit board, a laser beam is irradiated, and the reflected light is received by a light receiving means so that the leads of the electronic components are normal to the pads of the printed circuit board. Some have inspected whether it is in a state, a floating state, or an unsoldered state.

For example, there is an inspection apparatus shown in FIG. Hereinafter, this inspection device will be described. 1 is a laser light source such as a He-Ne laser gun for emitting laser light, and 2 is an extract for expanding the laser light emitted from the laser light source 1 into a parallel beam having a diameter of about 5 mm in order to sufficiently narrow the beam spot. It is a panda.

A Y-axis 3 scans a laser beam so that a beam spot is swept across a lead of an electronic component mounted on a printed circuit board P to be inspected mounted on an XY stage S. A galvanometer including a rotating mirror 3a and an X-axis rotating mirror 3b that scans a laser beam so that a beam spot is swept in the length direction of the front lead, and a three-dimensional object based on the movable range of each of the rotating mirrors 3a and 3b. The laser light is scanned within the corner.

[0005] Each of the mirrors 3a and 3b is servo-controlled by a signal of a built-in encoder. At this time, the position of the beam B irradiated on the printed board P is determined by the encoder signal.

Reference numeral 4 denotes a condensing lens for condensing the laser beam scanned by the galvanometer 3 on the printed wiring board P via a mirror 5 and a half mirror 6. Reference numeral 7 denotes a portion directly above a hole 9a of a light receiving means 9 described later. A light receiving element 8 receives the reflected light from the solder surface coming out of the hole 9. A lens 8 focuses the reflected light coming out of the hole 9 a on the light receiving element 7.

The light receiving means 9 is formed in a box shape having an open lower surface, and the light receiving elements 9b, 9b are formed on the entire inner upper surface and side surfaces.
c and a half mirror 6
A laser beam irradiating hole 9a for passing the laser beam reflected from the laser beam is formed, the light receiving element 9b on the upper surface is divided by a light receiving area surrounding the hole 9a with an equal width, and the light receiving element on the side surface is formed. The element 9c is divided by a light receiving region having a uniform width in the vertical direction (see FIG. 4).

For convenience of explanation, the light receiving element 9 on the upper surface and the side surface of the light receiving means 9 is shown as being divided in the vertical direction. However, in practice, the light receiving element is also divided in the horizontal direction. Has shown a box type, but it may be a dome shape, and in addition to attaching the light receiving element to the inner surface, in addition to the horizontal direction disclosed in Japanese Patent Application No. 8-99621 filed by the present applicant. A plurality of stages may be mounted.

Next, a control system in the present apparatus will be described with reference to the block diagram of FIG. The same reference numerals as those described above denote the same members, and a description thereof will be omitted. Reference numeral 10 denotes a processing device, which controls a lead floating inspection and the like of the mounted printed circuit board P based on data recorded in a storage device (not shown) and data input from a terminal device 11 and an operation unit 12 such as a display. Then, the results of various inspections are determined based on the inputs of the light receiving means 9 and the light receiving element 7. Reference numeral 13 denotes a printer for printing the inspection result by the laser beam.

Reference numeral 14 denotes a servo control unit, which comprises a servo control circuit 14a for driving and controlling the galvanometer 3 and a galvanometer driving circuit 14b. Reference numeral 15 denotes an XY stage control unit that controls the XY stage S, drives the XY stage S based on the position coordinates output from the processing device 10, and moves the printed circuit board P to a predetermined position. Things.

That is, a two-dimensional coordinate system in the X direction and the Y direction is set in the printed circuit board installation portion of the XY stage S, which is not shown, and a point on the two-dimensional coordinate system output from the processing device 10 is set. Drives the XY stage S so as to coincide with a fixed point such as the initial setting position of the beam spot.

Next, the operation will be described. First, before starting the inspection, inspection data such as a board name for identifying the type of the printed circuit board P to be inspected is registered in a storage device or the like in advance. When performing the inspection, the printed circuit board P to be inspected is placed on the XY stage S, and when the board name and the like are input from the operation unit 12, the printed board P is automatically determined based on the inspection data such as the position information of the inspection point recorded in advance. An inspection is to be performed.

One printed circuit board P to be inspected is sent on an XY stage S by a conveyor or the like, and is stopped and locked at a predetermined position by a stopper or the like. X in this state
-The Y stage S is configured such that a lead portion of an electronic component mounted on the printed circuit board P to be inspected has a hole 9 a in the light receiving means 9.
Is controlled so as to be located immediately below.

Next, when the position information for irradiating the beam spot is output from the processing device 10 to the servo control circuit 14a, the servo control circuit 14a
b, the galvano drive circuit 14b controls the X-axis rotating mirror 3b and the Y-axis rotating mirror 3a to irradiate the beam B to an accurate position based on the position information. And sweep.

Therefore, as shown in FIGS. 4 and 7, the beam B is applied to the lead E ₁ of the electronic component E mounted on the printed circuit board P to be inspected and the tip of the pad P ₁ to which the lead E ₁ is soldered. , And the reflected light is received by the light receiving means 9.
The position of the light receiving element in the above, that is, the light receiving element toward the ceiling from the opening of the light receiving means 9 is symbolized by a certain rule, and the arrangement of the symbols according to the light receiving result is determined by the shape of the solder, That is, the soldering state is determined.

[0016] For example, examples of soldering state of the read E ₁ with the pads P _1, a non-solder state soldering is not performed at all (Fig. 8a), soldering but is done read E ₁ is the pad lead float state that floats with respect to P ₁ 3 (FIG. 8b) and normal soldering conditions (FIG. 8c)
There is one. 8a, the reflected light is received just above the light receiving means 9, and the reflected light is received obliquely above and directly above the light receiving means 9 in the floating lead of FIG. 8b. Further, in the normal solder state shown in FIG. 8C, light is received obliquely upward and directly above the light receiving means 9 from below. Therefore, it can be determined whether the soldering is normal or not by determining at which light receiving position of the light receiving means 9 the reflected light is received.

In addition to the soldering state such as unsold, floating, normal, etc. as shown in FIG. 8, the fillet height, fillet length, solder height, solder length, etc. shown in FIG. 9 are sequentially determined. . That is, as shown in FIG. 6, whether the soldering state is normal (step S1), whether the fillet height is greater than or equal to the threshold value (step S2), whether the fillet length is greater than or equal to the threshold value (step S3), Whether the solder height is greater than or equal to the threshold (step S
4) and whether the solder length is greater than or equal to the threshold value (step S5), respectively, and if all are greater or equal, it is normal (non-defective), and if any one is smaller, it is abnormal (defective). ).

[0018]

By the way, in the above-mentioned determination that the product is defective, for example,
Even if the solder at the tip end of the lead is insufficient, if the solder is sufficiently attached to the side surface of the lead, or if the solder is sufficiently attached even if the lead is displaced from the pad, the soldering quality will be There is no hindrance, resulting in excessive quality control.

In a company that solders electronic components to a printed circuit board, a criterion for determining whether a product is good or defective is often different for each company. In the above-mentioned judgment criteria, since a standard one is manufactured by the manufacturer of the inspection apparatus, it does not match the request of each company, or it can be judged only for each inspection item. there were.

The present invention has been made to solve the above-mentioned problem, and it is an object of the present invention to enable each company which solders electronic components to easily set a criterion suitable for its own company and to carry out an excessive inspection. An object of the present invention is to provide a method for freely setting a criterion in a mounted printed circuit board inspection apparatus that prevents the printed circuit board from being inspected so that accurate and appropriate non-defective products can be selected.

[0021]

According to the present invention, there is provided a method for freely setting a criterion in a mounted printed circuit board inspection apparatus according to the present invention, in which the above object is achieved. In a method of inspecting a soldering state of an electronic component mounted on a printed circuit board by detecting a reflection direction of the reflected light with a light receiving unit, or comparing a luminance value and a luminance area of a solder surface with a camera, etc. Create a judgment formula composed of a plurality of inspection items by a list of set free setting judgment items, and after judging whether the logic of each of the inspection items in the judgment formulas matches, implement the judgment in the entire judgment expression, It is characterized in that it is determined whether or not the soldering state is normal.

It is preferable that a plurality of the above-mentioned judgment formulas are prepared, the test is executed sequentially from a judgment formula composed of the logic of the test item with high reliability, and the test is stopped when the condition is satisfied. For example, the tests are performed in order from the determination formula including the logic of the test item from which the highly reliable measurement data within the minimum standard desired by the user is obtained.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for freely setting a criterion in a printed circuit board inspection apparatus according to the present invention will be described below. First, a method of creating a determination formula will be described. A determination formula for detecting a solder state is set as, for example, the following determination formula. P1, α1 <250 & α2 <50 & α10 <60 & α1
1> 50 @ NG (Ub);

Here, "P1" is a decision formula inserted at the beginning of the decision flow. "P2" If there is no match in the determination formula of P1,
The same inspection is performed by performing a determination formula composed of logic for performing determination from another angle, for example, by performing the laser beam irradiation shown in FIG. 7 not in the width direction of the lead but in the length direction of the lead. Evaluation is made by a judgment formula consisting of inspection items. "Pn" A determination formula composed of logic for making another determination. "&" Logical OR. After “α”, the position information of the judgment item list (Table 1) is input. Note that the judgment formulas for P2 and Pn are created by a logic different from that of the inspection item of P1, and their illustration is omitted.

A list of free judgment items is as shown in Table 1. For example, α1 is for solder height, and α10 is for solder volume. "＄" Result ";" End. When using NG logic, "NG (U
n) ", and if OK logic is to be set," OK (U
n) ", and input an arbitrary value from a to z into n. The values of a to z indicate the inspection items. For example, a missing item, floating or unsoldering in the first trial, floating or unsoldering in the retry, floating or unsoldering by the surface data are represented by a. It is displayed by using the letters “ｚz”.

[0026]

[Table 1]

That is, the meaning of the above-mentioned judgment formula P1 is as follows.
α1 indicates the “solder height” where the vertical column 0 and the horizontal column 1 in Table 1 intersect, and the height is less than 250, and α2 is the same as the vertical column 0 and the horizontal column 2 Indicate a “cross-sectional index”, where the cross-sectional index is less than 50, and α
Reference numeral 10 denotes a “solder volume” in which the horizontal column 10 and the vertical column 0 intersect, and the solder volume is less than 60,
Α11 also indicates “6% on the pad” where 10 in the horizontal column and 1 in the vertical column intersect, and 6% on the pad is 50%
% Indicates that the result is NG when all the conditions are met.

It should be noted that the above-mentioned determination is based on the number and percentage of a specific symbol in the measurement data in which the reflection direction is represented by symbols (0, 1, 2,..., A, B, C,. However, since the setting of the inspection item and the criterion are arbitrary, the description of the details of each logic of this determination formula is omitted.

Next, a description will be given of the inspection judgment of the free setting by the above-mentioned judgment expression, with reference to the flowcharts of FIGS.
1 analyzes the determination expression written by user, a flowchart drop in the intermediate file, FIG. 2 is based on the intermediate file, perform the comparison between the actual measurement data, matching the condition It is a flowchart which judges whether or not and outputs a result.

Hereinafter, the flowchart of the intermediate file shown in FIG. 1 will be described. First, one line of the decision expression is specified (step S1), and it is determined whether or not there is a decision expression (step S2). If there is a decision expression, the first logic (in the aforementioned decision expression, α1 <250) (step S3). Next, it is determined whether or not there is a logic (step S4), and if not, the determination result is stored (step S5).

If there is, the first term (α1) of the first logic, the magnitude indication section (<), the second term (250)
And stored in the designated area (step S6). Next, it is determined whether or not the logic is final (step S
7) If it is not the final logic, the next area is secured (step S8), and the process returns to step S3, and the second area is returned.
The determination up to the step S7 is performed for the nth logic, and if it is determined that the logic is the final logic in the step S7, the determination result is stored in a step S5. Is determined (step S9), and if there is no, the process ends, and P2,
If there is a decision formula for P3, the process returns to step S1 to repeat the same operation as described above, and decides on the decision formulas P2 and P3.

A description will now be given, with reference to FIG. 2, of a judgment of comparing the size of actual data with the actual data based on the intermediate file.
First, the actual measurement data in FIG. 2 is read, and the above-described determination formula P1 is determined. That is, the first logical component of the determination formula P1 is determined, and the results are sequentially secured (step S110).

Here, the judgment of one logic is performed by comparing the judgment data for the inspection item of one logic stored in FIG. 1 with the data of the inspection item measured on the inspection printed circuit board. Is to store the result. Then, it is determined whether or not the determination of all the logics of the determination formula P1 has been completed.
Returning to step 110, the second and subsequent logics are determined (step S120).

Then, when the determinations in all the logics of the determination formula P1 are completed, it is determined whether or not all the logics match (step S130), and if it is determined that they match, OK or NG is determined. Is determined and a code is output (step S140).

On the other hand, if it is determined in step S130 that they do not match, the determination formula is P1
It is determined whether or not there is only P2 or P3 (step S150). When it is determined that there is another determination formula,
The next determination formula P2 is selected (step S16).
0), returning to step S110, and making a determination in each logic as described above.

Then, if it is determined that all the logics of the decision formula P2 match, then OK or NG is determined and a code is output (step S140). If not all the logics of the decision formula P2 match, Selects the judgment formula P3 and makes the same judgment as described above. If all the logics do not match, the judgment is terminated.

As described above, the conventional inspection based on oversight is improved by executing the judgment formula including the necessary test items first, and in the case of unknown or NG, performing the repair judgment using another judgment formula. can do.

In the above-described embodiment, the method of determining the soldering state of the leads of the integrated circuit has been described. By creating such a list and freely creating a judgment formula, the soldering inspection can be performed.

In this embodiment, a laser beam is irradiated perpendicularly to the surface of the printed circuit board, and reflected light from leads, solder, or the like is received by the light receiving means, and the solder shape is calculated from the total data of the reflected directions. Although the method of obtaining is described, a method of receiving reflected light from a solder surface by a ring light having a different irradiation angle with a multi-stage ring light known as step illumination and a camera arranged at the center of the ring light with a camera and detecting it from its luminance data (For example, Japanese Patent Application Laid-Open No. 7-275
No. 31), and a method of detecting solder shortage from a hue pattern (for example, Japanese Patent Application Laid-Open No. 5-358949).

In other words, in the method of detecting from the luminance data, the user obtained from the luminance data replaces an arbitrary solder length or fillet length with a judgment formula, and the three-dimensional shape such as height can be obtained. Can be determined from the change in the reflection area with respect to the oblique light angle. Further, the height may be measured by irradiating the solder surface with laser light or slit light and detecting the cross-sectional shape with a camera. Further, in the present invention, a judgment is made for each conventional test item, and an output of OK or NG is sent out and used in combination with a test method of terminating the test. When it is determined, it is of course possible to carry out further inspections by the method of the present invention.

Further, in the method of detecting from the hue pattern, the user can set an arbitrary pattern and replace it with a judgment formula, so that the judgment can be made by the method according to the present invention. As described above, the method of constructing an arbitrary judgment theory by the user using the table format proposed by the present invention is not limited to the laser light method, but various solder shape inspection methods including image processing. It is possible to apply to. Furthermore, the method of the present invention can of course be used in combination with a conventional inspection method that makes a determination for each conventional inspection item.

[0042]

According to the present invention as described above, it is possible to freely set the criteria of the soldering state in the user side carries out any soldering inspection comprising a plurality of criteria desired by the user Therefore, it is possible to prevent a non-defective product from being determined as a defective product due to a conventional inconsistency of one inspection standard, and to shorten the inspection time by using the method of claim 2. And the like.

[Brief description of the drawings]

[1] analyzing the discriminants user wrote a flowchart dropping the intermediate file.

FIG. 2 is a flowchart for comparing the size of actual measurement data with the actual measurement data based on the intermediate file, judging whether or not the condition is satisfied, and outputting the result.

FIG. 3 is a perspective view of an optical system used for a soldering inspection method.

FIG. 4 is a perspective view of a light receiving unit.

FIG. 5 is a block diagram showing a configuration of an entire apparatus used for a soldering inspection method.

FIG. 6 is a flowchart for performing a conventional soldering (unsoldered, lead floating) inspection.

FIG. 7 is a plan view of a lead and a pad.

FIG. 8 is a front view showing a soldered state between the lead and the pad, as viewed from the lead side.

FIG. 9 is a side view of a lead and a pad.

[Explanation of symbols]

P Printed circuit board P ₁ pad E Electronic component E ₁ lead 1 Laser gun 9 Light receiving means 10 Processing device

Claims (2)

(57) [Claims] 1. A method of irradiating a solder surface with a laser beam and detecting the direction of reflection of the reflected light by a light receiving means, or comparing the brightness value and the brightness area of the solder surface with a camera, and mounting on a printed circuit board. In the method of inspecting the soldering state of the electronic component, a judgment formula composed of a plurality of inspection items is created based on a list of preset free setting judgment items, and the judgment formula matches the logic of each inspection item. And determining whether the soldering state is normal or not, by determining the soldering condition is normal. 2. A plurality of judgment formulas are created, and tests are sequentially executed from a judgment formula composed of highly reliable test item logics.
2. The method according to claim 1, wherein the inspection is stopped when the condition is satisfied.