JP3434744B2 - IC appearance inspection method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an IC appearance inspection method for inspecting the appearance shape of an IC, and is particularly used for inspecting the presence of foreign matter around IC leads and the presence of resin burr around IC packages (semiconductor devices). It belongs to the IC visual inspection method.

[0002]

2. Description of the Related Art As a conventional lead inspection apparatus, JP-A-8-15166 discloses an apparatus for inspecting a cutting state of a tie bar cutting portion connecting leads of a semiconductor device to each other. In this lead inspection apparatus, the semiconductor device is supported at a predetermined position by the supporting means, and the lead of the semiconductor device supported by the supporting means is C from the plane direction.
Observe with a CD camera. Then, the tie bar cut portions of a plurality of leads are detected in the width direction from the image observed by the camera to obtain detection data consisting of the number of center positions of the leads and the intervals.

The detection data has an image processing means for detecting a non-cut portion in the width direction, comparing it with standard data composed of similar items, and outputting the result.

A concrete example of a conventional IC appearance inspection method is shown in FIG.
This will be described with reference to (a) to FIG. 6 (c). Figure 6 (a)
Is an image of the IC image on the background image 500 taken by a camera based on the X axis and the Y axis. FIG. 6B shows the number of dots. FIG. 6C shows a logical value .

The lead detection range window 602 is shown in FIG.
As shown in (a), the tie bar cutting section 610 is set to be limited to a range where it does not exist. When foreign matter 601 and 603 exist between the leads 600, only the foreign matter 603 within the lead detection range window 602 is detected as the defective shape partial projection data 604 shown in FIG. 6B on the projection graph. The lead projection area 607 shown in FIG.
Even on the top, only the defective projection area 606 is the lead projection area.
It is detected that the allowable width of 607 is exceeded.

Here, the foreign matter 601 near the tie bar cutting section 610 is outside the lead detection range window 602 and is not detected in the projection graph or the lead projection area 607 . The reference numeral 605 in FIG. 6B indicates a projection graph determination reference level.

[0007]

However, the foreign matter 601 near the tie bar cutting section 610 is outside the lead detection range window 602 and cannot be detected by the projection graph or the lead projection area 607 . Therefore, the conventional lead appearance inspection method cannot detect an IC lead shape defect near the tie bar cutting portion 610.

Therefore, an object of the present invention is to provide an IC appearance inspection method capable of easily detecting a defective IC shape and resin burr near the tie bar cut portion.

[0009]

According to the present invention, in the IC appearance inspection method for inspecting foreign matter existing between leads or around a semiconductor device, the position of a tie bar cutting portion interconnecting the leads is detected. and, after masking the tie bar cutting unit, lead to specify the existing range of the lead
The lead is processed by edge extraction processing in the detection range window.
And edge extraction image that detected the outline part of the lead shape defect
Projection graph judgment reference level on the projection graph with accumulated images
The lead projection area is detected depending on whether or not the value is reached, and the lead projection area is detected.
The width of the lead projection area for each card exceeds the specified range.
I is characterized by detecting the presence of the foreign matter depending on whether
A C visual inspection method can be obtained.

[0010]

The present invention detects the position of the tie bar cutting portion and accurately masks the tie bar cutting portion in order to inspect the external appearance of the IC, especially the presence of foreign matter on the IC lead. Foreign matter between leads can be detected.

[0011]

1 (a) to 1 (d) show an IC.
The first IC appearance inspection method for inspecting the presence of foreign matter on leads
The example of embodiment of is shown. FIG. 1A shows the X axis and the Y axis.
The IC image projected based on the axis is shown. Figure 1 (b)
Indicates the lead detection range window. Figure 1 (c)
Indicates the number of dots and defective shape partial projection data. FIG. 1D shows the logical value and the defective shape projection area.

Referring to FIG. 1A, the IC appearance inspection method according to the first embodiment employs an IC photographed image 101 obtained by photographing an IC package (semiconductor device) 100. The IC captured image 101 is I on the background image 103.
C image 102 is an image taken by a camera,
Is photographed by the camera and the IC image 102 is detected. The data processing range window 104 is a window that designates a specific lead 201 portion in the IC image 102 as an area for image processing, and cuts and extracts only a predetermined number of leads 201 from the IC image 102.

The lead detection range window 105 shown in FIG. 1 (b) is a window for narrowing the existing range of the lead 201 in the detection means such as pattern matching in the data processing range window 104 in which a wide range is specified. The lead 201 is extracted by limiting the range to the IC lead detection range in the data processing range window 104.

In FIG. 1B, the tie bar cutting portion 220 of the lead 201 is detected for the lead 201 captured in the data processing range window 104, and the tie bar cutting portion mask window 106 is set. When the IC has a defect in appearance, for example, the foreign matter 10 between the leads 201
7 may be attached on the lead 201. The tie bar cutting part mask window 106 cuts out the tie bar cutting part assumed range from each lead 201 in the lead detection range window 105, detects the tie bar cutting part assumed center position of each lead 201, and detects all the leads 201 within one side. From the above, the assumed center position of the tie bar cutting part within a certain range is divided, a tie bar cutting part center least square straight line passing through those points is drawn, and the coordinates on the tie bar cutting part center least square line passing through the midpoint of each lead 201 are calculated. This is a window in which a mask area is generated around the center coordinates of the tie bar portion.

In FIG. 1 (c), from the IC lead image captured in the lead detection range window 105, the lead portion excluding the area masked by the tie bar cutting portion mask window 106 is read by edge extraction processing. An edge portion is detected and luminance values are accumulated in the Y-axis direction for each X-axis coordinate to draw a projection graph.

The defective shape partial projection data 108 shown in FIG. 1C is subjected to edge extraction processing on each lead 201 excluding the area masked by the tie bar cutting portion mask window 106 in the lead detection area window 105 , and then X The cumulative waveform of the brightness value of each lead 201 when the brightness value is accumulated in the Y-axis direction for each coordinate on the axis is shown.

The defective shape partial projection data 108 is
In the graph showing the shape of each projected lead 201,
It is projection data that reflects an IC shape defect such as the foreign substance 107 between the leads 201 and indicates the existence of the defect. The projection graph determination reference level value 109 indicates a threshold level for indicating the existence range of the lead.

The lead projection area 110 shown in FIG.
Is the defective shape partial projection data 108 shown in FIG.
In the case where the portion that has reached the projection graph determination reference level value 109 is a logical value 1 and the portion that has not reached the projected graph determination reference level value 109 is a logical value 0, an area existing on the X axis of each lead 201 is shown.

Further, the lead projection area 110 is formed by the lead 2
The foreign matter 107 in the area 01 is projected onto the lead width by the shape defect projection area 1
Since the output is performed with the width added with 11, the presence of the lead shape defect is detected because the width exceeds the specified range.

In this way, the protruding portion of the tie bar cutting portion mask window 106 of each lead 201 is cut out, and the least square straight line passing through the protruding portion of the lead 201 on each side of the IC package 100 is drawn to cut the tie bar. Since the arrangement of the parts 220 is specified and the tie bar cutting part 220 of each lead 201 is masked, even if the foreign matter 107 between the leads 201 exists around the tie bar cutting part 220,
It can be detected as a lead shape defect.

In FIG. 1D, the lead projection area 110 shown by this graph is a portion where the data showing each lead 201 of the projection graph shown in FIG. 1C has reached the projection graph judgment reference level value 109. Indicates the range in which each lead 201 exists from the detected logical value of the projection graph in the X-axis direction, where is a logical value 1 and the portion that has not reached is a logical value 0.

When the foreign matter 107 between the leads 201 exists, it is represented in the graph as a portion of the shape defect projection area 111 on this graph.

Next, in FIG. 2A, the lead 20
From 1, the lead edge portion 202 is detected when the boundary portion between the background image 103 and the lead 201 is detected. Figure 2
In (b), a dX-Y graph for detecting a dX component differentiated in the X-axis direction of the lead edge portion 202 is displayed. In FIG. 2C, a histogram diagram in which dots on the dX-Y graph are accumulated in the Y-axis direction for each coordinate on the dX axis is drawn, and the dot peak value that is the dX value that maximizes the number of dots on the graph. Seeking 203.

In FIG. 2D, dX in FIG.
On the Y diagram, the plus-side effective range 205, which is the width of the dot peak value 203 and the dX value up to the plus side, is allowed.
Then, only the lead edge coordinates lying between the two values of the negative side effective range 204, which is allowed by the width up to n on the negative side, are registered as valid data.

In FIG. 2 (e), only the lead edge coordinates registered in FIG. 2 (d) are targeted, and X in FIG. 2 (a) is selected.
-Draw the lead edge least squares line 209 which is the least squares line on the Y coordinate. This lead edge least squares line (Y
= ΑX + β) is a straight line (Y = αX + β + m), which is a straight line (Y = αX + β + m) obtained by shifting the positive side of the X axis by a certain amount, and the lead edge least squares line 209 is similarly formed
A minus side lead edge allowable width (straight line) 207 which is a straight line (Y = αX + β-m) obtained by shifting (Y = αX + β) to the minus side of the X axis by a predetermined amount is set.

A region sandwiched by the permissible widths 207 and 208 of these straight lines is regarded as a straight line portion in the longitudinal direction of the lead, and tie bar cutting which is a continuous region outside the permissible widths (straight lines) 207 and 208 on the straight line region. The hypothetical range 206 is regarded as a region where the tie bar cutting part 220 exists.

The linear region in the longitudinal direction of the lead and the region where the tie bar cutting portion 220 exists are detected on the left and right sides of one lead 201 as shown in FIGS. 2 (a) to 2 (e), and further lead detection is performed. The same detection is performed for all the leads 201 in the range window 105.

Next, FIGS. 3A to 3C will be described. In FIG. 3A, the tie bar cutting portion assumed range 20 is based on the information of the linear region in the longitudinal direction of the lead 201 detected in FIG. 2 and the region where the tie bar cutting portion 220 exists.
The lead edge coordinate at the intermediate position in the Y-axis direction of 6 is set as the assumed center position 301 of the tie bar cutting portion. This is set for all leads 201. At this time, the lead 20
Even when a lead shape defect such as the foreign matter 107 between 1 is present, the inter-lead foreign matter center position 302 is similarly detected as a candidate for the tie bar cutting section 220.

In FIG. 3B, the candidate center positions of all the tie bar cutting portions 220 detected in FIG. 3A are accumulated in the number of candidate center position points in the X-axis direction for each Y-axis coordinate. Plot on the graph. The part where the number of dots is the largest is detected on this graph, and the continuous range of the set of dots is cut out as the tie bar cutting portion assumed center position effective range 303. At this time, unless the lead shape defect such as the foreign matter 107 between the leads 201 is near the tie bar cutting portion 220, the lead shape defect is located outside the tie bar cutting portion hypothetical center position effective range 303 on the graph shown in FIG. 3B. To be detected.

In FIG. 3 (c), the tie bar cutting which is the least squares line for all the assumed tie bar cutting part center positions 301 existing in the tie bar cutting part hypothetical center position effective range 303 in FIG. 3 (b). Center position of least square line 3
Subtract 05.

A point on the least square line 305 of the center position of the tie bar cutting part center position on the X axis of the left and right assumed tie bar cutting part center position 301 on each lead 201 is defined as the tie bar part center coordinate 304. , All leads within the detection range 20
Ask about 1.

The tie bar over part center coordinates 3 on each lead 201
A tie bar cutting portion mask window 106 in a range of x1 dot × y1 dot set in advance around 04 is set for all target leads.

Next, FIG. 4 will be described. Figure 1 (b)
The tie bar cutting portion mask window 106 set in step 3 is set as the non-detection area, and the lead detection range window 105 is set.
The image after edge extraction processing in FIG. 4 is obtained by performing edge extraction processing on the lead image inside.

The configuration of the embodiment has been described in detail above.
FIG. 2C is a projection process, FIG. 1D is a logical value graph, and FIG.
The histogram formation of (c), the histogram formation of FIG. 3 (b), and the edge extraction processing of FIG. 4 are well known to those skilled in the art, and since they are not directly related to the present invention, their detailed configuration will be omitted. .

The operation of the IC overview inspection method according to the first embodiment will be described with reference to FIGS.

In FIG. 1B, the lead detection range window 1
Each lead captured in 05 is divided into the left and right sides of the lead 201 in FIG. 2A, the lead edge portion 202 is detected, and the differential data of the X coordinate is detected in FIG. ), The protruding point of the shift amount in the X direction indicating the straight line portion of the lead is detected from the differential data.

FIG. 2D specifies a range which is regarded as a linear range of the lead 201 with the projected point of the detected X-direction displacement amount as the center. A least-squares straight line is drawn using the data on the straight line range identified in FIG. 2E, a range that can be regarded as a straight line on the lead 201 is designated, and a portion outside the range is set as the tie bar cutting portion assumed range 206. To detect.

In FIG. 3A, all the candidate points of the tie bar cutting part 220 are plotted as the assumed center position 301 of the tie bar cutting part, and the tie bar cutting part 220 is determined from the histogram of dots detected in FIG. 3B in the X-axis direction. The existing position is specified as a continuous mountain of dots, and the tie bar cutting unit 220
By limiting the range in which exists, the lead shape defect that becomes another noise component is separated.

FIG. 3 (c) in the tie bar off only tie bar cutting unit assumes a central position 301 within the tie bar cutting unit assumes a central position scope 303 identified above as effective dots
A least square line 305 of the center position of the breaking portion is drawn to separate the tie bar cutting portion 220 from the lead shape defect such as the foreign material 107 between the leads 201. The tie bar center coordinates 304 are specified from the least square straight line 305 of the tie bar cutting position position and the left and right edge points of the tie bar cutting section 220, and the tie bar cutting section mask window shown in FIG. Set to all leads 201 within the range.

After the tie bar cutting portion is masked, the lead detection range window 105 is subjected to edge extraction processing in FIG. 4 to raise the outline of the lead and the lead shape defect.

The edge extraction image detected in FIG.
Accumulate in the axial direction to obtain a projection graph.

At this time, since the tie bar cutting part 220 is masked, even if there is a foreign matter 107 between the leads 201 around the tie bar cutting part 220 which is projected near the same X coordinate position as the tie bar cutting part 220, a projected image is obtained. Will be detectable on top.

Each lead projection area 110 is detected in FIG. 1D depending on whether the projection graph judgment reference level value 109 on the projection graph is reached, and the lead projection area 110 of each lead 201 is detected. Lead 2 depending on whether the width exceeds the specified range
The presence of the foreign matter 107 between 01 can be detected. The above process is performed for each side of the lead 201.

5 (a) to 5 (d) show I of the present invention.
C shows the second embodiment of the appearance inspection method.
The basic configuration according to the second embodiment is the same as that of the first embodiment, and further another IC lead shape defect, particularly the mold of the IC package, is added to the configuration of the first embodiment. The resin burr 504 in the portion is devised so that the appearance can be inspected.

In FIG. 5A, the IC package 10
IC package position detection area 503 for grasping the position of 0
Are set at the upper left and lower right positions of the package 100.
Based on the position of the IC package 100 detected by the IC package position detection area 503, the resin burr mask range 50
5 is set. The other part is the first described above
This is the same as the embodiment described above.

Next, the operation of the IC visual inspection method in the second embodiment will be described with reference to FIGS. 5 (a) to 5 (d).

In FIG. 5A, the IC package 10
When the resin burr 504 is present at the end of the mold part on the 0, the I registered in advance by the pattern matching process is used.
The IC package position detection areas 503 are set at positions matching the upper left and lower right model images of the C package 100, respectively, and the position of the IC package 100 is accurately detected. IC package 10 detected in the upper left and lower right
The resin burr mask range 505 is set based on the position of 0, and the resin burr 504 within the mask range is set to be allowable.

In FIG. 5B, the lead detection range window 506 is set so as not to detect the inside of the resin burr mask range 505. The portion of the resin burr 504 that falls within the resin burr mask range 505 is outside the detection target.

Further, the resin burr 504 which is set in the mask window 507 of the tie bar cutting portion, which is set as in the previous embodiment, is also not detected. At this time, the resin burr 50
4 is a lead 2 whose image brightness is solder-plated
Since it is lower than 01, it does not affect the detection of the lead edge portion 202 .

In FIG. 5C, the resin burr 504 portion existing outside the upper two mask areas is detected in the form of defective shape partial projection data 509 as in the previous embodiment.

In FIG. 5D, the lead projection area 512 in the portion where the resin burr 504 exists is the resin burr 504.
Is detected in the form of a defective projection area 511, two lead projection areas 512 for two leads are connected to each other, and the set allowable width of the lead projection area 512 is exceeded. The presence of defects is detected.

As described above, in the first and second embodiments, the tie bar cutting portion 220 and the resin burr 504 near the IC package are masked, so that the tie bar cutting portion 2 is removed.
20 and IC package, and resin burr 5 within the allowable range
The resin burr inspection can be performed without erroneously recognizing 04.

[0053]

As described above, the present invention has the following effects.

The first effect is that since the tie bar cut portion is masked for inspection, it is possible to detect even if there is an external appearance defect around the tie bar cut portion.

As a second effect, since the position of the tie bar cutting portion is detected and masked for each IC, an area for masking is set. It is to be able to inspect without erroneously recognizing a defective shape.

[0056] As a third effect, and detects the position <br/> location of the tie bar cutting portion of a sequence status of the tie bar cutting portion of the entire aligned read on each side, in the vicinity of the tie bar cutting portion of rie de Even if there is an IC lead shape defect, the IC lead shape defect can be erroneously recognized as a tie bar cut portion and can be inspected without missing the defect.

[Brief description of drawings]

FIG. 1 shows a first embodiment of an IC appearance inspection method of the present invention, (a) shows an IC projected image, (b) shows a lead detection window, and (c) shows the number of dots and defective shape. The figure of partial projection data is shown, (d) is a figure showing a logical value and a poor-shaped projection field.

FIG. 2 shows a first embodiment of an IC appearance inspection method of the present invention, in which (a) is a view showing a lead edge portion,
(B) is a projection view displaying a dX-Y graph for detecting a dX component differentiated in the X-axis direction of the lead edge portion,
(C) is a histogram diagram in which dots on the dX-Y graph are accumulated in the Y-axis direction for each coordinate of the dX-axis, and (d) is a positive side effective range on the dX-Y diagram of (b). It is a figure which shows a negative side effective range, (e) is an XY of (a) targeting only the lead edge coordinate registered by (d).
It is a figure which shows the lead edge least squares line which is a least square straight line on a coordinate, plus side lead edge permissible width, and minus side lead edge permissible width.

3A and 3B show a first embodiment of an IC appearance inspection method of the present invention, FIG. 3A is a diagram showing an assumed center position of a tie bar cutting portion and a center position of a foreign substance between leads, and FIG. 3B is a set of dots. It is a figure which shows the continuous range of the tie bar cutting part hypothetical center position effective range, (c) is a tie bar cutting part center position minimum 2
It is a figure which shows a straight line and a tie bar part center coordinate.

FIG. 4 is a diagram showing the first embodiment of the IC visual inspection method of the present invention, showing an image after edge extraction processing.

5A and 5B show a second embodiment of an IC appearance inspection method of the present invention, FIG. 5A shows an IC image, FIG. 5B shows a lead detection window, and FIG. 5C shows a dot number and a defective shape portion. It shows projection data, (d) is a figure which shows a logical value and a poor-shaped projection area.

6A and 6B show a conventional IC appearance inspection method, in which FIG. 6A is an image of an IC image on a background image taken by a camera based on the X axis and Y axis, FIG. 6B shows the number of dots, and FIG. ) Is
It is a figure which shows a logical value .

[Explanation of symbols]

101 , 501 IC photographed image 102 , 502 IC image 103 , 500 background image 104 Data processing range window 105, 506, 602 Lead detection range window 106 , 507 Tie bar cutting part mask window 107 , 601, 603 Foreign matter 108 , 509, 604 Defective shape partial projection data 109 Projection graph judgment reference level values 111 , 511, 606 Shape defective projection area 201 , 600 Lead 203 Dot peak value 205 Positive side effective range 204 Negative side effective range 206 Tie bar cutting assumption range 207 Negative side lead edge Allowable width 208 Positive lead edge allowable width 220,610 Tie bar cutting part 301 Tie bar cutting part assumed center position 302 Lead-to-lead foreign substance center position 303 Tie bar cutting part assumed center position Effective range 304 Tie bar Part center coordinate 305 tie bar cutting portion center position the least squares straight line 503 IC package position detection region 504 resin burr 505 resin Barimasuku range 604 defective shape portion projection data 110,512, 607 lead the projection region

Continuation of the front page (56) Reference JP-A-11-166899 (JP, A) JP-A-8-15166 (JP, A) JP-A-9-49715 (JP, A) JP-A-9-213858 (JP , A) JP 60-165750 (JP, A) JP 8-14845 (JP, A) JP 61-35303 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB Name) G01B 11/00-11/30 G01N 21/88 H01L 21/66

Claims (5)

(57) [Claims] 1. A IC appearance inspection method for inspecting the foreign substance existing around the lead and between the semiconductor device detects the position of the tie bar cutting portion which connects the lead to each other, before
In terms of masking the serial tie bar cutting section, the presence of the lead
Edge extraction is performed within the lead detection range window that specifies the range.
The lead and the outline of the lead shape defect.
Projection on the projection graph by accumulating detected edge extraction images
Lead projection area depending on whether or not the graph judgment reference level value is reached
Area, and the width of the lead projection area for each lead is
Detects the presence of the foreign matter by checking whether it exceeds the specified range.
IC appearance inspection method characterized by that. 2. The IC appearance inspection method according to claim 1, wherein the lead captured within the lead detection range window is used.
X on the left and right sides of the
The differential data of the coordinates is detected, and from the differential data, the
Detects the protruding point of the displacement amount in the X direction, which indicates the straight part of the lead
Then, the detected X-direction displacement amount
The range that is considered to be the linear range of the lead is specified and
Least square of the lead edge using the data on the straight line range
Draw a straight line and specify the range that can be regarded as a straight line on the lead
Then, the part outside this range is detected as the tie bar cutting part assumed range.
The tie bar as the assumed center position of the cutting and tie bar cutting part
Plot all candidate points of the cutting part,
The tie bar cutting part is present from the histogram in the X-axis direction.
Specify the existing position as a continuous mountain of the dots,
By limiting the range where the tie bar cutting part exists, other
Isolate lead shape defects that are noise components and identify them first
Tie bar cutting at the assumed center position of the tie bar cutting part
Part tentative cutting center position within the effective range
Only the fixed center position is used as an effective dot Center of the tie bar cutting part
Draw a line of least squares for the position, and
In the tie bar part by separating the product and the lead shape defect
The center of the coordinate is the front of the least square line of the tie bar cutting center position.
Specify from the left and right edge points of the tie bar cutting part, and
Scope of tie bar cutting part mask window centered on points
IC visual inspection method characterized by setting all leads in the 3. The IC appearance inspection method according to claim 1 , wherein the lead detection range window specifies a wide range.
Pattern matching within the data processing range window
Specify the lead existence range as narrow as detection means such as
It is a window and within the data processing range window
The lead is extracted by limiting the range to the lead detection range.
A method for inspecting IC appearance, which is characterized in that 4. The IC appearance inspection method according to claim 1 , wherein a resin burr is provided at an end of a mold portion on the semiconductor device.
If it exists, it is registered in advance by pattern matching processing.
A model image of the upper left and lower right of the semiconductor device recorded and
Set the position detection area for each position to
Based on the position of the semiconductor device detected at the top and bottom right
An IC appearance inspection method characterized by setting a grease burr mask range . 5. The IC appearance inspection method according to claim 4 , wherein the lead projection region in a portion where the resin burr is present.
However, the resin burr is detected in the shape of the defective projection area.
An IC appearance inspection method characterized by being performed.