JP3574552B2 - Method and apparatus for detecting unfilling of resin-sealed package - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for detecting unfilling of a resin-encapsulated package of a semiconductor device, and more particularly to a method and apparatus for detecting unfilling of a resin-encapsulated package that can be accurately detected with a simple configuration.
[0002]
[Prior art]
Conventionally, a resin-encapsulated package (hereinafter, sometimes abbreviated as a package) with good mass productivity has been frequently used as a semiconductor package. However, in order to further reduce costs, the number of chips per mold area is increased. Is coming. For example, there is a method in which cavities are connected by a gate without using a runner in a mold, and a molten resin is sequentially filled.
[0003]
However, in order to form a large number of packages with a single mold, even if a multi-plunger type mold is used, a certain pressure loss occurs in the flow path of the molten resin, and it takes a long time to complete the filling. Become. On the other hand, if the pressure of the plunger is increased to increase the flow rate of the molten resin, the filling time can be shortened, but there is a limit because the generation of voids and the like must be avoided. As a result, production is performed after conditions are set such that no problems are caused by experiments or the like. However, since unfilling causes corrosion of the semiconductor element, its management must be stricter.
[0004]
Conventionally, as a method relating to detection of unfilled resin, there has been a method as shown in FIGS. 2 (a) and 3 (a). First, FIG. 2A shows a cross-sectional side view of a conventional unfilled detecting device that detects by vacuuming the surface of a package. In this figure, 5 is a resin-sealed package, 5a is a package formed without resin filling, 8 is a lead frame, and 9 is a vacuum pad.
[0005]
In the apparatus shown in FIG. 2A, a pressure gauge (not shown) and a vacuum generator are connected behind the vacuum pad 9. The vacuum pad 9 is formed from a rubber-based material and is in close contact with the package 5. Usually, when there is no unfilled, the pressure gauges connected to all the vacuum pads match at a predetermined pressure value, but when there is an unfilled package 5a, the outside air is sucked as shown by the arrow in the figure. Therefore, the absolute value of the pressure value of the pressure gauge connected to the vacuum pad 9 which is in close contact therewith decreases. As described above, the present apparatus detects non-filling by detecting the pressure difference depending on the presence or absence of the detection unfilling.
[0006]
On the other hand, FIG. 3A shows an example in which a pin is pressed vertically against a package and the amount of movement is detected by a sensor. 2A, the same reference numerals as those in FIG. 2A denote the same or corresponding components, 11 denotes a pin, and 12 denotes a beam sensor. In this example, when there is no unfilled portion, the pin 11 does not move, and the emitter and the receiver of the beam sensor 12 are connected by the LED light of the optical axis shown by the two-dot chain line in the figure, but there is the unfilled package 5a. In this case, the pin 11 moves in the direction indicated by the arrow in the figure, and the flange of the pin 11 blocks the LED light of the beam sensor 12. As described above, the present device detects the unfilled state by detecting the movement of the pin 11.
[0007]
[Problems to be solved by the invention]
However, if dust such as resin burrs or powder is generated in the above-described device, there is a risk that the piping will be clogged in the device of FIG. 2A, and in the device of FIG. There is a possibility that the depressions may be buried, which may lead to erroneous detection.
[0008]
In addition, the detection range is narrow, and unfilled portions that can be detected are limited. FIGS. 2B and 3B are top views of the packages in FIGS. 2A and 3A, respectively. Unfilling occurs when the molten resin first flowing out of the pot at the time of molding hardens with the lapse of time, and thus occurs at a position substantially facing the gate in the cavity. Therefore, unfilling occurs near the outer edge of the package. However, as shown in the figure, it cannot be detected unless a portion depressed by unfilling is applied to the area surrounded by the dotted lines indicated by reference numerals 10 and 13. Therefore, in order to expand the detection range, it is necessary to scan the vacuum pad and the pin, respectively, and the time required for the scanning affects the construction period.
[0009]
The present invention has been made in order to solve these problems, and an object of the present invention is to provide a method and an apparatus for detecting unfilling of a resin-encapsulated package that do not cause erroneous detection and can widen the range of unfilled detection. And
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to the method for detecting unfilling of a resin-encapsulated package according to the present invention provides a method for inspecting a defect-free resin-encapsulated package having the same surface roughness as the inspected resin-encapsulated package. Adjusting a pressure of the compressed air; a first step of pressing a cavity having an opening having substantially the same size as the front surface or the back surface of the resin-sealed package; a second step of sending compressed air into the cavity; A third step of setting the reference pressure by pressing the cavity against the front or back surface of the resin-encapsulated package to be inspected instead of the front or back surface of the defect-free resin-encapsulated package; A fifth step is to send compressed air set to the reference pressure into the body, and a step of detecting a difference between the pressure of the compressed air and the reference pressure in the fifth step.
[0011]
In addition, a cavity having an opening of substantially the same size as the front or back surface of the inspected resin-sealed package is formed on the front or back surface of the defect-free resin-sealed package having the same surface roughness as the inspected resin-sealed package. A first step of pressing, a second step of sending compressed air into the cavity, a third step of adjusting the pressure of the compressed air to set a reference pressure, and the defect-free resin-sealed package. A fourth step of pressing the cavity against the front surface or the back surface of the resin-sealed package to be inspected instead of the front surface or the back surface, a fifth step of sending compressed air set to the reference pressure into the cavity, And a step of detecting a difference between the flow rate of the compressed air in the step 5 and the flow rate of the compressed air in the second step.
[0012]
The reference pressure may be a pressure at which the compressed air does not leak from between the surface or back surface of the resin-sealed package having no defect and the cavity opening surface.
[0013]
Further, the invention relating to the unfilled detection device for a resin-sealed package according to the present invention is characterized in that the resin-sealed package is formed on all of the portions that sandwich the resin-sealed package formed on the lead frame and contact the front and back surfaces of the resin-sealed package. A plate with a through hole having an opening of substantially the same size as the front and back surfaces of the plate, an air regulator into which compressed air is fed to adjust the pressure of the compressed air, and a through hole of the air regulator and the plate. A defect-free resin seal comprising the communicating pipe and a pressure sensor disposed in the middle of the pipe, and having the same aperture on the air regulator and having the same surface roughness on both front and back surfaces as the resin-sealed package to be inspected. sandwiched state pressure and inspected resin sealed package in a sandwiched state of the sealed package at the plate with the plate And detecting a difference between the definitive pressure.
[0014]
Also, a through-hole having openings of substantially the same size as the front and back surfaces of the resin-encapsulated package is provided at all locations where the resin-encapsulated package formed on the lead frame is sandwiched and in contact with the front and back surfaces of the resin-encapsulated package. , An air regulator for adjusting the pressure of the compressed air by sending compressed air, a pipe communicating the air regulator with the through hole of the plate, and a flow sensor disposed in the middle of the pipe. And the flow rate of the compressed air in a state where a resin-sealed package without defects having the same surface roughness as the resin-sealed package to be inspected is sandwiched between the plates with the same aperture of the air regulator being the same. It is possible to detect a difference in the flow rate of the compressed air in a state where the resin package to be inspected is sandwiched between the plates. The features.
[0015]
The aperture of the air regulator is a pressure at which the compressed air does not leak between the front and back surfaces of the defect-free resin-sealed package and the through-hole in a state where the defect-free resin-sealed package is sandwiched between the plates. May be used as the aperture amount.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the same or corresponding components are denoted by the same reference symbols throughout a plurality of drawings, and redundant description is avoided.
[0017]
FIG. 1 is a view showing an embodiment of the present invention relating to an unfilled detection device for a resin-sealed package according to the present invention. Reference numeral 1 denotes an upper plate that supports an upper contact plate 3 and moves up and down. 3 is an upper contact plate that contacts the surface of the package 5, 4 is a lower contact plate that contacts the back surface of the package 5, and 3a and 4a are through holes provided in the upper contact plate 3 and the lower contact plate 4, respectively. Reference numeral 6 denotes a pressure sensor provided in the middle of the pipe, reference numeral 7 denotes an air regulator for adjusting pressure, and reference numeral 8 denotes a lead frame on which the package 5 is formed.
[0018]
Although not shown, the compressed air flowing into the air regulator 7 is generated from the air compressor, the drain is removed by the drain separator, the moisture is removed by the refrigerator, and the operation of the air compressor is performed by the air tank installed in the middle of the flow path.・ Pressure fluctuation due to non-operation or air release at the branch point of the flow path has been canceled. Such compressed air is kept at a low pressure by the air regulator 7 shown in the drawing, and finally contacts the package 5 through the plates 1 to 4, and the flow path therebetween is as described below.
[0019]
The flow path extending from the air regulator 7 branches into two on the front surface side and the rear surface side of the package, and a pressure sensor is disposed upstream of each of the branched flow paths. In each branch flow path, the wake downstream of the location where the pressure sensor is disposed is branched and connected to all of the through holes formed in the upper plate 1 or the lower plate 2. The through holes of the upper plate 1 are formed corresponding to the through holes of the upper contact plate 3, and the through holes of the upper contact plate 3 have the same area as the surface of the package 5 and are formed at positions corresponding to the respective packages. . That is, the compressed air contacts the surfaces of all the packages through these holes. The through holes 3a and 4a serve as cavities for forming a pressurized chamber together with the front and back surfaces of the package 5.
[0020]
Similarly, the through holes of the lower plate 2 are formed corresponding to the through holes of the lower contact plate 4, and the through holes of the lower contact plate 4 have the same area as the back surface of the package 5, and are located at positions corresponding to the respective packages. Is formed. Therefore, both the front and back surfaces of the package 5 come into contact with the compressed air.
[0021]
Next, a method of detecting unfilling of the resin-sealed package will be described. The upper plate 1 is connected to a linear actuator or the like (not shown) and can move up and down, and the lower plate 2 is fixed. When setting the package 5 in this apparatus, the upper plate 1 is moved upward, the package 5 is placed on the lower contact plate 4 supported by the lower plate 2 together with the lead frame 8, and then the upper plate 1 is moved downward. Then, the package 5 is clamped. Thereby, the through holes of the contact plates 3 and 4 are pressed against both the front and back surfaces of the package 5. First, a package 5 having no defect is set in such a procedure, and compressed air is sent into the through-hole through a pipe.
[0022]
Subsequently, the pressure of the compressed air is reduced to a predetermined value by adjusting the throttle amount of the air regulator 7, and the pressure sensor 6 is set to a limit using this as a reference pressure. Next, the package 5 having no defect is removed from the apparatus, and instead, the package 5 to be inspected, which is an ordinary mass-produced product flowing from the previous process, is set, and compressed air is similarly sent into the through-hole. At this time, the throttle amount of the air regulator 7 is set to be the same as when the reference pressure was previously set. Thereafter, the packages to be inspected are continuously set in the apparatus, and the inspection is continued.
[0023]
With such a configuration, if the package 5 to be inspected is normal, the pressure remains at the reference pressure, and thus the pressure sensor 6 does not operate. The compressed air leaks from the gap between the opening surface of the through hole and the depressed portion of the unfilled package 5a, the pressure drops below the reference pressure, and the pressure sensor 6 operates. An unillustrated alarm or lamp is connected to the pressure sensor 6 to notify occurrence of unfilling.
[0024]
By the way, the surface of the package 5 is engraved with a laser, so that the surface of the package 5 is given a predetermined surface roughness so that the engraved portion stands out. Generally, it is about 5 μmRz, but in some cases it is set to 8 to 11 μmRz. Since the present invention detects a pressure difference caused by leakage of compressed air, a large amount of leakage when a resin sealing package having no defect is set leads to erroneous detection. Therefore, the package 5 and the upper and lower contact plates 3 and 4 need to have sufficient adhesion. Therefore, the higher the surface roughness of the package 5, the higher the flexibility of the upper and lower contact plates 3, 4 is required.
[0025]
According to the experiment of the inventor, when the compressed air pressure is 0.3 kgf / cm 2 and the surface roughness of the package 5 is 5 μm or more, if urethane rubber is used as the material of the upper and lower contact plates, the adhesion will be improved. Thus, the leakage was able to be suppressed under the condition that the package 5 having no defect was set. In the case of a mirror system having a surface roughness of 5 μm or less, plastic such as Teflon may be used as the material of the upper and lower contact plates.
[0026]
Further, in the above embodiment, since compressed air is blown to the package through the through hole, dust is not clogged in the air flow path, and resin burrs and the like attached to the package surface can be removed by the blown compressed air. Particularly, it is effective to blow a large amount of compressed air immediately before the contact plate comes into contact with the package to be inspected.
[0027]
Further, in the above-described embodiment, the throttle of the air regulator is set so that the pressure does not leak in a package having no defect. Therefore, it is easy to detect the pressure difference from the case where there is a leak. That is, in a state where there is a leak, the air released from the leak portion becomes a turbulent flow, so that a slight pressure fluctuation occurs, and if this is used as a reference pressure, it is difficult to detect a delicate level of unfilling.
[0028]
As described above, the embodiments of the present invention have been described in detail, but the present invention is not limited thereto, and various changes can be made. For example, in the above embodiment, two pressure sensors are provided, but one may be provided since the static pressure of the compressed air in the pipe is constant. Further, in the above embodiment, the downstream of the air regulator is branched one by one to the front surface and the rear surface of the package, respectively. However, two branches are made from the air tank, and an air regulator and a pressure sensor are provided in each of the branched flow paths. , Respectively, may be connected to the through holes of the upper and lower plates. At this time, it is possible to specify whether unfilling has occurred on the front surface or the back surface of the package 5, and to obtain statistics on the statistics, which can be used as a reference when changing the size or shape of the gate or air vent of the mold. it can.
[0029]
In the above-described embodiment, the pressure difference is detected by the pressure sensor. However, the pressure sensor may be replaced with a flow sensor to detect the flow difference.
[0030]
Further, in the above-described embodiment, a resin-sealed package having no defect is used in the step of setting the reference pressure. However, a flat surface having the same surface roughness as the resin-sealed package to be inspected may be used. Alternatively, a dummy formed of only a package on a lead frame may be used.
[0031]
【The invention's effect】
As described above, since the configuration is such that compressed air is blown, resin burrs, dust, and the like attached to the package surface are blown off, thereby preventing erroneous detection.
[0032]
In addition, by making the opening of the cavity forming the pressurizing chamber such as a through hole approximately the same size as the front surface or the back surface of the package, it is possible to detect the vicinity of the outer edge of the resin-encapsulated package where unfilled resin occurs, Detection can be performed even with a slight unfilling, and the detection range can be expanded as compared with the conventional case.
[0033]
Further, by setting the pressure in a defect-free package to a level without leakage, more accurate unfilling detection can be performed.
[Brief description of the drawings]
FIG. 1 is a view showing an embodiment of a device for detecting unfilling of a resin-sealed package according to the present invention;
FIG. 2 is an explanatory diagram showing an example of a conventional method for detecting unfilling of a resin-sealed package.
FIG. 3 is an explanatory view showing another example of a conventional method for detecting unfilling of a resin-sealed package.
[Explanation of symbols]
1: Upper plate 2: Lower plate 3: Upper contact plate 4: Lower contact plate 5: Package 5a: Unfilled package 6: Pressure sensor 7: Air regulator 8: Lead frame 9: Vacuum pad 10: Detection range 11: Pin 12 : Beam sensor 13: Detection range

Claims (6)

Pressing a cavity having an opening of substantially the same size as the front or back surface of the inspected resin-sealed package on the front or back surface of the defect-free resin-sealed package having the same surface roughness as that of the inspected resin-sealed package; a first step, a second step of feeding the compressed air into the air cylinder, and a third step of setting a reference pressure by adjusting the pressure of the piezoelectric exploitation air, no resin sealing package surface of the defect or A fourth step of pressing the cavity against the front surface or the back surface of the resin-sealed package to be inspected instead of the back surface , a fifth step of sending compressed air set at the reference pressure into the cavity, Detecting a difference between the pressure of the compressed air and the reference pressure in a process. Pressing a cavity having an opening of substantially the same size as the front or back surface of the inspected resin-sealed package on the front or back surface of the defect-free resin-sealed package having the same surface roughness as that of the inspected resin-sealed package; a first step, a second step of feeding the compressed air into the air cylinder, and a third step of setting a reference pressure by adjusting the pressure of the piezoelectric exploitation air, no resin sealing package surface of the defect or A fourth step of pressing the cavity against the front surface or the back surface of the resin-sealed package to be inspected instead of the back surface , a fifth step of sending compressed air set at the reference pressure into the cavity, Detecting a difference between the flow rate of the compressed air in the step and the flow rate of the compressed air in the second step. The resin sealing according to claim 1, wherein the reference pressure is a pressure at which the compressed air does not leak from between a front surface or a rear surface of the resin sealing package having no defect and the cavity opening surface. A method for detecting unfilled packages. Through-holes having openings of substantially the same size as the front and back surfaces of the resin-sealed package are opened at all places where the resin-sealed package formed on the lead frame is sandwiched and in contact with the front and back surfaces of the resin-sealed package. The plate, the compressed air is sent to adjust the pressure of the compressed air, an air regulator, a pipe that communicates the air regulator with the through hole of the plate, and a pressure sensor disposed in the middle of the pipe. The pressure and the resin-insulated package to be inspected in a state where a defect-free resin-encapsulated package having the same surface roughness as the resin-encapsulated package to be inspected with the aperture of the air regulator being the same and sandwiched by the plate are used. Of a resin-sealed package, characterized by detecting a pressure difference in a state where the Filling detection device. Through-holes having openings of substantially the same size as the front and back surfaces of the resin-sealed package are opened at all places where the resin-sealed package formed on the lead frame is sandwiched and in contact with the front and back surfaces of the resin-sealed package. Plate, compressed air is sent, an air regulator that adjusts the pressure of the compressed air, a pipe that communicates the air regulator with the through-hole of the plate, and a flow sensor that is provided in the middle of the pipe. With the aperture of the air regulator being the same, the front and back surfaces of the compressed air flow and the inspection under the condition where the defect-free resin-encapsulated package having the same surface roughness as the inspected resin-encapsulated package is sandwiched between the plates, Detecting a difference in the flow rate of the compressed air when the resin-sealed package is sandwiched between the plates. Unfilled sensing device resin-sealed package to. The aperture of the air regulator has a pressure at which the compressed air does not leak between the front and back surfaces of the defect-free resin-sealed package and the through-hole in a state where the defect-free resin-sealed package is sandwiched between the plates. The non-filling detecting device for a resin-sealed package according to claim 4, wherein the amount is a drawing amount.

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