JPH0344421B2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention accommodates semiconductor circuit elements such as semiconductor integrated circuits (ICs), transistors, and diodes in a container body, and seams the cap to the container body. The present invention relates to a method for determining seam bonding defects in a microparallel seam bonding apparatus for hermetically sealing semiconductor circuit elements, and a device directly used to carry out this method.

(Prior art) Micro parallel seam bonding (Micro parallel seam bonding) is a method of hermetically sealing semiconductor circuit elements such as ICs.
A parallel seam joining method has been proposed. As shown in FIG. 3, this method involves brazing an annular sealing frame 2 to a ceramic substrate 1 to form a container body 3, fixing a semiconductor circuit element 4 within this sealing frame 2, and forming a thin plate cap. 5
The cap 5 is placed on the rotary table 6, and a pair of tapered roller electrodes 7, 8 are connected to the edge of the cap 5 under a predetermined pressure in an inert gas while energizing the cap 5, thereby attaching the cap 5 to the seal frame 2. It is a seam joint. In the case of a rectangular cap, move the table 6 in a straight line to join two sides, then rotate it 90 degrees and join the remaining two sides, or rotate the table 5 as in the case of a circular cap. A method of joining is used.

Here, a plating layer of gold or the like having a lower melting point than the seal frame 2 is previously formed on the upper surface of the seal frame 2, and a plating layer of gold or the like is similarly formed on the cap 5. Therefore, when the tapered roller electrodes 7 and 8 are energized, the plating layer interposed between the seal frame 2 and the cap 5 is melted and joined together.
At this time, the base materials of the seal frame 2 and the cap 5 do not melt, and no fused portions of the base materials, ie, nuggets, are formed as seen in normal spot welding.

In such micro-parallel seam joining, a current monitoring method is known as one of the methods for quality control of the joint, that is, for determining the quality of the seal joint. This is widely used in other electric welding methods such as spot welding, and detects the current between two tapered roller electrodes 7 and 8, and compares this current with a reference current value to detect if it is outside the allowable range. By determining this, the quality of the joint is determined.

(Problems with the prior art) However, in micro-parallel seam bonding, there are two bonding points in one seam bonding circuit.
Although it is possible to detect the total current flowing through these two junctions, the current density is not necessarily the same at each junction. For this reason, even if the temperature rise at each joint becomes unbalanced, it cannot be detected by the conventional method of monitoring current, and it has been difficult to accurately determine whether the seam joint is good or bad. For this reason, even if a container has poor airtightness due to poor seam jointing, the defect cannot be discovered without a destructive test or a leak tester, which has been a major factor in lowering product yields.

(Purpose of the Invention) The present invention was made in view of the above circumstances, and is an object of the present invention when hermetically sealing a container containing semiconductor circuit elements such as semiconductor integrated circuits, transistors, and diodes by micro-parallel seam bonding. A first object of the present invention is to provide a method for determining joint failure in a micro-parallel seam joining apparatus, which can detect the quality of seam joints with high precision and improve product yield. A second object of the present invention is to provide a bonding failure determination device that can be used directly to implement this method.

(Structure of the Invention) According to the present invention, the first object is to place a cap on a container body with an open top that accommodates a semiconductor circuit element, and to attach a pair of caps arranged so as to be in contact with symmetrical edges of the cap. A micro-parallel seam is formed in which the plating layer interposed between the cap and the container body is melted by seam-joining the cap to the container body by applying electricity while rolling a tapered roller electrode to the periphery of the cap from above. This is achieved by a method for determining joint failure in a micro-parallel seam joining apparatus, characterized in that in the joining apparatus, a joint failure due to displacement of the cap is determined based on vertical displacement of at least one of the tapered roller electrodes.

The second object is to place a cap on a container body with an open top that accommodates a semiconductor circuit element, and to attach a pair of tapered rollers to the periphery of the cap, the pair of tapered rollers being arranged so as to be in contact with the symmetrical periphery of the cap. In the micro-parallel seam joining device, which seam-joins the cap to the container body by melting the plating layer interposed between the cap and the container body by applying electricity while making contact from above, there is no displacement of the cap. a displacement detection circuit that detects the displacement of at least one of the tapered roller electrodes based on the state; a setting device that sets an allowable range of displacement of the tapered roller electrode; and a comparator that compares the displacement of the tapered roller electrode with the allowable range. This is achieved by a bonding defect determination device for a micro-parallel seam welding device, which is characterized in that a bonding defect is determined based on the fact that the displacement of the tapered roller electrode is out of the allowable range.

(Principle of the Invention) As a result of a detailed study of the cause of bonding failure in the micro-parallel seam bonding method, the inventor found that the major cause was misalignment of the cap with respect to the two tapered roller electrodes.

4 and 5 are diagrams explaining the principle. FIG. 4 illustrates a state in which the seal frame 2 is in its normal position but only the cap 5 is displaced. That is, in this figure, the normal position of the cap 5 is shown by the solid line, but if the cap 5 is shifted by x toward the taper roller electrode 7 on the left side of the figure and comes to the imaginary line position, the taper roller electrode 7 is The tapered roller electrode 8 moves up a distance H, and the tapered roller electrode 8 moves down a distance H. As a result, it can be seen that both tapered roller electrodes 7 and 8 move to the positions shown by the imaginary lines in the figure.

Further, FIG. 5 shows a state in which the seal frame 2 is shifted by x toward the tapered roller electrode 7 side.
In other words, while the solid line in the figure indicates the normal position, when the seal frame 2 is shifted toward the tapered roller electrode 7 by x, the cap 5 above it also moves by x.
These will come to the imaginary line positions in the diagram. As a result, both tapered roller electrodes 7 and 8 move to the positions shown by the imaginary lines in the figure.

In these cases, due to the displacement x of the cap 5, one tapered roller electrode 7 is raised by H=x tan θ, and the other tapered roller electrode 8 is lowered by the same amount. Here, θ is the taper angle of the tapered roller electrodes 7 and 8. In this way, the tapered roller electrodes 7, 8
When there is vertical movement, the radius of the portion where the tapered roller electrodes 7, 8 contact the cap 5 changes. Therefore, even if the load with which the tapered roller electrodes 7 and 8 press against the cap 5 is the same, the contact pressure changes because the contact area changes. As a result, the contact resistance between the tapered roller electrodes 7, 8 and the cap 5, and the contact resistance between the cap 5 and the seal frame 2 become unbalanced. Furthermore, the heat transfer characteristics of the tapered roller electrodes 7 and 8 also become unbalanced.

In this way, even if the total current at the two junctions is the same, the thermal conditions such as the amount of heat generated and the amount of heat dissipated at each junction become unbalanced, resulting in an imbalance in temperature and a junction failure. I realized that it was something.

Therefore, the inventor discovered the fourth cause of these problems.
If the cap 5 is misaligned as shown in the figure, or
Taper roller electrodes 7, 8
The idea is to detect this based on the displacement in the vertical direction of the cap 5, and to determine a bonding failure based on the fact that the displacement of the cap 5 is outside a predetermined tolerance range.

(Embodiment) FIG. 1 is a side view of a micro-parallel seam joining device which is an embodiment of the present invention, and FIG. 2 is a block diagram of the joining defect determination device.

In this embodiment, as shown in FIG. 3, a circular cap 5 is placed on a container body 3 that rotates together with a rotary table 6 and seam-bonded. Reference numerals 10 and 10 each indicate a gate-shaped static load type welding head, and although not shown in the figure, they are disposed facing each other on the same machine frame as shown in the figure. Therefore, the explanation of the bonding heads 10, 10 will be limited to only one bonding head 10, unless necessary. Reference numeral 11 denotes a frame, and this frame 11 has a shaft 13 movable up and down by a linear motion bearing 12.
is retained. A heavy hanger 14 is loaded on the upper end portion of the shaft 13 to apply a downward load to the shaft 13. An electrode support 15 is fixed to the lower end of the shaft 13, and the tapered roller electrode 7 or 8 is attached to the support 15.
It is rotatably mounted perpendicular to the axis of the A power supply band 16 is connected to the electrode support 15 to supply current to the tapered roller electrodes 7 and 8.

The rotary table 6 is placed below between the tapered roller electrodes 7 and 8, with the container body 3 and the cap 5 placed thereon. Therefore, the tapered roller electrodes 7, 8 are pressed against the cap 5 by the loads of the weights 14, 14. In this state, when the rotary table 6 is rotated by an electric motor (not shown) or the like, and current is applied to both the tapered roller electrodes 7 and 8, the portions pressed by the tapered roller electrodes 7 and 8 generate heat, and the container body 3 The plating layer of the seal frame and the plating layer of the cap 5 are melted and seam-joined.

The micro-parallel seam joining apparatus described above is the same as the conventional apparatus, and therefore the elevating mechanism for the tapered roller electrodes 7, 8 and the like have been omitted.

In this embodiment, in order to detect the displacement of the shafts 13, 13, position sensors 18, 18 made of, for example, differential transformers are attached to the shafts 13, 13, and the relative movement distance between the shaft 13 and the frame 11 is determined by voltage fluctuation. Detect as a value.

In FIG. 2, 20 is a displacement detection circuit, and this displacement detection circuit 20 is connected to the two position sensors 1.
8, 18, amplifier circuits 21, 21 for amplifying the outputs of these position sensors 18, 18, a differential amplifier circuit 22 for calculating the difference between the outputs, and an absolute value circuit 23 for calculating the absolute value of the output of this circuit 22. Equipped with.
The position sensors 18, 18 are zero setting devices 18a, 18
The zero setting devices 18a, 18a adjust the output voltages of the position sensors 18, 18 to zero when there is no displacement of the cap 5. Also, since the position sensors 18, 18 are differential transformers, the output when there is no displacement of the cap 5 is set to zero, and when there is a displacement of the cap 5, one position sensor 18 outputs a positive voltage to the other position. Sensor 18 outputs a negative voltage.

23 is an absolute value circuit, which determines the absolute value of the differential amplifier circuit 22.

A comparison circuit 24 compares the output of the absolute value circuit 23 with a set value of the setter 25, and when it becomes larger than this set value, it is determined that there is a defective bond and sends a defective bond signal to the control circuit 26. The setting value of the setting device 25 is to set the permissible range of displacement of the tapered roller electrodes 7 and 8, that is, the permissible range of displacement of the cap 5.

The control circuit 26 issues a warning with a warning lamp or a warning buzzer based on the joining failure signal, cuts off the current to the tapered roller electrodes 7 and 8, stops the rotary table 6, and stops the seam joining.

In this example, the diameter of cap 5 is 12.87
mm, and the taper angle θ of the tapered roller electrodes 7 and 8 is
The angle shall be 15°. If the deviation x from the normal position of the cap 5 is 1.0 mm, the taper roller electrode 7,
8 are respectively displaced upward and downward by H=1.0×tan15°=1.0×0.27=0.27 mm. rotary table 6
rotates 185° in about 11.2 seconds. Therefore, the tapered roller electrodes 7 and 8 cover 20.2 mm of the circumference of the cap 5.
While it takes 11.2 seconds to make contact, it will be displaced by 0.27mm.

The sum of the absolute values of the upward and downward displacements of the tapered roller electrodes 7 and 8 is determined by the displacement detection circuit 20, and if this amount of displacement falls outside the allowable range set by the setting device 25, the control circuit 26 issues a warning and removes the seam. Stop the joining operation.

In the above embodiment, the sum of the absolute values of the displacements of the two tapered roller electrodes 7 and 8 is determined by the displacement detector 20, but the present invention is not limited to this. For example, if the cap periphery always moves in a direction perpendicular to the rotation axis of the tapered roller electrode, the displacement of only one tapered roller electrode may be detected and its absolute value may be compared with a set value. Possible cases in which such a method can be applied include cases in which circular caps are rotated and seam-joined, and rectangular caps are moved parallel to the circumferential direction and seam-joined.

Alternatively, one position sensor may be used to detect the relative displacement of the two tapered roller electrodes, and the absolute value thereof may be compared with a set value. For example, when using a differential transformer as a position sensor, the coil side of this differential transformer is fixed to one shaft 13, and the movable iron core side is fixed to the other shaft 13, and the relative displacement of the two is calculated by a single shaft 13. It may also be detected by a differential transformer.

In this case, the output of the position sensor is
The sensitivity is improved because it is twice as large as that of the embodiment shown in the figure. This method has the advantage of being able to detect only the displacement due to cap misalignment even when two position sensors move up and down at the same time, such as when regular polygonal caps are seam-joined while being rotated.

Further, in the embodiment shown in FIGS. 1 and 2, a differential transformer is used as the position sensor 18, and the zero setter 18a
However, the displacement detection circuit according to the present invention is of course not limited to this. For example, the output of a position sensor indicating the position of the tapered roller electrode at or immediately before the start of energization to the tapered roller electrode may be stored, and the displacement determined from the difference between the output of the position sensor during subsequent seam joining and this stored value. good. In addition, various configurations are possible, such as finding the maximum and minimum values of the output of the position sensor and finding the maximum displacement from the difference between the two, or indirectly detecting the displacement of the cap from the rate of change in the output of the position sensor. . The present invention includes any method in which cap displacement is detected based on the displacement of a tapered roller electrode.

(Effects of the Invention) As described above, the present invention has a method of determining whether or not the displacement of the cap is within an allowable range based on the displacement of the tapered roller electrode when micro-parallel seam joining the containers of semiconductor circuit elements. Detects the quality of the seam joint. Therefore, the difference in the rotation radius of the two tapered roller electrodes in contact with the cap does not exceed the allowable range, and bonding defects due to temperature imbalance can be detected with high accuracy. As a result, the following various effects can be obtained.

(1) It is possible to prevent a decrease in the airtightness of containers due to poor seam joints, and to significantly increase product yield.

(2) A strong airtight seal that will not be damaged during post-process assembly work or use is possible.

(3) Since the temperature imbalance between the two joints is reduced, the temperature will not rise excessively and damage to the tapered roller electrode and container will not occur.

(4) Since the temperature does not rise excessively, it is possible to prevent the temperature from adversely affecting the characteristics of the semiconductor circuit elements accommodated.

[Brief explanation of drawings]

FIG. 1 is a side view of a device that is an embodiment of the present invention, FIG. 2 is a block diagram of a device for determining defective joints, and FIG. 3 is an explanatory diagram of a micro-parallel seam joining method.
4 and 5 are diagrams explaining the principle of the present invention. 3... Container body, 4... Semiconductor circuit element, 5...
... Cap, 7, 8 ... Taper roller electrode, 18
...Position sensor, 20...Displacement detection circuit, 22...
... Differential amplifier circuit, 23 ... Absolute value circuit, 24 ...
Comparison circuit, 25...setting device.

Claims (1)

[Scope of Claims] 1. A cap is placed on a top-opened container body that accommodates a semiconductor circuit element, and a pair of tapered roller electrodes arranged so as to be in contact with symmetrical peripheries of the cap are placed on top of the periphery of the cap. A micro-parallel seam joining device for seam-joining the cap to the container body by melting a plating layer interposed between the cap and the container body by applying electricity while making contact between the cap and the container body, wherein at least one of the tapered rollers 1. A method for determining bonding defects in a micro-parallel seam bonding apparatus, characterized in that bonding defects due to displacement of the cap are determined based on vertical displacement of an electrode. 2. The peripheral edge of the cap is relatively moved in a direction perpendicular to the rotation axis of the tapered roller electrode,
The micro-parallel seam welding apparatus according to claim 1 is used to determine a welding defect in the micro-parallel seam joining apparatus according to claim 1, wherein the displacement of one of the tapered roller electrodes is detected, and a welding defect is determined based on the fact that this displacement is out of a preset tolerance range. Method. 3. The micro-parallel seam joining device according to claim 1, wherein a relative displacement between the two tapered roller electrodes is detected, and a joint failure is determined based on the fact that this relative displacement is outside a preset tolerance range. Method for determining bonding failure. 4. A cap is placed on a container body with an open top that accommodates a semiconductor circuit element, and a pair of tapered roller electrodes arranged so as to be in contact with the symmetrical periphery of the cap are energized while being rolled into contact with the periphery of the cap from above. In a micro-parallel seam joining device for seam-joining the cap to the container body by melting the plating layer interposed between the cap and the container body, at least one of the caps is seam-joined, based on a state in which there is no displacement of the cap. a displacement detection circuit that detects the displacement of the tapered roller electrode, a setting device that sets an allowable range of displacement of the tapered roller electrode, and a comparator that compares the displacement of the tapered roller electrode with the allowable range; A bonding defect determination device for a micro-parallel seam welding device, characterized in that a bonding defect is determined based on a displacement of the micro-parallel seam joining device being outside the permissible range. 5 a pair of tapered roller electrodes are arranged opposite to each other on a straight line orthogonal to the moving direction of the peripheral edge of the cap;
The microparallel according to claim 4, wherein the displacement detection circuit includes a position sensor that detects the displacement of one of the tapered roller electrodes, and an absolute value circuit that calculates the absolute value of the output of this position sensor. Joint defect determination device for seam joining equipment. 6. Claim 4, characterized in that the displacement detection circuit includes one position sensor that detects the relative displacement of two tapered roller electrodes, and an absolute value circuit that calculates the absolute value of the output of this position sensor. Welding defect determination device for micro-parallel seam joining equipment. 7 The displacement detection circuit includes two position sensors that detect the displacement of each of the two tapered roller electrodes, a differential amplifier that determines the difference between the outputs of these position sensors, and an absolute value that determines the absolute value of the output of this differential amplifier. A bonding defect determination device for a micro-parallel seam bonding device according to claim 4, comprising a circuit.