JPS59198736A - Seam welding process - Google Patents

Abstract

PURPOSE:To make the width of fused part of a cover even along the overall side of the cover so that the cover may be evenly welded into the seal frame of a package by a method wherein angular velocity is controlled corresponding to the rotary angle of a cover so that the moving speed of the contact part of welding electrodes and the cover may be made constant along the overall side of the cover. CONSTITUTION:The angular velocity (W) is controlled corresponding to the rotary angle of a cover 3 so that the moving speed of the contact part of welding electrodes 7 and the cover 3 may be made constant along the overall side of the cover 3. For instance, an encoder 11 is fixed on a rotary axle 9 to detect the rotary angle of the cover by the encoder 11 and a photosenser 12 while the detected results are transmitted to a power supply 13 as signals by which the power supplied for a motor 10 from the power supply 13 is fluctuated corresponding to the rotary angle while the fluctuation is conducted through the rotary axle 9 and a jig 8 to a package substrate 1 so that the angular velocity (w) may be controlled as mentioned above.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to a seam welding method, more specifically, seam welding a lid of a semiconductor package to a sealing frame of a package base using a rotary seam welding machine. Concerning how to weld with.

(2) Background of the technology A seam welding machine that welds a lid to the seal frame of a semiconductor bank-type large tube (hereinafter referred to as "Punke-T-type") with a rectangular outline is shown in cross-sectional view in Figure 1.
2 is a package base, 2 is a sealing frame brazed to the pan cage L, 3 is a lid, 4 is a semiconductor chip, 5 is a wire for connecting the semiconductor chip, and 6 is a wire 5 that passes through a wiring layer in the package base 1 outer leet, connected to
Reference numeral 7 indicates a welding electrode (hereinafter simply referred to as an electrode), 8 a jig for storing and fixing the package for seam welding, and 9 a rotating shaft for transmitting the rotation of the motor 10 to the jig 8.

FIG. 2 is a schematic plan view of the electrode 7 and the package shown in FIG. 1, and when the aforementioned rotation axis rotates 90 times, the package rotates in the direction shown by the arrow in the figure. Note that in FIG. 2 and subsequent figures, the same parts as those already illustrated are designated by the same reference numerals.

The seal frame 2 is made of Kovar or 42 alloy and is brazed to the pan cage base 1. Lid 3 is also made of Kovar or 42 alloy. A voltage of 8 volts is applied between the electrodes 7, and current flows to 1508 to 180. The electrode 7 is in contact with the lid 2, and when current is passed through the electrode, the lid is melted by Joule heat,
It is firmly welded to the seal frame 2.

(3) Prior Art and Problems In the above-mentioned seam welding machine, since the rotating shaft 9 conventionally rotates at a constant speed, the moving speed (peripheral speed) of the contact portion between the electrode 7 and the lid 3 depends on the contour of the package. In the case of a rectangular package as shown in the structural plan view in Figure 3, it is not constant; in other words, the part along the long side of the package U is in contact with the electrode longer than the part near the corner, so the The width of the molten area (indicated by sand in the figure) is larger in the center of the long sides of the package and smaller at the corners.

In the prior art, the melt width is large at the center of the long sides of the package and small at the corners.

If the corner parts are not sufficiently welded, they will not be completely sealed (1・ti sealed), and the N2 gas inside will leak or the moisture from the outside will enter. This causes a decrease in semiconductor package manufacturing yield and reliability.

(4) Purpose of the Invention In view of the above-mentioned conventional problems, the present invention provides a system for attaching a lid to a rectangular semiconductor package with a rotating seam. g 4ji 41! To provide a seam welding method in which the width of the fused portion of the lid is uniform over the length of the lid when welding in A, and the lid can be welded to the sealing frame of the package with perfect uniformity.

(5) Structure and object of the invention According to the present invention, a pair of welding electrodes is brought into contact with a rectangular lid of a semiconductor package, the lid is rotated, and each side of the lid is seamed to a sealing frame of the package. Provided is a seam welding method characterized in that when welding, the angular velocity is controlled according to the rotation angle of the lid so that the moving speed of the contact part between the welding electrode and the lid is constant throughout the week of the lid. This is achieved by

(6) Examples of the invention An embodiment of the present invention will be explained below with reference to the drawings.

Referring to FIG. 4, when the length and width W of the lid are set as shown, when welding a rectangular package with a rotary seam welder, the moving speed of the contact area between the electrode and the lid is The values differ in some corners. (ω is the angular velocity) If the time for the electrode to pass through L/2 is t=Q, the moving speed ν of the contact portion is expressed as: ``--5ec2ωt = sec2(tan' L/
W) vl,.

So, when L/W=1, it is υ in the case of a square) is also π-2.

Therefore, in order to solve the above-mentioned conventional problems, in this actual journey example, the angular velocity ω is controlled so that the moving speed of the contact portion between the electrode 7 and the lid 3 is constant along the direction of the lid. The welding width was kept constant. That is, in FIG. 4, the movement speed of the welding electrode at the above-mentioned contact portion is adjusted according to the rotation angle of the lid so that the movement speed at the 7-cage angle portion is equal to the movement speed at the center of the pan. The melting width is made constant by controlling the angular velocity ω.

A device for this purpose is shown in FIG. An encoder 11 is fixed to the rotating shaft 9, the rotation angle of the lid is detected by the encoder 11 and the photo sensor 12, and the detected result is sent to the power source 13-4 as a signal, which is applied from the power source 13 to the motor 1o. The power is changed according to the rotation angle, and this change is transmitted to the rotating shaft 9, the jig 8, and the package base 1 to control the angular velocity ω.

(However, since the moving speed of the contact part is uniform when the electrode 7 is in contact with the long side of the lid and when the electrode 7 is in contact with the corner part of the lid, the lid is uniformly welded along its length, and the weld width described above is uniform over the length of the lid.

(7) Effects of the Invention As explained in detail above, according to the method of the present invention, when sealing a semiconductor package, the lid is welded to the seal frame of the pan cage base with the same width, so there is no possibility of gas leakage or moisture contamination. This method prevents danger and is highly effective in improving manufacturing yield and product reliability in semiconductor package manufacturing.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a conventional seam welder, Figure 2 is a plan view of the pan cage and electrode in Figure 1, Figure 3 is a plan view showing the welding width of the package lid in Figure 2, and Figure 4. 5 is a diagram showing the moving speed of the contact portion between the package lid and the electrode in the conventional method, and FIG. 5 is a layout diagram of a seam welding machine for carrying out the method of the present invention. 1-package base, 2-seal frame, 3-lid,
4-semiconductor chip, 5-wire, 6-outer lead, 7-welding electrode, 8-jig, 9-rotating shaft, 10-motor, 11-
encoder,. 12- Photosen No. 113- Power supply diagram 1

Claims (1)

[Claims] When a pair of welding electrodes is brought into contact with the rectangular lid of a semiconductor package, the lid is rotated, and each side of the lid is seam welded to the seal frame of the pan cage, the moving speed of the contact portion between the welding electrode and the lid is A seam welding method characterized in that the angular velocity is controlled according to the rotation angle of the lid so that it remains constant over the week of the lid.