A manufacturing method for improving positioning accuracy of two-piece frame packaging

Abstract

A manufacturing method for improving the positioning accuracy of a two-piece frame package comprises the following steps: a. positioning a lower frame (15); b. applying an appropriate amount of solder paste on a wafer carrier of the lower frame (15); c. mounting a chip on the lower frame (15); d. applying an appropriate amount of solder paste on a wafer carrier of an upper frame (14); e. covering the upper frame (14) on the lower frame (15); f. high-temperature welding the upper and lower frames; g. resin encapsulation; h. rib cutting and forming. In the resin encapsulation step, the upper and lower positioning holes are of unequal diameters, thereby avoiding further expansion of the misalignment between the frame and the encapsulation mold, effectively improving the positioning accuracy between the frame and the encapsulation mold in the resin encapsulation stage, thereby effectively avoiding damage to the frame caused by the mold in the encapsulation stage, and achieving high-precision product shape control, thereby avoiding the problem of inconsistent length of the product pins on the left and right due to large positioning deviation in the rib cutting and forming step.

Description

Technical Field

[0001] The invention relates to a manufacturing method for improving the positioning accuracy of a two-piece frame package. Background Art

[0002] With the increasing demand for electronic components in various industries and the requirement for lower procurement costs, some small electronic components with SMD appearance are developing towards high efficiency and low cost. Among them, the use of high-density and matrix frames is becoming an industry trend, especially the combination of upper and lower two-pieces, which is more prominent in cost saving and has been widely accepted by the industry.

[0003] However, in the traditional two-piece frame design, the positioning holes of the upper and lower frames are of equal diameter, which leads to the problem of positioning accuracy and positioning error accumulation: in the first step of welding, due to the control accuracy of the hole production and the clearance margin of the positioning pin, the misalignment of the upper and lower frames after welding can only be controlled within ≤0.04mm. In the subsequent resin encapsulation step, since the misalignment problem of the upper and lower frames caused by the previous step already exists, the diameter of the positioning pin must be further reduced. Considering that the frame has been subjected to a high temperature of more than 360°C during the welding stage, due to thermal expansion and contraction, the misalignment of the upper and lower frames must be further increased, so the positioning pin generally has to reserve a margin of 0.06mm or even larger, which results in the positioning accuracy between the frame and the encapsulation mold in the resin encapsulation step. It can only meet ≤0.06mm or even larger. The mold design accuracy error is ≤0.04mm, which will not only cause the mold to crush the frame, seriously affecting the life of the encapsulation mold and the appearance of the product, but also greatly reduce the controllability of the product design size.

[0004] In the rib cutting and forming step after the resin encapsulation step, positioning holes are still used for positioning. For the same reason, due to the misalignment of the upper and lower frames caused by the chip welding step, and the upper and lower frames can no longer move relative to each other after high-temperature welding, if the upper and lower round holes of equal diameter (the upper and lower round holes have been misaligned) are still used for positioning, the positioning deviation will inevitably be further expanded, resulting in the pins of the product after rib cutting and forming are of different lengths, which is the so-called "long and short pins". Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a manufacturing method for improving the positioning accuracy of a two-piece frame package, comprising the following steps:

[0006] a. Position the lower frame on the graphite jig;

[0007] b. Apply an appropriate amount of solder paste on the wafer carrier of the lower frame;

[0008] c. Mount the chip on the wafer carrier of the lower frame;

[0009] d. Apply an appropriate amount of solder paste on the wafer carrier of the upper frame;

[0010] e. Cover the upper frame on the lower frame, and use a positioning pin to pass through the welding step positioning circular hole group and the welding step positioning long hole group to align and position them;

[0011] f. Perform high temperature welding on the upper and lower frames that are combined together;

[0012] g. Use a positioning needle to penetrate the encapsulation step positioning round hole group and the encapsulation step positioning long hole group to perform resin encapsulation positioning;

[0013] h. Encapsulate the frame with resin after high temperature welding and repositioning;

[0014] i. Cut and shape the resin-encapsulated frame.

[0015] As an improvement of the present invention, the upper and lower positioning holes of the welding step positioning circular hole group and the welding step positioning long hole group have the same diameter.

[0016] As a further improvement of the present invention, the upper and lower positioning holes of the positioning circular hole group in the encapsulation step and the positioning long hole group in the encapsulation step have unequal diameters.

[0017] The beneficial effect of the present invention is that in the high-temperature welding step, the frame is positioned by using the circular hole group positioned in the welding step and the long hole group positioned in the welding step, and then high-temperature welding is performed. Since the two groups of positioning holes are of equal diameter, the misalignment of the upper and lower frames after welding can be controlled to be ≤0.04mm. In the resin encapsulation step, the circular hole group positioned in the encapsulation step and the long hole group positioned in the encapsulation step are used for positioning, and the upper and lower positioning holes are of unequal diameters. The diameter of the upper frame positioning hole is 1.5mm, and the diameter of the lower frame positioning hole is 1.8mm, which is 0.3mm larger than the aperture of the upper frame, thereby avoiding further expansion of the misalignment between the frame and the encapsulation mold, thereby effectively improving the positioning accuracy between the frame and the encapsulation mold in the resin encapsulation stage, and can still be controlled to be ≤0.04mm, thereby effectively avoiding damage to the frame caused by the mold in the encapsulation stage, and can achieve high-precision product shape control, avoiding the problem of inconsistent length of the product pins on the left and right due to large positioning deviation in the rib cutting and forming step. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram after the upper and lower frames are aligned and positioned.

[0019] Figure 2 This is a schematic diagram of the upper frame positioning hole group.

[0020] Figure 3 Schematic diagram of the positioning hole group for the lower frame.

[0021] Figure 4 Schematic diagram of the positioning design used in the high temperature welding step.

[0022] Figure 5 Schematic diagram of the positioning design used in the resin encapsulation step and the rib cutting and molding step.

[0023] In the figure, 1. upper frame positioning long hole, 2. upper frame positioning round hole, 3. upper frame positioning round hole, 4. upper frame positioning long hole, 5. lower frame positioning round hole, 6. lower frame positioning long hole, 7. lower frame positioning round hole, 8. lower frame positioning long hole, 9. encapsulation step positioning round hole group, 10. encapsulation step positioning long hole group, 11. welding step positioning round hole group, 12. welding step positioning long hole group, 13. positioning pin, 14. upper frame, 15. lower frame. DETAILED DESCRIPTION

[0024] like Figure 1-5 As shown, a manufacturing method for improving the positioning accuracy of a two-piece frame package comprises the following steps:

[0025] a. Position the lower frame 15 on the graphite jig;

[0026] b. Apply an appropriate amount of solder paste on the wafer carrier of the lower frame 15;

[0027] c. Mount the chip on the chip carrier of the lower frame 15;

[0028] d. Apply an appropriate amount of solder paste on the wafer carrier of the upper frame 14;

[0029] e. Cover the upper frame 14 on the lower frame 15, and use the positioning pin 13 to pass through the welding step positioning circular hole group 11 and the welding step positioning long hole group 12 to align and position;

[0030] f. Perform high temperature welding on the upper and lower frames that are combined together;

[0031] g. Use the positioning needle 13 to pass through the encapsulation step positioning circular hole group 9 and the encapsulation step positioning long hole group 10 to perform resin encapsulation positioning;

[0032] h. Encapsulate the frame after high temperature welding and positioning with resin;

[0033] i. Cut and shape the resin-encapsulated frame.

[0034] The diameters of the upper frame positioning circular holes 2 and 3 in the upper frame 14 are 1.5 mm, and the semicircular diameters of the upper frame positioning long holes 1 and 4 are also 1.5 mm. The diameters of the lower frame positioning circular holes 5 and the lower frame positioning long holes 6 in the lower frame 15 are 1.8 mm, and the diameters of the lower frame positioning circular holes 7 and the lower frame positioning long holes 8 are 1.5 mm. Figure 3As shown, after the upper and lower frames are put together, a positioning pin 13 with a diameter of 1.48 mm is used to pass through the welding step positioning circular hole group 11 and the welding step positioning long hole group 12 to position the frame, and then high-temperature welding is performed. Since the two groups of positioning holes are of equal diameter, the misalignment of the upper and lower frames after welding can be controlled to ≤0.04 mm.

[0035] In the resin encapsulation step after high-temperature welding, the encapsulation step positioning circular hole group 9 and the encapsulation step positioning long hole group 10 are used for positioning. The positioning pin 13 with a diameter of 1.48 mm is still used, which is equivalent to using only two holes with a diameter of 1.5 mm, the upper frame positioning long hole 1 and the upper frame positioning circular hole 2 in the upper frame 14, for positioning. Since the aperture of the lower frame positioning long hole 6 and the lower frame positioning circular hole 5 at the corresponding position in the lower frame 15 is 1.8 mm, which is 0.3 mm larger than the aperture of the corresponding position of the upper frame 14, there will be no obstruction after the centers of the two groups of holes of the upper and lower frames coincide, and there is no need to consider the misalignment problem of the upper and lower frames. In this way, the further expansion of the misalignment between the frame and the encapsulation mold is avoided, thereby effectively improving the positioning accuracy between the frame and the encapsulation mold in the resin encapsulation stage, which can still be controlled at ≤0.04 mm, thereby effectively avoiding the damage caused by the mold to the frame in the encapsulation stage, and can achieve high-precision product shape control, avoiding the problem of inconsistent length of the product pins on the left and right due to large positioning deviation in the rib cutting and forming step.

Claims

1. A manufacturing method for improving the positioning accuracy of a two-piece frame package, comprising the following steps: a. Position the lower frame (15) on the graphite jig; b. Apply an appropriate amount of solder paste on the wafer carrier of the lower frame (15); c. Mounting the chip on the chip carrier of the lower frame (15); d. Apply an appropriate amount of solder paste on the wafer carrier of the upper frame (14); e. Cover the upper frame (14) on the lower frame (15), and use a positioning pin (13) to pass through the welding step positioning circular hole group (11) and the welding step positioning long hole group (12) to align and position them; the upper and lower positioning holes of the welding step positioning circular hole group (11) and the welding step positioning long hole group (12) have the same diameter; f. Perform high temperature welding on the upper and lower frames that are combined together; g. Use a positioning needle (13) to penetrate the encapsulation step positioning circular hole group (9) and the encapsulation step positioning long hole group (10) to perform resin encapsulation positioning; the upper and lower positioning holes of the positioning circular hole group (9) and the positioning long hole group (10) are of unequal diameters, the lower positioning hole of the encapsulation step positioning circular hole group (9) is larger than the upper positioning hole of the encapsulation step positioning circular hole group (9), and the lower positioning hole of the encapsulation step positioning long hole group (10) is larger than the upper positioning hole of the encapsulation step positioning long hole group (10); h. Encapsulate the frame with resin after high temperature welding and repositioning; i. Cut and shape the resin-encapsulated frame.

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