CN111058006B

CN111058006B - A magnetron sputtering method for BGA electromagnetic shielding products

Info

Publication number: CN111058006B
Application number: CN201911266209.1A
Authority: CN
Inventors: 邢发军
Original assignee: Jiangsu Changjiang Electronics Technology Co Ltd
Current assignee: JCET Group Co Ltd
Priority date: 2019-12-11
Filing date: 2019-12-11
Publication date: 2021-07-27
Anticipated expiration: 2039-12-11
Also published as: CN111058006A

Abstract

The invention relates to a magnetron sputtering method of a BGA electromagnetic shielding product, which comprises the following steps: step one, taking a sputtering adhesive tape; secondly, punching a through hole with a corresponding size on the sputtering adhesive tape by using a heated punching die, and forming a slope on the surface of the sputtering adhesive tape close to the edge of the through hole in a pressing mode; thirdly, attaching the sputtering adhesive tape with the through hole to a sputtering carrier, then placing the BGA product on the position of the sputtering adhesive tape corresponding to the through hole, pressing down the BGA product by a pressing machine before sputtering, so that the solder balls on the outermost circle of the bottom edge of the BGA product can sink into the sputtering adhesive tape on the slope, and then performing sputtering operation; and step four, after the BGA product finishes the sputtering operation, heating the sputtering adhesive tape to above 175 ℃ to restore the plastic memory metal film to a memory shape, and spontaneously separating the BGA product from the sputtering adhesive tape. The invention can protect the solder ball from sputtering in the sputtering process by designing the structure and the material of the BGA sputtering adhesive tape, and the solder ball bounces from the sputtering adhesive tape which is plastically deformed, and simultaneously realize spontaneous separation of the product from the sputtering adhesive tape.

Description

Magnetron sputtering method of BGA electromagnetic shielding product

Technical Field

The invention relates to a magnetron sputtering method of a BGA electromagnetic shielding product, belonging to the technical field of semiconductor packaging.

Background

The basic fabrication process of conventional BGA sputtering is as follows:

as shown in fig. 1, a through hole 5 is formed in a sputtering adhesive tape 1, the sputtering adhesive tape 1 is firstly attached to a sputtering carrier 2 with an opening 3, then a BGA product 4 is placed on the position of the sputtering adhesive tape 1 corresponding to the through hole 5, the BGA product 4 needs to be pressed down by a pressing machine before sputtering, so that a solder ball 6 on the edge of the bottom of the BGA product 4 falls into the sputtering adhesive tape 1, the substrate is tightly attached to the sputtering adhesive tape, the bottom of the product is prevented from being overflowed during sputtering, then sputtering operation is performed, after sputtering is completed, a liftout machine with a thimble extends out of the opening 3 to separate the BGA product 4 from the sputtering adhesive tape 1, and finally the BGA product is placed in a receiving tray.

The conventional BGA sputtering process described above has the following disadvantages:

1. some BGA products have too large and excessive solder balls, the solder balls can not be completely sunk into the sputtering adhesive tape by virtue of pressing external force, and by adopting the traditional sputtering process, gaps between the products and the double-sided adhesive tape can cause the excessive plating of the products;

2. in the traditional BGA sputtering method, the solder balls are subjected to great stress in the process of being immersed into the adhesive tape, so that the sputtering adhesive tape of the pressure-sensitive material is remained on the surfaces of the solder balls;

3. according to the traditional BGA sputtering method, the solder balls are sunk into the sputtering adhesive tape by virtue of external force, and the elastic deformation of the sputtering adhesive tape can be gradually rebounded along with the change of time, so that the solder balls are popped out from the adhesive tape, and the product is overflowed;

4. according to the traditional BGA sputtering method, in the process of taking a part after sputtering, upward pressure is applied to the surface of the tin ball through the ejector pin, meanwhile, the surface of the product is sucked by the suction nozzle, the product is taken down from the sputtering adhesive tape and put into the material receiving disc, and the tin ball has a risk of damage in the process of taking the part, so that the appearance and the performance of the product are influenced.

Disclosure of Invention

The invention aims to solve the technical problem of providing a magnetron sputtering method of a BGA electromagnetic shielding product aiming at the prior art, which combines the basic principle of sputtering and can realize the protection of the bottom solder balls of the product from sputtering and the spontaneous separation of the product from the sputtering adhesive tape by designing the structure and the material of the BGA sputtering adhesive tape.

The technical scheme adopted by the invention for solving the problems is as follows: a magnetron sputtering method of a BGA electromagnetic shielding product, said method comprising the steps of:

step one, taking a sputtering adhesive tape;

the sputtering adhesive tape has a three-layer structure, wherein the base layer is a pressure-sensitive acrylic adhesive layer, the middle layer is a plastic memory metal layer, and the top layer is a pressure-sensitive acrylic adhesive layer;

punching a through hole with a corresponding size on the sputtering adhesive tape by using a punching die, and forming a slope on the surface of the sputtering adhesive tape close to the edge of the through hole in a heating and pressing mode;

thirdly, attaching the sputtering adhesive tape with the through hole to a sputtering carrier, then placing the BGA product on the position of the sputtering adhesive tape corresponding to the through hole, pressing down the BGA product by a pressing machine before sputtering, so that the solder balls on the outermost circle of the bottom edge of the BGA product can sink into the sputtering adhesive tape on the slope, and then performing sputtering operation;

and step four, after the BGA product finishes the sputtering operation, heating the sputtering adhesive tape to a temperature higher than 175 ℃ and lower than the melting point of tin, so that the plastic memory metal film is restored to a plane shape, and has upward bounce to the BGA product, so that the BGA product is separated from the sputtering adhesive tape spontaneously.

Preferably, the size of the through hole in the second step is smaller than the size of the outer contour of the BGA product.

Preferably, the included angle between the slope and the horizontal plane in the second step is 30-60 degrees.

Compared with the prior art, the invention has the advantages that:

1. the sputtering adhesive tape with the slope is used, so that the depth of the solder balls falling into the adhesive tape is reduced, and the pressure sensitive adhesive material is prevented from remaining on the surfaces of the solder balls to form residual adhesive;

2. the plastic memory metal layer can keep the deformation of the pressing before sputtering, the pressing pressure is not rebounded after being cancelled, the tin ball cannot bounce from the adhesive tape, namely, a gap is not generated between the BGA product and the sputtering adhesive tape, and the phenomenon of excessive plating can be avoided;

3. because the part is taken and a heating mode is adopted, the memory metal film recovers the memory shape so as to bounce the BGA product, no external force is required to be applied in the separation process of the BGA product and the sputtering adhesive tape, and the bottom tin balls can be protected from damage.

Drawings

FIG. 1 is a schematic diagram of the magnetron sputtering state of a conventional BGA product.

Fig. 2 is a schematic diagram of a magnetron sputtering state of a BGA electromagnetic shielding product of the present invention.

Fig. 3 is a schematic view showing a state where the BGA product is spontaneously separated from the sputtering tape by heating.

Wherein:

carrier 1

Sputtering adhesive tape 2

Opening 3

BGA product 4

Through-hole 5

And solder balls 6.

Detailed Description

The invention is described in further detail below with reference to the accompanying examples.

The invention relates to a magnetron sputtering method of a BGA electromagnetic shielding product, which comprises the following steps:

step one, taking a sputtering adhesive tape;

punching a through hole with a corresponding size on the sputtering adhesive tape by using a punching die, forming a slope on the surface of the sputtering adhesive tape close to the edge of the through hole in a heating and pressing mode, enabling the plastic memory metal film to form memory deformation under the conditions of high temperature and high pressure, and enabling the deformation to still maintain the memory shape at the initial high temperature after the plastic memory metal film is restored to the normal temperature;

the size of the through hole is smaller than the size of the outer contour of the BGA product;

the included angle between the slope and the horizontal plane is 30-60 degrees, the slope angle is matched with the arrangement of the product solder balls, and the solder balls on the outermost circle of the bottom edge of the BGA product can be guaranteed to be sunk into the top pressure-sensitive acrylic adhesive layer of the sputtering adhesive tape on the slope;

thirdly, attaching the sputtering adhesive tape with the through hole to a sputtering carrier, then placing the BGA product at the position of the sputtering adhesive tape corresponding to the through hole, pressing down the BGA product by using a pressing machine before sputtering, so that the outer solder balls on the outermost circle of the bottom edge of the BGA product sink into the adhesive tape at the slope, as shown in figure 2, and then performing sputtering operation;

and step four, after the BGA product finishes the sputtering operation, heating the sputtering adhesive tape to be more than 175 ℃ and less than the melting point of tin, and enabling the plastic memory metal layer to recover to a plane shape and have upward bounce to the BGA product so that the BGA product is separated from the sputtering adhesive tape spontaneously, as shown in figure 3.

In addition, the present invention also includes other embodiments, and any technical solutions formed by equivalent transformation or equivalent replacement should fall within the protection scope of the claims of the present invention.

Claims

1. a magnetron sputtering method of BGA electromagnetic shielding product, is characterized in that described method comprises the following steps:

Step 1, take a sputtering tape;

The sputtering tape has a three-layer structure of a base layer, an intermediate layer and a top layer, the base layer is a pressure-sensitive acrylic adhesive layer, the intermediate layer is a plastic memory metal layer, and the top layer is a pressure-sensitive acrylic adhesive layer;

Step 2, using a punching die to punch through holes of corresponding sizes on the sputtering tape, and forming a slope by heating and pressing on the surface of the sputtering tape near the edge of the through holes;

Step 3. First attach the sputtering tape with through holes to the sputtering carrier, then place the BGA product on the position of the sputtering tape corresponding to the through hole, and press down the BGA product with a pressing machine before sputtering to make the BGA product. The solder balls on the outermost ring of the bottom edge of the product can sink into the sputtering tape at the slope, and then perform the sputtering operation;

Step 4. After the BGA product completes the sputtering operation, heat the sputtering tape to a temperature above 175°C and below the melting point of tin, so that the plastic memory metal film returns to a flat shape, which has an upward rebound force for the BGA product, so that the BGA product spontaneously and the sputtering tape separation.

2. The magnetron sputtering method of a BGA electromagnetic shielding product according to claim 1, wherein in step 2, the size of the through hole is smaller than the outer contour size of the BGA product.

3 . The magnetron sputtering method of a BGA electromagnetic shielding product according to claim 1 , wherein the angle between the slope and the horizontal plane in step 2 is 30° to 60°. 4 .