Magnetron sputtering method of LGA packaged electronic product
Technical Field
The invention relates to a magnetron sputtering method of an LGA packaged electronic product, belonging to the technical field of semiconductor packaging.
Background
The basic manufacturing process method for sputtering the traditional packaged electronic product comprises the following steps:
1. the surface of the traditional LGA (land grid array) product is covered with green paint except for pins and exposed welding pads;
2. firstly, taking a PI film (polyimide film), peeling off a release film of the PI film by using a rubberizing machine, and flatly attaching the PI film to a wafer ring, wherein the PI film is required to be accurately attached to the wafer ring;
3. placing the LGA product in an effective area of a wafer ring with a PI film by using a placement machine, and pressing the product by using a pressing machine to make the product tightly attached to the PI film in order to ensure that the LGA is tightly contacted with the PI film and prevent the sputtered coating from being overflowed to a metal surface to cause short circuit;
4. and then, placing the wafer ring with the LGA product attached on a machine table for high-temperature sputtering, separating the product from the PI film by using a blanking machine after sputtering, and placing the product in a material receiving tray.
The use of conventional sputtering processes for LGA products has the following problems:
a. when the LGA product is stripped from the PI film, a large amount of sputtering burrs are adhered to the edge of the bottom of the product, and the sputtering burrs have the risks of movement and separation, which may cause short circuit;
b. the traditional sputtering product has relatively high temperature, and the back of the product is easy to discolor when being heated;
c. the product directly contacts the PI film, the PI film cannot ensure the cleanliness, and the product can cause adverse effects on the product in the sputtering process.
Disclosure of Invention
The invention aims to solve the technical problem of providing a magnetron sputtering method of an LGA packaged electronic product in the prior art, which uses a pre-pasting film with high temperature resistance and high flexibility to be pasted at the bottom of the product before cutting, and changes the design of a substrate to ensure that a single product pin forms a green paint-free covering area to the edge of the product, and burrs caused by redundant sputtering after the single product is stripped from the pre-pasting film are left on a waste PI film together with the pre-pasting film, so as to reduce the sputtering burrs at the four sides of the bottom of the product.
The technical scheme adopted by the invention for solving the problems is as follows: a magnetron sputtering method of an LGA packaged electronic product, the method comprising the steps of:
step one, taking an LGA product, wherein the LGA product comprises a plurality of unit products, a groove is arranged between the bottoms of two adjacent unit products, and the groove is a green paint-free coverage area;
step two, taking a pre-sticking film, wherein the pre-sticking film comprises a release film, an adhesive layer and a base material film which are sequentially arranged from top to bottom;
thirdly, sticking a pre-sticking film on the bottom surface of the LGA product, and covering the groove with the pre-sticking film;
continuously sticking a PI film on the pre-sticking film at the bottom of the LGA product, cutting the whole LGA product into unit products along a cutting channel until partial PI films are cut, and still covering the pre-sticking film on the bottom edge of each unit product after cutting;
sputtering the LGA product, and sputtering metal layers on the upper surface and four side surfaces of the LGA product by a sputtering machine;
sixthly, carrying out film uncovering operation on the sputtered product;
and step seven, putting the stripped unit products into a carrying tray, and putting the unit products to be delivered in sequence.
Preferably, the green paint coverage area at the bottom of the LGA product in step one extends to the outer edge of the pins at the bottom of the single unit product, namely 25 um.
Preferably, in the first step, the area outside the green paint covered area is a green paint free covered area to form the groove.
Preferably, the outer edge of the bottom pin of the single unit product in the first step is at least 150um away from the outer edge of the LGA product.
Preferably, the thickness of the bonding layer in the second step is 12um, and the thickness of the substrate film is 12 um.
Preferably, the width of the effective area covered by the pre-coated film at the groove in the fourth step must be larger than the width of the cutting track.
Compared with the prior art, the invention has the advantages that:
1. the invention can solve the problem of product sputtering burr after traditional sputtering through the combination of groove design and pre-pasting film, thereby avoiding the problem of product short circuit caused by sputtering burr and greatly improving the yield;
2. the invention uses the pre-film to carry out the sputtering process, can ensure that the product has relatively low temperature, and prevents the product from discoloring at the bottom pin when the product is heated.
Drawings
FIG. 1 is a schematic diagram of a structure of a first step of a magnetron sputtering method for an LGA packaged electronic product according to the present invention.
FIG. 2 is a bottom view of the LGA packaged electronic product according to the second step of the magnetron sputtering method of the present invention.
FIG. 3 is a schematic structural diagram of a pre-film in a second step of the magnetron sputtering method for LGA packaged electronic products according to the present invention.
Fig. 4-7 are schematic diagrams illustrating a third step to a sixth step of a magnetron sputtering method for an LGA packaged electronic product according to the present invention.
Wherein:
groove 1
Green paint coverage area 2
Pre-film 3
Release film 4
Adhesive layer 5
Base material 6
PI film 7
A metal layer 8.
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 an LGA packaged electronic product, which comprises the following steps:
step one, taking an LGA product, wherein the LGA product comprises a plurality of unit products, and a groove 1 is designed between the bottoms of two adjacent unit products, as shown in figures 1 and 2;
the green paint coverage area 2 at the bottom of the LGA product extends to the position of about 25um outside the bottom pin of a single unit product, the area outside the green paint coverage area 2 is a green paint-free coverage area to form a groove 1, and the distance from the outer edge of the bottom pin of the single unit product to the outer edge of the LGA product is at least more than 150 um;
step two, taking a pre-film 3, wherein the structure of the pre-film is shown in figure 3, and the pre-film comprises a release film 4, an adhesive layer 5 and a substrate film 6 which are sequentially arranged from top to bottom, wherein the thickness of the adhesive layer 5 is 12um, and the thickness of the substrate film 6 is 12 um;
step three, pasting a pre-pasting film 3 on the bottom surface of the LGA product, as shown in FIG. 4, covering the groove 1 with a pre-pasting film, wherein the width of the effective area covered by the pre-pasting film at the groove 1 must be larger than the width of the cutting path;
step four, continuously pasting a PI film 7 on the pre-pasting film 3 at the bottom of the LGA product, completing product positioning point identification and correction on a cutting machine, cutting the whole LGA product into unit products along a cutting path, as shown in figure 5, cutting to a part of PI film, and still covering the pre-pasting film on the bottom edge of each unit product after cutting;
step five, sputtering the LGA product, as shown in figure 6, sputtering a metal layer 8 on the upper surface and 4 sides of the LGA product by a sputtering machine to achieve the effect of electromagnetic shielding;
sixthly, carrying out film uncovering operation on the sputtered product;
after the fifth step is finished, separating the LGA product from the pre-sticking film, and simultaneously keeping the redundant sputtering burrs and the pre-sticking film on the PI film;
and step seven, placing the stripped unit products into a carrying disc to finish placement of the LGA packaged electronic products to be delivered.
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.