Preparation method of radio frequency chip

Abstract

The invention provides a preparation method of radio frequency chips, which comprises the following steps: (1) providing a substrate with a plurality of radio frequency chips on one surface, covering a plastic package layer on the surface of the substrate with the plurality of radio frequency chips, and pre-cutting along the periphery of each radio frequency chip to form a groove to expose a grounding layer of the substrate; (2) forming a first metal layer on one side, provided with the radio frequency chip, of the substrate, wherein the first metal layer covers the surface of the plastic package layer and the groove wall of the groove; (3) a second metal layer is formed on the surface of the first metal layer, the first metal layer and the second metal layer form a shielding layer, and the shielding layer is electrically connected with the grounding layer exposed after precutting; and (4) cutting along the groove to obtain a single radio frequency chip. The first metal layer and the second metal layer formed by the preparation method jointly form the shielding layer, so that the shielding effect is good and the reliability is high.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductors and relates to a method for preparing a radio frequency chip. Background Art

[0002] Radio frequency chips (RF packages) transmit communication signals, and electromagnetic interference is easily generated around the chip, so it is usually necessary to shield the electromagnetic interference.

[0003] The existing technology uses a shielding shell that matches the size of the RF chip and is directly nested outside the RF chip module for interference shielding. However, the following problems exist: (1) The shielding shell needs to be additionally welded to the ground terminal of the RF chip, and the welding process has poor stability and poor shielding effect; (2) The RF chip and the shielding shell are not an integral structure, and the installation process is prone to collisions that may damage the chip. There is also the problem of separation of the shielding shell and the chip; (3) The shielding cover of a single chip needs to be customized for products of different sizes, which is costly.

[0004] Therefore, there is an urgent need to provide an electromagnetic interference shielding solution to solve the above problems. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for preparing a radio frequency chip. The radio frequency chip preparation method provided by the present invention has good stability, high output, low cost and no requirements on the size of the radio frequency chip; the shielding layer is formed by the first metal layer and the second metal layer, and the shielding effect is good and the reliability is high. The shielding layer is directly electrically connected to the ground layer exposed after pre-cutting, and no additional welding is required; and the shielding layer and the radio frequency chip are an integral structure with extremely high bonding strength.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] The present invention provides a method for preparing a radio frequency chip, comprising the following steps:

[0008] (1) A substrate having a plurality of RF chips on one side is provided, wherein the substrate having the plurality of RF chips on one side is covered with a plastic packaging layer, and pre-cutting is performed along the periphery of each RF chip to form grooves to expose the ground layer of the substrate.

[0009] (2) A first metal layer is formed on a side of the substrate where the radio frequency chip is disposed, wherein the first metal layer covers the surface of the plastic encapsulation layer and the groove wall of the groove.

[0010] (3) forming a second metal layer on the surface of the first metal layer, wherein the first metal layer and the second metal layer constitute a shielding layer, and the shielding layer is electrically connected to the grounding layer exposed after the pre-cutting.

[0011] (4) Cutting is performed along the groove to obtain a single RF chip.

[0012] In the preparation method of the present invention, a first metal layer is formed on one side of the substrate where the RF chip is provided, so that it is changed from a non-conductor to a conductor, so as to facilitate the subsequent formation of a second metal layer. The first metal layer and the second metal layer together constitute a shielding layer, which has good shielding effect and high reliability; and the shielding layer composed of the two is directly electrically connected to the ground layer exposed after pre-cutting, without the need for additional welding.

[0013] The preparation method of the present invention has no requirements on the size of the radio frequency chip, and can produce products of various sizes at the same time without the need to select additional processing jigs for each product.

[0014] The shielding layer and radio frequency chip prepared by the method of the present invention are of an integral structure and have extremely high bonding strength, thereby avoiding the problems of installation collision and separation of the shielding layer from the body.

[0015] By adopting the preparation method of the present invention, each radio frequency chip on the substrate can have a shielding layer, and then separation can be achieved through a cutting step to obtain a single radio frequency chip with a shielding layer.

[0016] The preparation method of the invention has the advantages of good stability, high yield and low cost.

[0017] Preferably, before step (4), the method further includes the step of forming a protective layer on the surface of the shielding layer.

[0018] Preferably, the protective layer is an inert metal layer.

[0019] Preferably, the protective layer is formed by electroplating or evaporation.

[0020] Preferably, in step (2), before forming the first metal layer, a pretreatment step is further included, wherein the pretreatment step includes at least one of a surface roughening treatment, a degreasing treatment and an activation treatment.

[0021] Preferably, in step (2), before the pretreatment step, it also includes a step of applying a film on the side of the substrate where the radio frequency chip is not provided.

[0022] Preferably, the film is an anti-oxidation and high temperature resistant tape.

[0023] Preferably, in step (2), before the pretreatment step, the method further includes a step of baking the film.

[0024] Preferably, in step (2), before the film is attached, the surface of the plastic sealing layer of the substrate is cleaned.

[0025] Preferably, in step (4), before the cutting, the step of removing the film is also included.

[0026] Preferably, the first metal layer is formed by at least one of a physical vapor deposition process, a chemical vapor deposition process, an electroplating process or a chemical plating process.

[0027] Preferably, in the process of forming the first metal layer, the physical vapor deposition process includes an evaporation process and / or a sputtering process.

[0028] Preferably, the second metal layer is formed by at least one of a physical vapor deposition process, a chemical vapor deposition process, an electroplating process or a chemical plating process.

[0029] Preferably, in the process of forming the second metal layer, the physical vapor deposition process includes an evaporation process and / or a sputtering process.

[0030] Preferably, in step (3), before forming the second metal layer, a baking step is also included.

[0031] Preferably, in step (3), after the baking, the step of removing oxide from the surface of the first metal layer is also included.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] (1) In the preparation method of the present invention, a first metal layer is formed on a side of the substrate where the RF chip is provided, so that the non-conductor is changed into a conductor, so as to facilitate the subsequent formation of the second metal layer. The first metal layer and the second metal layer together constitute a shielding layer, which has good shielding effect and high reliability; and the shielding layer constituted by the two is directly electrically connected to the grounding layer exposed after pre-cutting, without the need for additional welding.

[0034] (2) The preparation method of the present invention has no requirements on the size of the RF chip, and products of various sizes can be produced simultaneously without the need to select additional processing jigs for each product.

[0035] (3) The shielding layer and the radio frequency chip prepared by the method of the present invention are of an integral structure and have extremely high bonding strength, which can avoid installation collision and separation of the shielding layer from the body.

[0036] (4) By adopting the preparation method of the present invention, each RF chip on the substrate can have a shielding layer, and then it can be separated by a cutting step to obtain a single RF chip with a shielding layer.

[0037] (5) The preparation method of the present invention has the advantages of good stability, high yield and low cost. DETAILED DESCRIPTION

[0038] To further illustrate the technical means and effects of the present invention, the present invention is further described below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention.

[0039] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0040] In one embodiment, the present invention provides a method for preparing a radio frequency chip, comprising the following steps:

[0041] (1) A substrate having a plurality of RF chips on one side is provided, wherein the substrate having the plurality of RF chips on one side is covered with a plastic packaging layer, and pre-cutting is performed along the periphery of each RF chip to form grooves to expose the ground layer of the substrate.

[0042] (2) A first metal layer is formed on a side of the substrate where the radio frequency chip is disposed, wherein the first metal layer covers the surface of the plastic encapsulation layer and the groove wall of the groove.

[0043] (3) forming a second metal layer on the surface of the first metal layer, wherein the first metal layer and the second metal layer constitute a shielding layer, and the shielding layer is electrically connected to the grounding layer exposed after the pre-cutting.

[0044] (4) Cutting is performed along the groove to obtain a single RF chip.

[0045] The "multiple" in the multiple RF chips refers to at least 2, for example, it can be 2, 5, 10, 15, 20, 30, 50 or 100, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0046] It should be noted that the pre-cutting in step (1) is to form a groove to expose the grounding layer of the substrate, but does not cut through the substrate. The cutting in step (4) is to cut through the substrate along the groove to obtain multiple single RF chips with a shielding layer.

[0047] In the preparation method of the present invention, a first metal layer is formed on one side of the substrate where the RF chip is provided, so that it is changed from a non-conductor to a conductor, so as to facilitate the subsequent formation of a second metal layer. The first metal layer and the second metal layer together constitute a shielding layer, which has good shielding effect and high reliability; and the shielding layer composed of the two is directly electrically connected to the ground layer exposed after pre-cutting, without the need for additional welding.

[0048] The preparation method of the present invention has no requirements on the size of the radio frequency chip, and can produce products of various sizes at the same time without the need to select additional processing jigs for each product.

[0049] The shielding layer and radio frequency chip prepared by the method of the present invention are of an integral structure and have extremely high bonding strength, thereby avoiding the problems of installation collision and separation of the shielding layer from the body.

[0050] By adopting the preparation method of the present invention, each radio frequency chip on the substrate can have a shielding layer, and then separation can be achieved through a cutting step to obtain a single radio frequency chip with a shielding layer.

[0051] The preparation method of the invention has the advantages of good stability, high yield and low cost.

[0052] In one embodiment, before step (4), the method further includes the step of forming a protective layer on the surface of the shielding layer.

[0053] In the present invention, a protective layer is formed on the surface of the shielding layer, which can protect the shielding layer from physical damage, prevent the shielding layer from being oxidized, and increase the reliability of the product.

[0054] In one embodiment, the protective layer is an inert metal layer.

[0055] In one embodiment, the inert metal of the inert metal layer includes nickel metal and / or chromium metal.

[0056] In one embodiment, the protective layer is formed by electroplating or evaporation.

[0057] In one embodiment, in step (2), before forming the first metal layer, a pretreatment step is further included, wherein the pretreatment step includes at least one of a surface roughening treatment, a degreasing treatment and an activation treatment.

[0058] In one embodiment, the surface roughening treatment comprises the following steps: immersing the substrate in a swelling solvent, taking it out, and then etching it using an alkaline chemical debonding agent.

[0059] During the surface roughening process of the present invention, an expansion solvent is used to soften the plastic sealing layer (such as an epoxy resin plastic sealing layer) and make the material loose; then etching is performed to increase the surface roughness and enhance the bonding strength between the subsequent RF chip body and the first metal layer.

[0060] In one embodiment, the alkaline chemical adhesive remover comprises an alkaline substance and potassium permanganate salt.

[0061] In one embodiment, the agent used in the degreasing treatment is an alkaline detergent, and the alkaline detergent includes an alkaline substance and a surfactant.

[0062] In the present invention, an alkaline cleaning agent including alkaline substances and surfactants is used to remove dirt and grease on the surface of the radio frequency chip body, and to change the surface electrical properties from weak negative charge to positive charge, thus laying a foundation for activation treatment.

[0063] In one embodiment, the surfactant includes diethyltriamine.

[0064] In one embodiment, the activation treatment comprises the following steps: placing the substrate in a solution containing tin salt and palladium salt for a first immersion, taking it out and placing it in an accelerating agent for a second immersion to obtain an activated substrate; the activated substrate has catalytic active centers.

[0065] In the present invention, the substrate is placed in a solution containing tin salt and palladium salt, and the tin salt and palladium salt react to generate negatively charged Sn-Pd micelles, which can be adsorbed on the surface of the radio frequency chip; then the Sn-Pd micelles are treated with an accelerating agent to peel off the Sn on the outer layer of Pd. 4+ The outer shell is removed to expose the Pd metal, and loose and unsolid palladium micelles or palladium ions and atoms are removed. The exposed Pd metal serves as a catalytic active center, which is beneficial to the subsequent formation of the first metal layer.

[0066] In one embodiment, the tin salt comprises tin chloride; and the palladium salt comprises palladium chloride.

[0067] In one embodiment, the accelerating agent comprises fluoroboric acid.

[0068] In one embodiment, in step (2), before the pretreatment step, it also includes a step of applying a film on the side of the substrate where the RF chip is not provided.

[0069] In the present invention, the film is applied to the side of the substrate where the radio frequency chip is not provided in order to prevent the side from being contaminated by chemicals in subsequent processing techniques.

[0070] In one embodiment, the film is an anti-oxidation and high temperature resistant tape.

[0071] In one embodiment, in step (2), before the pretreatment step, a step of baking the film is also included.

[0072] In the present invention, the film is baked before the pretreatment step, which can increase the bonding strength of the film and release the internal stress.

[0073] In one embodiment, in step (2), before the film is attached, the surface of the plastic sealing layer of the substrate is cleaned.

[0074] In one embodiment, the cleaning method includes plasma cleaning.

[0075] In one embodiment, in step (4), before the cutting, the step of removing the film is also included.

[0076] In one embodiment, the first metal layer is formed by at least one of a physical vapor deposition process, a chemical vapor deposition process, an electroplating process, or an electroless plating process.

[0077] The present invention forms a first metal layer on one side of the substrate where the radio frequency chip is arranged through at least one of a physical vapor deposition process, a chemical vapor deposition process, an electroplating process or a chemical plating process, so as to change the non-conductor into a conductor.

[0078] In one embodiment, in the process of forming the first metal layer, the physical vapor deposition process includes an evaporation process and / or a sputtering process.

[0079] In one embodiment, the material of the first metal layer includes at least one of copper, aluminum, nickel and iron. For example, the material of the first metal layer can be copper alone, aluminum alone or nickel-iron alloy.

[0080] In one embodiment, the second metal layer is formed by at least one of a physical vapor deposition process, a chemical vapor deposition process, an electroplating process, or an electroless plating process.

[0081] The present invention realizes rapid thickening through at least one of a physical vapor deposition process, a chemical vapor deposition process, an electroplating process or a chemical plating process to obtain a second metal layer.

[0082] In one embodiment, in the process of forming the second metal layer, the physical vapor deposition process includes an evaporation process and / or a sputtering process.

[0083] In one embodiment, in step (2), the pretreatment step includes surface roughening treatment, oil removal treatment and activation treatment performed in sequence; the process for forming the first metal layer is a chemical plating process; and the process for forming the second metal layer is an electroplating process.

[0084] In step (2) of the present invention, the substrate is subjected to surface roughening treatment, oil removal treatment and activation treatment in sequence, so that the substrate can be in a better state. Among them, since the surface of the RF chip after the oil removal treatment is positively charged, the Sn-Pd micelles can be effectively and fully adsorbed on the surface of the RF chip during the activation treatment, which is conducive to the formation of more catalytic active centers (Pd metal); the chemical plating process is to form a first metal layer by chemical reduction reaction deposition under the catalytic action of Pd, so more catalytic active centers are conducive to the formation of the first metal layer through the chemical plating process; after the first metal layer is formed, the electroplating process is used to facilitate rapid thickening to form the second metal layer.

[0085] In one embodiment, the material of the second metal layer includes at least one of copper, aluminum, nickel and iron. For example, the material of the second metal layer can be copper alone, aluminum alone or nickel-iron alloy.

[0086] In one embodiment, in step (3), before forming the second metal layer, a baking step is also included.

[0087] In the present invention, the baking step is performed before forming the second metal layer, so as to remove moisture inside the product and release the internal stress of the product.

[0088] In one embodiment, in step (3), after the baking, the step of removing oxide from the surface of the first metal layer is also included.

[0089] In the present invention, after the oxide on the surface of the first metal layer is removed, the bonding force between the second metal layer and the first metal layer can be increased.

[0090] In one embodiment, the method of removing oxide from the surface of the first metal layer comprises pickling.

[0091] In one embodiment, the present invention provides a method for preparing a radio frequency chip, which specifically comprises the following steps:

[0092] (I) providing a substrate having a plurality of RF chips on one side, wherein the side of the substrate having the plurality of RF chips is covered with a plastic sealing layer; performing pre-cutting along the periphery of each RF chip to form grooves to expose the grounding layer of the substrate.

[0093] (II) Plasma cleaning is performed on the surface of the plastic sealing layer of the substrate, and then an anti-oxidation and high-temperature resistant tape is mounted on the side of the substrate where the radio frequency chip is not provided, and then baking is performed.

[0094] (III) soaking the substrate treated in step (II) in an expansion solvent, taking it out, and then etching it with an alkaline chemical degumming agent, wherein the alkaline chemical degumming agent is composed of sodium hydroxide, potassium permanganate and a solvent; then degreasing it with an alkaline cleaning agent, wherein the alkaline cleaning agent is composed of sodium hydroxide, diethyltriamine and a solvent; then placing the substrate in a solution containing tin chloride and palladium chloride for a first soaking, taking it out, and placing it in fluoroboric acid for a second soaking to obtain an activated substrate, wherein the activated substrate has catalytic active centers.

[0095] (IV) placing the substrate treated in step (III) in a reaction raw material liquid, and performing a reduction reaction deposition under the catalytic action of the catalytic active center, thereby forming a first metal layer on the surface of the plastic encapsulation layer and the groove wall of the groove, and then drying; wherein the material of the first metal layer is copper element.

[0096] (V) pickling the substrate treated in step (IV) with dilute sulfuric acid, then placing the pickled substrate in an electroplating solution for electroplating to form a second metal layer on the surface of the first metal layer, thereby obtaining a shielding layer composed of the first metal layer and the second metal layer; then placing the obtained substrate in an electroplating solution and electroplating a protective layer on the surface of the shielding layer; wherein the material of the second metal layer is copper; and the material of the protective layer is an inert metal, wherein the inert metal is nickel metal and / or chromium metal.

[0097] (VI) removing the anti-oxidation and anti-high temperature tape on the substrate obtained in step (V), and then cutting along the groove to obtain a single radio frequency chip.

[0098] In summary, the RF chip preparation method provided by the present invention has good stability, high output, low cost and no requirements on the size of the RF chip; the shielding layer is formed by the first metal layer and the second metal layer, and the shielding effect is good and the reliability is high. The shielding layer is directly electrically connected to the ground layer exposed after pre-cutting; and the shielding layer and the RF chip belong to an integral structure and have extremely high bonding strength; by adopting the preparation method of the present invention, each RF chip on the substrate can have a shielding layer, and then it can be separated by a cutting step to obtain a single RF chip with a shielding layer.

[0099] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention are within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a radio frequency chip, characterized in that: The following steps are involved: (1) providing a substrate having a plurality of RF chips on one side, wherein the substrate having the plurality of RF chips on one side is covered with a plastic sealing layer, and pre-cutting is performed around each RF chip to form grooves to expose a ground layer of the substrate; (2) forming a first metal layer on a side of the substrate where the radio frequency chip is disposed, wherein the first metal layer covers the surface of the plastic encapsulation layer and the groove wall of the groove; (3) forming a second metal layer on the surface of the first metal layer, wherein the first metal layer and the second metal layer constitute a shielding layer, and the shielding layer is electrically connected to the grounding layer exposed after pre-cutting; (4) Cutting is performed along the groove to obtain a single RF chip.

2. The preparation method according to claim 1, characterized in that: Before step (4), the method further includes the step of forming a protective layer on the surface of the shielding layer.

3. The preparation method according to claim 2, characterized in that: The protective layer is an inert metal layer; Preferably, the protective layer is formed by electroplating or evaporation.

4. The preparation method according to claim 1, characterized in that: In step (2), before forming the first metal layer, a pretreatment step is also included, and the pretreatment step includes at least one of surface roughening treatment, degreasing treatment and activation treatment.

5. The preparation method according to claim 4, characterized in that: In step (2), before the pretreatment step, it also includes a step of laminating the surface of the substrate where the RF chip is not provided; Preferably, the film is an anti-oxidation and high temperature resistant tape; Preferably, in step (2), before the pretreatment step, the method further includes a step of baking the film.

6. The preparation method according to claim 5, characterized in that: In step (2), before the film is attached, the surface of the plastic sealing layer of the substrate is cleaned.

7. The preparation method according to claim 5, characterized in that: In step (4), before the cutting, the step of removing the film is also included.

8. The preparation method according to claim 1, characterized in that: forming a first metal layer by at least one of a physical vapor deposition process, a chemical vapor deposition process, an electroplating process, or an electroless plating process; Preferably, in the process of forming the first metal layer, the physical vapor deposition process includes an evaporation process and / or a sputtering process; Preferably, the second metal layer is formed by at least one of a physical vapor deposition process, a chemical vapor deposition process, an electroplating process or a chemical plating process; Preferably, in the process of forming the second metal layer, the physical vapor deposition process includes an evaporation process and / or a sputtering process.

9. The preparation method according to claim 1, characterized in that: In step (3), before forming the second metal layer, a baking step is also included.

10. The preparation method according to claim 9, characterized in that: In step (3), after the baking, the method further includes removing oxide from the surface of the first metal layer.