Chip plastic package material seepage cleaning process

Abstract

The invention provides a chip plastic package material seepage removal process, and a series of treatment procedures are further carried out after a plastic package device and comprise the steps of hanging, alkaline solvent soaking, high-pressure cleaning, electrolysis, electroplating, neutralization, water washing, drying and discharging. The electrolysis is characterized in that the plastic package device is immersed in an alkaline solution, a copper lead is used as a cathode, graphite or metallic titanium is used as an anode, electrolysis under safe voltage is carried out, hydrogen is generated on the surface of the cathode, and the immersion solution in a gap between a plastic package material and the copper lead is forcibly extruded. According to the invention, the lead is prevented from being polluted by a later-stage exudation solution, the redundant immersion solution is also prevented from permeating towards the direction of the chip and damaging the chip, and the overall manufacturing quality of the plastic package device is effectively improved.

Description

Technical Field

[0001] The invention relates to a plastic packaging technology for microelectronic components. Background Art

[0002] With the development of science and technology, the size of electronic devices is getting smaller and smaller, the integration is getting higher and higher, and the requirements for electronic packaging materials are becoming more and more stringent. Microelectronic packaging technology has gradually become one of the important factors affecting the development of microelectronic technology. Electronic packaging materials involve many disciplines, and polymers such as epoxy resin, silicone, and polyimide are the main materials for microelectronic packaging. The thermal shock and wet-heat stability of packaging materials are important factors affecting reliability. Moisture entering the plastic sealing gap will cause the packaging "popcorn effect", electrochemical migration and other consequences, causing the device to fail. There is also a situation where there is a gap between the plastic sealing material and the electronic components to be plastic sealed. During the production process, a solution penetrates into the gap. When used, the plastic sealing body may penetrate into the liquid, causing the lead frame connected inside and outside the plastic sealing body to corrode and discolor.

[0003] The invention with application number: 2020106701068 discloses a high-density aluminum silicon carbide material and a preparation method thereof, wherein silicon carbide powder, silicon carbide powder, silicon carbide powder and alcohol are ball-milled and then dried to obtain a mixed powder, paraffin is melted and then added to the mixed powder and silica sol to make a mixed slurry, and then die-casting is made into a ceramic body; the ceramic body is subjected to four temperature-raising treatments, and after wax removal and pre-sintering, a silicon carbide ceramic body is made; the silicon carbide ceramic is loaded into a graphite mold, loaded into a tooling barrel, the tooling barrel is fixed in the furnace chamber of the impregnation equipment, the furnace chamber temperature is controlled to preheat the tooling barrel, and the metal aluminum is placed in the lower furnace chamber of the impregnation equipment for smelting and refining; the molten aluminum liquid is infiltrated into the ceramic body in the tooling barrel to complete the infiltration. This invention is to penetrate from the outside to the inside. Summary of the invention

[0004] Purpose of the invention: The invention provides a chip plastic encapsulation material seepage removal process which can eliminate the solution accumulated in the gap and prevent the subsequent seepage from contaminating the copper lead and can be simply modified on the original production line.

[0005] Technical solution: The chip plastic encapsulation liquid removal process of the present application. It is used for the subsequent treatment of plastic encapsulated devices. The plastic encapsulated device refers to an object obtained by bonding the chip to a carrier of a copper lead frame (or copper lead or copper pin), and then curing the plastic encapsulation material (such as epoxy resin). The subsequent treatment of the plastic encapsulated device has the following processing steps in order: hanger (hanging the plastic encapsulated device on a bracket and transporting it to the subsequent process in turn), alkaline solvent immersion, cleaning (water washing), electrolysis (there is no such process in the traditional process, resulting in the finished plastic encapsulated device after electroplating or in use, the immersion liquid seeps out from the gap between the plastic encapsulation material and the copper lead, contaminating the copper pin or changing color), high-pressure cleaning (deionized water spray cleaning, removing the seeped immersion liquid), or activation (such as descaling), electroplating, or neutralization (acid-base neutralization is neutral), water washing (preferably ultrasonic hot water spraying, no other chemical medium is used, and no adverse components will penetrate into the gap), drying (such as hot air drying), unloading (removing the device from the bracket).

[0006] The alkaline solvent immersion is to immerse the plastic encapsulated device in a weak alkaline mixed solvent of amide, siloxane and alcohol (the immersion time is relatively long, 5-15 minutes, which helps to dissolve the release agent and grease, and does not dissolve or corrode the plastic encapsulation material), and heat the immersion to remove the release agent on the plastic encapsulation material and the grease on the copper lead.

[0007] The electrolysis is to immerse the plastic-encapsulated device in an alkaline solution (preferably a strong alkaline solution of potassium hydroxide or sodium hydroxide, which is fully ionized and produces a higher concentration of hydrogen during electrolysis; the electrolysis time is short, 5-15 seconds, to reduce corrosion to the plastic-encapsulating material), use a copper lead as an electrolysis cathode, and use graphite or metal titanium as an electrolysis anode, preferably electrolyzing at a safe voltage (such as 12-36V). During the electrolysis reaction, hydrogen is generated on the cathode surface. When the hydrogen overflows, a large hydrogen pressure is generated in the narrow gap (micrometer level), and the immersion solution in the gap between the plastic-encapsulating material and the copper lead will be forcibly squeezed out and removed in the subsequent cleaning process.

[0008] The electroplating method comprises the following steps: immersing a plastic-sealed device (the copper lead wire can be immersed in the solution by adjusting the liquid level of the solution, and the plastic-sealed part may not be immersed or not fully immersed) in an electroplating solution (containing an organic tin solution), using the copper lead wire as an electroplating cathode, and using metal tin (tin ball, tin block) as an electroplating anode, or a titanium electrode or a graphite electrode as an electroplating anode (in this case, an organic tin solution is supplemented); a layer of tin can be electroplated on the copper lead wire to prevent the copper lead wire from being oxidized and discolored, thereby extending its service life.

[0009] Beneficial effects: The present invention can complete all the processes from immersion cleaning to electroplating and drying of the plastic-encapsulated device, cleans it and has good electroplating quality. In particular, the electrolysis process is provided to remove the remaining solution in the gap between the plastic-encapsulated material and the copper lead, thereby avoiding the later seepage solution from contaminating the lead and preventing the excess immersion solution from penetrating toward the chip and damaging the chip, thereby effectively improving the overall manufacturing quality of the plastic-encapsulated device.

[0010] Different solutions are used for immersion, electrolysis and electroplating respectively. It is easy to replace the solution on the production line, and the immersion depth of the electroplating solution can be adjusted, which effectively protects the cleanliness, appearance and internal quality of the device in the later stage of electroplating. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a schematic diagram of an apparatus for an electrolysis process of the present invention; Figure 2 It is a schematic diagram of an apparatus for an electroplating process of the present invention.

[0012] In the figure, 1-plastic encapsulation material; 2-copper lead; 3-electrolytic cell; 4-electrolytic cathode; 5-electrolytic anode; 6-electrolytic solution; 7-electroplating cell; 8-electroplating cathode; 9-electroplating anode; 10-electroplating solution; 11-tin ball; 12-chip. DETAILED DESCRIPTION

[0013] Embodiment 1: The chip plastic packaging material seepage removal process of the present invention comprises a plastic packaging device having subsequent processing steps in sequence: soaking, cleaning, electrolysis in a dilute strong alkaline solution, electroplating, and water washing.

[0014] In the electrolysis process, the Figure 1 In the device shown, the plastic-encapsulated device is immersed in an electrolyte 6, a copper lead 2 is used as a cathode 4, and graphite is used as an anode 5, and electrolysis is performed at a voltage of 12-36 V. Hydrogen is generated on the surface of the cathode 4, and the immersion solution in the gap between the plastic-encapsulating material 1 and the copper lead 2 is forcibly squeezed out, and then removed in the subsequent cleaning process.

[0015] The main component of the electrolyte 6 is potassium hydroxide, the tank concentration is 20%-40%, and the electrolyte temperature is about 40°C.

[0016] The main components of the electroplating solution 10 are: dilute sulfuric acid, with a bath concentration of 10-20%, stannous sulfate, with a bath concentration of 60-100 g / L, and other additives. The electroplating solution temperature is about 30-45°C.

[0017] Embodiment 2: The chip plastic packaging material seepage removal process of the present invention comprises the following processing steps of plastic packaging components: racking, alkaline solvent immersion, cleaning, electrolysis, high-pressure cleaning, activation, electroplating, neutralization, ultrasonic hot water cleaning, and unloading from the bracket.

[0018] The main components of the soaking liquid are: alcohol solvent, content 30%; methyl silicone oil, content 22%; liquid amide, content 25%; the soaking liquid temperature is about 60-70°C.

[0019] The main component of the electrolyte 6 is sodium hydroxide, the tank concentration is 20%-30%, and the electrolyte temperature is about 40°C.

[0020] The main components of the electroplating solution 10 are: methanesulfonic acid, with a bath concentration of 160-240 g / L, organic tin sulfonate, with a bath concentration of 40-80 g / L, other additives, with a bath concentration of 80-120 ml / L, and the electroplating solution temperature is about 40-50°C.

[0021] In the electrolysis process, the Figure 1 In the device shown, the plastic-encapsulated device is immersed in an electrolyte 6, a copper lead 2 is used as a cathode 4, and graphite is used as an anode 5, and electrolysis is performed at a voltage of 24-36 V. Hydrogen is generated on the surface of the cathode 4, and the immersion solution in the gap between the plastic-encapsulating material 1 and the copper lead 2 is forcibly squeezed out, and then removed in the subsequent high-pressure cleaning process of the high-pressure water flow.

[0022] In the electroplating process, the Figure 2 In the device shown, the electroplating cathode 8 is connected to the copper lead 2, the copper lead 2 is immersed in the electroplating solution 10, and the upper part of the plastic packaging material 1 does not need to be immersed; the electroplating anode 9 is a metal tin rod or tin ball 11.

Claims

1. A chip plastic encapsulation material seepage removal process, wherein the plastic encapsulated device has all or part of the following processing steps in sequence: hanging, soaking, cleaning, activation, electroplating, neutralization, water washing, and unloading, wherein soaking and electroplating are necessary steps; the plastic encapsulated device has a plastic encapsulation material (1) and a copper lead (2), characterized in that: There is an electrolysis step between the soaking step and the electroplating step. In the electrolysis step, the copper lead (2) is connected to the electrolysis cathode (4). During the electrolysis process, hydrogen is generated and adheres to the surface of the electrolysis cathode (4). When the hydrogen overflows, the soaking solution in the gap between the plastic packaging material (1) and the copper lead (2) is forcibly squeezed out and removed.

2. The chip plastic packaging material seepage removal process according to claim 1, characterized in that: The electrolysis is performed by immersing the plastic-sealed device in a strong alkaline solution, using graphite or metal titanium as the electrolytic anode (5) of the electrolytic cell, and performing the electrolysis at a safe voltage of 12-36V.

3. The chip plastic packaging material seepage removal process according to claim 1, characterized in that: The soaking is to soak the plastic packaged device in a weakly alkaline mixed solvent of amide, siloxane and alcohol, and then heat and soak it.

4. The chip plastic packaging material seepage removal process according to claim 1, characterized in that: The electroplating process comprises immersing the copper lead wire (2) of the plastic-encapsulated device in an organic tin electroplating solution (10), using the copper lead wire (2) as an electroplating cathode (8), using metal tin as an electroplating anode (9), and electroplating a layer of tin on the copper lead wire (2).

5. The chip plastic packaging material seepage removal process according to claim 1, 2 or 3, characterized in that: The soaking time is 5-15 minutes and the electrolysis time is 5-15 seconds.

Images