Application of Plasma Cleaning BGA Packaging Process

• Categories:Industry News
• Author:plasma cleaning machine-surface treatment equipment-CRF plasma machine-Sing Fung Intelligent Manufacturing
• Origin:
• Time of issue:2021-03-31
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(Summary description)The substrate or intermediate layer is an important part of the BGA package and can be used for impedance control and inductor/resistor/capacitor integration in addition to interconnection wiring. Therefore, the substrate is required to have high glass conversion temperature rS(about 175~230℃), high dimensional stability and low moisture absorption performance, and has good electrical properties and high reliability. In addition, there is a high adhesion between the metal film, the insulating layer and the substrate medium. 1. Lead bonding PBGA packaging process: 1) Preparation of PBGA substrate The two sides of the BT resin/glass core plate were pressed into extremely thin copper foil (12~18 microns thick), and the metal was drilled and metallized through holes. Using traditional PCB process, guide tape, electrode and welding zone array mounted with solder ball are made on both sides of the substrate. Then a solder mask is added to make a pattern of exposed electrodes and welds. In order to improve production efficiency, a substrate usually contains more than one PBG substrate. 2) Packaging process WAFer thinning → wafer cutting → chip bonding → plasma cleaning → lead bonding → plasma cleaning → molded packaging → solder ball assembly → reflow soldering → surface marking → separation → inspection → test packaging Silver-filled epoxy binder is used to bond the IC chip to the substrate, and then the connection between the chip and the substrate is realized by gold wire connection, and then the chip, welding line and pad are protected by molding encapsulation or liquid glue pasting. A specially designed solder ball 62/36/2Sn/Pb/Ag or 63/37/Sn/Pb with a diameter of 30mil(0.75mm) with a melting point of 183℃ is used for reflow soldering in a common reflow furnace. The high temperature processing temperature cannot exceed 230℃. Substrates are then centrifugally cleaned with a CFC inorganic cleaner to remove residual solder and fiber particles, followed by marking, separation, inspection, testing, and packaging. The above is the lead bond PBGA packaging process. 2. FC-CBGA packaging process: 1) Ceramic substrate Because the FC-CBGA substrate is multilayer ceramic substrate, its production is difficult. Due to the high wiring density of the substrate, narrow spacing, and many through holes, as well as the substrate coplanar requirements for higher reasons. The main process is: first, the multi-layer ceramic sheet substrate is co-fired into multi-layer ceramic metallized substrate at high temperature, and then the multi-layer metal wire is made on the substrate, and then electroplating. In the process of CBGA assembly, the CTE mismatch between the substrate, chip and PCB is the main cause of product failure. In order to improve this situation, in addition to the use of CCGA structure, another ceramic substrate can also be used - HITCE ceramic substrate. 2) Packaging process The preparation of the flanges: groan cut → groan chip flip and reflow soldering → bottom filling groan heat transfer grease, sealing distribution of solder + cap bucket assembly solder ball → reflow bucket marking + separation groan → inspection → test packaging 3. Packaging process of lead connection TBGA: 1) TBGA loading TBGA is usually made of polyimide material. Manufacturing, the first two sides of the copper copper coating, and then nickel plating, gold plating, and then punching, through the hole metallization, made into graphics. Because in this lead connection TBGA, the packaging heat sink is the addition solid of the packaging and the core cavity base of the shell, the carrier tape should be bonded to the heat sink with pressure-sensitive adhesive before packaging. 2) Packaging process WAFer thinning → wafer cutting → chip bonding → cleaning → lead bonding → plasma cleaning → liquid sealant filling → solder ball assembly → reflow soldering → surface marking → separation → inspection → test → packaging