Manufacturing method for single chip COB USB devices with optional embedded LED
According to certain embodiments of the invention, a single chip COB USB manufacturing is using chip-on-board (COB) processes on a PCB panel with multiple individual USB PCB substrates. This single chip COB USB is laid out in an array of N×M matrixes. The advantages of this method are: 1) use molding over PCBA, versus conventional of using SMT process to mount all necessary component on substrate to form PCBA; 2) simpler rectangular structure to fit any external decorative shell package for added value; and 3) package is moisture resistance if not water proof.
1. A method of fabricating flash memory devices, the method comprising:
providing a PCB (printed circuit board) panel having a plurality of PCB boards disposed in an N×M matrix such that the plurality of PCB boards can be separated with one or more single directional cuts, wherein each PCB corresponds to a single chip COB (chip-on-board) USB (universal serial bus) memory device to be manufactured;
performing an SMT (surface mount technology) process on the PCB panel to place one or more passive electronic components of a single chip COB USB memory device on a bottom surface of each PCB board, the one or more passive electronic components including at least one resister, capacitor, optional LED (light emitting diode), and oscillator;
performing a die bonding process to place one or more active electronic components of a single chip COB USB memory device on the bottom surface of each PCB board, the one or more active electronic components including a flash memory controller die and a flash memory die;
performing a wire bonding process to place electrical connections among the active and passive components of a single chip COB USB memory device on each PCB board;
performing an encapsulation process to encapsulate the active and passive electronic components of each PCB board to form an individual single chip COB USB memory device, using a transfer or injection molding process on the bottom surface of each PCB board which exposes a top surface of each PCB board with a plurality of metal contacts for physical and electrical contact with metal pads of a host interface socket when inserted.
2. The method of claim 1 , further comprising performing a singulation process on the PCB panel after the molding process to separate the single chip COB USB memory devices from the PCB panel using a disc saw to perform the one or more single directional cuts.
3. The method of claim 2 , wherein performing an encapsulation process comprises:
depositing the PCB panel into a bottom molding block, the bottom molding block including an outer rim that defines a highest surface of the bottom molding block, a block cavity edge that defines a slight larger outline than a dimension of the PCB panel, and a cavity depth that defines a package thickness of the flash memory devices;
lowering a top molding block onto the bottom molding block which encloses the PCB panel therein;
pouring molding material via one or more run gates of the top and bottom molding blocks into air space between the top and bottom molding blocks thereby encapsulating the PCB panel therein; and
performing a curing operation on the molding material to allow the molding material hardens which forms the molded PCB panel having individual single chip COB USB memory devices.