LCM outer lead connection

- Aug 03, 2018-

         

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The connection methods in the assembly of the liquid crystal display device are: conductive rubber connection, metal pin connection, thermal film connection, direct integrated connection.

    Conductive rubber connection, which is a common connection that can be called traditional. The outer lead of the liquid crystal is an ITO conductive film and cannot be soldered. However, it is easy to connect the LCD and the circuit board (PCB) by using a conductive rubber strip. When using a conductive rubber connection, the LCD and the conductive rubber must be used with a structural member. The PCB boards are fixed together, which is the function of the press frame. One type of press frame is molded by hard plastic, and the other type of press frame is stamped with metal.

    Metal pin connection, because people are accustomed to and trust soldered connection, for this reason, the metal pin connection method is designed, the metal pin is fixed on the LCD outer lead, and the LCD can be directly soldered on the PCB board, or the LCD can be inserted. On the socket of the PCB board, the pins are generally not installed by the customer, but are installed by the LCD manufacturer. The installation structure is to place a silver paste point on the outer lead of the LCD, and then insert the pin, solidify and then the whole The step is coated with a layer of insulating epoxy glue. The structure of the pin is mainly suitable for the reverse type LCD. It is suitable for the LCD with narrow glass and outer lead, so as not to be higher than the upper surface of the LCD. It should be noted that when inserting the socket, the pin end should be inserted into the socket, and the insertion direction should be vertical, and the insertion should not be shaken. It should also avoid repeated insertion and removal to avoid loose connection between the pin and the LCD. When soldering, apply low melting point solder and fast soldering. Good, and can not be repeatedly desoldered to avoid overheating and damage the pins to the LCD conductive film. The pins are made of metal stamping. Since the pins are stamped from metal, the plug always has a certain width, so any lead size cannot be applied. Commonly used sizes are 2.54mm, 2.25mm, 2.00mm, 1.80mm and 1.5mm.

    Hot-press film connection, also known as soft film connection, is the latest connection method that is convenient and reliable to use. The key to hot-pressed film is the hot-pressing glue between the conductive strips, which can be bonded to various strong bonds such as glass and epoxy board under pressure at a certain temperature. Moreover, the longer the time, the stronger the bonding.

    The following table shows typical performance parameters for hot pressed film:

    Performance parameters

    Conductive strip resistance 3kΩ or higher <900Ω/□


    Insulation resistance 1×108

    Insulation strength is greater than AC.250V, 1min

    Electrode gap 0.6mm

    Peel strength greater than 600g/cm 900 peeling, 50mm/min

    Operating temperature range -20°C~+70°C 240h

    Storage temperature range -20°C~+70°C 240h

    Recommended storage conditions 8 months sealed, cold, and protected from light less than 25 ° C

    The connection and use method of the hot pressed film is: tearing off the protective film, attaching one end of the adhesive surface to the LCD glass, and the other end to the PCB board at 110~130 ° C (the actual rubber surface should be 180~200) Under the condition of °C), the pressure of 30kg/cm2 can be about 5s. Since the base is soft, it is very convenient to fix when used, and the mounting thickness is very thin.

    Direct integration connection, the integrated connection here is to directly connect the LCD and IC circuits. The connected whole still has to be connected to the PCB.

    The LCD external lead is designed to be concentrated on a small area, and the special LSI-IC chip for LCD is glued therebetween, and the end points are welded together by the welding wire, and then a drop of sealing glue can be cast on the top. . The input end of the IC is also designed on the outer lead glass of the LCD, and is also soldered to the input terminal of the chip. At this time, the LCD with the chip has formed a complete LCD module, as long as the hot pressed film is used. Connect it to the PCB. This is a highly integrated, miniature, and thin connection method, which has broad application prospects and high use value in the development of current miniaturized instruments.