Electronic grade fiberglass cloth (hereinafter referred to as “electronic yarn and electronic cloth”) is not only a rising star in the series of electrical insulation glass fiber products, but also a essential base material for CCL and printed circuit board .
Electronic grade glass fiber nurture grow in the “mother” of the tank furnace, and with the gradual development of the tank furnace and continuous improvement and growth, drawing from the crucible into the tank furnace drawing process. Since the 20th century, 60 years, the glass fiber products enter the electronics industry as the representative of the emerging industrial applications and become one of the main raw materials. Because of its high-speed and high efficiency gradually replace the traditional crucible method of production technology and promote the development of tank furnace fiber drawing technology so that most of the spinning yarn turn into the tank furnace production. At the same time, the rapid rise of emerging electronics industry plays a role in fueling on the replacement of electronic grade glass fiber products.
In this paper, I work on numbers of technical issues on the practice of electronic yarn, electronic cloth.
Electronic yarn production quality control
The electronic yarn adopts the multi-drawing process of multi-hole and large-leakage board of the tank furnace, which made by forced cooling, modified starch-type infiltration agent, roller-type monofilament oil impregnated, , and finally the use of big package frequency conversion velocity modulation drawing and the leakage board temperature compensation technology. At present, commonly used electronic yarn brands include G-75, E-225, D-450, now add DE-300, D-900, D-1800, BC-1800, BC-3000 and C-1200 , Monofilament diameter from the original 5μm, 7μm, 9μm, expanded to 4μm, 4.5μm. Generally speaking, the control electronic yarn quality mainly includes several aspects.
Physical properties. Properties affecting the quality of electronic yarns include tensile strength, electrical properties, tex control level and control accuracy, Sizing agent content and consistency. The forming and appearance quality of the precursor yarn also have a significant effect on the quality of the electronic yarn. Therefore, before the twisting , the original fiberglass need to be in accordance with the requirements of the original test one by one, If the glass composition in the alkali metal oxide content exceeds the standard, tex number exceeded, sizing agent content exceeding, uneven oil, forming bad, stains, bumps of raw fiberglass are not in line with the quality requirements of electronic yarn.
No joints are allowed during twisting and the original package is too small should be removed. For example, the nominal mass of 4 kg of the original fiberglass, according to the fixed length of the actual requirements of about 3.5kg, 1.5kg below the original fiberglass is not used. The nominal weight of 8kg of the original fiberglass, the actual weight of about 7.2kg, the minimum access to the weight of 2.5kg. Non-full tube of the original wire in the twister is not connected, Weaving as weft.
Single yarn for weaving electronic cloth to be used to change the program several times forming the principle of winding into a bottle-shaped tube yarn. Multi-forming is a multi-cycle after the cycle of winding into a full pipe. This winding principle can only be increased by increasing the number of loop cycles of the winding, the pitch and the pitch of each layer of yarn can be selected to be larger, and the forming cone angle can also be much larger than that of one forming step, ,and the tube structure is stable, rarely appear, the phenomenon of collapse, high-speed withdrawal is not easy when the ring off, forming a more ideal.
Electronic yarn purification requirements are high, does not allow stains, water stains, perspiration and flying wire, dust and other pollution, large package of single yarn cheese is not allowed to have joints, a full tube yarn twisting a long time, 4kg of 68tex yarn in the twister for processing nearly 7h, 8kg of yarn is nearly 14h, once the contamination of the entire tube should be scrapped, therefore, it is important to keep the electronic yarn clean as much as possible.
The water content of the electronic yarn should be controlled within a certain range. In the weaving process, the electronic yarn moisture content is too high and the yarn is sticky, back resistance is too large, resulting in warping and weaving difficult. In general, the requirements of electronic yarn moisture content control in 0.2%, In practice if they can reach 0.1% or less is better.
The stiffness of the electronic yarn is controlled in a suitable range. The stiffness of the single yarn is closely related to the sizing agent formulation, the sizing agent content, and the coating condition of the sizing agent. It is also related to the twist condition and the moisture content of the single yarn. Starch-based infiltrating agent to improve the oil content, yarn stiffness decreased, adjust the stiffness of yarn, it is necessary to master this law.
Electronic yarn adapt in batches and modified by modified corn starch sizing
Electronic cloth for warp tension uniformity demanding, therefore, the precision control warping tension and to maintain uniformity of warp tension are the key to the whole process. The warp tension of the warping in batches is divided into several parts, such as single yarn tension, warping tension and winding pressure, which can be fully adjusted and controlled to meet this requirement. The main purpose of using modified corn starch sizing is to improve the weaving performance of the warp. Electronic yarn is a collection of single-fiber, if one of the separation is likely to cause single-fiber breakage, and the adjacent yarn winding, which is the reasons for fluff and broken. Therefore, it is desired to increase the bundling property between single fibers by sizing. In addition, the low-twist single yarn sizing also has a stable twist effect, thereby ,so that enhance the weaving performance.
The modified corn starch has high water dispersibility and high water solubility, slurry viscosity stability, Gel phenomenon is significantly reduced, the slurry is not easy to freeze when cooled. The fluidity of the slurry is also improved, and the adhesion with the glass fiber is also improved. Serosa more transparent, tough and flexible, serous surface is more smooth and detailed, with good weaving performance. Electronic yarn sizing is to improve the weaving performance, while the sizing rate directly affects the weaving sizing performance. In general, the sizing rate is slightly higher, weaving performance is better, but when the sizing rate exceeds a certain limit, the weaving performance of the warp decreased. The best sizing rate of electronic yarn sizing, generally within the range of 2% to 6%. And the difference between the varieties is not, the overall trend is thin spun yarn sizing rate is slightly higher; high quality requirements, especially for hairiness requirements of varieties of sizing rate should be slightly higher. Slightly worse quality of the warp or weaving conditions are poor, the sizing rate is also set a little higher. In addition, the required slurry to be easy desizing , thermal residue after washing less, not to cause the surface chemical treatment, CCL and circuit board processing and application of obstacles. Special attention should be paid to the burning of the slurry, the residual ash requirements shall not exceed 0.3%; and shall not contain trace metal salts.