pcb麥拉膜怎么貼在板面上？

要光面向下，這是因為在做曝光的時候，光的一面向下是用來透光的，光面能使光更加均勻的透過紫外線光，使曝光質量更高；

而粗面要緊貼PCB線路板，為了更好的貼緊麥拉膜，要使用抽氣抽真空，如果這面也是光面的話，就會使麥拉膜與PCB之間形成氣泡，影響曝光效果。

而粗面的作用正是使麥拉膜和PCB之間形成一定的空隙，這樣在抽氣的時候就能把空氣抽干凈。

麥拉具有尺寸穩定、平直和優良的抗撕拉強度，耐熱耐寒、耐潮耐水、耐化學腐蝕，并具有超強的絕緣性能，優異的電氣、力學、耐熱、耐化學性能。

The light surface should be downward, because when making exposure, the downward side of the light is used to transmit light. The light surface can make the light pass through the ultraviolet light more evenly and improve the exposure quality;

The rough surface should be close to the PCB circuit board. In order to better adhere to the Mylar film, air extraction and vacuum should be used. If this surface is also smooth, bubbles will be formed between the Mylar film and PCB, affecting the exposure effect.

The function of rough surface is to form a certain gap between Mylar film and PCB, so that the air can be pumped clean when pumping.

Mylar has stable size, straightness and excellent tear strength, heat and cold resistance, moisture and water resistance, chemical corrosion resistance, super insulation performance, excellent electrical, mechanical, heat resistance and chemical resistance.