Solder mask bridge, also known as green oil bridge or solder mask dam, is a "isolation tape" made by factories to prevent short circuits in SMD component pins during batch placement. The so-called green oil bridge is a bridge for environmentally friendly oxidation removal and reducing the surface tension of the PCB being soldered. Solder mask window is a measure taken for special needs such as heat dissipation of the front plate, good contact with the shell, and so on. The green oil bridge is the green oil between SMD and SMD components (the width of the solder mask is reserved between two solder mask windows, generally>6mil), mainly to prevent short circuits. The following figure shows PCB boards with and without green oil bridges generated. Solder mask window refers to the size of the exposed copper part at the position that needs to be welded, that is, the size of the part without ink cover. Wire cover refers to the size and amount of solder mask oil covering the circuit part. If the distance between the cover lines is too small, it will cause exposed lines during the production process.

In PCB pad design, the solder mask pad is generally slightly larger than the normal pad because the circuit is made first and the solder mask is made later. It is impossible for the solder mask pad to be 100% aligned with the circuit pad, so the solder mask window must be larger than the circuit pad. As for how much larger it is, it generally depends on the manufacturing process and the production capacity of the PCB factory.

Conventional UV oil or other screen printing solder mask, the solder mask window is generally 0.15-0.20mm larger on one side than the circuit pad, because this process uses screen printing. For photosensitive solder mask, the window side is usually 0.05-0.10mm or right, because this process is made by exposure.

When welding, there is no solder mask between the pins, which makes it easy to solder, so it is best to add a solder bridge between the pins. This involves trade-offs in design, and for distances that are large enough, there is generally no problem with this. The problem is that nowadays designs are becoming more and more miniaturized, so it is difficult to choose between IC or pad spacing that is small enough to maintain the distance between solder bridges. Without solder bridges, it is easy to solder. It depends on how you choose.

Based on our years of experience, there are generally several ways to handle it:

1、 It is suggested that the customer cancel the solder bridge to facilitate production. If the customer has a solution to the soldering problem, they will accept this suggestion;

2、 The minimum green oil bridge is retained, typically between 0.07 and 0.15mm;

3、 It is to cancel the solder mask bridge, retain the white oil bridge in the character layer when printing characters, and allow for slight placement of wire pads (such as accepting 2 mil of wire pads on one side);

The solder mask is as large as the circuit pad, which is not a problem. For example, before production, Jiepei will do engineering treatment and adjust according to the factory's production capacity.