PCB design is based on circuit schematics to achieve the functions required by the circuit designer. PCB design is a highly technical task that requires years of experience. The following are some common problems in PCB circuit design summarized by a PCB manufacturer for your reference.

　　I. Overlapping Pads

　　1. Overlapping pads (excluding surface mount pads) means overlapping holes. During the drilling process, multiple drilling in one location can break the drill bit and damage the hole.

　　2. Overlapping holes in multilayer boards, such as one hole being an isolation pad and the other a connection pad (floral pad), will appear as an isolation pad on the circuit board, resulting in scrap.

　　II. Misuse of Graphic Layers

　　1. Unnecessary connections are made on some graphic layers. What should be a four-layer board is designed as a five-layer or higher circuit, causing misunderstanding.

　　2. Taking shortcuts in design, for example, using Protel software to draw lines present on all layers using the Board layer, and also using the Board layer for annotation lines. This leads to missed connections and broken circuits during photoplotting because the Board layer wasn't selected, or short circuits because the Board layer's annotation lines were selected. Therefore, maintain the integrity and clarity of the graphic layers during design.

　　3. Violating conventional design practices, such as designing component sides on the Bottom layer and solder sides on the Top layer, causes inconvenience.

　　III. Misplaced Characters

　　1. Characters covering SMD pads cause inconvenience for continuity testing and component soldering on the printed circuit board.

　　2. Characters that are too small cause difficulties in screen printing; characters that are too large overlap and are difficult to distinguish.

　　IV. Setting the Hole Diameter of Single-Sided Pads

　　1. Single-sided pads generally do not have holes. If holes are drilled and need annotation, their diameter should be designed to be zero. If a numerical value is set, the hole coordinates will appear at this location when generating drilling data, causing problems. 2. Drilling holes in single-sided pads should be specially marked.

　　V. Using fill blocks to draw pads

　　While using fill blocks to draw pads may pass DRC checks during circuit design, it is not suitable for manufacturing. This is because such pads cannot directly generate solder resist data. When applying solder resist, the fill block area will be covered by the resist, making component soldering difficult.