Frequently Asked Questions about SMT Patches in Small and Medium Batches
- 2020-01-30-

Frequently Asked Questions about SMT Patches in Small and Medium Batches

1. Overlapping of small and medium batch SMT patch pads

1,Small and medium batch SMT patchThe overlap of the pads (except the surface mount pads) means the overlap of the holes. During the drilling process, the drill bit will be broken due to multiple drilling in one place, resulting in damage to the holes.

2. Two holes in the multi-layer board overlap. For example, one hole is an isolation disk and the other hole is a connection disk (flower pad), so that the film will appear as an isolation disk after drawing the film, resulting in scrap.


2. Misuse of the graphic layer of SMT patches in small and medium batches

1. Some useless connections were made on some graphics layers. The original four-layer board was designed with more than five layers, which caused misunderstandings.

2. It saves trouble when designing. Take the Protel software as an example to use the Board layer to draw the lines on each layer, and use the Board layer to mark the lines, so that when the light drawing data is performed, the Board layer is not selected, and the board layer is omitted. The connection is broken, or it may be short-circuited due to the selection of the marking line of the Board layer, so the integrity and clarity of the graphics layer is maintained during the design.

3. Violation of conventional design, such as component surface design in Bottom layer and welding surface design in Top, causing inconvenience.

3. Random placement of SMT patch characters in small and medium batches

1. The character cover pad SMD soldering piece brings inconvenience to the on-off test of the printed board and the soldering of the components.

2. The character design is too small, resulting in difficulties in screen printing, and too large will cause the characters to overlap and be difficult to distinguish.

Fourth, the setting of the single-sided pad aperture

1. Single-sided pads are generally not drilled. If the drilled holes need to be marked, the hole diameter should be designed to be zero. If the numerical value is designed, then when the drilling data is generated, the coordinates of the hole appear at this position, and there is a problem.

2. Single-sided pads should be specially marked for drilling holes.

Five, use filler blocks to draw pads

Filling pads for small and medium-sized SMT patches can pass the DRC inspection when designing the circuit, but it is not for processing. Therefore, the type of pads cannot directly generate solder mask data. When the solder resist is applied, the filler block area will be Solder resist coverage makes it difficult to solder the device.

Sixth, the electrical ground layer is also a flower pad and a connection

Because the power supply is designed as a flower pad, the ground layer is opposite to the image on the actual printed board. All the connections are isolated lines. The designer should be very clear about this. By the way, you should be careful when drawing the isolation lines for several sets of power supplies or grounds. You should not leave gaps, short-circuit the two sets of power supplies, and block the connected area (make a set of power supplies separated).

Seven, the processing level is not clearly defined

1. The single-sided board is designed on the TOP layer. If the front and back are not specified, the manufactured board may not be easy to be soldered with components installed.

2. For example, a four-layer board is designed with four layers of TOP mid1 and mid2 bottom, but it is not placed in this order during processing, which requires explanation.

8. There are too many filling blocks in the design of small and medium-sized SMT patches or the filling blocks are filled with very thin lines

1. The gerber data is lost, and the gerber data is incomplete.

2. Because the filling block is drawn with lines one by one when processing the light drawing data, the amount of light drawing data generated is quite large, which increases the difficulty of data processing.