- 1.Why need to make the the panel?
After PCB design, SMT should be installed on the assembly line to attach components. According to the processing requirements of the assembly line, every SMT processing factory will specify the most appropriate size of the circuit board. For example, if the size is too small or too large, the fixture for fixing the pcb on the assembly line cannot be fixed.
So if the size of our PCB itself is smaller than the size specified by the factory? That means we need to piece together the circuit boards, multiple circuit boards into one piece.Both for high – speed mounter and wave soldering can significantly improve efficiency.
1) Outline size
A. In order to facilitate the processing, veneer edge of voids or process should be R chamfering, generally rounded Φ diameter 5, small plate can be adjusted.
B. PCB with single board size less than 100mm×70mm shall be assembled
2) Irregular Shape for the PCB
PCB with irregular shape and no panel board should be added with tooling strip. If there is a hole on the PCB greater than or equal to 5mm×5mm, the hole should be completed first in the design to avoid the deformation of mantineer and plate during welding. The completed part and the original PCB part should be connected by several points on one side and removed after wave soldering.
When the connection between the tooling strip and PCB is v-shaped groove, the distance between the outer edge of the device and v-shaped groove is ≥2mm;When the connection between the process edge and the PCB is a stamp hole, no device or circuit shall be arranged within 2mm of the stamp hole.
The direction of the panel shall be designed in parallel to the direction of the edge of the transmission, except where the size cannot meet the requirements of the above size of the panel.It is generally required that the number of “v-cut” or stamp hole lines is less than or equal to 3 (except for long and thin single boards).
Of special-shaped board, pay attention to the connection between sub-board and sub-board, try to make the connection of each step separated in a line.
4.Some notes for PCB panel
In general, PCB production will carry out the so-called Panelization operation to increase the production efficiency of SMT production line. What details should be paid attention to in PCB assembly? Please check those as below:
1) The outer frame (clamping edge) of the PCB panel shall be designed in a closed loop to ensure that the PCB panel will not deform when fixed to the fixture.
2) PCB panel shape need to square as close as possible , recommended to use 2×2, 3×3,……panel, but no make the differ board ( yin-yang).
3) The width of Panel size ≤260mm（SIEMENS line）or ≤300mm（FUJI line). If need to automatic dispensing, the width x length ≤125mm×180mm for the panel size.
4) Each small board in PCB panel shall have at least three tooling holes, 3≤ hole diameter ≤ 6mm, wiring or SMT is not allowed within 1mm of edge tooling hole.
5) The center distance between the small board should be controlled between 75mm and 145mm.
6) When setting the reference tooling hole, it is common to leave an open welding area 1.5mm larger around the tooling hole.
7) There should be no large devices or protruding devices near the connection point between the outer frame of the panel and the internal panel, and between the panel and the panel. Besides, there should be more than 0.5mm space between the components and the edge of the PCB board to ensure the normal operation of the cutting tool.
8) Four tooling holes with an hole diameter of 4mm±0.01mm were opened at the four corners of the outer frame of the panel.The strength of the hole should be moderate to ensure that it will not break during the process of upper and lower plate;Aperture and position accuracy should be high, the hole wall smooth without burr.
9) In principle, QFP with spacing less than 0.65mm should be set in its diagonal position.The positioning reference symbols used for the PCB subboard of the assembly shall be used in pairs, arranged diagonally on the positioning elements.
10) Large components shall have positioning posts or positioning holes, such as I/O interface, microphone, battery interface, microswitch, headphone jack, motor, etc.