Special Reminders

Specifial reminders for PCB asemlby

Three Special Reminders for your PCB Assembly: (Very Important,please refer below when you start to design of PCBA project)

1. Necessary spare components

Proper SMT machine setup and operation requires parts overages. Unused and excessive parts supplied by you or purchased by us will be packaged and returned to you with the assembled boards.

SMT parts which are not supplied on reels should be on one continuous strip of tape.

If you need to assemble the same SMT part in different boards, do not cut them into strips, please keep them in the continuous strip of tape or on the reels.

Resistors, Capacitors, Diodes (0603, 0805, 1206, 2225, SOT, SOD, MELF – packages) require a minimum of 50 pieces and have to exceed the required quantity by 30 pieces. (e.g.: assemble quantity 40 pieces – we will need 70 pieces – this meets our minimum of 50 pieces plus 30 pieces over assemble quantity).

Resistors, Capacitors, Diodes (0201, 0402, miniMelf, miniature packages) require a minimum of 100 pieces have to exceed the required quantity by 50 pieces. (e.g.: assemble quantity 80 pieces – we will need 130 pieces- this meets our minimum of 100 pieces plus 50 pieces over assemble quantity).

A small number of excess(1-5 pieces based on the total quantity of assemblies) is requested for expensive parts such as IC, BGA, QFP, Connectors, etc., this will ensure smooth assembling and shipping your assembled boards on time. If you have any question or doubt, please send more extra or contact us for answers.

2. Necessary Panelization for PCB manufacturing

If your PCB dimension is smaller than 50mmx100mm, or if your PCB is of any shapes (circular, or odd shape) other than rectangle, your boards must be panelized in an array for assembly. As we also fabricate your PCB for you, so once we start fabricating your boards we will have the panelization file (solder paste data), we will transfer the data to PCBA department to create the stencil to match the panelized PCB.

Panel drwing for PCB assembly

3. Necessary Break-away Rails (Break-away Tabs,also called strips below)

If the clearance between the board’s edge and copper features is less than 3.5mm (138mil), or your boards need to be panelized for some reason, Break-away rails (Break-away tabs) must be added at the two longer paralleled edges of the boards to ensure that the boards can be assembled by the machine.

necessary break away tab for PCB assembly

4. About “Change surface finishing HAL or HAL lead free to immersion gold”

Most PCB designer do not care the surface finishing of the PCB and always specify “HAL lead free or HAL” when they design a PCB board, and most PCB manufactures do not raise up a professional suggestion when the make DFM reviewing.

As a professional PCB assembly manufacturer, it is our advantage that to provide professional suggestion to customer that surface finishing is the premise to get a high quality of assembled PCB board:

When your PCB would be populated many high Precision component such as IC with BGA and QFN package, the better surface finishing is immersion gold not HAL or HAL lead free, or neither of others. This is because immersion gold surface finishing have good features of flat surface, which HAL or HAL lead free do not have. The defects would very less in BGA and  QFN joint if your boards was designed from immersion gold. On the contrary, some  defects would be deeply hidden for HAL lead free PCB finishing PCB board even it is inspected by AOI inspection, as these hidden defects can only be detected out by further functional test.

HASL lead free PCB assembly

HASL lead free PCB assembly

Electroless nickel immersion gold PCB assembly

Electroless nickel immersion gold PCB assembly

For the more difference and advantages of immersion gold and HAL lead free, please visit https://wellerpcba.com/pcb-surface-finish/

 

2019-07-26T16:12:26+00:00November 13th, 2016|Uncategorized|