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Become a master of mounting! – Points of solder application amount -

This article introduces the points of the solder printing process.

The important point in preventing defects during solder mounting is to control the amount of solder applied.
No matter too much or too little, you have to print just the right amount of solder.
This article introduces points that must be kept in mind for achieving proper soldering control.


Panasonic explained that the dimension of each opening of a metal mask can be used to control the amount of solder applied. Please refer to the following website after reviewing the control method for ensuring the proper amount of solder applied.


※Appropriate amount of solder applied = recommended metal mask opening area x recommended metal mask thickness


This appropriate amount of solder applied is calculated so as to allow the formation of a solder fillet, as shown in Figure 1.
Solder mounting by allowing the formation of such a fillet can improve solder strength and prevent soldering defects.
Our company uses the recommended metal mask opening dimension drawings and printed-circuit board recommended processing drawings in the specifications to define respective dimensions to provide the proper amount of solder for achieving the formation of the ideal fillets.
Please start by referring to these dimensional data for performing solder printing.

Figure 1: Ideal fillet profile during solder mounting


Actually, there may be cases where the amount of solder applied is higher or lower than the target amount. The rest of this article introduces measures to improve such cases.

First, when the amount of solder applied is higher than the target value, please review the thickness of the PC board used.
When a thin PC board is used and has insufficient support during printing, it yields to the pressure of the squeegee, which may result in a larger amount of printed solder than the target value.

Conversely, when the amount of printed solder is lower than the target value, there is a possibility that the problem is caused by defects in solder transfer during solder printing (Figure 2).

Figure 2: Conceptual diagram of a defect in solder transfer during the solder printing process



A defect occurring during solder transfer is a phenomenon whereby some of the solder to be printed on the pattern remains on the metal mask, resulting in a lower amount of printed solder than the target value.
In this case, please select a metal mask or solder printer resistant to solder transfer defects. The solder release characteristics when a metal mask is released from a printed-circuit board differ depending on the types of metal masks.


How were the explanations above? This article introduced the basics of the solder application amount along with the points to achieve an appropriate amount of solder. Please make good use of this information for rectifying soldering defects and improving the soldering process.