Tom
10-25-2002, 03:00 PM
IPC Advanced Study Guide Page Reference: Page 31 Section 1.4
Tenting is a process usually delegated to dry film masks. In this process the via is completely covered to prevent cleaning solutions or flux residue from entering the plated-through hole. An issue still in debate is whether to tent one side or both sides of the via. Many users have different opinions as to which method works best in a good assembly process. With the advent and the increased use of liquid photoimageable masks, the tenting of vias has not always been possible.
The liquid polymer applied to the surface, some solder mask gets into the hole. However, there can be skips or other process conditions where the solder mask does not properly cover or prevent entrance into the barrel of the plated-through hole. Thus, capping* or plugging* has come about. This is usually a secondary process to ensure that plated-through holes are really prevented from being open to contamination from some of the assembly cleaning and plating process chemistries.
Capping - Via holes are Capped with Overplate
Plugging - Via holes are Plugged with LPI mask or DuPont Silver Epoxy
Tenting is a process usually delegated to dry film masks. In this process the via is completely covered to prevent cleaning solutions or flux residue from entering the plated-through hole. An issue still in debate is whether to tent one side or both sides of the via. Many users have different opinions as to which method works best in a good assembly process. With the advent and the increased use of liquid photoimageable masks, the tenting of vias has not always been possible.
The liquid polymer applied to the surface, some solder mask gets into the hole. However, there can be skips or other process conditions where the solder mask does not properly cover or prevent entrance into the barrel of the plated-through hole. Thus, capping* or plugging* has come about. This is usually a secondary process to ensure that plated-through holes are really prevented from being open to contamination from some of the assembly cleaning and plating process chemistries.
Capping - Via holes are Capped with Overplate
Plugging - Via holes are Plugged with LPI mask or DuPont Silver Epoxy