The discovery in the process is assembled in PCBA PCB has line drawback, common main watch is existing and undermentioned a few kinds of forms.

 

Feature: Most via blackens in via wall while, the wall of underside also is corroded and do not have copper, most in assembling a process to save a process medium or for a long time happening, if pursue 1 with the graph 2 are shown.

 

Graph 1 rupture the wall is local graph

 

Graph the 2 via that are corroded by incomplete fluid

 

Feature: As the via open a way that PCB substrate comes off between in-house layer and appears, if pursue,3 are shown.

 

Graph 3 come off between the layer the via open a way that bring about

 

Feature: Colophony or other contamination exist between the film of blind aperture and blind aperture land, bring about a contact undesirable and open circuit, if pursue,4 are shown.

 

Graph 4 profane the blind aperture open a way that bring about

 

Feature: The cupreous layer of PCB is very thin, whenever sirocco makes wire of the copper when smooth craft or wave crest solder,meet by frit corrode thereby open circuit, if pursue,5 are shown.

 

Graph 5 by solder frit corrode cupreous wire

 

Feature: Triangular bruise is deeper, front a little the place of connective disconnects form open a way, if pursue,6 are shown.

 

Graph doubt of 6 electrostatic injury is like open circuit

 

The corrode juice that makes the remain in the process in PCB was not kept clear of clean, close inside via, chronically corrodes the wall of via, cause via open a way thereby.

 

(1) PCB base material sucks tide.

(2) HASL craft temperature exorbitant or time is too long.

(3) PCBA is assembled shed temperature of the peak value when soldering again exorbitant or immerse below peak value temperature time is too long.

 

Use laminose craft to make multilayer board, cleared when laser bore profane not complete, make colophony remain is on the land of blind aperture, bring about blind aperture open a way thereby.

 

This phenomenon happens in HASL working procedure normally or wave crest solders working procedure. Pass as a result of the cupreous wire ply that designs on substrate thin or lead width is too fine, below soldering high temperature, the solder of melt will make to the frit corrode action of Cu cupreous wire becomes thinner, finer, once suffer stress effect,can rupture in PCBA use process and open circuit.

 

Form a reason: Graph 6 it is electrostatic destroy occurrence peculiar triangle bruise, most advanced join a little, once suffer action of some kind of stress to be able to disconnect, cause open circuit thereby.

 

1. incomplete fluid corrodes the via open a way that bring about. Feedback to the supplier, strengthen the quality monitoring in making a process to PCB.

 

① strengthens moistureproof measure in PCB substrate production process, parameter of craft of strict monitoring HASL (temperature and time) .

What ② notices PCB in assembling a process is moistureproof, choose appropriate flow again solder peak value temperature reachs what fall in peak value temperature to immerse time, avoid temperature exorbitant or time is too long.

3. profanes the blind aperture open a way that bring about. PCB makes a manufacturer should enhance pair of PCB workmanship processes and quality superintend and control.

 

When ① wiring is designed, should avoid to had used thin, meticulous copper wire.

② executive HASL and wave crest solder when craft, the canal that should strengthen pair of operation temperature and time accuses, avoid by all means operates temperature to cross Gao Hecao to make time grow too.

 

Doubt of 5. electrostatic injury is like open circuit. Make in PCB, memory, carry reach the electrostatic preventive measure that executive rigor wants in assembling a process, take strict precautions against electrostatic injury.