Why PCB vias must taphole?

Why PCB vias must Jack?


The Via and hole conductive hole directing the through hole, in order to meet the requirements of customers, PCB vias must plug, after a lot of practice, change the traditional aluminum plug hole process, complete the line plate welding and Jack White net. Stable production, reliable quality.


Via hole via line connected conducting function, the development of electronic industry, promote the development of the PCB at the same time, the production process and surface mount technology put forward higher requirements for printed boards. Via hole came into being Jack process, at the same time should meet the following requirements:


(a) via hole in copper solder can be Saikebusai;


(two) conducting tin lead to hole, a certain thickness (4 microns), no solder resist ink into the hole, the hole caused by hidden solder;


(3) the vias must have solder resist ink hole is not transparent, there shall be no tin solder and flat circle, etc..


With the development of electronic products to "light, thin, short and small, PCB to high density and high difficulty of development, so the emergence of a large number of SMT, BGA PCB, and the customer requirements in the jack mount components, there are five main effects:


(a) to prevent PCB in wave soldering tin from the through-hole component side short-circuit; especially we put Kong Fang on BGA pad, you must first do Jack, and then plated, welding for BGA.


(two) avoid the flux remaining in the through hole;


(three) after the surface mount and component assembly of the electronic factory are completed, the PCB will be sucked into vacuum to form a negative pressure:


(four) surface to prevent the solder paste into the holes caused by weld, impact mount;


(five) to prevent the wave soldering tin pops up, causing a short circuit.


The process of conducting hole hole


For surface mount board, especially installed via hole must be affixed to the formation of BGA and IC, and positive and negative 1mil, may not have holes on the edge of red tin; via Cangxi beads, in order to meet the requirements of customers, via hole process is all kinds of process, especially the long process it is difficult to control and often have resistance to soldering experiment in hot air leveling and green oil out of oil; oil explosion problem occurred after curing.  According to the actual condition of production, a variety of PCB Jack process are summarized, some comparison and analysis of advantages and disadvantages in the process:



Hot air leveling Jack process


This process is: the surface resistance welding - HAL - plug and curing. The production process of hot air leveling jack, with aluminum screen or ink retaining net to complete all customer requirements via Fort jack. Jack used photosensitive ink ink or thermosetting ink to ensure consistent color film, wet conditions, the best use of the same plate and Jack ink ink. This process can ensure the hot air leveling holes out of oil, but easy to cause pollution, uneven surface of ink hole. Customers in the mount due to the weld (especially in BGA). So many customers don't accept this method.



The process of short time, high utilization rate of equipment, can guarantee the hot air leveling off oil, through hole via hole is on the tin, but due to the printing of Jack, in a lot of memory via air, air expansion in curing, and break through the solder mask, causing holes, uneven, hot air there will be a small amount of leveling via Cangxi. At present, our company through a lot of experiments, and choose different types of ink viscosity, adjust the printing pressure, basically solved via hole and smooth, has been using this process for mass production.


 

(Source: internal information)

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