Summaries of special electroplating methods for SMT PCB

Today author from QiHe smt pick and place machine price sharing you with Summaries of special electroplating methods for SMT PCB

It is often necessary to plate rare metals on board edge connectors,
The protruding contacts or gold fingers on the edge of the board provide lower touch resistance and higher wear resistance,
This technique is called finger row plating or prominent part plating.
Gold is often plated on the outstanding contacts of board edge connectors whose inner plating is nickel.
The protruding part of the gold finger or the edge of the board adopts manual or automatic electroplating technology,
At present, the gold plating on the touch plug or gold finger has been replaced by basking, lead plating, and button plating.

Its process is as follows:

1) Strip coating to remove tin or tin-lead coating on prominent contacts
2) Rinse with washing water
3) Wipe with abrasives
4) Activated by immersion in 10% sulfuric acid
5) The thickness of nickel plating on the outstanding contacts is 4 -5μm
6) Rinse with demineralized water
7) Gold impregnation solution treatment
8) Gold plating
9) Cleaning
10) drying

The second type: through-hole plating

There are many ways to establish a layer of electroplating that meets the requirements on the wall of the substrate drilled hole.
This is called pore wall activation in industrial use,
Its printed circuit commercial production process requires multiple central storage tanks,
Each storage tank has its own control and maintenance requirements.
Through-hole plating is a necessary follow-up manufacturing process of the drilling manufacturing process,
As the drill drills through the copper foil and the underlying substrate,
The heat generated melts the insulating synthetic resin that makes up the matrix of most substrates,
Molten resin and other drilling debris build up around the hole,
Coated on newly exposed hole walls in copper foil,
In fact this is detrimental to the subsequent plating surface.
The molten resin will also leave a layer of thermal axis on the wall of the substrate hole,
It exhibits poor adhesion to most activators
This required the development of a class of techniques similar to stain removal and etch back chemistry.

A method more suitable for prototyping of printed circuit boards is to use a specially designed low viscosity ink,
Used to form a highly adhesive, highly conductive coating on the inner wall of each through hole.
This eliminates the need for multiple chemical treatments,
Only one application process, followed by heat curing,
It is possible to form a continuous coating on the inside of all the hole walls,
It can be directly plated without further processing.
This ink is a resin based substance,
It has very strong adhesiveness,
Bonds effortlessly to most thermally polished hole walls,
This eliminates the process of etch back.

The third type: scroll wheel linkage type selection plating

Pins and pins of electronic components,
Such as connectors, integrated circuits, transistors and flexible printed circuits, etc.
All use selective plating to obtain good contact resistance and corrosion resistance.
This electroplating method can adopt manual method,
QHSMT suggest active methods can also be used,
It is very expensive to select and plate each pin individually.
Therefore, it is necessary to use batch welding.
Generally, both ends of the metal foil rolled to the desired thickness are punched,
cleaning by chemical or mechanical means,
Then there are selective options like nickel, gold, silver, rhodium, button
Or tin-nickel alloy, copper-nickel alloy, nickel-lead alloy, etc. for continuous electroplating.
When choosing the plating method,
First, a layer of resist film is covered on the part of the metal copper foil board that does not require electroplating.
Electroplating is performed only on selected portions of the copper foil.

The fourth type: brush plating

Another method of selective plating is called “brush plating”.
It is an electrodeposition technology,
Not all parts are submerged in the electrolyte during the electroplating process.
In this electroplating technique,
Plating only a limited area,
It has no effect on other parts.
Generally, rare metals are plated on selected parts of the printed circuit board,
For example areas like board edge connectors etc.
Brush plating is used more often in electronic assembly shops to repair discarded circuit boards.
Wrap a special anode (a chemically inert anode such as graphite) in an absorbent material (cotton swab)
Use it to bring the electroplating solution to the place where electroplating is required.

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