Aluminum alloy plating process

Aluminum and Aluminum Alloys by the addition of various alloy elements will be present in several different forms in the aluminum alloy . Example: in the form of solid solution into the aluminum character ; in the element itself or in the form of microscopic particles of aluminum or other alloying elements of the intermetallic compound in the form of particles in the aluminum alloy . Therefore, to find a different universal aluminum pretreatment and pre-plating process , the forks with the same satisfactory results are very difficult to teach . In the plating process , we learn from the steel parts repair plating process . Namely:

Cathodic degreasing → ??washing → washing technique anode activation → → washing → → pre- tinned copper

Activation with removal step can produce a thin oxide film thickness of the oxide film on a solid removed by use machine maple .

Aluminum is a reactive metal in the air easily oxidized , coated each step interval should be as short as possible . And kept moist , never dry spots formed . Once the formation of dry spots , it means that the surface re- oxidized, reduced junction platform strength coating the activated surface after washing and order as soon as possible with the remaining complex , preventing in -process workpiece surface is re- oxidation.

Although the plating process according to the above process operation. Of industrial pure aluminum and aluminum- manganese alloy forging is ideal, but the aluminum- magnesium , aluminum- magnesium, silicon , magnesium, aluminum -zinc alloy in the production of still occur due to junction station and force bad batch rework loop resistance elevated . After many trials attack , we improved the activation solution composition used in the activation of dilute hydrochloric acid instead of sulfuric acid , preferably the best value , improved aluminum magnesium alloy for plating a junction station force .

Ancient volume on high silicon cast alloy , fork right amount added HF, although a trace amount added , but the effect is very obvious.

Meanwhile, after Wei -phase detection cartridge tin layer , we believe that the production process caused loop resistance is too high and causes peeling thickness with pre-plating , the current size is closely related to the degree eagle . This also includes the brush plating current density . Mo brush transition with alkaline copper plating solution , plating repeated too thick. Easily cause great stress coating . Causing peeling. Current density is too too , brush plating layer , layer particle technetium big sister , grain and grain together appear crosslinked network structure transition chain ring loose micro display is not dense , and the substrate junction station is weak , it brush or causes blistering hot baking tin after blistering after the invasion when corrosive gases , exacerbating the region corrosion and ultimately lead to increased loop resistance tin layer peeling off.

After several experimented , we use the following brush tin process:

( 1 ) Brush the surface with water sandpaper carefully polished , Chen lost oxide.

( 2 ) cathodic degreasing , 12 ~ 15V5 ~ 15s, to the workpiece surface is not hanging drops, washed clean .

( 3 ) anode activation, do not ask the appropriate material selection activation solution , the voltage l5V around , 8 ~ 12s, to the surface dark gray, washed with alkaline copper plating solution without electricity wipe the surface .

( 4 ) pre- plating copper . Voltage of about 10V , l ~ 2min, washed clean .

( 5 ) Brush tin , 8 ~ 12V, power consumption is calculated by time .

According to the above process operation. Junction station to check the strength , thermal shock test according to GB5270 do . Oven heating the part to a person 150 ± 10. C, time was 2h, after removing the parts into the chilling tank , found that the coating and substrate junction station well, no blistering and peeling of the test loop resistance from the assembly plant type test group testing, electrical connectors T- , L -Block , etc. contact resistance are maintained at l5 ~ 25m '~, breaks the electrical contact elements Taipower performance standards .