How does led pcb board manufacturer develop lead free assembly?2021-09-07
Over the past few years, many solutions have been proposed, for contributing in an enhanced and strengthened digital world. And the results obtained deserve every respect. Led pcb board manufacturer solves real world problems
The article analyzes the process of assembling electronic modules without the use of lead as of the spring months of 2007. And provides an overview of the latest achievements that may deserve the attention of manufacturers of highly reliable products.
Significance of led pcb board manufacturer
Almost the only motive for switching to lead-free assembly technologies is often a change in the composition. It is of the working surfaces of the components used. There are many areas to work on in this regard.
The updated lines of components, which are emerging in the process of constant miniaturization of products. These are now available in housings, the finishing of the terminals of which presupposes exclusively lead-free formulations. Led pcb board manufacturer provides high quality products.
An overview of electronic market
In general, the consumer electronics market still has many lead-coated PCBs. Without any difficulty on the part of assemblers. However, if the product is to have increased reliability, assemblers cannot alter the composition of the lead-containing coating.
The manufacturer needs to ensure constant monitoring of the composition of the solder alloy on the surface of the component leads. For example, the Energy Dispersive X-ray Fluorescence (EOXRF) method has proven itself well. The portable device can be common for Led pcb board manufacturer
Models for lead free technology
To examine the characteristics of each product and match the equipment’s capabilities to their own needs. At the same time, soldering PCBs with lead-free lead-plating on lead-containing boards is only half the battle for product quality.
How to build reliable interconnections in led pcb board
Equally problematic are BGAs with pins in the form of tiny metal balls arranged in a grid on the bottom of the package. Here, the lead-free led pcb board manufacturer of the beads plays a major role. This is not only a question of applying a layer of additional metallization followed by brazing on copper.
Types of PCB coatings (Air Solders)
Given ahead are the main types of PCB coatings
1.Hot air solder and its limitations
Such coatings (Hot-Air Solder Level – HASL) are most often common in highly reliable products. Solder tin-lead is quite cost-effective, provides high-quality soldering with the underlying copper layer and has a certain “experience” of reliability indicators. However, hot air applied solders have a downside.
The domed uplift effect created by the solder on the pads limits the application of this coating. It is in Led pcb board manufacturer. And not limit components with small lead pitches (less than 20 mil). However, tin-lead solder is still common as a topcoat for multi-plated products, i.e tin-lead solder interconnection
2.Lead-free hot air applied solders and its unsuitability
There are several lead-free hot air applied solders on the market. The lower contact angle of lead-free solders provides less dome-shaped lift than tin-lead alloys. However, the most common lead-free solder, SAC 305, is poorly suited for hot air application and is therefore rarely used.
Unsuitability of this alloy is due to its predisposition to extremely rapid dissolution of copper. Therefore, alloys in led pcb board manufacturer with low or no silver content are typical alternative lead-free hot air solder alloys due to the slow dissolution rate of copper. Everyone understands
High temperature organic coatings
Following are the three types of soldering:
1.Organic Solderability Preservatives – OSP
This topcoat (Organic Solderability Preservatives – OSP) owes its popularity to its cost-effectiveness, smooth and even finish, and the ability to apply solder in extremely fine increments. Has a long shelf life and even recyclability if commonincorrectly or after the recommended shelf life.
The weaknesses of high temperature organic coatings are insufficient hole filling, which can be observed during wave soldering. If in led pcb board manufacturer preliminary reflow operation is provided, and insufficient spread of lead-free solder during reflow.
For PCB soldering processes with lead-free solders at higher temperatures, new generation OBR coatings are available. These high temperature formulations are generally fully compatible with legacy reagents and perform well in tin-lead processes, outperforming traditional OBR coatings.
That is, in a lead-free production environment, new high-temperature organic coatings exhibit practically the same or slightly better characteristics than old OBR coatings under production conditions using a tin-lead alloy.
3. Tin-lead solders for led pcb board manufacturer
On the other hand, although older high temperature organic coatings designed for tin-lead solders by Led pcb board manufacturer. These are occasionally common in lead-free environments; they exhibit poorer performance at higher temperatures.
An insight on immersion silver in led pcb board manufacturer
Immersion silver is a promising topcoat for lead-free assembly production. Some of the earlier types of immersion silver coatings had a serious drawback – the so-called mechanism of planar formation of micro voids, reminiscent of “champagne bubbles”.
A weak spot in accumulation of these microscopic bubbles in the plane of the intermetallic zone of the brazed joint could lead to premature failure of the joint. In led pcb board manufacturer there are several types of immersion silver coatings on the market today, for most of them the planar formation of micro voids is not typical.
Planar micro voids in led pcb board manufacturer
It is reported that the problem of the formation of planar micro voids in products, in which they were observed earlier, has been solved. Immersion silver coatings provide a smooth, even surface suitable for drawing, when common in conjunction with SAC solder pastes.
They have good wetting and spreading properties and retain high degree of wave solderability after reflowing. At same time, the shelf life of various variants of this coating is in a very wide range. Also, under led pcb board manufacturer, for high sulfur conditions, all immersion silver coatings tend to tarnish.
Surface coatings nickel-immersion gold
Electroless deposition (ENIG) nickel-gold surface coatings are also commonly common in highly reliable applications. Due to its resistance to oxidation, gold provides an ideal surface for long-term storage, and if the board is still saturated with moisture during storage, it is possible to anneal.
The flat microrelief of the coating surface by led pcb board manufacturer makes it ideal for screen printing. ENIG is the best choice for SAC alloys, resulting in the most complete contact pads coverage during reflow soldering and top-hole filling of the PCB with wave soldering.
ENIG coating leading to voids formation
The ENIG coating has been theoretically proven to inhibit the formation of voids in the solder by some factors.
- First, using a barrier film of nickel in contact with copper
- Also, surface coating neither discolorizes not lose its durability
- Above all, when common improves the quality of product