SMT factory incoming PCB material inspection, China PCB assembly factory SysPCB_
Technical
What are the advantages and applications of flexible microcircuits?
FPC Reinforcement Types
Criteria for Classification of electronic Component Classes
Four softwares suitable for beginners to draw PCB circuit boards
What information is needed for SMT processing?
What are the advantages of small and medium batch SMT processing?
PCB related knowledge- The purpose of each layer of the PCB
How to do heat resistance testing for PCB board
Detailed explanation of rigid-flex board and IC carrier board
PCBA prototype procedure
Defects which can be detected by the SPI
What are the spacing requirements for designing PCB circuit boards?
What are the classification and advantages of PCB metal substrates?
Difference between the processing technology of 1Layer AL PCB and 2Layer AL PCB
Introduction of FPC Cable and its usage
advantages of Shenzhen SMT assembly factory
inspection items before PCB ordering
usages of ceramic substrates
main applications of PCB boards
Cost-effective PCB product services
How to check short circuit of a circuit board during manual soldering
Identify the polarity of electronic components during PCBA processing
Means Which Can Prevent Component Shifting in SMT Processing
Skills of PCB prototype manual soldering
Reasons for the shift of Components in the SMT Process
Seven Types of PCB Probes
What Should Be Paid Attention to in Layout of High-frequency PCB
Precautions for PCB CCL Selection
Advantages of LED Plant growth light
Advantages of using LED grow lights to grow industrial hemp
Detailed explanation of PCB manufacturing process and precautions
Detailed explanation of PCB manufacturing process and precautions
How to draw multilayer PCB on Altium Designer
Three basic elements of interference and how to suppression them.
Decrease interference between digital circuit and analog circuit
SMT Component Placement Process Of Parts : Manual Placement
SMT factory incoming PCB material inspection
Basic concepts commonly used in PCB design
Ideas and principles of High speed PCB layout
Component layout rules and safety distance considerations
SMT assembly process quality specification
5 points in PCB layout
Professional interpretation of SMT
Advantages and disadvantages of different PCB surface treatment
Special process in PCB prototype
Why the via hole become open after component assembly
Keep the cost of the PCB as low as possible
what are the causes of PCB board heating radiation problem
Pad size and via diameter dimensions consideration in PCB prototyping
How to Judge the Acceptance of PCB Quality
Which Color Circuit Board Sells the Most Expensive
Method to Solve the Noise Interference of Power Supply on High-frequency PCB Board
Disassembly Skills of Chip Components on PCB
What Factors Should Be Considered in the Selection of High-frequency PCB CCL
How to Place Special Components during PCB Layout
What Are the Functions of Capacitors in Circuits?
Testing Techniques for Common Electronics Components
What to do if There is a Short Circuit on the PCB
Desoldering Principles and knowhow during PCBA Processing
Black Oxidation of the Inner Layer of the Multilayer PCB
How to Ensure the High-performance Design of PCB
What Is the Printing Process of SMT Solder Paste?
PCB without fiducial mark, Is There Any Way to do SMT for It
What Are the Benefits of Reserving Break-up Tab for PCB Production
How Does SMT Affect PCB Production Time and Speed It Up
Classification of PCBs from three aspects
Common Problems and Solutions for Dry Film pasting during PCB Manufacturing process
Several Elements to Inspect after PCB Design
What is a halogen-free circuit board?
What Do Capacitive Coupling and Decoupling Mean?
What Are the Differences Between PCB Paste Mask and Solder Mask?
How PCBA Is Packaged and Shipped
How long can PCBA finished products be stored?
What Are the Differences and Relations Between PCB, PCBA, and SMT?
PCB Baking Specifications
PCB "Solder Mask Tenting" and "Solder Mask Opening"
Five reasons for PCB deformation and six solutions
Importance of first article inspection of PCBA board
Temperature zone standard for SMT reflow soldering
Small and medium volume PCB manufacturers in China
The main reason for PCBA cleaning
For power filter, the more capacitors, the better?
What does PCBA programming mean?
Content of PCB incoming testing
What conditions must be met for PCB circuit board soldering?
What is Blind via and Buried via
PCBA Manufacturers Temperature and Humidity Sensitive Components Management

SMT factory incoming PCB material inspection

After nearly 20 years of rapid development, China SMT from small to large, has now become the world's largest SMT application countries. Now SMT not only takes cell phone products, consumer electronic products, PC peripheral products as the leading production, but also automobile electronics, medical equipment and telecommunication devices, and more military products are put into production.

 

At the beginning only the most simple devices to now can mount a variety of packages of resistors and capacitors, various sizes of BGA, chips and integrated modules, etc.. Of course, the high-end SMT technology is gradually refined with the integration of materials and package changes, so the maturity of SMT technology is established on the basis of high-quality materials, the two are complementary to each other. In summary, material inspection is essential for SMT welding technology, is an essential process in the production, the following China SMT factory SysPCB talk about material inspection from several aspects.

 

First, the PCB

PCB is the overall substrate of the product, the quality of PCB directly affects the quality of welding and the product's range of application, life. The following we use visual inspection with five aspects of PCB, warping and twisting, solderability, appearance, gold fingers and special materials, using calipers and other tools to introduce PCB pre-solder inspection. Need to emphasize a premise, as long as the SMT materials related to the contact. SMT factory workers are required to bring anti-static gloves and wristbands to avoid damage to the device, or contamination of the PCB etc.

 

1, warping, twisting

PCB warping, twisting for many reasons, in addition to the design of the reasons, may be due to the preservation of a humid environment or placed in a position that does not meet the horizontal requirements, according to the provisions of the acceptable range should be controlled in the diagonal length of the PCB board 0. 5% or less, of course, for the complexity of the board the range should also have a floating margin, for example, the PCB with the large number of BGA, high integration, the board warpage should be controlled more strictly, the same if the PCB only with some small chips and resistive parts, low integration, the range can be appropriately relaxed. At present, the electronic assembly plant allows the warpage, regardless of double-sided or multi-layer. 1.6mm thickness, usually 0.70 ~ 0.75%, many SMT, BGA boards, the requirement is 0.5%.

Some electronic factories are encouraging to raise the warpage standard to 0.3%, and the method of testing warpage follows GB4677.5-84 or IPC-TM-650.2.4.22B. The warpage of the board can be calculated by putting the board on a certified platform and inserting a test pin into the area with the greatest warpage degree.

 

2, Solderability

PCB pads in the air for a long time exposure is easy to be oxidized, if the pads are oxidized after continuing to weld will cause poor pad wetting resulting in a series of problems such as pseudo soldering, so the PCB must be solderability tested before welding. Detection methods generally use visual inspection, for the generation of suspicion PCB in edge dipping test. Visual inspection can be directly concerned about the brightness of the pad.

 

General tinned pads or gold-plated pads are oxidized to appear darker; for the indeterminate can be swabbed with an eraser on a certain part, with the previous comparison is also a simple means of detecting PCB oxidation.

 

There is also flash gold this special pads, flash gold plate color compared with the normal color of gold-plated board is much lighter, this pad plating layer is very thin, Au layer of the thinnest place only 0.05um, Ni layer is easy to oxidation, very bad solderability, resulting in many welding defects.

 

SMT Processing plant encountered this PCB, incoming inspection must be carried out before mounting, can not be exposed to air for a long time, open the vacuum packaging immediately start SMT, otherwise adhere to the principle of no mounting no open.

 

3, Appearance

PCB appearance for the direct sale of finished PCB customers is very important, of course, may also have a direct impact on the function of the product, so the appearance of the damage can simply be divided into the following two cases by visual inspection.

(1), only affect the appearance of the board, does not have an impact on the use of the board

Knock corner, Halo ring

friction injury scratches (no damage to the solder resist layer and no obvious depth)

exposed copper (no obvious depth, to ensure that the wire does not have any damage, you can fill the solder resist oil)

The above five cases such as customers do not sell the bare board or appearance of special requirements can continue to use, does not affect the performance of the product itself, but if the customer will be sold directly to the finished product, the above situation is not acceptable.

 

(2) changes in appearance may lead to the destruction of the PCB as a whole

blistering / delamination (will affect the PCB internal circuitry)

scratches (broken ring solder resist layer, there is a certain depth, may cause cuts to the PCB lines)

encounter these two irreparable problems, you can directly request a replacement PCB, because the consequences of these two situations are unknown and not can be used blindly.

 

4, gold fingers

Gold finger for the PCB is also relatively special, it is the connection pins of PCB and other devices such as motherboards, chassis and other electrical, so its quality is very important for the entire product, so the incoming inspection should be relatively strict. General inspection needs to pay attention to the following aspects.

1), scratches or dents in the middle 3/5 region of the gold finger, mainly in deeper wounds, resulting in copper leakage, depression area of more than 6mil, or a whole row of gold fingers on more than 30% of the pressure wound

2), Gold finger oxidation, mainly in the color darkening or reddening.

3), Plating stripping, need to do peel test after the plating stripping or buckling.

4), Gold finger contamination, gold finger

tin, paint, glue or other contaminants.

5), Gold fingers not beveled or beveled edge length is not good

6), gold finger cutting edge bad, manifested in the glass bundle protruding, missing corners, cutting edge is not straight, there are hairy head. If the above problems, we need to promptly feedback with the customer, requesting replacement of PCB.