PCB inks refers to a printed circuit board (Printed circuit board, referred to as PCB) used in ink, which is the important physical properties of the ink viscosity, thixotropy and finesse. Often widely used in printing, marking, and for other purposes.
Outline
PCB inks refers to a printed circuit board (Printed circuit board, referred to as PCB) used in ink, which is the important physical properties of the ink viscosity, thixotropy and finesse. These physical characteristics, you need to know in order to improve the ability to use ink.
Feature
1 . Viscosity and thixotropy
In the printed circuit board manufacturing process, screen printing is one of the important processes indispensable .
To obtain an image of fidelity replication requires ink must have good adhesion and appropriate thixotropy. Is the so-called internal friction of the liquid viscosity , which means under the action of external forces, so that a layer of liquid on a slide in another layer of the liquid , the liquid applied to the friction lining . Mechanical resistance of the inner slide across a thick liquid was larger than the thin liquid resistance. Viscosity measurement unit is parked . Special care should be noted that temperature has a significant effect on viscosity .
Thixotropy is a physical characteristic of the fluid , i.e., its viscosity decreases under stirring , then allowed to stand to be quickly restored to its original viscosity characteristics . By stirring, thixotropic effects last long enough to re- constitute the internal structure . To achieve the effect of a high quality screen printing , thixotropic ink is important . In particular, the process of the blade , the ink is stirred , and then to liquefy .
This role to accelerate the speed of ink through the mesh , and promote the original cable separately fused ink evenly . Once the blade stop motion, back to the rest state of the ink , the viscosity is quickly restored to the original data is required .
2 . Finesse :
Usually pigments and mineral fillers are solid , after fine grinding , the particle size of not more than 4 / 5 microns, and in the form of a homogeneous solid state of flow . Therefore , the ink having a fineness requirement is very important.
Precautions
According to the actual experience of the ink used in the majority of manufacturers , the use of ink must be implemented in accordance with the following provisions with reference to :
1 . In any case , the ink temperature must be kept below 20-25 ℃, temperature changes can not be too large, otherwise it will affect the viscosity and the quality and effectiveness of screen printing inks .
Especially when the ink is deposited or stored outdoors at different temperatures , before re-use must be placed in an ambient temperature of the ink barrel adapt days or so as to achieve a suitable temperature. This is because the cold will cause the screen printing ink failure , resulting in unnecessary trouble. Therefore, to maintain the quality of the ink, preferably stored at room temperature or stored in process conditions .
2 . Must be fully and carefully by hand or machine ink Stir before using . If the ink into the air , allowed to stand for some time to use . If you need to be diluted , we must first fully mixed , and then detect its viscosity. Must be sealed immediately after the ink by the barrel . To simultaneously on the screen will not put back the ink and the ink bucket unused ink mixed.
3 . Best use of mutual adaptation cleaners clear the net, but also very thorough and clean. When then washed , preferably clean solvent.
4 . Drying the ink must have a good exhaust system in the apparatus .
5. To keep the process operating conditions shall comply with the technical requirements of the job carried Cams screen printing operations.
Common problems
Oil ink will not have
The board can not even attached to the ink dots of ink strip or sheet of white point ( not under the ink )
· Insufficient ink mixing time
· Ink mixing error
· Board oil or water residue ( pre-treatment unclean )
· Ink impurities ( oil mixed tape and damage the surface tension )
· Scraping film material adverse
· Screen cleaning dirty
· After using expired ink mixing
Countermeasure
· Check the pre-treatment line to confirm the quality of the drying section of the drying operation
· Check the pre-treatment process is in compliance with paragraphs standard ( water breaking , grinding marks )
• Check ink mixing parameters
· Cleaning screen , replacing the use of tools such as scrapers
2. large copper surface to air bubbles
( 1 ) Large copper full coverage of the surface area of the ink and ink copper surface separation
· Poor pre-treatment
· Plate surface impurities attached
· Copper surface depressions
· Ink bad mix
· Uneven thickness of the copper surface ink
· Ink surface subjected to impact damage
· Oven temperature and baking inadequate or uneven distribution overbake
· Repeatedly spray or spray tin tin tin temperature is too high
Countermeasure
· Check the pre-treatment line , to confirm whether the working section can meet the quality requirements
• Make sure the oven baking temperature and temperature distribution curve
• Check ink mixing parameters
· Check the production process to reduce the external impact
· Confirm HAL job parameters and conditions
( 2 ) large copper surface or line side corner full ink coverage area separated from the ink and the copper surface
· Ink is too thin
· Pre-treatment processing lame in line around the corner
· Baking inadequate
· Repeatedly spray or spray tin tin tin temperature is too high
· Soak too long Flux
· Flux attack is too strong
· Ink damaged corner
Countermeasure
• Adjust the thickness of the solder printing
· Reduce line plating thickness
• Make sure the oven baking conditions and the distribution of heating curve
· Confirm HAL job parameters and conditions
· Check the production process to reduce the external impact
· Check to confirm pre-treatment line drying drying quality requirements in paragraph
3. plug hole borehole
( 1 ) the exposure of the ink overflow
1 . Exposure negatives catch air malfunction
2 . Exposure bad vacuum pump
3 . Positioning piece is not inserted into the hole
4 . Vacuum suction pressure instability
5. Debris attached to the film
Countermeasure
1 . When exposed negatives need snapping job board
2 . Use job boards thinner than the air guide bar
3 . Positioned securely into the positioning hole PIN required
4 . Check the negatives and independent inspection
( 2 ) After baking the ink overflow
1 . No section of the warming
2 . Section of the low-temperature heating temperature is too high
3 . Section of the lack of time to heat up the cold section
4 . Section of the baking temperature is not continuous
5. Oven temperature is uneven or direction is not fixed
Countermeasure
1 . After warming ovens must sections
2 . Continuous baking section of the heating needs
3 . Recognized in the oven to heat up the regions of the curve
4 . The same direction as the direction of the hot air must be
5. Confirm job parameters
( 3 ) After HAL ink overflow
· Section of the heating temperature is too low temperature section
· Section of the heating temperature period of time less than
· Oven temperature is uneven or direction is not fixed
Adverse · oven exhaust
· Spray tin plate before the job is not pre- heated baking
· Repeatedly HAL
· Negatives poor design
Countermeasure
• Make sure the oven temperature curve of each region
After check the baking operation parameters
· Confirm HAL operating parameters and circumstances.
Ink properties and parameters
PCB ink quality is excellent , in principle, from the combination of the above may be several components. Excellent ink quality, is a comprehensive reflection of scientific, advanced and environmentally friendly formulations . Which is reflected in:
1. Viscosity
Is the dynamic viscosity (dynamicviscosity) for short. Said viscosity is generally used , i.e. the shear stress divided by the fluid flow direction, the flow velocity gradient layer , international units Pa / sec (Pa. S) or mPa / s (mPa. S). PCB production means in the ink generated by the external force mobility .
Viscosity conversion between units :
1Pa. S = 10P = 1000mPa. S = 1000CP = 10dpa.s
2. plasticity
Refers to the ink by the external forces deform the nature of the deformation remains before it . Help to improve the plasticity of ink printing precision ;
3. Thixotropic (thixotropic)
Standing gel ink , while the viscosity occurs when a property changes being touched , also known as thixotropy , sag resistance ;
4. Liquidity
( Leveling ) the degree of ink external force , expanded to four weeks . Fluidity is the reciprocal of viscosity , fluidity and thixotropy of the ink on plastic . Plastic and thixotropic big , big mobility ; mobility of the imprinted easily expanded . Mobility of small , prone webs , resulting knot Mexican phenomenon , also known as textured ;
5. viscoelastic
Refers to the ink in the squeegee blade , shear fracture of the ink was quickly rebound performance. Requirements deformation speed ink , ink rebound quickly and be conducive to printing;
6. dry
After the required ink dried on the screen slower the better , but I hope the ink is transferred to the substrate , it is required sooner the better ;
7. fineness
Pigments and particle size of the solid material , PCB ink is generally less than 10μm, the size should be less than the fineness of the mesh opening of the third ;
8. drawing of
When ink spatula to stir the ink , the ink filaments called the degree of stretching without breaking stringiness .
Ink silk long filaments in a lot of ink and the printing surface face , so stick substrates and dirty plates , not even printing ;
9. The ink transparency and opacity
For PCB ink , depending on the purpose and requirements of transparency and opacity inks also made various demands .
Generally , the line ink, conductive inks and ink characters , are required to have a high hiding power. The solder resist is more flexible.
10 . Inks chemical resistance
PCB ink according to the purpose of the different requirements of the corresponding acids, bases , salts and solvents and other requirements are stringent standards ;
11. Resistance to the physical characteristics of the ink
PCB ink must comply with external scratch resistant , thermal shock , mechanical stripping, and achieve a variety of stringent electrical performance requirements ;
12. Use of safe and environmentally friendly inks
PCB ink requirements have low toxicity , odorless , safe and environmentally friendly .
The above summarizes the basic performance of the twelve PCB ink , which in the actual operation of the screen printing process , the operator is closely related to viscosity problems .
Low viscosity for screen printing smoothly or not, the relationship is great. Therefore, technical papers and inks PCB QC report, the viscosity too clearly marked to indicate under what conditions , what type of viscosity measurement instruments. In the actual printing process, if the ink viscosity is high , difficulties in printing will cause leakage , graphics edge serrated serious, in order to improve the printing results, the diluent is added , the viscosity to meet the requirements . But difficult to find, in many cases , in order to want to get the desired resolution ( resolving power ) , no matter what you use viscosity, are never able to achieve . Why? After in-depth study of classics, only to find that the ink viscosity is an important factor, but not the only one. Another quite important factor - thixotropic . Is it also affects the printing accuracy .
PCB ink efficient automatic mixing technology
From the characteristics of the ink and the use of PCB attention matters , we know that PCB ink before use must be adequately and carefully stir evenly . Currently there is a latest patented technologies and products - " rotational vibration device" for stirring PCB ink has great innovative advantage. Seoul by Shenzhen Haili Technology Co., Ltd. developed the " Monkey King " efficient automatic churning machine (R-S01-2) using a rotary vibration device, mechanical suspension system is domestic and foreign pioneered high-performance products, materials stirring, mixing , dispersing , grinding aspects at the international advanced level.
"Monkey " efficient automatic stir , stir oil machine is characterized by mutual penetration of the material at high speed bi-directional rotation and vibration into a two-way , grinding each other to achieve full uniform, full and smooth. " Rotational vibration + " is not 1 +1 = 2, which may be a +1 > 10 . Among the currently large PCB ( electronic circuit boards ) was stirred in an ink plant has been widely used.
Prior to this, enclosed materials are based on a simple rotary agitation or vibration using a simple formula to achieve, there are many limitations. Due to the structural design of the past, people have been driven by an electric motor will not rotate and vibration together. After years of research and development, can now be superimposed with the rotation and vibration , which is churning efficient automatic equipment technological breakthroughs ;
When pure rotation mode mixing is due to the different mix between the proportion of a variety of materials , centrifugal force will appear stratification. At the same time the speed increases to a certain value, the centrifugal force of all materials close to the wall and can not mix. Produce pure oscillation mode is the need to rely on coercion , such as a cam or eccentric ways to produce , wear , high failure rate , the intensity of the vibration generated is also inadequate. The method for stirring the viscosity of the material can not achieve a greater effect satisfied . Now , the " rotation + vibration " approach these topics have been addressed. Moreover , the " rotation + vibration " technology vibration is generated due to the rotation , no eccentric cam or other vulnerable parts , work safety, reliability , long life .
Material container at high speed rotation and vibration superimposed , materials in vibration loosening rotation speed while in an instant , due to the presence of vibration , rotation origin is constantly changing , the size and direction of the centrifugal force suffered materials are constantly changing, greatly increased turbulence stream , greatly reducing the influence of centrifugal force on the stratification , which can effectively increase the mix or grinding, testing and practical materials show that the effect can be times to progress .
Efficient automatic churning equipment advanced design , fair structure. Vibration force generation does not rely cam, eccentric and so easy to wear parts. Advanced structure through the " vibrations in the rotation , rotation vibration "design to achieve a superposition of rotation and vibration . Smooth rotation, strong vibration, high efficiency, low wear, low fault. Work more than 100 hours, almost no vibration friction surface wear. Currently various usage information indicates that this is an excellent mix of oil equipment to domestic and foreign properties , the effect of outstanding churning tool, it is called "Monkey " (MONkey King).
"Monkey " churning device fully uses advanced automation technology . Material containers automatic clamping , automatic reset when the work is completed , automatic release , running time can be automatically adjusted to choose the rotation speed can be equipped with safety devices . So this churning device manipulation easily and securely .
R-S01-2 " Monkey King" churning efficient automatic equipment ( midrange ) churning Range: 0.25 liters - 20 liters of canned material. 1 liter ink tank can stir a pot of oil 1 to 8 cans. That one can stir up to 8 ink tanks, 4 to 6 minutes of time, even the time required for each ink tank less than 1 minute .
Automatic control of the situation:
1, each boot, the machine automatically self-test operation, there are topics will remind ensure power safety;
2, the machine operation time can be adjusted on the panel;
3, the rotation speed can be selected on the panel;
4, frequency start , smooth operation , automatic reset shutdown;
5, automatically feel the size and weight of material the size of the container, automatically adjust the clamping force sizes, finished running automatically loose Open;
6, with emergency stop switch and temporarily stop switch;
7, the relevant parameters are automatically displayed. Automatically displays the fault type when a fault.
Application process liquid photosensitive ink lines
CB manufacturing process (Technology) , both single and double sided and multilayer (MLB), the most basic and most crucial step is to pattern transfer , upcoming photographic negatives (Art-work) pattern transfer to the copper-clad base material on . Pattern transfer is the production of critical control points , but also the technical difficulty lies. There are many ways the process , such as screen printing (Screen Printing) pattern transfer process , a dry film (Dry Film) pattern transfer process , the liquid photoresist (Liquid Photoresist) pattern transfer process , electrodeposition photoresist ( ED film ) production technology and laser direct imaging technique (Laser Drect Image). Instead of today can dry pattern transfer process of the devaluation of liquid photoresist pattern transfer process, the process in a thin film , the resolution (Resolution) , low cost , low operating conditions require the advantages of widely used. In this paper, the transfer of the liquid on the PCB graphics photoresist and its production technology for analysis .
Application of liquid photosensitive ink flow chart : > substrate surface treatment - > Coating ( screen ) - > Pre- bake - > Exposure - > development - > Drying - > Check - > etch - > faded film - > check ( Note: the inner plate ) surface treatment of the substrate - > coating ( screen ) - > pre- bake - > exposure - > development - > Drying - > Check - > electroplating - - > faded film - > etch - > check ( Note : the outer plates ) one . Liquid photoresist (Liquid Photoresist) liquid photoresist ( abbreviated wet film ) is composed of a photosensitive resin , with the photosensitive agent , colorants, fillers, and the like solvents , light generated by the light irradiation after the polymerization reaction get graphics, sexy photopolymerizable is negative .
And compared to conventional dry film resist ink and has the following characteristics :
Does not require the system stencil . Contact exposure using negative imaging (Contact Printig), to avoid infiltration caused by screen printing , stain , shadow, image distortion and other defects. Resolution (Resolution) has greatly improved resolution of traditional ink 200um, wet film up to 40um. b) because it is light curing reaction conjunctiva , adhesiveness its membrane binding , corrosion resistance (Etch Resistance) and anti- plating capacity better than conventional inks . c) Wet film coating is flexible , diverse and craft workable , easy to master. d) Compared with the dry , wet liquid film and the substrate adhesiveness , and can be filled with the copper foil surface minor pits , scratches and other defects. Furthermore a thin wet film of up to 5 ~ 10um, the dry film only about 1/3 , and the film does not cover the top of the wet film ( dry film thickness of the upper layer is covered with a polyester cover film is about 25um ) and therefore the resolution of the graphics , high definition . Such as: when the exposure time is 4S/7K , dry the resolution of 75um, and the wet film can reach 40um. Thus ensuring product quality. e) warped previously used often appear dry , plating diffusion coating , irregular lines and other issues . Wet film is a liquid film , not warped , diffusion coating , neat lines , coating processes to overt step aside to allow time up to 48hr, resolve conflicts association between production processes and improve productivity. f) For today's increasingly promote electroless nickel gold process , generally dry impatience plating solution , and the wet film -resistant plating solution . g) Due to the wet film is a liquid , flexible and strong , especially for the flexible board (Flexible Printed Board) production. h) wet film thickness decreases because of their reduced physical d material costs , and compared with the dry , no carrier polyester cover film (Polyester Cover sheet) and the protective effect of polyethylene membrane (Polyettylene Separator Sheet), and not as large as the dry crop waste , does not require subsequent processing of waste film can be wet film of approximately 30 to 50% cost per square meter . i) wet film is a single fluid ink easy storage custody, generally placed temperature of 20 ± 2 ℃, relative humidity of 55 ± 5%, sealed and stored in a cool place , the storage period (Storage Life): 4 ~ 6 months. j) using a wide range of graphics production line can be used as MLB and the inner hole of the plate -resistant plating graphics production , can also be combined as a mask etch resist and plugging holes graphics technology , can be used for graphics template production. However, the wet film thickness (Thickness) uniformity less dry , the degree of drying after the coating is not easy to master. Carefully when it is operating . In addition, the wet film additives, solvents , lead to volatile agents , environmental pollution , especially the operator has some damage. Therefore, the workplace must be well ventilated . Currently , the liquid photoresist is used , the appearance of viscous , more color blue (Blue).
About PCBway
Since 2003 PCBWAY has been the leading PCB quick turn manufacturer specializing in both Prototype and Production quantities, Initially produced single-sided and double-sided printed circuit boards for the consumer electronics market. PCBWAY is ranked among the top 4 board fabricators in asia and is well-known for its expedited turn time capabilities and its reliable best on-time shipping record.
Today, we have over 450 operators with high modern facilities to manufacture multi-layer PCB up to 12 layers. Backing up with a group of professional engineers, and well established quality system. PCBWay has grown to become a major PCB manufacturer in Asia to serve in diverse customers base such as electronics appliance, communication, educational electronics, power supplies, Automationsetc.
Our mission is to become one of leading PCB manufacturer that provide in high quality product with total customer satisfaction.
