Keyword: PCB laminate, printed circuit board, PCB products, PCB manufacturer
Printed circuit board according to the layer to have single panel, double panel and sandwich plate. The making craft of single and double panel is simple! This paper is in the process of Multilayer PCB laminate technology! Multilayer printed circuit board is composed of more than three layers of conductive graphics layer and insulation layer alternately by laminated gluing together and form of the PCB, and meet the design requirements stipulated conductive graphics interconnection between the layers. It has high density, small volume, light weight, high reliability, etc, output value is the highest, fastest growing type of PCB products. With towards high-speed, multi-functional electronic technology, large capacity and portable low consumption direction development, the application of multilayer printed circuit board is more and more widely, its layers and the density is becoming more and more high, the corresponding structure is becoming more and more complex. Laminated technology, refers to the use of half cure piece (by epoxy glass cloth dipping, baking to solvent is made of a sheet material. The resin B stage, under the effect of temperature and pressure, the liquid and can be quickly solidified and complete bonding.) The conductive graphics of gluing technology under high temperature and high pressure.
Multilayer PCB laminate technology according to the positioning system adopted by the different, can be divided into laminated before positioning system technology (PIN - LAN) and positioning system after laminated technology (MASS - LAM). The former location accuracy is high, but low efficiency, high cost, only applies to the number of high-level, high precision production of multilayer printed circuit board, and the latter while positioning accuracy is low, but high efficiency, low cost, so this method is the present domestic most of the PCB manufacturer for laminated process method is generally used to mass production.
1 before positioning system lamination technology
1.1 before positioning system introduction
Circuit graphics positioning system is throughout the multilayer film production, graphic transfer inside and outside layer, laminated and CNC drilling process, such as a common problems. Every layer of multilayer PCB circuit graphics, relative to other layers must be accurate positioning, to ensure that multi-layer PCB circuit between each layer can be correctly connected to the hole metallization. For the number of high-level, high density and large panels laminated is particularly important.
Review of a multilayer laminated making used pin positioning method, there are two round hole pin positioning method, a hole slot pin positioning method, three round hole or four round hole positioning method, and this article will introduce four slots positioning method. The positioning method is a Multiline company, using its provide a series of four slots positioning equipment, in the lining of the photographic template, to produce four slots on the single chip. Then use the corresponding four grooved pin to achieve graphics transfer, laminated, laminated and CNC drilling and a series of process of the position.
1.2 positioning system before laminating process
According to former positioning system of multilayer PCB laminate, mostly adopts the single chip laminated technology in the past, in the process of the whole inner graphic production, of one side of the external layer of protection, not only brought trouble to make, and the production efficiency is low; Especially for four layer board can produce the problem such as the plate warping. The copper foil laminated technology widely used now, every mouth can suppress 2 ~ 3 pieces, improve the production efficiency, and fundamentally solve the four layer board surface buckling problem in production. (if using laminated after positioning system, while still using the same press, as a result of not using heavy molds, protect the compressor every opening can be suppressed even 6 piece of sandwich plate.) Here is only a brief introduction to the copper foil laminated technology USES.
(1) a curing slice preparation
(a) in clean and dust-free environment, will be cut into strip coil, and then use paper cutting knife cut into piece, size according to the monolithic blank width enlarge to 10 mm;
(b) in the positioning hole position, into a pile with a bench drill positioning hole, aperture is bigger than locating pin diameter 1.5 ~ 2.0 mm;
(c) every half piece has broken fiber, big grain on curing glue, impurity defects should be removed, operation should be Dai Qingjie yarn gloves, it is strictly prohibited to hand sweat, oil pollution;
(d) cutting half curing, to wear a mask to avoid inhaling powder tree. Wear gown trousers, avoid tree powder stick to the skin and cause itching or irritation. At the same time, should avoid tree powder into eyes;
(e) cutting processing good half cure piece, should be promptly put in more than 1 x 10-1 Tuo vacuum ark, excluding volatile and damp, ban into the oven or refrigerator and moisture, prevent aging, bonding. In a vacuum storage cabinet platoon is wet should be greater than 48 hours
(f) should be carried out on the new half curing performance measurement. As the growth of the storage period, material aging, directly affect the fluidity and gelation time, it is closely related to the quality of the product, is the basis of process parameters. On performance measurement and calculation, see the section quality control.
(2) inner monolithic black and dry
(a) the inner black PCB process
upper plate → unoil → wash →wash → Microetching → The secondary countercurrent washing → preimpregnation → melanism → wash → wash → Also protect the → hot wash → wash→The lower
(b) using ammat company provides the darkening of the solution;
(c) the corrosion rate control range: 1.0 2.0 mu m/cycle.
(d) black weighing control range: 0.2 0.35 mg/cm2.
(e) after the appearance of the dry, the surface is black, graze without black powder falling;
(f) inspection after laminated peel strength test, the peeling strength should be above 2.0 N/mm;
(g) after the black single chip with hook hanging in the electrothermal constant temperature drying box, 90 ~ 100 ℃, drying at least 60 minutes.
( 3 ) Other requirements before loading mode
(a) new leader of die application will protect the oil clean gasoline at the surface should be cleared with the mold resin dust, dirt , can not scratch the surface of the cleaning process , the mold surface may not have pits and projections of particles ;
(b) with 0.05mm polyester film for stripping material, to prevent the outflow of epoxy resin and die bonding, die cut material dimension greater than about 15 ~ 20mm, the site of punching or drilling dowel pins , dowel pins aperture greater than 2mm ;
(c) hobs should pad about 10 layers of kraft paper , on the one hand as a buffer layer of heat transfer , while protecting the furnace board without strain. For uneven mold , pin up on the die, the die size less than 200mm × 200mm who should be the appropriate measures, or does not allow direct pressure to prevent the causing local deformation , damage stove plate flatness ;
(d) prepreg model number of sheets of prepreg fill should be based on the total thickness of the inner piece , product design thickness requirements or process card labeling process requirements, while pressing the actually used , the actual performance and the actual thickness of the pressure test after to decide ( fill prepreg , 1080 shall not be less than two , to prevent the phenomenon of micro- bubbles caused due to insufficient amount of glue ) ;
(e) For larger mold weight and prevent injured and out of the mold .
( 4 ) into the mold preload
Prior to preload into the mold , the press should be heated to 175 ± 2 ℃, into the mold to ensure begin immediately after lamination .
(a) 100T PHI press :
Pre- pressure : 0.8 ~ 1.5Mpa (8 ~ 15 kg / cm ) , time: 4 to 8 minutes ;
(b) 140T really Compressor (OEM companies ) :
Pre- pressure : 0.56 ~ 0.7Mpa (80 ~ 100 lbs. / Square inch ) , Time: 7 to 8 minutes ;
After preloading squish one minute ;
(c) after preloading pressure applied into the mold , the size is generally determined by the prepreg situation . When prepreg flow was reduced, may be appropriate to increase the preload pressure.
(d) Characteristics time by preloading stage prepreg , laminating temperature , buffer paper thickness , size of PCB and PCB layers affected .
If preloading period is too short , the full pressure is applied too early will cause excessive loss of resin , and in severe shortage of rubber , layered ; If preloading period is too long , too late, that full pressure is applied between layers of air and volatiles copies are not completely excluded , the gap has not been filled resin will produce bubbles and other defects in the multilayer . Therefore , it is important to grasp the opportunity to pressure changes .
When the prepreg flow index below 30 %, should be shortened pre-press time , or even directly from full pressure operation.
In short , due to the characteristics of the relationship between pre-press cycle and prepreg very close, pre-press cycle is not the same level , pressure test must be passed in multilayer laminated good basis for a comprehensive inspection on the pre- pressure cycles make the appropriate adjustments before formally put into production .
(5) ShiQuan pressure and heat/pressure
After the preloading, on the premise of keeping constant temperature, turn pressure ShiQuan operation. And according to the requirements of the process parameters of heat/pressure.
(a) 100 t PHI press:
All pressure: 1.5 ~ 3.0 Mpa (15 ~ 30 kg/cm2), time: 90 minutes;
(b) 140 t vacuum compressor (OEM) : All pressure: 1.12 ~ 1.4 Mpa (160 ~ 200 pounds per square inch), time: 80 minutes;
(c) when half cure piece of fluidity decrease, can be appropriately increased pressure. Completely finished bubble, caulking, ensure that the thickness and the best resin content.
(d) pressure switches used high temperature transformation way. When half the curing temperature of up to 115 ~ 125 ℃, from preloading to total pressure.
(6) temperature preservation pressure (cold) Total pressure and heat/pressure after the operation, cold press operation can adopt the following ways:
(a) stop heat press, under the condition of the pressure unchanged, laminate cooling to room temperature;
(b) laminate to cold press machine, cold press operation.
(7) the mold, mold release
(a) after the laminate temperature down to room temperature, open press, take out the mold;
(b) on the demoulding special work table, remove the mould pin, remove the laminate.
(8) to remove waste flow glue edge
(a) laminated discharge residual glue, irregular salivate, thickness is not consistent, to ensure that after the punching and application shears to scrap edge cutting, cutting to the edge of blank, but it can't destroy the positioning hole;
(b) when the board face appear distorted or bow bend uneven phenomenon, should be dealt with leveling, warps quantity control in the range of 0.5% of the diagonal.
(9) print Numbers
After pressing the multilayer board of semi-finished products, the two outer for copper foil, to prevent confusion, immediately with seal characters on the blank of product profile for print out the figure number and suppress record number, the handwriting must be clear, does not cause the wrong number.
(10) after curing processing
Board to be included in the electrothermal constant temperature drying box, heated to 140 ℃ and keep 4 hours.
2 after laminated positioning system technology
2.1 after positioning system introduction
After positioning system is adopted to improve the multilayer printed circuit board production, without multilayer positioning equipment, direct use of copper foil and half cured. And adopts the production of the base material for copper-clad laminated, besides saving laminated positioning device, also it can save and the inner line production layer of protection of dry film and production operation; In addition, the base material and equipment, can be fully used to increase the number of press each opening of the platen, improve production efficiency.
Particular way is: (1) in each inner graphics border lines, according to the technological requirements add 3 hole location hole mark;
(2) inner graphics border lines outside the four corners, according to the technological requirements add tool hole mark;
(3) to make the inner graphics, and in the corners of coining tool hole;
(4) inner black of single chip processing;
(5) laminated front panel operation (for more than four layers of laminated, by means of special rivets in among the inner hole located in riveting, to ensure that the interlayer contact ratio; among the inner fill half cure piece according to the requirements of process.) ;
(6) according to the technological requirements for laminating operation;
(7) plate, hole line, secondary shear plate, in the position for milling copper, drill positioning hole operation.
2.2 positioning system after laminating process
Cutting half cure piece→ The inner single piece of black →The inner walkthrough plate → Row plate → laminated → patch→ Some hole line → After the cutting board → Making plate, → After the baking plate →Milling to positioning hole copper sheet →Positioning hole →The quality inspection
(1) cutting half cured
Half of the roll will solidify size requirements as stipulated in the process, on the special curing cutting machine cut into the required size of the chunks. Half curing types mainly include 1080, 2116 and 7628.
(a) According to the specified materials and plate process, calculation need to cut half piece of the number of curing;
(b) cutting half cure piece before (and after), need to clean the table;
(c) pulling away half cure piece from the roller shelf to the required size, after cutting,
(d) after cutting each volume, need a vacuum cleaner gettering sala tree of powder;
(e) Dai Qingjie gloves during operation;
(f) resin cloth do not flex, do not have any impurities, and maintain dry resin cloth;
(g) All landowners cut half piece of purifying workshop to curing, and control the temperature and humidity.
According to the requirements of the above half of cutting piece can be directly used in curing row plate and then laminating production.
(2) inner monolithic black
(a) inner monolithic darkening use: in addition to the oil - micro corrosion - presoak - black - after leaching process;
(b) using the Mac Dermid company provides the black liquid medicine;
(c) after the black plate of drying condition is: temperature 110 ~ 120 ℃ 45 minutes;
(d) after the black plate in a row between the storage time of valid for 48 hours.
(3) the inner walkthrough board
More than six layer and layer of the multilayer needs for the operation.
(a) according to the selection process indicating the inner half of black monolithic between curing type and quantity;
(b) according to the single tool hole position on the half cure piece of round hole punch the corresponding;
(c) will be half of black monolithic and intermediate sandwich curing in tool hole position, using special rivet rivet;
(d) the operation should be carried out within the purification room, and the need for temperature and humidity control.
(4) row plate
Will be approved by black treated four layer board or the walkthrough plate after six layer and above board, according to the process of the drainage plate method and half-and-half curing to the request of the quantity and size and outer copper foil, in a BOOK.
(a) the base plate and the fixed number of kraft paper, shipped to the special line of plate on the table;
(b) according to the technological requirements check half solidification and copper foil;
(c) with a special wax cloth clean steel plate, and placed in a brown paper;
(d) put the copper foil on the steel plate, pay attention to smooth down, then with wax between steel and copper foil clean once again: (there is also a clean steel and copper foil in advance, and USES the hot melt adhesive stick method of copper foil will stick together.)
(e) half of the required curing on the copper foil, perhaps with a clear sundry;
( f ). Put the lining board on the resin cloth, eliminate possible adhesion on the lining plate of debris (with makeup, need according to the technological requirements for the arrangement of inner plate);
(g) All landowners puts half cure piece of lining board (placed before must flip);
(h) Today the required of the copper foil on half cure piece, copper foil smooth upward;
(i) Pet-name ruby with wax cloth to clean the copper foil surface, and at the same time puts good clean side of the plate on the copper foil;
(j) Attending again another surface clean steel plate;
(k) repeated (d) to attending the operation until the complete process of every BOOK number of laminated composite board;
(l) the required number of kraft paper on the steel plate, and then put the aluminum panel on the kraft paper, this BOOK plate is complete.
(5) the laminated
program temperature increasing and adopted by preloading by turn pressure until the high pressure laminated model. Press used for 800 t vacuum laminating machine, for the configuration of two hot-pressing machine, a cold press machine.
(a) before laminating, check that the oven door rubber edge is normal;
(b) charging, check whether the temperature at 155 ~ 165 ℃
(c) according to the process of the laminated parameters, by analogy to adjust the pressure;
(d) for pressure plate charging, vacuum and 60 ~ 70 MMHG, hot pressing according to the technological requirements, the entire process takes about 140 minutes;
(e) will complete the hot plate to cold press machine, the calibration of pressure to 160 kg/cm2 for cold press operation, takes 80 minutes;
(f). Considering the cold press time, the two best hot press platen of interval time is 90 minutes.
(g) the laminating process, need to have automatic temperature curve drawing instrument, moreover has yet to record information about the clamp, is advantageous for the quality tracking. See the following table 3.
(6) patch
(a) discharge every BOOK in the top panel, remove the kraft paper;
(b) removal of steel plate, and clean; (all the steel plate must be separated with sponge pieces.)
(c) with the number plate with a marker pen to write on the edge, and placed in a movable table; (between separated with kraft paper board.
(d) repeat (2) - (3) the operation until the demolition of all board.
(7) hole line
(a)Reference process of plate method, in not decoloring pen points out three positioning hole position of each plate;
(b) and plate number of the corresponding template with a pencil, draw the corners of sheet metal;
(c) every six floors above board, point positioning hole or crossed, can first presented four hole tools and sheet metal in the four nail holes overlapping position right after, can point hole line.
(8) after cutting board
(a) the shear plane with kraft paper, paper can't touch any stains or debris;
(b) according to the process of the product appearance size, reference line position, after the school completed the shear size cutting board;
(c) after cut the first board, subject to size inspection. After qualified, cut the rest of the board;
(d) between the plate and the plate must be separated by kraft paper.
(e) Also can make the shape of the number plate frame in advance, puts the plate on the blanking. (can improve the production efficiency and the dimensions of consistency.)
(9) Making plate
Will play Shanghai the top right corner of each plate board, avoid the phenomenon of mixed plate. (operation, plate should be flat on the stage, do not end up in their hands, curved plate.)
(10) After the baking plate
Sheet contraction in stable condition, eliminate the failure to remove stress within the cold press, facilitate customer connect plate immediately after the drilling operation.
(a) will have a number plate of sheet metal, with wax cloth to clean on the surface, is consistent with the size of the kraft paper separation between plate;
(b) before charging, first clean every fold at the bottom of the thick steel plate, and then into the plate. Each pack no more than 15 pieces, each pile of thin plate panel should be placed a;
(c) the baking plate for 4 hours, the temperature control in 125 ~ 135 ℃ (each batch plate charging and released, all needs to fill in the record.)
(d) sheet after, need to cool to room temperature, can operation of next working procedure.
(11) milling to positioning hole copper sheet
Marking location hole cut size and location of the sandwich plate, using special milling surface copper of the copper sheet machine milling to positioning hole position, in order to arrange another procedure operation. (need kraft paper separate plate, and avoid scratching and wear and tear.)
(12) Positioning hole
Drone with laminated positioning hole is special and, in three positioning hole. (semi-automatic and fully automatic drone.)
Source: //www.seekic.com
