Special element
Sensitive parts?
(65438+ Parts with humidity sensitivity level 6, whether vacuum packed or not, must be baked before use, and must be refluxed within the time limit specified on the humidity sensitivity attention label. ?
(2)ESD sensitive components: For components with high ESD sensitivity, it is required to indicate on the BOM that special ESD protection measures should be taken in storage, unsealing, taking and placing, inspection, rework and packaging. ?
(3) Temperature-sensitive components: Note that electrolytic capacitors, organic film capacitors, connectors, inductors, crystals and other components are all low-temperature resistant components. If there are these components on the board, it is necessary to test the temperature change curves of these components during welding to evaluate whether the furnace temperature setting is safe.
Special integrated circuit components?
(1) For BGA and CSP components, it is necessary to formulate a special SOP for rework, evaluate whether it is necessary to make BGA ball mounting fixtures and purchase qualified solder balls. For FLASH ROM components, it is necessary to evaluate whether firmware burning is needed, and whether there are suitable burning devices and burning seats.
Parts with abnormal volume and weight?
(1) Overweight and large parts: For parts with large volume and weight, special treatment is required. The patch element can be fixed at the bottom with patch adhesive, the through-hole element can be reinforced with rivets, and the element body can be fixed with auxiliary adhesive. ?
(2) Subminiature SMD components: It is necessary to evaluate whether the external dimensions of SMD are within the mountable components of the mounter. ?
Special through-hole element?
(1) special pin-shaped through-hole assembly: it is necessary to evaluate whether the existing molding equipment can meet the requirements of its special pin shape, and whether it is necessary to purchase new molding equipment or make special molding fixtures. ?
(2) Through-hole components with bayonet: Through-hole components with bayonet need to be inserted with great pressure, which will bring great vibration to PCB and make the inserted components jump out of the jack, so it is necessary to arrange pre-assembly stations before the insertion process. ?
(3) Polar through-hole components with no obvious appearance: For such components, it is necessary to evaluate appropriate inspection methods, including multimeter testing or making simple test fixtures. ?
(4) Manual welding of through-hole components: evaluate whether there are through-hole components that need manual welding, and whether the solder pads of these components have tin removal positions (the direction is opposite to the walking direction, and the opening is 0.5mm- 1mm) to prevent plugging during wave soldering. If the tin position has not been removed, it is necessary to evaluate whether to stick masking tape or arrange someone to pick up the tin hole with an electric soldering iron behind the furnace. Whether it is necessary to make manual welding fixture to improve efficiency and quality.
Special through-hole element?
(1) special pin-shaped through-hole assembly: it is necessary to evaluate whether the existing molding equipment can meet the requirements of its special pin shape, and whether it is necessary to purchase new molding equipment or make special molding fixtures. ?
(2) Through-hole components with bayonet: Through-hole components with bayonet need to be inserted with great pressure, which will bring great vibration to PCB and make the inserted components jump out of the jack, so it is necessary to arrange pre-assembly stations before the insertion process. ?
(3) Polar through-hole components with no obvious appearance: For such components, it is necessary to evaluate appropriate inspection methods, including multimeter testing or making simple test fixtures. ?
(4) Manual welding of through-hole components: evaluate whether there are through-hole components that need manual welding, and whether the solder pads of these components have tin removal positions (the direction is opposite to the walking direction, and the opening is 0.5mm- 1mm) to prevent plugging during wave soldering. If the tin position has not been removed, it is necessary to evaluate whether to stick masking tape or arrange someone to pick up the tin hole with an electric soldering iron behind the furnace. Whether it is necessary to make manual welding fixture to improve efficiency and quality.
Specially packaged and encapsulated components?
(1) There are more and more new SMD packages, so it is necessary to pay special attention to the newly packaged IC, connectors and other special-shaped components, and consider whether to customize the suction nozzle suitable for this package, so as to ensure a high material extraction rate, and at the same time, study appropriate detection methods and mounting speed, reduce the material throwing rate and ensure mounting accuracy. ?
(2) Packaging types of patch components: The general packaging types of patches include tray, patch, adhesive tape, bulk, etc. , respectively, need different feeders, and the mounting efficiency and accuracy are also very different. It is necessary to evaluate whether the existing feeder resources are sufficient, and whether it is necessary to manually change the packaging method, such as rewinding the bulk components into adhesive tapes and disassembling the adhesive tapes into trays. Although it consumes labor costs, it is also helpless to consider it in the case of insufficient feeder resources.
Special requirements of customers?
PCB appearance requirements?
(1) It is necessary to clarify the customer's requirements for PCB surface cleanliness, focus on the items such as flux residue, tin slag and tin beads, and evaluate whether it is necessary to increase the process of cleaning the board surface, and what kind of cleaner and cleaning method should be adopted. ?
(2) Generally, the color of paper PCB will darken in different degrees after passing through the furnace. It is necessary to clarify the customer's requirements for PCB discoloration, evaluate and determine the furnace temperature curve and the limit of passing through the furnace. ?
(3)PCB may be deformed after many passes, especially PCB with large area and thin thickness, V-notch multi-link board, paper PCB, etc. Therefore, it is necessary to define the customer's acceptance criteria, evaluate and determine the furnace temperature curve and the furnace penetration limit, and use the carrier plate to penetrate the furnace when necessary. ?
(4) Make clear the requirements of customers for the floating height of through-hole components, and evaluate whether it is necessary to make a carrier pressure head. Parts with strict floating height should be pressed down. ?
(5) It is necessary to make clear the customer's requirements for the pin length of through-hole components exposed from PCB, and evaluate whether the preforming of component pins can meet the requirements, whether it is necessary to arrange special personnel to cut the feet after furnace, and whether it is necessary to repair welding after cutting the feet. ?
Test requirements?
(1) Need to clarify the customer's AOI testing requirements. If the customer does not require it, the customer can also determine the test requirements, evaluate the feasibility of AOI test and the applicable machines, and arrange te to write the test program. ?
(2) It is necessary to clarify the customer's ICT test requirements, determine the coverage and blind spots of ICT test, evaluate whether it is necessary to make a visual inspection kit, confirm the circuit schematic diagram and GERBER file provided by the customer, and fill in the application form for ICT test needle bed. ?
(3) It is necessary to clarify the customer's FCT test requirements, determine the detailed content of FCT test and the source of FCT test fixture, and fill in the FCT test fixture purchase form as required. If you need to test the software, please provide it. ?
Other requirements?
(1) It is necessary to specify the packaging requirements of customers. If the existing packaging materials can't meet the needs of customers, you can complete the design and fill in the purchase order of packaging materials. ?
(2) The customer's requirements for finished product identification must be made clear. ?
(3) It is necessary to clarify the customer's requirements for plate splitting, and evaluate whether the existing plate splitting equipment meets the requirements and whether it is necessary to make plate splitting fixtures. ?
(4) Make clear the customer's requirements for the temperature measuring board, and confirm whether to use the analog board or the real board. If the real board is used, the source of the real board and the undertaker of the scrap cost of the real board need to be determined. ?
(5) Need to know whether the customer needs IC burning, and if so, ask the customer to provide burning firmware. ?
(6) It is necessary to know whether the customer's requirements for steel mesh, carrier plate and fixture are provided by the customer. If it is provided by customers, it is necessary to evaluate the rationality of the design and test the production quality. If problems are found, it is necessary to discuss solutions with customers, and if necessary, you can reapply for making new fixtures yourself.
(7) It is necessary to know whether the customer's requirements for the production of accessories are provided by the customer. If so, it is necessary to evaluate the rationality of the quota. If the customer specifies a brand model, it is necessary to consult an approved supplier. If the customer does not specify it, you need to choose from the existing production accessories. ?
Through the process review, we need to ensure that the new SMT products are ready before the sample, including:
(1) Find out the defects in DFM design and coordinate with customers to modify PCB design; ?
(2) In view of the slight design defects of PCB DFM and the weakness of special components, remedial measures should be considered in the process flow arrangement; ?
(3) Determine and arrange the production of various necessary steel meshes, carrier plates, fixtures, temperature measuring plates, etc. ?
(4) Determine the appropriate SMT production line configuration and the necessity of purchasing new equipment; ?
(5) Determine the brand model of the production parts; ?
(6) Determine the customer's quality acceptance standards (especially appearance standards), burn firmware, test software, etc. ?
According to the results of process review, before introducing new products into samples, we need to determine the configuration of production line equipment that can make the best quality and maximize benefits, and whether to buy new production equipment, auxiliary equipment, testing instruments, etc. It is necessary to arrange the production of temperature measuring plates, printed steel meshes, visual observation tables and various carrier plates (including printed carrier plates, reflow carrier plates, wave crest carrier plates, etc.). ) and various fixtures (including ICT test needle bed, FCT test fixture, hand welding fixture, ball planting fixture, indexing fixture, shaping fixture, etc.). ), determine the brand model of production accessories, and determine the things provided by customers (including burning firmware and testing). Only by making full preparations for process review can we formulate a feasible new product sample plan, foresee and prevent various problems that may occur during the sample process, ensure the timely delivery of qualified products to customers, win their satisfaction and trust, and be invincible in the market competition.