Standardize the design / manufacturing standard of wave soldering furnace pass fixture, and improve the product furnace pass ppm and quality process requirements. Scope of application: this standard is applicable to the design and manufacture of wave soldering furnace clamp:during the introduction of new products, the product engineer shall evaluate with me whether it is necessary to make fixtures according to the minutes of product design and trial production meeting; Be responsible for the design and maintenance of new fixtures, and the acceptance of existing fixtures; Ie provides fixture demand; Purchase orders are placed according to the demand. Operating procedures: 1 Materials and data preparation: when designing wave soldering furnace fixtures, the materials selected should be materials with high resistance, high temperature and anti-static properties (our company generally uses synthetic stone and glass fiber board materials, which can be made according to the customer's requirements when the customer has special requirements); 2. Data preparation: Gerber document, PCBA board. The maximum external dimension of the furnace tool is 420 long *320 width, and the width of the gauge is 320MM. The length should be determined according to the combination of PCB plates. In order to save the flux of spray flux, the length of the fixture is as short as possible. (there should not be too many spare parts in the length direction); 45 degree chamfer edge of fixture; A stop strip shall be added around the wave crest fixture, and the gap between the stop strips shall be less than 0.1mm (to prevent the tin liquid from flowing to the PCB board). The first two stop strips shall be welded in parallel wave crest. If the height of solder SMD component is less than 3mm, the thickness of fixture is made of 4mm material. The height of SMD assembly on the solder surface (expressed by H) is 4mm, h is greater than 3mm (the height of patch device is not more than 4mm), and the thickness of fixture is 5mm; The fixture shall be made of 8mm material. Where the height of SMD component is less than 3mm, the thickness of the fixture must be polished by 4mm. If the SMD component is 5mm higher, the fixture shall be made of material. A patch shall be added at the bottom and the R angle shall be inverted. The total thickness of the fixture shall be less than 10mm;

In order to prevent the furnace passing fixture from blocking at the wave crest, all screws (screws) cannot be punched from the bottom of the fixture, but must be punched from the element facing the tin passing surface; If there are grounding via pads (such as SK, kJ, etc.) in the bottom production of the main chip, holes shall be opened and tin shall be applied to the furnace; If there is a through hole (through hole) in the middle of BGA pad, the hole must be blocked to prevent tin from causing defects; The IC filled with QFN is to prevent tin from flowing out of the furnace, which must be sealed when making the fixture (the details shall be confirmed by the product engineer and pie engineer before making); There are led lights on the main board. For products requiring floating height in the process of infrared receiving head, a fixed support must be made on the fixture. For some models of horizontal high frequency head, the elastic pressure needs to be increased (depending on the specific model, PE determines whether it needs to be increased during production); At the position where SMT components are discussed on the solder surface of PCB board, the overcurrent on the working surface of furnace fixture shall be controlled at about 2mm; The track edge with a width of 10mm and a thickness of 2.5mm shall be opened around the fixture, and the arc reverse R angle shall be milled at the C end to avoid jamming or poor operation; The fixed stop strip around the fixture shall be made of FR4 material with a width of 12mm, and a screw shall be locked every 95mm (60mm of the smaller main board). The junction of two adjacent stop strips shall be locked with screws to avoid the deformation of the fixture. The passing direction, fixture number, applicable model and other information of the fixture must be identified in the fixture (specifically according to the manufacturing requirements provided by me). The distance between the fixed stop strip around the fixture and the PCBA rotating groove is 15mm. One positioning press buckle needs to be locked every 90mm. The distance between the positioning press buckle and the fixed stop strip is 5mm. Each press buckle position of positioning PCB on the fixture must be selected at the position without component interference at the edge of PCB. The size of the groove protecting the SMD component on the fixture must be milled on the inner side of the SMD component silk screen on the B side, and the depth is generally 0.3mm higher than the height of the component body. If the B side component is BGA, connect, CCD sensor and other thermal components, it is necessary to open and close the ventilation channel 0.6mm higher than the height of the component body to avoid bad effects caused by high temperature. The wall thickness of the groove protecting SMD components on the fixture shall be at least 1mm; A symmetrical plate taking slot must be opened on the fixture to facilitate the taking and placing of the base plate.

The position of the plate taking slot must be in the position without the interference of dip components. The opening chamfer of PTH assembly shall be large enough. On the premise of ensuring that the groove wall of SMT assembly is not broken, the chamfer shall be increased as much as possible. The chamfer angle is generally 140 degrees and the inclination angle is to reduce the resistance of tin flow. The height of the tin surface component is less than 3mm, the thickness of the fixture is made of 4mm material, the chamfer must be greater than 140 degrees, the height of the solder component is more than 3mm, and the thickness of the fixture is made according to the customized materials of the components; The difference between the size of the inner groove of the fixture and the size of the PCB shall not exceed 0.2mm, and the width error of the peripheral dimension of the same batch of fixture shall not exceed 0.2mm (in special cases, the engineer can require the positioning column to be made in the inner groove of the fixture). The design and manufacture of all fixtures need to be checked and made to prevent stupidity; Plug in components and SMD components. The distance between the element and the sealing edge of the bottom cover shall not exceed 1.2mm. The distance between the control element and the SMT cover is more than 0.8mm. The distance between the pad edge of SMT SMT chip element in red glue process and the hole wall shall not be less than 1.5mm, and the chamfer shall be 45-60 degrees. The distance between the element pin and the opening wall shall not be less than 2.5mm. The sealing thickness of the bottom cover of SMT patch element is 1.5-1.9mm and above. The distance from the pin of the component nearest to the plate transfer soldier to the edge of the opening shall not be less than 5mm. The contact surface between all fixtures and PCB must be flat and in the same plane (0.2mm), without protrusion and subsidence. All the materials used on the fixture must be tin free materials, and the mechanical strength should be sufficient without bending deformation.