| With the progress of modern electronic industry,electronic devices are evolving towards miniaturization,light weight and multifunction.Molded interconnect device?MID?is widely used in the electronic industry,especially in intelligent electronic products.In recent ten years,laser direct structuring?LDS?technology has attracted extensive attention because of its advantages such as greatly flexible manufacture procedure,high precision of the produced MID circuits?with line width and line spacing precise to 150?m?,and the ability to prepare three-dimensional circuits.LDS material is a special-purpose material specially developed for the application of LDS.But the current LDS materials are mostly monopolized by patents of foreign companies,the independent production,research and development of LDS material in China is still in the initial stage,the LDS materials provided by most enterprises in China have poor performance in reliability testing,the plating has weak adhesive force?low grade in paint adhesion testing,e.g.,merely 3B?,the circuit is not fine enough?overflow plating occurs after chemical plating?,the mechanical properties are poor?such as big fragility in low temperature,unable to adapt to the low temperature serviceable range-40oC of smart phones?,and the requirements raised by LG and other large electronic enterprises on LDS material are not met in environmental testing.Therefore,in this paper,the current synthetic method of laser activator is improved,the two types of laser activators CuCr2O4 and Cu2PO4?OH?synthesized by experiment are used to mix with the polymer matrix for further preparation of LDS material,a series of LDS materials are prepared using different formulas,various performance tests are conducted to screen out the optimal modified formula for the preparation of LDS material,and related applied research and reliability testing of the LDS material prepared by the optimal formula are carried out.The main research contents and results are as follows:?1?The two-step method of co-precipitation plus high temperature solid phase reaction was adopted to synthesize laser activator CuCr2O4,and the influence of sintering temperature and dosage of dispersant PEG on the crystal structure,grain size and grain dispersity of CuCr2O4 was investigated.The results showed that,the CuCr2O4prepared when sintering temperature is 1,000 oC,and the dosage of PEG4000 is 20g has excellent thermal stability.Then the crystal structure was characterized by XRD,and the crystal morphology was observed by SEM.The results showed that CuCr2O4 is a spinel crystal with perfect crystalline,low agglomeration and good dispersity.The analysis of crystal size distribution of CuCr2O4 using laser particle analyzer showed that the grain size is mostly between 0.5 and 1?m and the size distribution is very uniform.Next,Cu2PO4?OH?was synthesized using liquid phase method,a more economical production formula for the preparation of Cu2PO4?OH?was determined,and the thermal properties,crystal size and size distribution of Cu2PO4?OH?prepared by the production formula were investigated.The study showed that Cu2PO4?OH?prepared by Formula 4 has good thermal stability,hardly any thermal weight loss below 200oC in TG analysis,and tiny thermal weight loss between 200 and 540oC.The crystal morphology observation under SEM showed almost no aggregation,and the test data of laser particle analyzer indicated that over 68%of the crystal size is between 0.69 and 5.79?m.?2?In view of the flexible wearable device,PP was used as the matrix resin,and Formula 11?10%CuCr2O4 and 30%kaolin?was determined to be the optimal scheme by means of changing the dosage of laser activator and coarsening agent in the preparation formula of LDS material.Scotch tape test showed that the material reaches the highest grade of 5B and has excellent plating adhesive force.And it is also good toughness?elongation at break reaches 380%?,and heat distortion temperature of over90oC,so it completely meets the requirements raised by the flexible wearable device on material mechanics properties and plating adhesive force.For the LDS material with high requirements of mechanical properties and heat distortion temperature,PC/ABS was adopted as the matrix resin,and Formula 33?Japanese Sumitomo toughening agent7M,with dosage of 6%,PC/ABS=70/30?was determined to be optimal by adjusting the type and dosage of the toughening agent as well as the weight ratios of PC to ABS in the formula.A series of performance tests showed that for LDS material prepared using Formula 33,the tensile strength and bending strength reach respectively 56MPa and65MPa,the impact strength of notched izod at 23oC and-40oC is respectively 55 KJ/m2and 25 KJ/m2,and the heat distortion temperature is up to 118 oC,so the material completely meets the performance requirements of smart phone built-in aerial on LDS material.?3?In this paper,some tests were done to validate reliability of LDS materials.First,using the electrical performance parameters(dielectric constant 3.0,dielectric loss7×10-3)of Formula 33,the directional diagram of GPS quadrifilar helix antenna was simulated.Second,based on the simulation design,the GPS navigation quadrifilar helix antenna was made.The results showed that compared with some commercially available GPS microstrip antenna?dielectric constant 25,size 25×25×4mm,antenna efficiency 26.38%under GPS center frequency of 1,575MHz?made by SrXBa1-XTi03ceramic,LDS quadrifilar helix antenna?size?8mm×70mm,antenna efficiency 37.16%under GPS center frequency of 1,575MHz?has smaller volume and significantly better visibility to satellites.Third,the actual antenna for smart phone was made,and the study showed that all the reliability indexes of LDS material can meet the standards set by Korean LG Company,and the material can completely satisfy the requirements of smart phone antenna on material structural strength,laser etching,chemical plating properties and environmental testing.Finally,this material was applied in the MID of a type of ATM machine.Then it was observed under electronic magnifying glass?magnification of 100 times,200 times and 400 times?that the conductor has clear border,smooth fracture surface,and excellent consistency of plating,so the material is very suitable for being applied in MID parts with high performance requirements of thinning antenna. |
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