車窗外罩注射模具設(shè)計-塑料注塑模側(cè)抽芯1模2腔含proe三維及16張CAD圖帶開題報告.zip,車窗,外罩,注射,模具設(shè)計,塑料,注塑,模側(cè)抽芯,proe,三維,16,CAD,開題,報告 Sensors and Actuators A 125 2006 367 375 Abstract dif a The structured compared that K 1 strate optical cation related dimensions w if propagation directions w DOE track detector is optical 0924 4247 doi 10 1016 j sna 2005 07 025 Injection molding and injection compression molding of three beam grating of DVD pickup lens Cheng Hsien Wu Wei Shiu Chen Department of Mechanical and Automation Engineering Da Yeh University Chang Hwa 51505 Taiwan Received 21 January 2005 received in revised form 8 July 2005 accepted 14 July 2005 Available online 5 October 2005 The objective of this paper is to investigate the application of injection molding and injection compression molding processes to produce fraction gratings A mold was designed to produce a diffraction rating connected with the fixed bushing The combined part was verified to have good diffraction performance Integrated grating eliminates the assembly cost and error Photolithography was applied to make the mold insert Taguchi method and parametric analysis were applied to study the effects of molding parameters on grating quality The design fabrication of mold surfaces and the results of the replication by injection molding IM and injection compression molding ICM are presented and The diffraction angle of ICM grating is more accurate than that of IM grating Grating made by ICM has a much smaller warpage than made by IM The diffraction pattern shows that ICM is a better process than IM to replicate a diffraction grating 2005 Elsevier B V All rights reserved eywords Injection molding Injection compression molding Grating Replication Introduction The master is usually a metal copy of a DOE original fabri cated by one or a combination of high resolution lithographic All parts in an optical pickup including the recording sub and a number of components are required to have superior performance This requires a very accurate shape repli and low optical anisotropy as induced by the molding stresses Whenever a travelling wave encounters an obstruction with similar to its wavelength some of the energy in the ave is scattered 1 2 If the obstruction is periodic or indeed there is a periodic variation of any parameter which affects the of the wave energy is scattered into various discrete or diffracted orders and a structure which acts in this ay may be referred to as a diffraction grating In the optical pickup of the player diffractive optical elements are used to split the main laser beam into three beams for following but also to deflect the returning beam onto the area The classical method of manufacturing gratings to scribe burnish or emboss a series of grooves upon a good surface 3 Corresponding author Tel 886 4 8511227 fax 886 4 8511224 E mail address chengwu mail dyu edu tw C H Wu steps be film original can or a follo cemented carefully at resin e production of There nick strate ies time see front matter 2005 Elsevier B V All rights reserved 4 5 The material in which the original is fabricated can resist quartz silicon or virtually any suitable high resolution or substrate The master is typically fabricated from the by electroplating in nickel although in certain cases it be another material such as quartz plastic or another metal even the original itself The master grating is first coated with thin layer of some non adherent material e g gold This is wed by a substantial layer of aluminum The master is then with the aid of a thin film of a low viscosity resin to the cleaned replica blank allowing the resin to polymerize a constant temperature generally a slow process When the has cured the replica and the master are separated How ver the process takes too much time and is not suitable for mass To be a major technology for the low cost mass production DOEs alternative replication methods are applied as follows are three alternative replication methods to replicate the el master casting embossing and injection molding IM In casting a thin film of epoxy is applied on a solid sub blank Both room temperature and thermally cured epox have been used The main disadvantage is the long curing A related technique of particular interest for DOEs is the 368 and Actuator replication glass embossing under will Since mal decorati ciple replica The the to iors mercial parts for tic methods currently tant mak mated components read write pumps nents polymer a filling stable e 8 ca ca high were than such minimizing une density of emplo of W ments tw electron beam filling 140 de bottom 0 5 tion half can and polycarbonate tinely tion al structure is sol gel micro nano structure ha materials glass micro structures The of tolithography optical or of T C H Wu W S Chen Sensors into a thin film of UV curable material coated onto a or polymer substrate An even faster method of making grating replicas involves a plastic film by passing it over a heated cylinder some pressure from a smooth back up roll The cylinder typically have a nickel electroplated wrapping around it this is a continuous process the unit cost will be mini but quality is limited to student experiments or more likely ve devices such as holograms Injection molding is a classic low cost process and in prin could produce gratings by inserting a nickel electroplated derived from a precision master into appropriate molds accuracy of injection molded gratings is always limited by molding conditions of the process Efforts need to be made identify the significant factors that affect micro filling behav In recent years plastics have begun to show great com potential especially in manufacturing micro structured Injection molding represents the most important process manufacturing plastic parts While many prototype plas micro devices are fabricated using precision engineering such as laser machining micro injection molding is being investigated all over the world 6 7 An impor advantage of injection molding is that with it we can e complex geometries in one production step in an auto process Many micro devices such as watches and camera automotive crash acceleration distance sensors heads of hard discs CD drives medical sensors surgical instruments and telecommunications compo have been successfully injection molded The injection molding process involves the injection of a melt into a mold where the melt cools and solidifies to form plastic part It is generally a three phase process including packing and cooling phases After the cavity becomes the product is ejected from the mold Despite many advantages the injection molding process xperiences some inherent problems in molding micro features The main difficulty is that the molten polymer in a tiny vity instantaneously freezes upon touching the relatively cold vity wall The problem gets worse when micro features with aspect ratios are to be molded The best replication results achieved when melt and mold temperatures were higher normal values 9 Injection compression molding ICM has the advantages as decreasing molding pressure reducing residual stress molecular orientation packing evenly reducing ven shrinkage overcoming sink mark and warpage reducing variation and increasing dimensional accuracy Because these advantages injection compression molding is often yed to produce parts of high accurate dimension and free residual stress especially for the optical parts Instead of using a micro injection molding machine imberger Friedl 7 fabricated sub H9262m grating optical ele by conventional injection molding Inserts were made by o different processes reactive ion etching RIE in SiO 2 and lithography followed by nickel electroplating No problem was encountered with a mold temperature of the design of 2 2 1 it beams by CD track pits on 20 placed these tw will central on then of three beam s A 125 2006 367 375 C However SEM micrographs show that there is a shape viation i e the structures are thicker at the top than at the Grating elements were designed to have a pitch below H9262m and depths in excess of 1 5H9262m By splitting the func over the two surfaces of the retardation elements only a filling depth was necessary The effect of shape deviation be reduced Grating structures with a record depth of 2H9262m a pitch of 0 5H9262m were replicated by injection molding with Features with high aspect ratio proved difficult to form rou however it is envisaged that further optimization of injec molding will resolve these difficulties 10 Parashar et 11 employed a two step pattern transfer to replicate the in glass first a polydimethylsiloxane PDMS replica obtained from a master structure and secondly a layer of material is applied on the PDMS soft replica to get in glass after drying and annealing They ve established the effectiveness of in house developed sol gel derived from metal alkoxides in nano replication of micro nano structure Obi et al 12 presented a replication method to fabricate UV curable sol gel is used as base material basic fabrication process involves deposition and patterning a sacrificial spacer layer and a combined molding and pho step This fabrication process can be applied for MEMS devices that incorporate lenses diffractive optics waveguides The objective of this paper is to investigate the application IM and ICM processes to produce diffraction gratings The aguchi method and parametric analysis were applied to study effects of molding parameters on the grating quality The fabrication of structured mold surfaces and the results the replication by IM and ICM are presented Transmission diffraction grating Application example optical pickup When the laser beam goes through the diffraction grating is split up into a central bright beam plus a number of side The central beam and one beam on each side are used the CD for the tracking system Consider a segment of the player containing several tracks If the optical head is on then the primary beam will be centered on a track with and bumps and the two secondary beams will be centered land The three spots are deliberately offset approximately H9262m with respect to each other Two additional detectors are alongside the main quadrant detector in order to pickup subsidiary beams If the three beams are on track then the o subsidiary photodetectors have equal amounts of light and be quite bright because they are only tracking on land The beam will be reduced in brightness because it is tracking both land and pits However if the optical head is off track the center spot gets more light because there are fewer pits f track and the side detectors will be misbalanced The most common optical train in modern CD players is the pickup depicted in Fig 1 The light is emitted by the and Actuator laser the peak anism This ing The into then reflected no the will w paper beam before the The nism 2 2 of Early point no at lengths the d where tion 2 3 uously issue gratings ment C H Wu W S Chen Sensors Fig 1 Schematic illustration of an optical pickup diode and enters a diffraction grating The grating converts light into a central peak plus side peaks The main central and two side peaks are important in the tracking mech The three beams go through a polarizing beam splitter only transmits polarizations parallel to the page The emerg light now polarized parallel to the page is then collimated collimated light goes through a 4 plate This converts it circularly polarized light The circularly polarized light is focused down onto the disk If the light strikes land it is back into the objective lens If the light strikes the pit w a bump it is not reflected The light then passes through 4 plate again Since it is going in the reverse direction it be polarized perpendicular to the original beam in other ords the light polarization is now vertical with respect to the When the vertically polarized light hits the polarizing splitter this time it will be reflected not transmitted as Thus it will reflect through the focusing lens and then cylindrical lens and be imaged on the photodetector array cylindrical lens is important in the auto focusing mecha The general grating equation A transmission diffraction grating is a slide with large number parallel closely spaced slits transparent spaces drawn on it ones were carbon covered glass slides etched by a needle w they tend to be printed onto a slide It is excellent separating the colors in incident light because different wave are diffracted at different angles Fig 2 according to grating relationship sin n 1 d is the distance between the slits the angle of diffrac the wavelength of the light and n is the order of diffraction Diffraction efficiency Diffraction efficiencies of standard phase gratings contin blazed or multilevel approximations are a fundamental in diffractive micro optics In nearly all applications where are used a high diffraction efficiency is a major require Achievable efficiency in practice depends on numerous f ogy etc dif Therefore appear ings 1 2 surf measurement cienc 3 3 1 of Corp density between ture for 3 2 machining s A 125 2006 367 375 369 Fig 2 A transmission grating actors the type and performance of the fabrication technol used the grating period to wavelength ratio the materials Additionally the actual value depends on the definition of fraction efficiency since a unique definition does not exist it is often quite difficult to compare results which in the literature In order to characterize the performance of diffraction grat two numbers are often used The overall efficiency o 1 This overall efficiency is defined as o 1 intensity of first order intensity of incident beam The diffraction efficiency d 1 The diffraction efficiency is defined as d 1 intensity of first order intensity of transmitted beam through unstruc tured substrate With the second definition losses due to scattering from ace roughness at the grating interface are contained in the of efficiency In this study the diffraction effi y d 1 is used Experimental procedures Material The material used in this study is a high heat injection grade polymethylmethacrylate PMMA CM 205 from Chi Mei Taiwan The melt flow index is 1 8 g 10 min and the bulk is 1 19 g cm 3 The recommended barrel temperature is 210 and 250 C and the recommended mold tempera between 50 and 70 C The material was pre dried at 90 C 4 h using a dehumidifying drier before molding Part geometry and mold design Diffraction gratings were machined on a glass substrate After the grating has to be assembled into a fixing bushing 370 and Actuator as and and the whole diameter w 1 5 gated symmetrically mold a sprue runners 3 3 tion e design photolithography ferred 16 000 to w Fig Fig 5 Schematic illustration of cavity arrangement remove contaminants from the wafer surface in order to obtain C H Wu W S Chen Sensors Fig 3 The grating and the fixing bushing shown in Fig 3 Assembly requires much production time labor cost It also creates positioning error and angle error then reduces the accuracy of an optical pickup In this study product was designed to combine grating and bushing The part has a diameter of 7 mm The grating portion with a of 4 mm is located at the center The nickel mold insert as designed with a periodicity of 20H9262m The notch depth was H9262m The electroplated nickel mold insert was installed in a center mold base as shown in Fig 4 The mold has two cavities located on the opposite sides of the sprue The plates are made of S45C tool steel The cavity is fed by sprue two runners and two fan gates as shown in Fig 5 The is 48mm long and 5 mm in diameter The dimensions of are 1 55 mm 3 50 mm 5 68 mm Mold insert fabrication Our photolithography process involves photomask fabrica wafer cleaning spin coating soft baking exposure post xposure baking developing and hard baking A high resolution transparency containing the features created in a CAD program was used as the mask in In this study the mask pattern was trans onto a transparency using a high resolution laser printer dpi Fig 6 shows the schematic of the fabrication steps required produce a nickel electroplated mold insert A silicon wafer as used as the substrate Wafer cleaning is a necessary step to 4 A center gated mold base with an electroplated nickel mold insert high v cleaned or ized 50 1 to deionized spun hot surf amethyldisilane the placing is diately w while w Fig s A 125 2006 367 375 performance and high reliability of products and to pre ent contamination of process equipment The wafer surface was with a 4 1 H 2 SO 4 H 2 O 2 for 10 min at 120 C to remove ganic contaminants The wafer surface was rinsed using deion DI water until the water resistance was higher than 8 Omega1 A H 2 O HF step for 10 min at room temperature was applied remove chemical oxides The wafer surface was rinsed using water again After wafer cleaning the substrate was blown dry using heated nitrogen and then placed on a plate 120 C for 3 min to drive off any water vapor on the ace This step is called dehydration baking To improve the adhesion of resists to the silicon wafer hex HMDS is often applied HMDS was applied to wafer by spinning at room temperature HMDS was dried by the wafer on a hot plate for 2 min at 90 C The next step spinning the resist on to the wafer and it should be done imme after the HMDS application A positive resist AZ9260 as used in this study The resist is dispensed onto the wafer the wafer is spinning to produce a uniform layer on the afer The spin speed of the spin coater was increased to 500 rpm 6 Fabrication schematic to produce nickel electroplated mold inserts and Actuator with spin 300 the conditions study for plishes lar Finally ation temperature is ods Contact The resist by w The damage printing capability ried gradually mize w AZ400K DI de blo insert bak resistance bak the photoresist mold for rinsed a minimize ing nick w 1 h 3 4 ing can is machine Fig 7 Experimental set up used to measure the diffraction efficiency of gratings and diffraction pattern of a laminar grating structure under laser illumination Under each set of process conditions 10 shots were made to ensure that the process was stable before samples were col lected If no significant variation was observed during these first 10 runs the molded parts from the next 5 runs were collected as the samples for product characterization 3 5 Quality measurement Two major performances of a diffraction grating are the accu C H Wu W S Chen Sensors an acceleration of 500 rpm s for 10 s For another 30 s the speed and acceleration of the spin coater were 300 rpm and rpm s respectively The spin speed at this step determines final thickness of the resist about 50H9262m in this study The next step in the lithography is the pre bake Pre bake depend on the thickness of the photoresist In this the substrate was placed on a leveled hot plate at 50 C 10 min and at 90 C for 10 min The pre bake step accom three things Firstly the remaining solvent in the resist gely evaporates Secondly adhesion of the resist improves stresses in the resist are relieved through thermal relax The substrate was then gradually cooled down to room in order to minimize residual stresses The next step wafer exposure which can be divided into three basic meth contact printing proximity printing and projection printing printing is the oldest and the simplest printing process mask is placed print side down in direct contact with the layer on the wafer Exposure of the resist then takes place shining light through the mask Aligning the mask to patterns as carried out with a contact mask aligner Karl Suss MA 6 hard contact between the mask and the wafer results in to both the mask and the resist layer However contact was applied in this study for its high resolution printing Exposure time was 3 min The next step is a post exposure bake PEB PEB was car out at 90 C for 1 min After PEB the substrate was again cooled down to room temperature in order to mini stresses and prevent the resist from cracking The substrate as immersed into the beaker containing the developer 1 3 water for about 5 min After all th